Chemistry in Water

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Jul 152016

Chemistry in Water

Isley et al. reported the use of the nonionic amphiphile TPGS-750-M (2 wt %) in water to facilitate nucleophilic aromatic substitution reactions (S_NAr) with oxygen, nitrogen, and sulfur nucleophiles. The team eliminated the use of dipolar aprotic organic solvents traditionally required for S_NAr reactions, such as dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP).

Moderate to high yields at ambient or slightly elevated temperatures (up to 45 °C) were observed, and a diverse substrate scope with respect to thermal stability was established. The team additionally demonstrated the ability to recycle the water/micelle mixture by extracting the product with organic solvent. Recycling of the aqueous media resulted in improving the E-factor and reducing aqueous waste ( Org. Lett. 2015, 17,4734−4737).

, Supporting Info

Nucleophilic Aromatic Substitution Reactions in Water Enabled by Micellar Catalysis

Nicholas A. Isley^†, Roscoe T. H. Linstadt^†, Sean M. Kelly^†, Fabrice Gallou^‡, and Bruce H. Lipshutz^*^†

^† Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States

^‡ Chemical & Analytical Development, Novartis Pharma AG, 4056 Basel, Switzerland

Org. Lett., 2015, 17 (19), pp 4734–4737

DOI: 10.1021/acs.orglett.5b02240

*E-mail: lipshutz@chem.ucsb.edu.

Wang et al. described the development of a copper-catalyzed hydroxylation of aryl halides in water. The syntheses of phenols generally require the use of energy intensive and/or harsh reaction conditions which can impact the substrate scope. This methodology utilized a hydroxylated phenanthroline ligand to improve solubility in water. Optimization of this method through screening resulted in the selection of copper(I) oxide (Cu₂O) as the copper source and tetrabutyl-ammonium hydroxide (TBAOH) at 110 °C. The TBAOH was proposed to function as both phase transfer catalyst and nucleophile, resulting in high yields and excellent selectivity toward phenol versus biphenyl ether.

The scope of this method with substituted aryl halides was demonstrated, affording excellent yields and high selectivity for para-substituted electron-rich and electron-deficient aryl bromides, as well as meta-substituted bromo-halides. Functional groups such as carboxyl and hydroxyl groups were also tolerated. The team additionally demonstrated a one-pot synthesis of either alkyl aryl ethers or benzofuran by trapping the in situ generated phenol with an alkyl bromide or through intramolecular cyclization ( Green Chem. 2015, 17, 3910−3915).

Graphical abstract: Copper-catalyzed hydroxylation of aryl halides: efficient synthesis of phenols, alkyl aryl ethers and benzofuran derivatives in neat water

Copper-catalyzed hydroxylation of aryl halides: efficient synthesis of phenols, alkyl aryl ethers and benzofuran derivatives in neat water

Yangxin Wang,^a^b Chunshan Zhou^a and Ruihu Wang*^a

*Corresponding authors

^aState Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, China
E-mail: ruihu@fjirsm.ac.cn

^bUniversity of Chinese Academy of Sciences, Beijing, China

Green Chem., 2015, 17, 3910-3915
DOI: 10.1039/C5GC00871A , supporting info,

An efficient catalytic protocol for hydroxylation of aryl halides in water is proposed to prepare phenols, ethers and benzofuran derivatives.

A thorough study of environmentally friendly hydroxylation of aryl halides is presented. The best protocol consists of hydroxylation of different aryl bromides and electron-deficient aryl chlorides by water solution of tetrabutylammonium hydroxide catalyzed by Cu₂O/4,7-dihydroxy-1,10-phenanthroline. Various phenol derivatives can be obtained in excellent selectivity and great functional group tolerance. This methodology also provides a direct pathway for the formation of alkyl aryl ethers and benzofuran derivatives in a one-pot tandem reaction.

Jung et al. reported the use of a continuous flow reactor to synthesize propargylamines in an atom economic fashion using stoichiometric quantities of reagents, water as solvent, and generating only CO₂ and water as byproducts. The team exploited the use of a pressurized tube reactor to achieve temperatures above the boiling point of water, enabling excellent yields (≥88%) and reasonable residence time (2 h).

This procedure improved the atom economy of previously reported methods for this transformation by eliminating the use of transition metal catalysts and excess of reagents. The substrate scope was demonstrated for multiple alkynyl carboxylic acids and secondary amines ( Tetrahedron. Lett. 2015, 56, 4697−4700).

Tetrahedron Letters

Volume 52, Issue 36, 7 September 2011, Pages 4697–4700

Basic alumina supported tandem synthesis of bridged polycyclic quinolino/isoquinolinooxazocines under microwave irradiation

Department of Chemistry, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India

Wang et al. reported the synthesis of an easily accessible diammonium functionalized Ru-alkylidene complex capable of ring-closing metathesis (RCM) and cross metathesis (CM) reactions in water. The NHBoc penultimate intermediate was isolated as an air-stable, nonhygroscopic Ru-alkylidene complex. Acidic cleavage of the Boc groups with trifluoroacetic acid (TFA) in dichloromethane generated the diammonium catalyst as a green solid after removal of volatiles under reduced pressure. The diammonium catalyst (5 mol %) achieved modest to high conversion to cyclic RCM products in D₂O at ambient to elevated temperatures (up to 80 °C). Lowering the catalyst loading to 0.1 mol % established a turnover number (TON) of >900.

Homocoupling of allyl alcohol and long chain alkenylammonium salts provided the desired diammonium cross products in high yield/conversion. Short chain alkenyl-ammonium salts were poor substrates for the CM reaction.

Catalyst deactivation was attributed to the ammonium:free amine equilibration in water followed by Lewis basic nitrogen coordination to the Ru-center (Green Chem. 2015, 17, 3407−3414).

A simple and practical preparation of an efficient water soluble olefin metathesis catalyst

Zhen J. Wang,^a W. Roy Jackson^a and Andrea J. Robinson*^a

*Corresponding authors

^aSchool of Chemistry, Monash University, Clayton 3800, Australia
E-mail: andrea.robinson@monash.edu

Green Chem., 2015,17, 3407-3414

DOI: 10.1039/C5GC00252D, supp info

The same research group additionally reported the divergent functionalization of L-tyrosine to generate a family of tyrosine-derived Ru-alkylidene RCM catalysts. This common ligand precursor approach was utilized to successfully create not only a hydrophilic/water-soluble PEG Ru-alkylidene, but a hydrophobic alkane Ru-alkylidene for solvent-free catalysis and a solid-phase supported Ru-alkylidene to access a potentially recyclable precatalyst system.

The PEG Ru-alkylidene complex displayed poor solubility in water at 40 °C under ultrasonication, providing the desired model RCM product in only 25% conversion. >95% conversion was achieved by utilizing a 1:1 water–MeOH solvent system at 40 °C with 2.5 mol % catalyst loading. It was rationalized in the Green Chemistry report (vide supra) that functionalization of the benzylidene ligand to increase aqueous solubility may be problematic due to the dissociation of the labile ligand during the catalytic cycle, whereas functionalization of nondissociating NHC ligand could sustain the desired solubility throughout the reaction.

The hydrophobic alkane Ru-alkylidene provided solvent-free RCM and CM products in high conversion. The solid-phase Ru-alkylidene also provided the desired RCM products in high conversion and demonstrated stable performance after multiple catalyst recovery/reuse operations. Sustained leaching of Ru metal into the reaction media was monitored and observed for the recycled solid-phase catalyst method. However, this iterative loss of metal did not negatively impact conversion ( J. Org. Chem. 2015, 80, 7205−7211).

Divergent Approach to a Family of Tyrosine-Derived Ru−Alkylidene Olefin Metathesis Catalysts

divergent

Authors	Ellen C. Gleeson, Zhen J. Wang, W. Roy Jackson, and Andrea J. Robinson
Published	Journal of Organic Chemistry
Graphical abstract
Abstract	A simple and generic approach to access a new family of Ru−alkylidene olefin metathesis catalysts with specialized properties is reported. This strategy utilizes a late stage, utilitarian Hoveyda-type ligand derived from tyrosine, which can be accessed via a multigram-scale synthesis. Further functionalization allows the catalyst properties to be tuned, giving access to modified second-generation Hoveyda−Grubbs-type catalysts. This divergent synthetic approach can be used to access solid-supported catalysts and catalysts that function under solvent-free and aqueous conditions.
Citation	Ellen C. Gleeson, Zhen J. Wang, W. Roy Jackson, and Andrea J. Robinson, J. Org. Chem., 2015, 80(14), 7205–7211
Pdf	Article
Doi	10.1021/acs.joc.5b01091

Bhowmick et al. published a review “Water: the most versatile and nature’s friendly media in asymmetric organocatalyzed direct aldol reactions”. This review addressed the various types of organocatalysts based on (1) l-proline, (2) 4-hydroxy-l-proline, (3) amino acid derivatives, (4) enzymes, and (5) other miscellaneous catalysts applied to the aldol reaction in aqueous media. In general, the intermolecular asymmetric aldol reaction has been shown to perform poorly in pure aqueous media and is typically performed in organic solvents such as DMF, DMSO, etc.

However, structural modifications to l-proline and 4-hydroxy-l-proline have generated catalysts capable of asymmetric aldol reactions in aqueous media.

Examples provided in this review highlight (a) instances of enhanced reactivity using water as a solvent, cosolvent, or additive, (b) formation of enzyme mimics that use hydrophobic forces to reinforce substrate/catalyst binding, (c) the use of aqueous media to interrogate proposed transition state geometries, and (d) the pH dependence of organocatalyzed aldol reactions. Limitations presented in the review include (a) substrate specific catalyst activities, (b) multistep/low-yielding synthesis of the organocatalysts, (c) slow catalysis rate in pure aqueous media, (d) high catalyst loading, and (e) poor to moderate selectivity (Tetrahedron: Asymmetry 2015, 26, 1215−1244).

Tetrahedron: Asymmetry

Volume 26, Issues 21–22, 1 December 2015, Pages 1215–1244

Tetrahedron: Asymmetry Report Number 159

Water: the most versatile and nature’s friendly media in asymmetric organocatalyzed direct aldol reactions

Division of Organic Synthesis, Department of Chemistry, Visva-Bharati (A Central University), Bolpur, West Bengal 731 235, India

Hot water’s ability to promote unexpected reactions without any other reagents or catalysts.

Chinese and Japanese chemists have highlighted hot water’s ability to promote unexpected reactions without any other reagents or catalysts. The work should expand our understanding of how to harness the physicochemical properties of water to potentially replace more complex reagents and catalysts.

Above its critical point at 374°C and 218atm the properties of water change quite dramatically, explains Hiizu Iwamura from Nihon University in Tokyo. But even below that point, as water is heated, hydrogen bonding and hydrophobic interactions are disrupted. ‘This means that organic compounds get more soluble and salts become insoluble in hot pressurised water,’ Iwamura says. Dissociation of water into hydroxide (OH^–) and hydronium (H₃O⁺) ions also increases, he adds, so there are higher concentrations of these ions available to act as catalysts for reactions.

Iwamura was synthesising triaroylbenzene molecules for a previous project on molecular magnets, using base-catalysed Michael addition reactions, when he first became interested in whether the reactions might work in water. He teamed up with a chemical engineer colleague, Toshihiko Hiaki, who is more familiar with working at the required temperatures and pressures. Together, they found that 4-methoxy-3-buten-2-one could be transformed into 1,3,5-triacetylbenzene in pressurised water at 150°C, with no other additives (see reaction scheme).¹

Meanwhile, Jin Qu and her team at Nankai University in Tianjin have been investigating water-promoted reactions at lower temperatures, without the need for pressurised vessels, which Qu says is more accessible for many researchers and makes monitoring reactions easier. ‘In 2008, one of my students found he could hydrolyse epoxides in pure water at 60°C, in 90% yields,’ she explains. ‘At first I thought it was not very interesting, just a hydrogen-bonding effect, but as we found more examples I got more interested.’

More than a thermal effect

When Qu’s team hydrolysed an epoxide made from (-)-α-pinene, they found that at room temperature they got (-)-sobrerol, the product they expected. But at 60°C or higher, the sobrerol began to racemise, giving a mixture of the (+)- and (-)-forms (see reaction scheme). ‘We couldn’t understand why this was happening at first,’ says Qu, but eventually it became clear that the allylic alcohol group in the sobrerol, which is much less reactive than the epoxide in pinene, was also being hydrolysed. The same reactions happen at room temperature if acid is added, Qu says, but don’t happen in propanol or other alcoholic and hydrogen-bonding solvents heated to the same temperatures, so it is not simply a thermal effect.

Qu points out that these observations, along with those of Iwamura’s team, show that molecules that might usually be considered unreactive in water can undergo useful transformations. And these reactions can take place without other reagents or solvents, which would create extra waste streams. Also, owing to the decreased solubility of the organic product molecules when the solutions are cooled back to room temperature, they are often easy to purify as well.

Iwamura suggests that there are many other simple acid- and base-catalysed reactions that might be suitable for reacting in hot water. However, reactions with thermally unstable molecules, or those requiring delicate selectivity, are unlikely to be so effective at higher temperatures, he adds. He also makes a distinction between Qu’s work – in which the water molecules are directly involved in the reaction – and his own group’s, in which the water acts as the reaction medium and provides the catalyst. ‘Our reaction did not take place in water heated at reflux,’ Iwamura adds.

However, Hiaki points out that the potential environmental benefits of reduced waste streams will have little impact on industrial chemistry if the reactions remain confined to batch processes. ‘High temperature and pressure is detrimental for the scale up to commercial chemical plants,’ he says. For that reason, the team is developing a flow microreactor system that should be more industry compatible.REFERENCES, 1 T Iwado et al, J. Org. Chem., 2012, DOI: 10.1021/jo301979p, 2 Z-B Xu and J Qu, Chem. Eur. J., 2012 DOI: 10.1002/chem.201202886

Hydration: A process which adds water.

In this hydration reaction, 1-methyl cyclohexene (an alkene) is reacted with aqueous H₃O⁺ (formed from water and a strong acid such as H₂SO₄), resulting in Markovnikov addition of water across the pi bond. The product is an alcohol.

Syn, anti-Markovnikov addition of water to an alkene can be achieved via a hydroboration-oxidation reaction.

–to be added–		–to be added–
CuSO₄ (anhydrous)		CuSO₄ ^. 5 H₂O

Anhydrous CuSO₄ (colorless) absorbs water vapor from the air, hydrating it to CuSO₄ ^. 5 H₂O (copper sulfate pentahydrate; blue).

///////////Chemistry in Water

Besifloxacin hydrochloride (Besivance)

Uncategorized Comments Off

Jul 132016

Besifloxacin

SS 734, BOL 303224A, ISV-403

MW 430.301, MF C₁₉H₂₁ClFN₃O₃

141388-76-3 CAS

7-[(3R)-3-aminoazepan-1-yl]-8-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid

(R)-(+)-7-(3-amino-2,3,4,5,6,7-hexahydro-1H-azepin-1-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

(R) -7- (3- amino-hexahydro-azepin -1H- mushroom-1-yl) -8-chloro-1-cyclopropylmethyl -6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid

Synthesis of the molecule (R)-(+)-7-(3-amino-2,3,4,5,6,7-hexahydro-1H-azepin-1-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid is disclosed in U.S. Pat. No. 5,447,926,

Besifloxacin is a fourth generation fluoroquinolone-type opthalmic antibiotic for the treatment of bacterial conjunctivitis. FDA approved on May 28, 2009. by Bausch & Lomb, for the treatment of non-viral bacterial conjunctivitis

Besifloxacin, (+)-7-[(3R)-3-aminohexahydro-1H-azepin-1-yl]-8-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid hydrochloride, developed by SS Pharmaceutical (SSP) Co.Ltd. was a fourth-generation fluoroquinolone antibiotic . Besifloxacin hydrochloride eye drop was used to treat bacterial conjunctivitis caused by aerobic and facultative Gram-positive microorganisms and aerobic and facultative Gram-negative microorganisms

Besifloxacin (INN/USAN) is a fourth-generation fluoroquinolone antibiotic. The marketed compound is besifloxacin hydrochloride. It was developed by SSP Co. Ltd., Japan, and designated SS734. SSP licensed U.S. and European rights to SS734 for ophthalmic useto InSite Vision Incorporated (OTCBB: INSV) in 2000. InSite Vision developed an eye drop formulation (ISV-403) and conducted preliminary clinical trials before selling the product and all rights to Bausch & Lomb in 2003.^[1]

The eye drop was approved by the United States Food and Drug Administration (FDA) on May 29, 2009 and marketed under the trade name Besivance.^[2]

Name	Dosage	Strength	Route	Labeller	Marketing Start	Marketing End
Besivance	suspension	6 mg/mL	ophthalmic	Bausch & Lomb Incorporated	2009-05-28	Not applicable
Besivance	suspension	0.6 %	ophthalmic	Bausch & Lomb Inc	2010-01-27	Not applicable
Besivance	suspension	6 mg/mL	ophthalmic	Physicians Total Care, Inc.	2011-07-13	Not applicable

405165-61-9 CAS

Besifloxacin Hydrochloride

Besifloxacin hydrochloride is a fourth-generation fluoroquinolone antibiotic.
IC50 Value:
Target: Antibacterial
Besifloxacin has been found to inhibit production of pro-inflammatory cytokines in vitro. Besifloxacin is a novel 8-chloro-fluoroquinolone agent with potent, bactericidal activity against prevalent and drug-resistant pathogens.besifloxacin is the most potent agent tested against gram-positive pathogens and anaerobes and is generally equivalent to comparator fluoroquinolones in activity against most gram-negative pathogens. Besifloxacin demonstrates potent, broad-spectrum activity, which is particularly notable against gram-positive and gram-negative isolates that are resistant to other fluoroquinolones and classes of antibacterial agents.

Clinical Information of Besifloxacin Hydrochloride

Product Name	Sponsor Only	Condition	Start Date	End Date	Phase	Last Change Date
Besifloxacin Hydrochloride	Bucci Laser Vision Institute	Bacterial infection	31-MAY-11	31-DEC-11	Phase 4	05-JUN-13
	Bucci Laser Vision Institute		31-MAY-11	31-DEC-11	Phase 4	03-JUN-13
	Innovative Medical Services		30-SEP-10	31-OCT-12	Phase 4	11-SEP-13
	Ophthalmology Consultants, Ltd	Cataract	30-SEP-10	28-FEB-11	Phase 4	11-SEP-13
	University of Louisville	Blepharitis	31-AUG-11	31-OCT-11	Phase 4	01-DEC-11

Pharmacodynamics

Besifloxacin is a fluoroquinolone that has a broad spectrum in vitro activity against a wide range of Gram-positive and Gram-negativeocular pathogens: e.g., Corynebacterium pseudodiphtheriticum, Moraxella lacunata, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, Streptococcus mitis, Streptococcus oralis, Streptococcus pneumoniae and Streptococcus salivarius. Besifloxacin has been found to inhibit production of pro-inflammatory cytokines in vitro.^[3] The mechanism of action of besifloxacin involves inhibition of two enzymes which are essential for the synthesis and replication of bacterial DNA: the bacterialDNA gyrase and topoisomerase IV.

Medical Use

Besifloxacin is indicated in the treatment of bacterial conjunctivitis caused by sensitive germs,^[4] as well as in the prevention of infectious complications in patients undergoing laser therapy for the treatment of cataracts.^[5]^[6]

Adverse Effects

During the treatment, the most frequently reported ocular adverse reaction was the appearance of conjunctival redness (approximately 2% of patients). Other possible adverse reactions, reported in subjects treated with besifloxacin were: eye pain, itching of the eye, blurred vision, swelling of the eye or eyelid.

MORE SYNTHESIS COMING, WATCH THIS SPACE…………………..

PATENT

WO 2010111116

https://www.google.com/patents/WO2010111116A1?cl=en

PATENT

CN 104592196

https://www.google.com/patents/CN104592196A?cl=en

The method comprises performing condensation reaction of 1-cyclopropyl-6,7-dichloro-1,4-dihydro-4-oxy-3-quinoline carboxylic acid with (R)-3-aminohexahydroazepine in the presence of org. base in org. solvent I at 45°C-solvent b.p. temp. under refluxing, washing with acid, vacuum concg. to obtain (R)-7-(3-amino-hexahydro-1H-azepine-1-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxy-3-quinoline carboxylic acid, dissolving in 5-10 fold org. solvent II, reacting with thionyl chloride at 0-40°C, and vacuum concg. to obtain (R) -7- (3- amino-hexahydro-azepin -1H- mushroom-1-yl) -8-chloro-1-cyclopropylmethyl -6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid hydrochloride

Preparation method of the present invention provides hydrochloride Besifloxacin, comprising the steps of:

(1), in three _6 flask of 1-cyclopropyl, 6,7-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid 10g of acetonitrile added 100mL, was added (R ) -3-amino-hexahydro-aza mushroom 4.73g and 7.2mL of triethylamine was heated at reflux for 5h TLC plate detection point, the reaction was complete spin dry plus 100mL dissolved in chloroform and then 200mL 1M hydrochloric acid and washed twice with saturated brine The organic phase to pH 4-6, the organic phase was poured into the jar and dried to obtain the single (R) -7- (3- amino-hexahydro-azepin -1H- leather-yl) cyclopropyl-6 -1_ fluoro-1,4-dihydro-4-oxo-3-quinoline-carboxylic acid in chloroform solution; spin-dried to give (R) -7- (3- amino-hexahydro-azepin -1H- leather-yl) cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid.

(2), obtained in the previous step (R) -7- (3_ atmosphere atmosphere -1H- gas hybrid group six leather-1-yl) cyclopropyl-6-fluoro-1,4 _1_ dihydro-4-oxo-3-quinolinecarboxylic acid in chloroform solution was cooled to 0 ° C, was slowly added dropwise under constant stirring 18mL S0C12, temperature does not exceed 5 ° C added, the mixture was stirred at 0 ° C after 2h l to room temperature, TLC detection, after completion of the reaction was evaporated to dryness to column chromatography to give (R) -7- (3- amino-hexahydro-azepin -1H- mushroom-1-yl) -8-chloro-1-cyclopropylmethyl -6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid hydrochloride 5. 12g.

PATENT

US 20110144329

https://www.google.com/patents/US20110144329

EXAMPLE 1Preparation of Besifloxacin Free Base Solid

Besifloxacin free base was prepared from besifloxacin hydrochloride addition salt.

An amount of about 5 g of besifloxacin HCl (HCl addition salt of besifloxacin made, for example, by the method of U.S. Pat. No. 5,447,926; which is incorporated herein by reference in its entirety) was added to about 750 ml of water. The besifloxacin HCl was allowed to dissolve in said water. Twenty milliliters of 1N NaOH solution were added slowly to the besifloxacin aqueous solution while stirring (final pH 10.2). Besifloxacin free base started to precipitate. Eight milliliters of 1N HCl solution were added slowly while stirring (final pH of 9.7). The resulting mixture was allowed to mix for 2 hours while besifloxacin free base continued to precipitate. At the end of 2 hours, the precipitated besifloxacin free base was filtered through a Millipore type RA 1.2 μm filter. The besifloxacin free base thus collected was dried in a vacuum oven at room temperature. 4.35 g of besifloxacin free base was recovered.

FIG. 1 shows a UV absorption spectrum of besifloxacin free base starting material of Example 1.

FIG. 3 shows an IR spectrum of free base starting material of Example 1.

PATENT

https://www.google.com/patents/CN103044397A?cl=en

Example 6 (R) -7_ (3- amino-hexahydro–1H- diazepan-1-yl) -8_ chloro-1-cyclopropyl-6-fluoro-1,4- Hydrogen oxo – quinoline-3-carboxylic acid (Besifloxacin). [0021] The reaction vessel was added chloroform (50ml) as a reaction solvent, in the case of a solid material was added with stirring (III) (3. 59g, O. Olmol), until the intermediate (III) is completely dissolved, was added dropwise under ice- chlorosulfonic acid, stirred for I hour under ice-cooling, gradually warmed to room temperature, stirred for 6 hours, and then reacted at reflux temperature for 6 hours. After completion of the reaction by TLC, the reaction solution was cooled to 0 ° C, white solid was precipitated, filtered, washed with a small amount of dichloromethane to give a crude product besifloxacin (3. 65g, 93. 01%). [0022] Example 7 (R) -7_ (3- amino-hexahydro–1H- diazepan-1-yl) -8_ chloro-1-cyclopropyl-6-fluoro-1,4- Hydrogen oxo – quinoline-3-carboxylic acid (Besifloxacin). [0023] The reaction vessel was added chloroform (50ml) as a reaction solvent, in the case of a solid material was added with stirring (III) (3. 59g, 0. Olmol), until the intermediate (III) is completely dissolved, was added dropwise under ice- chlorosulfonic acid was stirred for I hour under ice-cooling, gradually warmed to room temperature, stirred for 6 hours, and then reacted at reflux temperature for 12 hours. After completion of the reaction by TLC, the reaction solution was cooled to 0 ° C, the precipitated white solid was filtered , washed with a little dichloromethane to give Besifloxacin crude (3. 05g, 77. 22%).

PAPER

Molbank 2013, 2013(2), M801; doi:10.3390/M801

Short Note

(R)-7-(Azepan-3-ylamino)-8-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic Acid Hydrochloride

Zhengjun Xia, Zaixin Chen * and Shuitao Yu

http://www.mdpi.com/1422-8599/2013/2/M801

Supplementary File 3:Support Information (PDF, 340 KB)

Download PDF [188 KB, 27 May 2013; original version 22 May 2013]

R&D Center, Jiangsu Yabang Pharmaceutical Group, Changzhou 213200, China

In this paper (R)-7-(azepan-3-ylamino)-8-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid hydrochloride 1was isolated and identified as the N-substituted regioisomer of besifloxacin, which has been synthesized from the reaction of 8-chloro-1-cyclopropyl-6,7-difluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 3 with (R)-tert-butyl 3-aminoazepane-1-carboxylate 2in acetonitrile as solvent in 37% yield. The chemical structure of compound 1 was established on the basis of ¹H-NMR, ¹³C-NMR, mass spectrometry data and elemental analysis

REGIOMER OF BESIFLOXACIN

BESIFLOXACIN

References

“InSite Vision Reaches Agreement to Sell ISV-403 to Bausch & Lomb” (Press release). InSite Vision. 2003-12-19. Retrieved 2009-08-15.
“Bausch & Lomb Receives FDA Approval of Besivance, New Topical Ophthalmic Antibacterial for the Treatment of Bacterial Conjunctivitis (“Pink Eye”)” (Press release). Bausch & Lomb. 2009-05-29. Retrieved 2009-05-29.
Zhang JZ, Ward KW (January 2008). “Besifloxacin, a novel fluoroquinolone antimicrobial agent, exhibits potent inhibition of pro-inflammatory cytokines in human THP-1 monocytes”. J. Antimicrob. Chemother. 61 (1): 111–6. doi:10.1093/jac/dkm398. PMID 17965029.
Malhotra R, Ackerman S, Gearinger LS, Morris TW, Allaire C (December 2013). “The safety of besifloxacin ophthalmic suspension 0.6 % used three times daily for 7 days in the treatment of bacterial conjunctivitis”. Drugs in R&D 13 (4): 243–52. doi:10.1007/s40268-013-0029-1. PMC 3851703. PMID 24142473. Retrieved 2015-01-06.
Majmudar PA, Clinch TE (May 2014). “Safety of besifloxacin ophthalmic suspension 0.6% in cataract and LASIK surgery patients”. Cornea33 (5): 457–62. doi:10.1097/ICO.0000000000000098. PMC 4195578. PMID 24637269. Retrieved 2015-01-06.
Nielsen SA, McDonald MB, Majmudar PA (2013). “Safety of besifloxacin ophthalmic suspension 0.6% in refractive surgery: a retrospective chart review of post-LASIK patients”. Clinical Ophthalmology (Auckland, N.Z.) 7: 149–56. doi:10.2147/OPTH.S38279. PMC 3552478. PMID 23355771. Retrieved 2015-01-06.

CLIPS

Besifloxacin hydrochloride (Besivance) Besifloxacin is a fourth-generation fluoroquinolone antibiotic which is marketed as besifloxacin hydrochloride. It was originally developed by the Japanese firm SSP Co. Ltd and designated SS734. SSP then licensed U.S. and European rights of SS734 for ophthalmic use to InSite Vision, Inc., in 2000, who then developed an eye drop formulation (ISV-403) and conducted preliminary clinical trials before selling the product and all rights to Bausch & Lomb in 2003.

The eye drop was approved by the United States Food and Drug Administration (FDA) on May 29, 2009 and marketed under the trade name Besivance.24a

Besifloxacin has been found to inhibit production of pro-inflammatory cytokines in vitro. The synthesis of besifloxacin commences with commercially available ethyl 3-(3-chloro-2,4,5-trifluorophenyl)-3-oxopropanoate (13, Scheme3).24b

Condensation of this ketoester with triethyl orthoformate resulted in a mixture of vinylogous esters 14. Substitution with cyclopropanamine converts 14 to the vinylogous amide 15 as an unreported distribution of cis- and trans-isomers. This mixture was treated with base at elevated temperature to give 16.

Presumably, the trans-isomer isomerizes to the cis-isomer, which subsequently undergoes an intramolecular nucleophilic aromatic substitution with concomitant saponification to construct quinolone acid 16.

Quinolone 16 is then subjected to another nucleophilic substitution involving readily available iminoazepine 17 and the displacement reaction proceeds regioselectively to furnish the atomic framework of besifloxacin (18).

Acidic methanolysis of 18 at elevated temperature gave besiflozacin (III).

24. (a) Bertino, J. S.; Zhang, J.-Z. Expert Opin. Pharmacother. 2009, 10, 2545; (b) Harms, A. E.; Arul, R.; Soni, A. K. U.S. 2009561283 A1, 2009.

US5447926 *	Sep 16, 1994	Sep 5, 1995	Ss Pharmaceutical Co., Ltd.	Quinolone carboxylic acid derivatives

Citing Patent	Filing date	Publication date	Applicant	Title
CN104458945A *	Nov 27, 2014	Mar 25, 2015	广东东阳光药业有限公司	Separation and measurement method of besifloxacin hydrochloride and isomer of besifloxacin hydrochloride

CN102659761A *	Apr 27, 2012	Sep 12, 2012	常州亚邦制药有限公司	Method for preparing besifloxacin hydrochloride
US5385900 *	Nov 8, 1993	Jan 31, 1995	Ss Pharmaceutical Co., Ltd.	Quinoline carboxylic acid derivatives

Reference
1	*	黄山等: “克林沙星的 2, 4, 5-三氟苯甲酸路线合成“, 《中国医药工业杂志》, vol. 31, no. 8, 31 December 2000 (2000-12-31)

Citing Patent	Filing date	Publication date	Applicant	Title
CN103709100A *	Dec 31, 2013	Apr 9, 2014	南京工业大学	Preparation method of 8-chloroquinolone derivatives

Besifloxacin
Systematic (IUPAC) name


7-[(3R)-3-Aminoazepam-1-yl]-8-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid
Clinical data
Trade names	Besivance
AHFS/Drugs.com	Monograph
MedlinePlus	a610011
License data	US FDA: Besifloxacin
Routes of administration	Ophthalmic
Legal status
Legal status	US: ℞-only
Identifiers
CAS Number	141388-76-3
ATC code	S01AE08 (WHO)
PubChem	CID 10178705
ChemSpider	8354210
UNII	BFE2NBZ7NX
ChEMBL	CHEMBL1201760
Chemical data
Formula	C₁₉H₂₁ClFN₃O₃
Molar mass	393.84 g·mol⁻¹

Patent Number	Pediatric Extension	Approved	Expires (estimated)
US5,447,926	No	1995-09-05	2012-09-05
US5447926	No	1996-04-13	2016-04-13
US6,685,958	No	2004-02-03	2021-06-20
US6,699,492	No	2004-03-02	2019-03-31
US6685958	No	2001-06-29	2021-06-29
US6699492	No	1999-03-31	2019-03-31
US8415342	No	2010-11-07	2030-11-07
US8481526	No	2011-01-09	2031-01-09
US8604020	No	2010-03-12	2030-03-12
US8937062	No	2009-11-13	2029-11-13

O’Brien TP: Besifloxacin ophthalmic suspension, 0.6%: a novel topical fluoroquinolone for bacterial conjunctivitis. Adv Ther. 2012 Jun;29(6):473-90. doi: 10.1007/s12325-012-0027-7. Epub 2012 Jun 20. [PubMed:22729919 ]
Proksch JW, Granvil CP, Siou-Mermet R, Comstock TL, Paterno MR, Ward KW: Ocular pharmacokinetics of besifloxacin following topical administration to rabbits, monkeys, and humans. J Ocul Pharmacol Ther. 2009 Aug;25(4):335-44. doi: 10.1089/jop.2008.0116. [PubMed:19492955 ]
Besifloxacin Hydrochloride

[1]. Wang Z, Wang S, Zhu F, Chen Z, Yu L, Zeng S. Determination of enantiomeric impurity in besifloxacin hydrochloride by chiral high-performance liquid chromatography with precolumn derivatization. Chirality. 2012 Jul;24(7):526-31. doi: 10.1002/chir.22042.
Abstract
Besifloxacin hydrochloride is a novel chiral broad-spectrum fluoroquinolone developed for the treatment of bacterial conjunctivitis. R-besifloxacin hydrochloride is used in clinics as a consequence of its higher antibacterial activity. To establish an enantiomeric impurity determination method, some chiral stationary phases (CSPs) were screened. Besifloxacin enantiomers can be separated to a certain extent on Chiral CD-Ph (Shiseido Co., Ltd., Japan), Chiral AGP, and Crownpak CR (+) (Daicel Chemical IND., Ltd., Japan). However, the selectivity and sensitivity were both unsatisfactory on these three CSPs. Therefore, Chiral AGP, Chiral CD-Ph, and Crownpak CR (+) were not used in the enantiomeric impurity determination of besifloxacin hydrochloride. The separation of enantiomers of besifloxacin was further performed using a precolumn derivatization chiral high-performance liquid chromatography method. 2,3,4,6-Tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate was used as the derivatization reagent. Besifloxacin enantiomer derivates were well separated on a C(18) column (250 × 4.6 mm, 5 μm) with a mobile phase that consisted of methanol-KH(2)PO(4) buffer solution (20 mM; pH 3.0) (50:50, v/v). Selectivity, sensitivity, linearity, accuracy, precision, stability, and robustness of this method were all satisfied with the method validation requirement. The method was suitable for the quality control of enantiomeric impurity in besifloxacin hydrochloride.

[2]. Hussar DA. New drugs: golimumab, besifloxacin hydrochloride, and artemether/lumefantrine. J Am Pharm Assoc (2003). 2009 Jul-Aug;49(4):570-4.

[3]. Nafziger AN, Bertino JS Jr. Besifloxacin ophthalmic suspension for bacterial conjunctivitis. Drugs Today (Barc). 2009 Aug;45(8):577-88.
Abstract
Besifloxacin hydrochloride ophthalmic suspension 0.6% (Besivance) is a recently approved fluoroquinolone for the topical treatment of bacterial conjunctivitis. The drug is rapidly bactericidal against common bacterial pathogens causing conjunctivitis, i.e., coagulase-negative Staphylococcus, Streptococcus pneumoniae, Staphylococcus aureus and Haemophilus influenzae as well as against other less common organisms. In addition to being a potent agent against Gram-positive and Gram-negative pathogens including those resistant to other fluoroquinolones, besifloxacin has balanced DNA gyrase and topoisomerase IV activity, which should slow the development of resistance. Topical administration achieves high sustained concentrations in human tears and good ocular tissue penetration in animals while demonstrating an excellent safety profile. Besifloxacin’s pharmacokinetic and pharmacodynamic characteristics meet the criteria for successful eradication of many Gram-positive and Gram-negative bacteria while demonstrating minimal systemic exposure. The biochemical properties, achievement of target pharmacokinetic/pharmacodynamic goals and the restriction of besifloxacin to topical ophthalmic use should result in slower development of bacterial resistance, making besifloxacin a new, appealing option for empiric therapy in acute bacterial conjunctivitis.

[4]. Proksch JW, Ward KW. Ocular pharmacokinetics/pharmacodynamics of besifloxacin, moxifloxacin, and gatifloxacin following topical administration to pigmented rabbits. J Ocul Pharmacol Ther. 2010 Oct;26(5):449-58.
Abstract
PURPOSE: The purpose of this investigation was to evaluate the ocular pharmacokinetic/pharmacodynamic (PK/PD) relationship for besifloxacin, moxifloxacin, and gatifloxacin using rabbit ocular PK data, along with in vitro minimum inhibitory concentration (MIC90) values against methicillin- and ciprofloxacin-resistant Staphylococcus aureus (MRSA-CR) and Staphylococcus epidermidis (MRSE-CR).METHODS: Rabbits received a topical instillation of Besivance? (besifloxacin ophthalmic suspension, 0.6%), Vigamox (moxifloxacin hydrochloride ophthalmic solution, 0.5% as base), or Zymar (gatifloxacin ophthalmic solution, 0.3%), and ocular tissues and plasma were collected from 4 animals/treatment/collection time at 8 predetermined time intervals during the 24h after dosing. Ocular levels of each agent were measured by LC/MS/MS, and PK parameters (Cmax, Tmax, and AUC????) were determined. AUC????/MIC?? ratios were calculated for tears, conjunctiva, cornea, and aqueous humor using previously reported MIC??values for MRSA-CR and MRSE-CR.RESULTS: All of the fluoroquinolones tested demonstrated rapid penetration into ocular tissues after a single instillation. Besifloxacin demonstrated the highest exposure in tear fluid, while exposure in conjunctiva was comparable for all 3 compounds. Peak concentrations of all fluoroquinolones in aqueous humor were at or below ~1g/mL. In comparison with their MIC??values against MRSE-CR and MRSA-CR, besifloxacin achieved an AUC????/MIC?? ratio of ~800 in tears, compared with values of ≤10 for moxifloxacin and gatifloxacin. In cornea, conjunctiva, and aqueous humor, the AUC????/MIC?? ratios were <10 for all compounds. However, in these tissues AUC????/MIC?? ratios for besifloxacin were 1.5- to 38-fold higher than moxifloxacin and gatifloxacin….

[5]. Comstock TL, Paterno MR, Usner DW, Pichichero ME. Efficacy and safety of besifloxacin ophthalmic suspension 0.6% in children and adolescents with bacterial conjunctivitis: a post hoc, subgroup analysis of three randomized, double-masked, parallel-group, multicenter clinical trials. Paediatr Drugs. 2010 Apr 1;12(2):105-12. doi: 10.2165/11534380-000000000-00000.
Abstract
BACKGROUND: Acute conjunctivitis is the most frequent eye disorder seen by primary care physicians and one that often affects children. Besifloxacin is a new topical fluoroquinolone, the first chlorofluoroquinolone, for the treatment of bacterial conjunctivitis.OBJECTIVE: To examine the efficacy and safety of besifloxacin ophthalmic suspension 0.6% in patients aged 1-17 years with bacterial conjunctivitis.METHODS: This was a post hoc analysis of a subgroup of pediatric patients aged 1-17 years who had participated in three previously reported, randomized, double-masked, parallel-group, multicenter, clinical trials evaluating the safety and efficacy of besifloxacin in the treatment of bacterial conjunctivitis. The studies were conducted in a community setting (clinical centers). All three clinical trials included children (aged > or = 1 year) with a clinical diagnosis of bacterial conjunctivitis in at least one eye, based on the presence at baseline of grade 1 or greater purulent conjunctival discharge and conjunctival injection, and pin-hole visual acuity of at least 20/200 in both eyes for verbal patients. Two trials were vehicle controlled; the third trial was comparator controlled (moxifloxacin hydrochloride ophthalmic solution 0.5% as base). In all studies, besifloxacin ophthalmic suspension 0.6% was administered as one drop in the affected eye(s) three times daily, at approximately 6-hourly intervals, for 5 days. The main outcome measures were clinical resolution and microbial eradication at visit 2 (day 4 +/- 1 in one study; day 5 +/- 1 in the other two studies) and visit 3 (day 8 or 9). Data from the two vehicle-controlled studies were combined for the assessments to provide greater statistical power.RESULTS: This analysis included 815 pediatric patients aged 1-17 years (447 with culture-confirmed bacterial conjunctivitis). Clinical resolution was significantly greater (p < 0.05) in the besifloxacin group than in the vehicle group at both visit 2 (53.7% vs 41.3%) and visit 3 (88.1% vs 73.0%). Similarly, microbial eradication was significantly higher with besifloxacin than with vehicle at visit 2 (85.8% vs 56.3%) and visit 3 (82.8% vs 68.3%). No significant differences in clinical resolution and microbial eradication were noted between besifloxacin and moxifloxacin. Besifloxacin was well tolerated, with similar incidences of adverse events in the besifloxacin, vehicle, and moxifloxacin groups.CONCLUSION: Besifloxacin ophthalmic suspension 0.6% was shown to be safe and effective for the treatment of bacterial conjunctivitis in children and adolescents aged 1-17 years.

///////Besifloxacin hydrochloride, Besivance, Besifloxacin, SS734, 141388-76-3, 405165-61-9, BOL 303224A, ISV-403, Bausch & Lomb, treatment of non-viral bacterial conjunctivitis

Fc1c(c(Cl)c2c(c1)C(=O)C(\C(=O)O)=C/N2C3CC3)N4CCCC[C@@H](N)C4

Febuxostat

Uncategorized Comments Off

Jul 102016

Febuxostat

Febuxostat; 144060-53-7; Uloric; Adenuric; Tei 6720; 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid;
Molecular Formula:	C₁₆H₁₆N₂O₃S
Molecular Weight:	316.37484 g/mol

2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methyl-1,3-thiazole-5-carboxylic acid

Febuxostat is a thiazole derivative and inhibitor of XANTHINE OXIDASE that is used for the treatment of HYPERURICEMIA in patients with chronic GOUT.

CAS 144060-53-7

2-[3-Cyano-4-(2-methylpropoxy)phenyl]-4-methyl-5-thiazolecarboxylic acid
2-(3-Cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid
FBX
Febugood
Feburic
Febutaz
TMX 67
Zurig

Febuxostat (INN; trade names Adenuric in Europe and New Zealand, Uloric in the US, Goturic in Latin America, Feburic in Japan) is a drug that inhibits xanthine oxidase, thus reducing production of uric acid in the body. It is used in the treatment of chronicgout and hyperuricemia.

Febuxostat was discovered by scientists at the Japanese pharmaceutical company Teijin in 1998. Teijin partnered the drug with TAP Pharmaceuticals in the US and Ipsen in Europe. Ipsen obtained marketing approval for febuxostat from the European Medicines Agency in April 2008, Takeda obtained FDA approval in February 2009, and Teijin obtained approval from the Japanese “Pharmaceuticals and Medical Devices Agency” in 2011.

Medical uses

Febuxostat is used to treat chronic gout and hyperuricemia.^[2] National Institute for Health and Clinical Excellence concluded that febuxostat is more effective than standard doses of allopurinol, but not more effective than higher doses of allopurinol.^[2]

Uloric 40 mg tablet

Febuxostat is in the US pregnancy category C; there are no adequate and well-controlled studies in pregnant women.^[3]

Side effects

The adverse effects associated with febuxostat therapy include nausea, diarrhea, arthralgia, headache, increased hepatic serum enzyme levels and rash.^[3]^[4]

Drug interactions

Febuxostat is contraindicated with concomitant use of theophylline and chemotherapeutic agents, namely azathioprine and 6-mercaptopurine, because it could increase blood plasma concentrations of these drugs, and therefore their toxicity.^[3]^[5]

Mechanism of action

Febuxostat is a non-purine-selective inhibitor of xanthine oxidase.^[3] It works by non-competitively blocking the molybdenum pterincenter which is the active site on xanthine oxidase. Xanthine oxidase is needed to successively oxidize both hypoxanthine andxanthine to uric acid. Hence, febuxostat inhibits xanthine oxidase, therefore reducing production of uric acid. Febuxostat inhibits both oxidized as well as reduced form of xanthine oxidase because of which febuxostat cannot be easily displaced from the molybdenum pterin site.^[4]

History

Febuxostat was discovered by scientists at the Japanese pharmaceutical company Teijin in 1998.^[6] Teijin partnered the drug withTAP Pharmaceuticals in the US and Ipsen in Europe.^[7]^[8]^[9]

Ipsen obtained marketing approval for febuxostat from the European Medicines Agency in April 2008,^[10] Takeda obtained FDA approval in February 2009,^[11]^[12] and Teijin obtained approval from the Japanese authorities in 2011.^[13] Ipsen exclusively licensed its European rights to Menarini in 2009.^[14] Teijin partnered with Astellas for distribution in China and southeast Asia.^[15]^[16]

Society and culture

Cost

In the UK, NICE has found that febuxostat has a higher cost/benefit ratio than allopurinol and on that basis recommended febuxostat as a second-line drug for people who cannot use allopurinol.^[2]

Trade names

Febuxostat is marketed as Adenuric in Europe and New Zealand, Uloric in the US, Goturic and Goutex in Latin America, Feburic in Japan, and is generic in several countries and is available by many names in those countries.^[1]

Febuxostat (Formula I) is an inhibitor of xanthine oxidase, which was discovered by the Japanese company Teijin Pharma Ltd and it is indicated for use in the treatment of hyperuricemia and chronic gout. Its chemical name is 2-(3-cyano-4-isobutoxyphenyl)-4-methyl- l,3-thiazole-5-carboxylic acid. It is marketed under the brand names Adenuric in Europe, Feburic in Japan and Uloric in USA and Canada.

In EP0513379B1 Febuxostat is prepared from 4-hydroxy-3-nitrobenzaldehyde, according to the following scheme.

This particular process suffers from major drawbacks. Not only it is very long, including seven steps from the starting material to the final product, but, most importantly, it employs the use of cyanides, which are extremely toxic reagents. Cyanide salts are likely to generate hydrocyanide, which sets a high amount of risk in an industrial scale process.

In Japanese patent JP06345724A(JP2706037B) the intermediate ethyl ester of Febuxostat is prepared from p-cyano-nitrobenzene, in three steps. Febuxostat may, then, be prepared by alkaline hydrolysis, according to prior art.

MeCSNH,

The use of extremely toxic potassium cyanide makes this process unsuitable for manufacturing purposes.

Route A

In Japanese patent JP3202607B Febuxostat ethyl ester is prepared, according to the above scheme, through two similar routes. Route A uses flash column chromatography for the purification of the hydroxylamine reaction product, while Route B suffers from low yield and the use of chlorinated solvents for recrystallization. In addition, the reaction solvent is, in both cases, formic acid which causes severe skin burns and eye damage to humans. Formic acid is also corrosive towards metal-based materials of construction (MOC), like stainless steel and nickel alloys, limiting the options, essentially, to glass reactors or vessels. The drawbacks of using this solvent are also related to the high volumes of formic acid required per batch, which hinder the waste treatment.

In CN101723915B focus is made to the improvement of the hydroxylamine reaction. Formic acid is replaced with dimethylformamide (DMF) and other solvents. However, according to widely used organic chemistry textbooks, such as March’s Advanced Organic Chemistry, pi 287, 6^th edition, M. B. Smith and J. March, ISBN 0-471-72091-7, the mechanism of the reaction involves the formation of an oxime, upon the action of hydroxylamine, which further dehydrates to form a nitrile, with the aid of a suitable reagent, for example formic acid, or acetic anhydride. In the absence of such a reagent, it is expected that the reaction will, at least, not lead to completion, thereby leading to low yields and undesired impurity levels, namely the intermediate oxime. Such impurities, arising from the reactions of the process and which exhibit similar structure of the desired product, are often difficult to remove with common industrial techniques, e.g. crystallization.

In WO2010142653A1 the intermediate Febuxostat ethyl ester is prepared from 4-cyanophenol, through a five-step process. Febuxostat can be prepared from its respective ethyl ester via alkaline hydrolysis, as in the previous case.

1: patents US5614520 febuxostat synthetic process:

2: Patent JP1994329647 febuxostat synthesis

PATENT

https://www.google.com/patents/CN102936230A?cl=en

Gout occurs because the body produces too much uric acid and renal clearance capacity decreased, uric acid accumulation in the body, leading to urate crystals deposited in the joints and organs. Therefore, it means the treatment of gout usually taken to be: to promote uric acid excretion and suppression of uric acid, and the use of appropriate measures to improve symptoms. Uric acid formation and purine metabolism, the final step in the purine metabolism, hypoxanthine generation xanthine xanthine oxidoreductase (XOR) effect, further generate uric acid, inhibit the activity of the enzyme can effectively reduce uric acid production. Febuxostat is currently the world’s newly developed XOR inhibitors, which act by highly selective to the oxidase, reduce uric acid synthesis, reduce uric acid levels, so as to effectively treat the disease ventilation.

Compared with the traditional treatment of gout drug allopurinol, febuxostat has obvious advantages: (1) allopurinol reduced the XOR only inhibit rather than febuxostat of oxidized and reduced form are XOR significant inhibition, thus reducing the role of uric acid, which is more powerful and lasting; (2) Since allopurinol is a purine analogue, the inevitable result of the purine and other activity related to the impact of pyridine metabolism. So allopurinol treatment should be repeated large doses of the drug to maintain a high level. Which also brought serious or even fatal adverse reactions due to drug accumulation due.Instead of febuxostat non-purine XOR inhibitors, so it has better security.

Document TMX-67. Drugs Fut2001, 26, I, 32, and EP0513379, US5614520, W09209279, public

The detailed preparation febuxostat. Using 3-nitro-4-hydroxybenzaldehyde as the starting material is first reacted with hydroxylamine hydrochloride, to give 3-nitro-4-hydroxybenzonitrile. In effect then HCl, reaction with thioacetamide to give 3-nitro-4-hydroxy-thiobenzamide. Closed loop then reacted with 2-chloro ethyl acetoacetate to give 2- (3_ nitro-4-hydroxyphenyl) methyl-5-thiazolyl -4_ carboxylic acid ethyl ester. Followed by potassium carbonate effect, isobutane is reacted with bromo, to give 2- (3_ nitro-4-isobutyloxyphenyl) -4-methyl-5-carboxylic acid ethyl ester. Under the catalytic action of palladium on carbon, hydrogen reduction to give 2- (3-amino-4-isobutyloxyphenyl) -4-methyl-5-thiazole carboxylic acid ethyl ester. Followed by diazotization with sodium nitrite occur, was added cuprous cyanide and potassium cyanide, to give 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl-5-thiazolecarboxylic acid ethyl ester. Finally, under the effect of the hydrolysis of sodium hydroxide, to give the product 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl – thiazole-5-carboxylic acid, to obtain febuxostat.The process route is as follows:

This route in the preparation of febuxostat, there are many disadvantages: raw 3-nitro-4-hydroxybenzaldehyde in the country is difficult to buy; requires the use of palladium-carbon catalytic hydrogenation reaction under the factory equipment higher requirements, there is a certain danger; the cyano preparation, the need to use sodium nitrite diazotization, could easily lead to corrosion of equipment; the cyano preparation, the need to use toxic cyanide copper, potassium cyanide, pollution, higher risk.

Document JP1994329647, JP1998045733, US3518279 reported another synthesis of febuxostat

Methods. From 4-hydroxy-thiobenzamide as a starting material, and the cyclization reaction to give ethyl 2-bromo-acetyl occurred

2- (4_ hydroxyphenyl) -4_ methyl-5-carboxylic acid ethyl ester in polyphosphoric acid effect, HMTA (hexamethylene tetramine) reacts with 2- (3_ aldehyde – 4-hydroxyphenyl) methyl-5-thiazolyl -4_ carboxylic acid ethyl ester. Then two cases: the first case, the effect of potassium carbonate, is reacted with isobutane to give bromo-2- (4-isobutyloxyphenyl 3_ aldehyde) -4_-methyl-5- thiazole carboxylic acid ethyl ester, and then reacted with hydroxylamine hydrochloride to give 2- (3_-cyano-4-isobutyloxyphenyl) -4_-methyl-5-thiazole carboxylic acid ethyl ester; second case is the first with hydroxylamine hydrochloride to give 2- (3_ cyano-4-hydroxyphenyl) methyl-5-thiazolecarboxylic -4_ carboxylic acid ethyl ester, and then under the effect of potassium carbonate, and reacted with isobutane to give bromo-2- (3 _-cyano-4-isobutyloxyphenyl) -4-methyl-5-carboxylic acid ethyl ester.

Finally, under the effect of the hydrolysis of sodium hydroxide, to give the product 2- (3_-cyano-4-isobutyloxyphenyl) -4_ methyl – thiazole-5-carboxylic acid, i.e., to obtain febuxostat . The process route is as follows:

This synthesis route febuxostat process, since the introduction of aldehyde HMTA in PPA (polyphosphoric acid) effect. So there are a lot of phosphorus wastewater, serious environmental pollution, but also because PPA has great viscosity, and therefore difficult to stir the production, operation is extremely inconvenient.

Document Heterocyclesl998, 47,2,857 JP1994345724 also reported the synthesis method of febuxostat, using p-nitrophenyl-carbonitrile as a starting material in the reaction with potassium cyanide in DMSO solvent, and then the carbonate lower potassium catalyzed reaction of isobutane and brominated 1,3-cyano-4-diisobutoxybenzene ether. By reaction with thioacetamide to afford

3-cyano-4-isobutyloxyphenyl thiobenzamide. Under heating, and 2-chloro ethyl acetoacetate, ring closure reaction occurs to give 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl-5-carboxylic acid ethyl ester, and finally hydrolysis under the effect of sodium hydroxide, to give the product 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl – thiazole-5-carboxylic acid, to obtain febuxostat.

The present invention febuxostat new technology system, comprising the steps of:

(1) 2-hydroxy-5-cyano – NaSH reacted with benzaldehyde to give 4-hydroxy-3- aldehyde thiobenzamide;

(2) the step (I) to give 4-hydroxy-3-aldehyde thiobenzamide reaction with ethyl 2-halo-acetyl, closed

Ring to give 2- (3-aldehyde-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole;

X is a halogen, preferably Cl or Br;

(3) the step (2) to give 2- (3-aldehyde-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole with hydroxylamine in formic acid in the reaction solution to give 2- (3- cyano-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole;

(4) The step (3) to give 2- (3-cyano-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole isobutane with halo effect in potassium carbonate, to give 2- (3-aldehyde-4-isobutyloxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole;

(5) in step (4) to give 2- (3-aldehyde-4-isobutyloxyphenyl) -4-methyl-5-ethoxycarbonyl-thiazol-off hydrolyzable ester group, to obtain a non-Tendon Disposition Tanzania.

[0011] Scheme of the method is as follows:

X is halogen, may be Cl, Br;

Preparation 5 febuxostat Example

To a 500ml reaction flask was added 200ml of absolute ethanol, the product of Step 4 was added with stirring (60g, O. 174mol),

5% sodium hydroxide was added 100ml. Stirring heated to 40 degrees, until it is completely dissolved. 40 degrees heat, reaction 4h. The reaction by TLC tracking. After completion of the reaction, the reaction solution was added 10% hydrochloric acid to adjust the pH to 3, the precipitated solid was filtered. And dried to give a pale yellow solid. Dried over anhydrous recrystallized from methanol to give 31. 2g of white crystals, yield 56.7%.

TLC monitoring of the reaction. Eluent: petroleum ether / ethyl acetate = 3: 1 Melting point:. 201 · 7 ~202 30C (literature value 201 ~202 ° C)

1H-NMR δ:. 1 01 (m, 6H), 2.06 (m, lH), 2.57 (m, 3 H), 3.96 (d, 2H), 7.30 (d, lH), 8.13 (m, 1H), 8. 19 (d, 1H);

MS (m / z):. 316 O (M +)

Infrared detection: 3550-3400cm_1; 2961, 2933,2874; 2227cm_1; 1680U604U511cm_1; 1425cm_1; 1296U283CHT1;

Elemental analysis for C, Η, N, S purified product actual measurement of the content of C, H, N, S content: C:. 60 57%, H:. 5 32%, N:. 8 86%, S: 10. 16%; theoretical value: In C16H16N203S calculated C: 60 74%, H: 510%, N: 885%, S: 1014%..

CLIP

Facile OnePot Transformation of Arenes into Aromatic Nitriles …

onlinelibrary.wiley.com

Facile OnePot Transformation of Arenes into Aromatic Nitriles under MetalCyanideFree Conditions

Patent

http://www.google.com/patents/WO2011141933A2?cl=en

The present invention relates to an improved process for the preparation of anti- hyperuricemia drug 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methylthiazole-5- carboxylic acid (commonly known as Febuxostat) and its pharmaceutically acceptable salts, represented by the following structural formula- 1.

Formula- 1

Further, the present invention provides novel amine salts of compound of formula- 1 and its process for the preparation.

The present invention also provides a novel process for the preparation of crystalline forms A, B and G of Febuxostat. Febuxostat is an inhibitor of xanthine oxidase that is indicated for use in the treatment of hyperuricemia and gout.

Febuxostat was approved by the European Medicines and the U.S. Food and Drug Administration. Febuxostat is marketed by Takeda Pharmaceuticals with the brand names Adenuric (EU) and Uloric (US).

Background of Invention:

2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methylthiazole-5-carboxylic acid was first disclosed in US 5614520. The disclosed process comprises of reacting the ethyl 2-[4- hydroxy-3-nitrophenyl]-4-methyl-5-thiazolecarboxylate with 1 -bromo-2-methylpropane in the presence of potassium carbonate in dimethyl formamide provides ethyl 2-[4-(2- methylpropoxy)-3-nitrophenyl]-4-methyl-5-thiazole carboxylate which is reduced with Pd/C and the obtained compound is treated with sodium nitrite in water and followed by a mixture of cuprous cyanide and potassium cyanide provides ethyl 2-[4-(2- methylpropoxy)-3-cyanophenyl]-4-methyl-5-thiazolecarboxylate. The obtained ethyl 2- [3-cyano-4-(2-methylpropoxy)phenyl)-4-methyl-5-thiazolecarboxylate was hydrolyzed by treating with aqueous sodium hydroxide in a mixture of ethanol and tetrahydrofuran provides 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methylthiazole-5-carboxylic acid having melting range of 238 – 239°C with the yield of 33%. The above process utilizes Pd/C, which is difficult to handle in the laboratory, hence it is not recommended on large scale. However, the yield and purity were also not satisfactory. The said process involves more number of steps, hence there is a need to produce the process for the preparation of 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methylthiazole-5-carboxylic acid with less number of steps.

Heterocycles, 1998, Vol. 47, No. 2, 857-864 disclosed a process for the preparation of 2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid which comprises of reacting 4-(2-methylpropoxy)-l,3-benzenedicarbonitrile in the presence of hydrochloric acid with thioacetamide in dimethyl formamide provides 4-(2- methylpropoxy)-3-cyanobenzthioarnide. It was reacted with ethyl 2-chloroacetoacetate in ethanol provides ethyl 2-[4-(2-methylpropoxy)-3-nitrophenyl]-4-methyl-5-thiazole carboxylate which is further hydrolyzed with aqueous sodium hydroxide solution in a mixture of tetrahydrofuran and ethanol provides 2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid with the yield of 35% which on further recrystallized from acetone provides a colorless crystals having the melting range of 201 – 202°C. However the yield and purity were not satisfactory. JP10-045733 disclosed a process for the preparation of 2-[3-cyano-4-(2- methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid which comprises of reacting ethyl 2-(3-formyl-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate with hydroxyl amine in 2011/000328 presence of formic acid and sodium formate provide ethyl 2-(3-cyano-4-hydroxyphenyl)-4- methylthiazole-5-carboxylate. The obtained compound was reacted with l-bromo-2- methylpropane in presence of potassium carbonate provides ethyl 2-[3-cyano-4-(2- methylpropoxy) phenyl]-4-methylthiazole-5-carboxylate, which on further hydrolysis with aq sodium hydroxide provides 2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5- carboxylic acid.

2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid produced by the above processes contains 2-[3-carbamoyl-4-(2-methylpropoxy)phenyl]-4- methylthiazole-5-carboxylic acid as an impurity. So there is a need for the purification to get the highly pure 2-[3-cyano-4-(2-methylpropoxy) phenyI]-4-methylthiazole-5-carboxylic acid.WO2011141933

In general, febuxostat prepared by the reported processes contain impurities like amide impurity, ethyl ester impurity and methyl ester impurity etc. It is important that any pharmaceutical compound or intermediate should free of impurities or if present they must be limited to the maximum level set by ICH guidelines. The purification technique of by recrystallisation of the compound from a suitable solvent such as the recrystallisation of febuxostat as disclosed in Heterocycles, Vol. 47, No. 2, 1998 does not yields the desired purity. Hence it is necessary to have an alternate purification technique for the preparation of highly pure febuxostat.

In the aforementioned processes using aqueous sodium hydroxide for hydrolyzation of ethyl 2-[4-(2-methylpropoxy)-3-nitrophenyl]-4-methyl-5-thiazole carboxylate, which lead to the formation of impurities such as ethyl ester impurity, methyl ester impurity, amide impurity and high polar impurities. Hence there is a need to develop a process for the preparation of highly pure febuxostat with high yield.

The crystalline forms A, B, C, D and G of febuxostat and their preparation were first disclosed in US 6225474. However as on date, there is no alternative processes were reported in the prior art for preparing the said polymorphs. Henceforth, there is a need to develop a novel process for the preparation of said crystalline polymorphs.

In view of the foregoing, there is a necessity for the improved process which overcome the problems of prior art and to produce the highly pure 2-[3-cyano-4-(2- methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid with high yield.

Advantages of Present Invention:

• Avoids the usage of Pd/ C .

• Provides the highly pure 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methyl-5- thiazole carboxylic acid with high yield.

• Controls the impurities (such as methyl impurity, ethyl impurity, amide impurity and high polar impurities) levels to meet the ICH guidelines.

• Provides a novel process for the preparation of crystalline forms A, B and G of 2-[3- cyano-4-(2 -methylpropoxy) phenyl]-4-methyl-5-thiazolecarboxylic acid.

· Provides a novel and improved processes for the preparation of 4-(2-methylpropoxy)- 1,3 -benzene dicarbonitrile and also provides a simplest process for the purification of 2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methyl-5-thiazole carboxylic acid.

• Eco-friendly process.

• Uses simple, milder reagents which are easier to handle and use in large scale.

WO2011141933

Formula-6 ForrauIa-

Scheme-II:

Scheme-Ill:

Example 8: Preparation of Febuxostat (Formula-1)

A mixture of compound of formula-5 (50 g), sodium hydroxide (23.25 g), tetrahydrofuran (250 ml) and water (13 ml) was heated to 60-65°C and stirred for 8 hours. After completion of the reaction, the reaction mixture was cooled to 25-30°C and quenched it with water. The reaction mixture was stirred for 1 hour at 25-30°C. A solution of hydrose (2.5 g) in water (25 ml) was added to the reaction mixture at 25-30°C and stirred for 30 minutes. The p^H of the reaction mixture was adjusted to 1.3 with hydrochloric acid. The reaction mixture was extracted thrice with ethylacetate, washed with water and the organic layer was dried with sodium sulfate. Carbon (2.5 g) was added to the organic layer and stirred for 30 minutes. The reaction mixture was filtered through hyflow bed and washed with ethylacetate. Distilled off the solvent completely from the obtained filtrate to get the solid. Ethyl acetate (200 ml) was added to the obtained solid and heated to reflux temperature and stirred for 30 minutes. The reaction mixture was cooled to 25-30°C, filtered the solid obtained and washed with ethyl acetate. Acetone (250 ml) was added to the wet solid obtained, heated to 55-60°C and stirred for 15 minutes. Water (250 ml) was added to the reaction mixture and stirred for 2 hours. The obtained solid was filtered, washed with aqueous acetone and then dried to get the title compound. Yield: 38 grams.

Example 9: Preparation of Febuxostat (Formula-1)

A mixture of compound of formula-5 (50 g), sodium hydroxide (23.25 g), tetrahydrofuran (250 ml) and water (13 ml) was heated to 60-65°C and stirred for 8 hours. After completion of the reaction, the reaction mixture was cooled to 25-30°C and quenched it with water. The reaction mixture was stirred for 1 hour at 25-30°C. A solution of hydrose (2.5 g) in water (25 ml) was added to the reaction mixture at 25-30°C and stirred for 30 minutes. The p^H of the reaction mixture was adjusted to 1.3 with hydrochloric acid. The compound was extracted thrice with ethyl acetate, washed with water and the organic layer was dried with sodium sulfate. Carbon (2.5 g) was added to the reaction mixture and stirred for 30 minutes. The reaction mixture was filtered through hyflow bed and washed with ethylacetate. Distilled off the solvent completely from the obtained filtrate to get the solid. Acetone (250 ml) was added to the solid obtained, heated to 55-60°C and stirred for 15 minutes. Water (250 ml) was added to the reaction mixture and stirred for 45 minutes . Cooled the reaction mixture to 25-30°C and stirred for 30 minutes, further to 0-5 °C and stirred for 2 hours. The obtained solid was filtered, washed with aqueous acetone and then dried. Ethylacetate (200 ml) was added to the obtained solid and heated to reflux temperature and stirred for 30 minutes. The reaction mixture was cooled to 25-30°C. Filtered the solid, washed with ethyl acetate and then dried to get the pure title compound. Yield: 39 grams

Example 10: Preparation of ethyl 2-[3-formyl-4-(2-methyIpropoxy) phenyl]-4- methylthiazole-5-carboxylate compound of formula-12.

To a stirred solution of ethyl 2-[3-formyl-4-hydroxyphenyl]-4-methylthiazole-5- carboxylate (10 gms) in dimethylformamide (40 ml) added potassium carbonate (9.78 gms) and potassium iodide (2.35 gms). Heated the reaction mixture to 70 – 75°C and stirred for 30 minutes. To the above reaction added a solution of l-bromo-2- methylpropane (9.72 gms) in dimethyl formamide (10 ml) and stirred for 5 hours. Cooled the reaction mixture to 25°C, quenched with water and stirred for one hour. Filtered the precipitated solid and dried the material to get the title compound. Yield: 9 gms.

Example 11: Preparation of ethyl 2-[3-cyano-4-(2-methyIpropoxy) phenyl]-4- methyIthiazoIe-5-carboxylate compound of formuIa-5.

To the solution of ethyl 2-[3-formyl-4-(2-methylpropoxy) phenyl]-4- methylthiazole-5-carboxylate compound of formula-12 (10 gms) in formic acid (40 ml) was added hydroxylamine hydrochloride (2.38 gms) and sodium formate (2.35 gms).

Stirred the reaction mixture for 10 minutes. Heated the reaction mixture to 100°C and stirred for four hours at same temperature. Cooled the reaction mixture to 25 °C and quenched with water. Stirred the reaction mixture for 10 hours, filtered the precipitated solid and washed with water. Dried the material to get the title compound. Yield: 10 gms. Take the dry material, added 30 ml of ethyl acetate and heated to reflux temperature. Stirred the reaction mixture for 30 minutes at reflux temperature. Cooled the reaction mixture to 25°C and filtered the precipitated solid. Dry the material to get the title compound as a pure material. Yield: 8.5 gms.

http://www.google.com/patents/WO2011141933A2?cl=en

Clip

synthesis describes synthesis of febuxostat (I) from 4-hydroxybenzonitrile (II) in six stages. The synthesis shown is a short, concise route and does not require use of poisonous reagents such as KCN (14). Compound II was converted to 4-hydroxybenzothioamide (III) with 85% yield using NaHS in the presence of hydrated magnesium chloride as Lewis acid. Intermediate III, on cyclization with ethyl-2-chloroacetoacetate, gave thiazole ester (IV) with quantitative yield. In these two stages, the source of potential impurities was identified as an ortho isomer (i.e., 2-hydroxybenzonitrile), which can lead to Impurity VIII and subsequently to Impurity IX . Impurities VIII and IX can be controlled in starting material II with appropriate specification.

Figure 2: Impurities identified during the various stages of synthesis of febuxostat.

The ortho formylation of hydroxyl compound IV by using Duff condition (hexamine/TFA) gave aldehyde V (15). The major impurity identified in this reaction was dialdehyde X. Although we have used only 1.0 equivalence of hexamine with respect to Compound IV, the dialdehyde X impurity was formed to a 5-10% ratio in only 2.5 h. It is, therefore, impossible to get rid of this impurity during the reaction, and only effective recrystallization will eliminate it. Impurity X was minimized (≤ 2%) by recrystallization using IPA/H₂O (3:5) to get aldehyde V with 50% yield and & #8805; 97% HPLC purity.

Aldehyde V, on alkylation with isobutyl bromide in the presence of potassium carbonate base, gave compound VI with 90% yield. In this stage, Impurities XI and XII were alkylations of carryover Compound IV and dialdehyde, respectively. Two more isomeric impurities n-butyl-aldehyde XIII and 1-methyl propyl-aldehyde XIV were also identified in this stage. Both isomeric impurities can be controlled with appropriate specification for isobutyl bromide. The reaction of Compound VI with hydroxylamine hydrochloride and sodium formate in formic acid at reflux temperature gave Compound VII with 85% yield. Impurities XIII and XIV will also carry forward to impurities n-butyl-nitrile XV and 1-methyl propyl-nitrile XVI, respectively.

In the final step, Compound VII was hydrolyzed using sodium hydroxide in a MeOH:THF:H2O (1:1:1) solvent combination to yield febuxostat (85%). During saponification, methyl ester Impurity XVII was identified via trans-esterification. Its hydrolysis was comparatively slower than its ethyl isomer VII. One way to avoid Impurity XVII is to replace methanol with ethanol. Carryover impurities XI, XV, and XVI were also hydrolyzed to their respective acid derivatives impurities XVIII, XIX, and XX. However, the acid derivatives of impurities X and XII were unexpectedly absent as impurities. It is believed that, because they were present in low concentrations during workup, they were eliminated in the mother liquor. Two additional impurities, amide XXI and diacid XXII, formed by the side reaction of the febuxostat nitrile group with sodium hydroxide, were identified during saponification. The amide XXI and diacid XXII impurities can be controlled by using appropriate equivalence of sodium hydroxide and controlled reaction time. Febuxostat, on acetone recrystallization and seed Crystal A at 45°C, gave pure febuxostat with 75% yield.

http://www.pharmtech.com/investigation-various-impurities-febuxostat

References

Drugs.com Drugs.com international names for febuxostat Page accessed June 25, 2015
Febuxostat for the management of hyperuricaemia in people with gout (TA164) Chapter 4. Consideration of the evidence
Uloric label Updated February, 2009.
Love BL, Barrons R, Veverka A, Snider KM (2010). “Urate-lowering therapy for gout: focus on febuxostat”. Pharmacotherapy 30 (6): 594–608. doi:10.1592/phco.30.6.594.PMID 20500048.
Ashraf Mozayani; Lionel Raymon (2011). Handbook of Drug Interactions: A Clinical and Forensic Guide. Springer Science+Business Media.
Teijin Febuxostat Story Page accessed June 25, 2015
Tomlinson B. Febuxostat (Teijin/Ipsen/TAP). Curr Opin Investig Drugs. 2005 Nov;6(11):1168-78. PMID 16312139
Bruce Japsen for the Chicago Tribune. August 17, 2006. FDA puts gout treatment on hold
Note: TAP Pharmaceuticals was a joint venture between Abbott Laboratories and Takedathat was dissolved in 2008 per this press release: Takeda, Abbott Announce Plans to Conclude TAP Joint Venture
“Adenuric (febuxostat) receives marketing authorisation in the European Union” (PDF). Retrieved 2008-05-28.
“Uloric Approved for Gout”. U.S. News and World Report. Retrieved 2009-02-16.
Teijin and Takeda. February 14, 2009 Press release: ULORIC® (TMX-67, febuxostat) Receives FDA Approval for the Chronic Management of Hyperuricemia in Patients with Gout
Teijin. January 21, 2011 Press release: TMX-67 (febuxostat) Approved in Japan
Genetic Engineering News. October 2009. Menarini to Market Takeda/Ipsen Gout Therapy in 41 European Countries
First Word Pharma. April 1st, 2010 Teijin Pharma and Astellas Pharma enter into agreement for marketing rights of TMX-67 in China and Hong Kong
Research Views. Aug 11 2011 Teijin Pharma Enters Into Distribution Agreement With Astellas Pharma For Febuxostat

Febuxostat is an inhibitor of xanthine oxidase, and was developed by Teijin pharma. This compound is known as a new drug that is effective against gout and hyperuricemia, and it has been 40 years since the last time a drug of this kind of drug was developed.

Febuxostat has therefore gained a lot of popularity and it has already been accepted as a drug in Europe, USA, Korea and Japan. The synthesis of this molecule have been reported in patents by Teijin pharma as shown below.^[1,2]

Recently, Itami group was reported the rapoid synthesis of febxostat by using Ni-catalyzed direct coupling of azoles and arylhalides^[3]

References

Sorbera, L.A.; Castaner, J.; Rabasseda, X.; Revel, L.; TMX-67. Drugs Fut 2001, 26, 1, 32

[1] Hasegawa, M.; A facile one-pot synthesis of 4-alkoxy-1,3-benzenedicarbonitrile. Heterocycles 1998, 47, 2, 857. [2] Hasegawa, M.; Hasegawa, M.; Komoriya, K. (Teijin Ltd.); Cyano cpds. and their preparation method. JP 1994345724 . [3] “Nickel-Catalyzed Biaryl Coupling of Heteroarenes and Aryl Halides/Triflates”

Canivet, J.; Yamaguchi, J.; Ban, I.; Itami, K. Org. Lett. 2009, 11, 1733-1736. DOI: 10.1021/ol9001587

Ni-based catalytic systems for the arylation of heteroarenes with aryl halides and triflates have been established. Ni(OAc)2/bipy is a general catalyst for aryl bromides/iodides, and Ni(OAc)2/dppf is effective for aryl chlorides/triflates. Thiazole, benzothiazole, oxazole, benzoxazole, and benzimidazole are applicable as heteroarene coupling partners. A rapid synthesis of febuxostat, a drug for gout and hyperuricemia, is also demonstrated.

A CLIP

A final example of a thiazole containing drug is given in the novel xanthine oxidase inhibitor febuxostat (359, Uloric) which was approved by the FDA in 2009. This inhibitor works by blocking xanthine oxidase in a non-competitive fashion. Consequently, the amount of the oxidation product uric acid is reduced. Thus it is an efficient treatment for hyperuricemia in gout. In order to prepare febuxostat first a synthesis of the noncommercial 4-isobutoxy-1,3-dicyanobenzene building block (363), has to be conducted. An elegant way of achieving this was shown through the reaction of 4-nitrocyanobenzene (360) with potassium cyanide in dry DMSO followed by quenching with isobutyl bromide under basic conditions (Scheme 70). It is suggested that a Meisenheimer-complex intermediate 361 is initially formed, which after rearomatisation, undergoes nucleophilic aromatic substitution of the nitro group by the DMSO solvent [107]. Upon hydrolysis and O-alkylation the desired 4-isobutoxy-1,3-dicyanobenzene (363) is obtained in good overall yield. Subsequently, the less hindered nitrile is converted to the corresponding thioamide 365 in an intriguing reaction using thioacetamide (364). The thiazole ring is then formed by condensation with chloroacetoacetate 366 followed by ester hydrolysis (Scheme 70).

107 Hasegawa, M. Heterocycles 1998, 47, 857–864. doi:10.3987/COM-97-S(N)89

Paper | Special issue | Vol 47, No. 2, 1998, pp.857-864

DOI: 10.3987/COM-97-S(N)89

■ A Facile One-Pot Synthesis of 4-Alkoxy-1,3-benzenedicarbonitrile

Masaichi Hasegawa

*Teijin Institute, Bio-Medical Research, Asahigaoka 4-3-2, Hino, Tokyo 191, Japan

Abstract

2-(3-Cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxlic acid (TEI-6720) was prepared. The introduction of cyano group to 4-nitrobenzonitrile with KCN in dry DMSO followed by quenching with alkyl halide afforded the key intermediates, 4-alkoky-1,3-benzenedicarbonitriles, in good yield. The reaction was completed in dry DMSO, while no reaction occurred in dry DMF. This observation can be suggested by the participation of DMSO in the reaction.

PDF (208KB)

http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-7-57#S70

A CLIP

Synthesis and characterization of process-related impurities of an anti-hyperuricemia drug-Febuxostat

Venkateswara Rao Vallu,$ Krunal Girishbhai Desai, Sandip Dhaya Patil, Rajendra Agarwal, Pratap Reddy Padi and Mahesh Reddy Ghanta

*Process Research Laboratory-I, Research & Development Centre, Macleods Pharmaceuticals Ltd, G-2, Mahakali Caves Road, Shantinagar, Andheri (East), Mumbai, Maharastra, India

$Department of Chemistry, Pacific University, Pacific Hills, Airport Road, Pratap Nagar Extension, Debari, Udaipur, Rajasthan, India _____________________________________________________________________

Der Pharma Chemica, 2014, 6(3):300-311 (http://derpharmachemica.com/archive.html)

http://derpharmachemica.com/vol6-iss3/DPC-2014-6-3-300-311.pdf

Synthesis of 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (1) [10] A solution of 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (1 tech grade, 5.0 g, 0.015 mol.) in methanol (50.0 mL) was heated the reaction mass at 60-65°C till clear solution was obtained. Water (50.0 mL) was added drop wise into reaction mass with in 30.0 min. at 60-65°C. Resultant white crystalline solid was filtrated, Mahesh Reddy Ghanta et al Der Pharma Chemica, 2014, 6 (3):300-311 _____________________________________________________________________________ 302 www.scholarsresearchlibrary.com washed with water (10.0 mL) and dried in vacuum tray drier at 50-55°C under vacuum to give

2-(3-cyano-4- isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (1). Yield: 95.0 % (4.75 g)

mp 239°C. Purity by HPLC: 99.74 % (10.2 min. retention time),

Anal. Calcd for C16H16N2O3S: C, 60.74; H, 5.10; N, 8.85. Found: C, 60.70; H, 5.11; N, 8.87 %;

IR (KBr) υmax (in cm−1): 3834.61, 3742.03, 3680.30, 3556.85, 3456.55, 2962.76, 2877.89, 2661.85, 2546.12, 2353.23, 2229.79, 2168.06, 2029.18, 1921.16, 1790.00, 1674.27, 1604.83, 1512.24, 1427.37, 1381.08, 1280.78, 1172.76, 1118.75, 1010.73, 918.15, 833.28, 771.55, 725.26, 648.10, 524.66, 462.93; 1H NMR (300 MHz, CDCl3 or DMSO-d6) δH (in ppm): 1.00-1.02 (d, 6H, (CH3)2-CH-), 2.49-2.50 (m, 1H, (CH3)2-CH-), 3.97-3.99 (d, 2H, -CH-CH2−), 7.33–8.25 (d, dd, 3H, Ar-H), 2.64 (s, 3H, -CH3), 13.39 (s, 1H, -COOH);

13C NMR (300 MHz, DMSO–d6) δC (in ppm) (Positiona ): 166.3 (l), 162.9 (p), 162.2 (n), 159.6 (e), 133.1 (g), 131.6 (i), 125.5 (m), 123.0 (h), 115.5 (k), 114.0 (f), 101.7 (j), 75.2 (d), 27.7 (b), 18.8 (a, c), 17.1 (o);

MS m/z (%) (70 eV): m/z =317.0 (100.0 %) [M+1], 318.0 (16.0 %) [M+2], 403.0 (63.0 %), 512.0 (47.0 %), 482.0 (46.0 %), 405.0 (27.0 %), 468.0 (25.0 %), 570.0 (24.0 %).

PATENT

WO 2012066561

https://www.google.com/patents/WO2012066561A1?cl=en

As per the present invention, hydroxylamine hydrochloride is added to compound of Formula-Ill in presence of a polar aprotic solvent like DMSO, DMA, ACN or DMF. To this reaction mixture acetyl halides or sulfonyl chlorides are added and temperature raised to 70 -80 °C. Acetyl halides are selected from acetyl bromide or acetyl chloride. Sulfonyl chlorides are selected from methane sulfonyl chloride or para toluene sulfonyl chloride. To this reaction mixture a base selected from alkali metal carbonates like potassium carbonate or sodium carbonate, preferably potassium carbonate and alkyl halide selected from isobutyl bromide is successively added. The reaction mass is washed with water and compound of Formula-II is isolated. In one embodiment the present invention provides, process for the preparation of Febuxostat comprising the steps of:

a) reacting the compound of Formula-III(a) with hydroxylamine hydrochloride in presence of organic solvent;

Formula-III(a)

b) adding acyl halides or sulfonyl chlorides to the reaction mixture;

c) optionally isolating compound of Formula- IV (a)

Formula-IV(a)

d) reacting with isobutyl bromide in presence of base;

e) isolating the compound of Formula-II(a); and

FormuIa-II(a)

f) hydrolyzing the compound of Formula-II(a) to get Febuxostat.

The following examples are provided to illustrate the process of the present invention. They, are however, not intended to limiting the scope of the present invention in any way and several variants of these examples would be evident to person ordinarily skilled in the art. Experimental procedure:

Example – 1: Preparation of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyI thiozole -5-carboxylate

A mixture of 10. Og of Ethyl -2-(3-formyl-4-hydroxy phenyl)-4-methyl thiozole -5- carboxylate and 2.85 g of hydroxylamine hydrochloride were stirred for 30 minutes in 40 g of Dimethyl sulfoxide. To this reaction mixture 3.3 grams of acetyl chloride was added and stirred at 70 -80°C for 2-3 hours. Reaction mass was cooled to room temperature and to this 19 g of potassium carbonate and 19 g of isobutyl bromide was added successively. The reaction mass was stirred for 5 hours at 70-80°C. Reaction mass was diluted with 200 ml of purified water. The reaction mass was filtered and washed with purified water to give 10.0 g of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxyltae (yield 84.0%)

Example – 2: Preparation of Ethyl-2-(3-cyano-4-hydroxyphenyl)-4-methyl thiozole – 5-carboxylate

A mixture of 10. Og of Ethyl-2-(3-formyl-4-hydroxy phenyl)-4-methyl thiozole -5- carboxylate and 2.85 g of hydroxylamine hydrochloride were stirred for 30 minutes in 30 g of Dimethylformamide. To this reaction mixture 3.3 grams of acetyl chloride was added and stirred at 90°C for 2-3 hours. Reaction mass was cooled to room temperature and diluted with 100 ml of water and stir for 2 hours. The reaction mass was filtered and washed with purified water to give 10.0 g of Ethyl-2-(3-cyano-4-hydroxy phenyl)-4- methyl thiozole -5-carboxyltae (yield 99.0%).

Example – 3: Preparation of Ethyl 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylate

A mixture of 10. Og of Ethyl-2-(3-cyano-4-hydroxy phenyl)-4-methyl thiozole -5- carboxylate, 30 g of NMP, 9.6 g of potassium carbonate and 7.2 g of isobutyl bromide were stirred for 3 hours at 90°C. Reaction mass was diluted with 100 ml of purified water. The reaction mass was filtered and washed with purified water and ethanol to give 10.5 g of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxyltae (yield 88.0%). Example – 4: Preparation of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5- carboxylic acid

A mixture of 10. Og of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5- carboxyltae, 2.0g of sodium hydroxide was heated at 45-60°C in 75 ml of aqueous methanol for 1 hour. Reaction mass was cooled to ambient temperature and pH adjusted to 2.0 to 2.5 with dilute hydrochloric acid and precipitated crystal was collected by filtration to give 8.8g of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid (yield 95.8%).

Example – 5-13: Preparation of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole – 5-carboxylic acid

The above compound was prepared by following the procedure as disclosed in Example- 4, using the below listed solvents instead of aqueous methanol.

Example – 14: Preparation of pure 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid

10.0 g of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid was dissolved in 100 ml of ethanol at reflux temperature. After dissolution reaction mass was cooled and precipitated crystal was collected by filtration to give 9.6 g of pure 2-(3- cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid (yield 96%).

PATENT

KR 201603732

PATENT

WO 2015018507

https://www.google.com/patents/WO2015018507A2?cl=en

EXPERIMENTAL

of compound of formula lib

Dissolve 14.14g of ethyl 2-(3-formyl-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (Formula III) in 55 ml dimethylformamide, at ambient temperature. Add 40g of potassium carbonate, along with 15.9 ml isobutyl bromide. Heat the reaction to 75-80 °C and stir for 4 hours. Cool to 25-30 °C, while 165 ml process water is added. Further cool to 0-5 °C and stir for 30 minutes at this temperature. Filter off the precipitated solid and wash the filter cake with 55 ml process water. The wet cake is dried under vacuum at 40 °C for 7 hours, to furnish 16.43 g of ethyl 2-(3-formyl-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula lib).

of compound of formula Illb

In a 25 mL round-bottomed flask charge under stirring at 25-30 °C, 1.0 g (2.88 mmol) of ethyl 2-(3-formyl-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate in 3.0 mL dimethylformamide. Add 34 mg (0.19 mmol) copper acetate under stirring at 25-30 °C. Flush with oxygen (0₂) and add 0.66 ml (34.92 mmol) 25% aqueous ammonia. Flush again with 0₂. Heat the reaction mixture to 80-82 °C overnight. Check the progress of the reaction by TLC (cyclohexanerethyl acetate 3:1). Cool reaction mass to 25-30 °C. Add 25mL ethyl acetate and 25mL brine at the reaction mass, separate organic layer and extract aqueous layer twice with 25mL ethyl acetate. Combine organic layers, dry over anhydrous sodium sulfate, filter off and concentrate till dry. The residue is purified with column chromatography (cyclohexane:ethyl acetate 9:1). afforded 0.754g of ethyl 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula Illb) Yield: 75.4%.

EXAMPLE 3: Preparation of compound of formula Illb

In a 25 mL round-bottomed flask charge under stirring at 25-30 °C, 0.17 g (0.49 mmol) of ethyl 2-(3-formyl-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate in 2.5 mL tetrahydrofuran. Add 2.9 mL (153.43 mmol) 25% aqueous ammonia, under stirring at 25-30 °C. Add 137 mg (0.54 mmol) iodine (I₂) to the reaction mass, stir the reaction mixture at 25-30 °C for 15-30 min. Check the progress of the reaction by TLC (cyclohexane: ethyl acetate 3:1). Starting material is consumed. Add 2.5 mL 5% w/v aqueous sodium thiosulfate Na₂S₂0₃ and 15mL ethyl acetate at the reaction mass, separate organic layer and extract twice aqueous layer with 15mL ethyl acetate. Combine organic layers, dry over anhydrous sodium sulfate, filter off and concentrate till dry. 0.158g of ethyl 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula Illb) are collected.

EXAMPLE 4: Preparation of Febuxostat

In a 100 ml 2-neck round-bottomed flask charge 2.407g of ethyl-2-(3-cyano-4-isobutoxyphenyl)-4-methylhiazole-carboxylate in 20ml tetrahydrofuran under stirring, at 25-35 °C, 0.748g of sodium hydroxide and heat reaction mass to 60-65 °C for approximately 8 hrs. Check the progress of the reaction by TLC (cyclohexane:ethyl acetate 3:1). Cool reaction mass to 0-5 °C and add 50 ml process water keeping temperature within 0-5 °C. Adjust pH to 1-2 with 4.5 ml 6 N hydrochloric acid, keeping temperature within 0-5 °C. Warm up reaction mass to 25-30 °C and stir reaction mass at the above temperature for 15 min. Filter off the precipitated solid through Buchner funnel under reduced pressure, spray wash with 2 ml process water and suck dry for 20-30 min. Transfer the crude solid in a 50 ml round-bottomed flask, charge 12 ml process water and 12 ml acetone at 25-30°C. Heat the reaction mass to 50-60 °C for 60 min. Cool down reaction mass to 0-5 °C and stir for 60 min at the above temperature. Filter off the precipitated solid though Buchner funnel under reduced pressure, spray wash with 2 ml of a 1 : 1 mixture of acetone and process water and suck dry for 30-45 min. Dry under vacuum at 60 °C. 1.821g of (compound I) Febuxostat are collected, Purity: 82.6%, Yield: 0.62w/w.

on of compound of formula Ilia

In a 50 mL round-bottomed flask charge under stirring 0.5g (1.72 mmol) of ethyl 2-(3-formyl-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate in 8.6 mL THF, at 25-30 °C. Add 10.3 mL (544.94 mmol) 25% aqueous ammonia, under stirring at 25-30 °C. Add 480 mg (1.89 mmol) iodine (I₂) to the reaction mass, stir the reaction mixture at 25-30 °C for 15-30 min. Check the progress of the reaction by TLC (cyclohexane: ethyl acetate 1 :1). Starting material is consumed. Add 8.6 mL 5% w/v aqueous thiosulfate and 40 mL ethyl acetate at the reaction mass, separate organic layer and extract aqueous layer twice with 40 mL ethyl acetate. Combine organic layers, dry over anhydrous sodium sulfate, filter off and concentrate to dryness. Purification of the residue with column chromatography (cyclohexane: ethyl acetate 3: 1) afforded 0.213 g of ethyl 2-(3-cyano-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (Formula Ilia). Yield : 42.6%.

EXAMPLE 6: Preparation of compound Illb

Dissolve 2.2 g of ethyl 2-(3-cyano-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (Formula VI) in 7 ml dimethylformamide and to this mixture add 6.6 g of potassium carbonate and 3.14 g of isobutyl bromide. Stir the reaction at 75 °C for 15 hours and then cool to 40 °C. Add 15 ml process water and cool to 0-5 °C. Filter the precipitated solid off and wash with 15 ml process water, which, after drying, affords 2.28 g of ethyl 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula Illb).

EXAMPLE 7: Preparation of compound I (Febuxostat)

In a 100 ml 2-neck round-bottomed flask charge 2.131 g of ethyl-2(3-cyano-4-isobutoxyphenyl)-4-methylhiazole-carboxylate, 64 ml methanol and 2.5 ml process water are added under stirring at 25-35 °C. Add 1.718 g potassium carbonate and heat reaction mass to reflux for approximately 2-3 hrs. Check the progress of the reaction by TLC (cyclohexane: ethyl acetate 3:1). Cool reaction mass to 20-25 °C. Concentrate solvent at below 40 °C. To the residue add 43 ml process water, 21 ml ethyl acetate and stir for 30 min at 25-35 °C. Separate layers and transfer aqueous layer in a 100 ml round-bottomed flask. Adjust pH to 2.3-2.7 with 25 ml 1 N hydrochloric acid, at 25-35 °C. Warm up reaction mass to 40 °C and stir reaction mass at this temperature for 60-90 min. Cool down reaction mass to 25-35 °C. Filter off the precipitated solid through Buchner funnel under reduced pressure, spray wash with 5 ml process water and suck dry for 30-45 min. Dry under vacuum at 60 °C. 1.708g of (compound I) Febuxostat are collected, Purity: 86.7%, Yield: 0.69w/w.

EXAMPLE 8: Preparation of Febuxostat crystalline form III

In a 250 mL round-bottomedflask charge under stirring at 25-30 °C 10 g of crude 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (Febuxostat) in 200 mL ethyl acetate. Heat reaction mass to reflux and stir for 30 min. Cool reaction mass to 25-30°C. Warm again reaction mass and partially distill off solvent from the reaction mass at temperature below 40 °C under reduced pressure. Cool reaction mass to 25-30°C. Filter off the precipitated solid through Buchner funnel under reduced pressure and spray wash with 10 mL ethyl acetate. Dry under vacuum at 60°C. 8.5 g of Febuxostat are collected. Yield: 85 % w/w. XRPD of crystalline compound is in accordance with the one reported in Chinese patent CN101412700B.

PATENT

CN 104418823

https://www.google.com/patents/CN104418823A?cl=zh

Figure CN104418823AD00042

PATENT

CN 103588723

https://www.google.com/patents/CN103588723A?cl=zh

Chinese patent CN1275126 described by the Japanese company Teijin invention relates febuxostat Form A, B, C, D, G, and six kinds of amorphous and crystalline preparation method, reported in the literature Form A relatively stable . The method used is a solvent of methanol and water, patent phase diagram (Figure 7 Zone I) can be obtained in anhydrous crystalline Form A (hereinafter referred to as “Form A”), the mixing process by a temperature and the formation of methanol and water to determine the composition of the solvent, and the need to add a certain amount of Form a as a seed crystal to induce precipitation of crystals to control crystallization conditions are very harsh, operable range is very small, easy to form methanol solvate, hydrate or stable crystalline type C, to obtain reproducible single crystal type a low, it is difficult to achieve industrial production, and no mention of the preparation of Form a yield and purity in this patent.

[0011]

[0012] Chinese patent CN102267957A invention discloses a method for preparing febuxostat Form A, the solvent is preferably acetone, dissolved into 25 ~ 40 ° C was allowed to stand, when there began to crystallize when stirred for 20 to 40 minutes, then placed in -15 ~ 0 ° C to continue the crystallization of 8 to 10 hours. The crystallization process need to well below zero, when industrial mass production, resulting in high production costs, is not conducive to industrial production, the process yield up to 95.4%.

[0013] Chinese patent CN101139325 of Example 7 discloses the preparation of Form A with acetone method, although the process is simple, but the yield is low, only 50%.

[0014] Although the Chinese patent CN101684108A isopropyl alcohol as a solvent is disclosed a method for preparing crystalline form, the crystalline form of preparation is used to cool and heat a phased manner was allowed to stand, the crystallization temperature, long crystallization time, about 30 hours, the yield is low, and its products are not crystalline Form A.

[0015] In addition, Chinese patent CN101525319A, CN101805310, CN101926795A, CN101926794, W02012020272A2 are disclosed ethanol as a solvent or aqueous ethanol as a solvent preparation methods, and its products are crystalline ethanol solvate.

[0016] World Patent W02011139886A2 discloses the use of a mixed solvent of alcohol, and its products are not obtained polymorph A0

PAPER

Letters in Organic Chemistry (2015), 12(3), 217-221

Synthesis of the Major Metabolites of Febuxostat

Author(s): Xiao Long Li, Rui Qiu, Wei Li Wan, Xu Cheng, Li Hai and Yong Wu

Affiliation: Key Laboratory of Drug Targeting of Education Ministry, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.

Graphical Abstract:

Abstract:

Total synthesis of three Febuxostat metabolites, named 67M-1, 67M-2, and 67M-4,is described in this article. Through condensation of the key intermediate compound A with different side chains, and then oxidation and hydrolysis, we obtained three target compounds with an overall yield of 19.5%-28.0%.

VOLUME: 12
ISSUE: 3
Page: [217 – 221]
Pages: 5
DOI: 10.2174/1570178612666150108000805, http://www.eurekaselect.com/127479/article

ULORIC (febuxostat) is a xanthine oxidase inhibitor. The active ingredient in ULORIC is 2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid, with a molecular weight of 316.38. The empirical formula is C₁₆H₁₆N₂O₃S.

The chemical structure is:

ULORIC (febuxostat) Structural Formula Illustration

Febuxostat is a non-hygroscopic, white crystalline powder that is freely soluble in dimethylformamide; soluble in dimethylsulfoxide; sparingly soluble in ethanol; slightly soluble in methanol and acetonitrile; and practically insoluble in water. The melting range is 205°C to 208°C.

LORIC tablets for oral use contain the active ingredient, febuxostat, and are available in two dosage strengths, 40 mg and 80 mg. Inactive ingredients include lactose monohydrate, microcrystalline cellulose, hydroxypropyl cellulose, sodium croscarmellose, silicon dioxide and magnesium stearate. ULORIC tablets are coated with Opadry II, green.

CN1642546A *	Mar 28, 2003	Jul 20, 2005	Teijin Ltd.	Containing a single crystalline solid preparation
CN102471295A *	Jul 14, 2010	May 23, 2012	Teijin Pharma Ltd.	The method of manufacturing the poor solvent additive method of 2- (3-cyano-4-isobutyl-phenyl) -4-methyl-5-carboxylic acid crystalline polymorph of
EP2502920A1 *	Mar 25, 2011	Sep 26, 2012	Sandoz Ag	Crystallization process of Febuxostat from A
JP2011020950A *				Title not available

WO2015018507A3 *	Jul 30, 2014	Oct 22, 2015	Pharmathen S.A.	A novel process for the preparation of febuxostat
CN103304512A *	Jun 4, 2013	Sep 18, 2013	华南理工大学	Preparation method for febuxostat

WO2011031409A1 *	Aug 12, 2010	Mar 17, 2011	Teva Pharmaceutical Industries Ltd.	Processes for preparing febuxostat
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US5614520	Jan 30, 1995	Mar 25, 1997	Teijin Limited	2-arylthiazole derivatives and pharmaceutical composition thereof

CN102229581A *	Nov 15, 2010	Nov 2, 2011	邹巧根	Preparation method for febuxostat intermediate
JPH1045733A *	Title not available

CN101497589A *	Feb 26, 2009	Aug 5, 2009	沈阳药科大学	Method for synthesizing 2-(3-cyano-4- isobutoxy phenyl)-4-methyl-carboxylate
CN101863854A *	Jun 29, 2010	Oct 20, 2010	沈阳药科大学	Synthesis method of 2-(3-cyan-4-isobutoxy) phenyl-4-methyl-5-thiazole formic acid
JP2706037B2 *				Title not available

Reference
1	*	HASEGAWA, M. ET AL.: ‘A facile one-pot synthesis of 4-alkoxy-1,3-benzenedicarbonitrile‘ HETEROCYCLES vol. 47, no. 2, 1998, pages 857 – 864

WO2012131590A1 *	Mar 28, 2012	Oct 4, 2012	Sandoz Ag	An improved process for preparation of febuxostat and its polymorphic crystalline form c thereof
WO2014009817A1 *	Mar 19, 2013	Jan 16, 2014	Alembic Pharmaceuticals Limited	Pharmaceutical composition of febuxostat
WO2014057461A1	Oct 10, 2013	Apr 17, 2014	Ranbaxy Laboratories Limited	Process for the preparation of crystalline form g of febuxostat
WO2015018507A3 *	Jul 30, 2014	Oct 22, 2015	Pharmathen S.A.	A novel process for the preparation of febuxostat
CN102631943A *	Mar 21, 2012	Aug 15, 2012	中国科学院大连化学物理研究所	Iron-phosphorus-base catalyst for preparing bromomethane by methane oxybromination, and preparation method and application thereof
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CN102964313A *	Nov 27, 2012	Mar 13, 2013	周广连	Synthetic method of febuxostat
CN102964313B *	Nov 27, 2012	Apr 29, 2015	周广连	Synthetic method of febuxostat
CN103936688A *	Jan 21, 2013	Jul 23, 2014	上海华拓医药科技发展股份有限公司	Preparation method of 2-(3-cyano-4-(2-methyl propoxy) phenyl)-4-methyl-5-thiazolecarboxylic acid crystal A

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WO2012131590A1 *	Mar 28, 2012	Oct 4, 2012	Sandoz Ag	An improved process for preparation of febuxostat and its polymorphic crystalline form c thereof
WO2014009817A1 *	Mar 19, 2013	Jan 16, 2014	Alembic Pharmaceuticals Limited	Pharmaceutical composition of febuxostat
WO2014057461A1	Oct 10, 2013	Apr 17, 2014	Ranbaxy Laboratories Limited	Process for the preparation of crystalline form g of febuxostat

Febuxostat
Systematic (IUPAC) name

2-(3-cyano-4-isobutoxyphenyl)-4-methyl- 1,3-thiazole-5-carboxylic acid
Clinical data
Trade names	Uloric, Adenuric, Atenurix, Feburic, Goturic, Goutex. Generic in several countries.^[1]
AHFS/Drugs.com	Monograph
MedlinePlus	a609020
License data	EU EMA: Adenuric US FDA: Febuxostat
Pregnancy category	US: C (Risk not ruled out)
Routes of administration	Oral
Legal status
Legal status	US: ℞-only
Pharmacokinetic data
Bioavailability	~49% absorbed
Protein binding	~99% to albumin
Metabolism	via CYP1A2, 2C8, 2C9,UGT1A1, 1A3, 1A9, 2B7
Biological half-life	~5-8 hours
Excretion	Urine (~49% mostly as metabolites, 3% as unchanged drug); feces (~45% mostly as metabolites, 12% as unchanged drug)
Identifiers
CAS Number	144060-53-7
ATC code	M04AA03 (WHO)
PubChem	CID 134018
IUPHAR/BPS	6817
DrugBank	DB04854
ChemSpider	118173
UNII	101V0R1N2E
KEGG	D01206
ChEMBL	CHEMBL1164729
Chemical data
Formula	C₁₆H₁₆N₂O₃S
Molar mass	316.374 g/mol

/////////Febuxostat, 144060-53-7, Uloric, Adenuric, Tei 6720, thiazole derivative, inhibitor of XANTHINE OXIDASE, treatment of HYPERURICEMIA, chronic GOUT, FBX, Febugood, Feburic, Febutaz, TMX 67, Zurig

CC1=C(SC(=N1)C2=CC(=C(C=C2)OCC(C)C)C#N)C(=O)O

Mastoparan

Uncategorized Comments Off

Jul 082016

Mastoparan, Peptide (H-INLKALAALAKKIL-NH₂)

IUPAC Condensed

H-Ile-Asn-Leu-Lys-Ala-Leu-Ala-Ala-Leu-Ala-Lys-Lys-xiIle-Leu-NH2

LINUCS

[][L-Leu-NH2]{[(1+2)][L-xiIle]{[(1+2)][L-Lys]{[(1+2)][L-Lys]{[(1+2)][L-Ala]{[(1+2)][L-Leu]{[(1+2)][L-Ala]{[(1+2)][L-Ala]{[(1+2)][L-Leu]{[(1+2)][L-Ala]{[(1+2)][L-Lys]{[(1+2)][L-Leu]{[(1+2)][L-Asn]{[(1+2)][L-Ile]{}}}}}}}}}}}}}}

Sequence

INLKALAALAKKXL

HELM

PEPTIDE1{I.N.L.K.A.L.A.A.L.A.K.K.[*N[C@H](C(=O)*)C(C)CC |$_R1;;;;;_R2;;;;$|].L.[am]}$$$$

Mastoparan

Ile – Asn – Leu – Lys – Ala – Leu – Ala – Ala – Leu – Ala – Lys – Lys – Ile – Leu -NH₂

(2S)-N-[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-amino-4-methyl-1-oxopentan-2-yl]amino]-3-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxopropan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxopropan-2-yl]amino]-1-oxopropan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxopropan-2-yl]amino]-1-oxohexan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]-2-[[(2S,3S)-2-amino-3-methylpentanoyl]amino]butanediamide

Mastoparan; Mast cell degranulating peptide (Vespula lewisii); NSC351907; CAS 72093-21-1;
Molecular Formula:	C₇₀H₁₃₁N₁₉O₁₅
Molecular Weight:	1478.90744 g/mol

18: PN: WO0181408 SEQID: 37 claimed protein
18: PN: WO2010069074 SEQID: 16 claimed protein
L-Leucinamide, L-isoleucyl-L-asparaginyl-L-leucyl-L-lysyl-L-alanyl-L-leucyl-L-alanyl-L-alanyl-L-leucyl-L-alanyl-L-lysyl-L-lysyl-L-isoleucyl-
Mastoparan 1

NSC 351907

Description

Mastoparan (Vespula lewisii) has been shown to cause an increase in the production of Arachidonic Acid (sc-200770) catalyzed by PLA2 from porcine pancreas and bee venom. This compound also displays toxicity by regulating G proteins via mimicking of G-protein-coupled receptors. Additionally, Mastoparan has been reported as a stimulator of insulin release by pancreatic islets, which acts through GTP-binding proteins and PLA2. In other experiments, this agent has demonstrated the ability to cause exocytosis of rat peritoneal mast cells and also stimulate the accumulation of inositol phosphates in hepatocytes. Additionally, Mastoparan has been noted to act as a mitogen in Swiss 3T3 cells and stimulate pertussis toxin-sensitive Arachidonate release without phosphoinositide breakdown. Mastoparan (Vespula lewisii) is an inhibitor of CaM. Mastoparan (Vespula lewisii) is an activator of Heterotrimeric G Protein and PLA2.

Technical Information

Physical State:	Solid
Derived from:	Synthetic. Originally isolated from wasp venom (Vespula lewisii)
Solubility:	Soluble in water (2.6 mg/ml), and 100% ethanol.
Storage:	Store at -20° C
Refractive Index:	n²⁰_D 1.53
IC50:	Na+,K+-ATPase: IC₅₀ = 7.5 µM

Mastoparan is a peptide toxin from wasp venom. It has the chemical structure Ile-Asn-Leu-Lys-Ala-Leu-Ala-Ala-Leu-Ala-Lys-Lys-Ile-Leu-NH2.^[2]

The net effect of mastoparan’s mode of action depends on cell type, but seemingly always involves exocytosis. In mast cells, this takes the form of histamine secretion, while in platelets and chromaffin cells release serotonin and catecholamines are found, respectively. Mastoparan activity in the anterior pituitary gland leads to prolactin release.

In the case of histamine secretion, the effect of mastoparan takes place via its interference with G protein activity. By stimulating theGTPase activity of certain subunits, mastoparan shortens the lifespan of active G protein. At the same time, it promotes dissociation of any bound GDP from the protein, enhancing GTP binding. In effect, the GTP turnover of G proteins is greatly increased by mastoparan. These properties of the toxin follow from the fact that it structurally resembles activated G protein receptors when placed in a phospholipid environment. The resultant G protein-mediated signaling cascade leads to intracellular IP₃ release and the resultant influx of Ca²⁺.

In an experimental study conducted by Tsutomu Higashijima and his counterparts, mastoparan was compared to melittin, which is found in bee venom.^[2] Mainly, the structure and reaction to phosphate was studied in each toxin. Using Circular Dichroism (CD), it was found that when mastoparan was exposed to methanol, an alpha helical form existed. It was concluded that strong intramolecular hydrogen bonding occurred. Also, two negative bands were present on the CD spectrum. In an aqueous environment, mastoparan took on a nonhelical, unordered form. In this case, only one negative band was observed on the CD spectrum. Adding phosphate buffer to mastoparan resulted in no effect.

Melittin produced a different conformational change than mastoparan. In an aqueous solution, melittin went from a nonhelical form to an alpha helix when phosphate was added to the solution. The binding of melittin to the membrane was believed to result fromelectrostatic interactions, not hydrophobic interactions.

Infections caused by multidrug resistant bacteria are currently an important problem worldwide. Taking into account data recently published by the WHO, lower respiratory infections are the third cause of death in the world with around 3.2 million deaths per year, this number being higher compared to that related to AIDS or diabetes mellitus [1]. It is therefore important to solve this issue, although the perspectives for the future are not very optimistic. During the last 30 years an enormous increase has been observed of superbugs isolated in the clinical setting, especially from the group called ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) which show high resistance to all the antibacterial agents available [2]. We will focus on Acinetobacter baumannii, the pathogen colloquially called “iraquibacter” for its emergence in the Iraq war. It is a Gram-negative cocobacillus and normally affects people with a compromised immune system, such as patients in the intensive care unit (ICU) [3] and [4]. Together with Escherichia coliand P. aeruginosa, A. baumannii are the most common cause of nosocomial infections among Gram-negative bacilli. The options to treat infections caused by this pathogen are diminishing since pan-drug resistant strains (strains resistant to all the antibacterial agents) have been isolated in several hospitals [5]. The last option to treat these infections is colistin, which has been used in spite of its nephrotoxic effects [6]. The evolution of the resistance of A. baumannii clinical isolates has been established by comparing studies performed over different years, with the percentage of resistance to imipenem being 3% in 1993 increasing up to 70% in 2007. The same effect was observed with quinolones, with an increase from 30 to 97% over the same period of time[7]. In Spain the same evolution has been observed with carbapenems; in 2001 the percentage of resistance was around 45%, rising to more than 80% 10 years later [8]. Taking this scenario into account, there is an urgent need for new options to fight against this pathogen. One possible option is the use of antimicrobial peptides (AMPs) [9],[10] and [11], and especially peptides isolated from a natural source [12]. One of the main drawbacks of using peptides as antimicrobial agents is the low stability or half-life in human serum due to the action of peptidases and proteases present in the human body[13], however there are several ways to increase their stability, such as using fluorinated peptides [14] and [15]. One way to circumvent this effect is to study the susceptible points of the peptide and try to enhance the stability by protecting the most protease labile amide bonds, while at the same time maintaining the activity of the original compound. Another point regarding the use of antimicrobial peptides is the mechanism of action. There are several mechanisms of action for the antimicrobial peptides, although the global positive charge of most of the peptides leads to a mechanism of action involving the membrane of the bacteria [16]. AMPs has the ability to defeat bacteria creating pores into the membrane [17], also acting as detergents [18], or by the carpet mechanism [19]. We have previously reported the activity of different peptides against colistin-susceptible and colistin-resistant A. baumannii clinical isolates, showing that mastoparan, a wasp generated peptide (H-INLKALAALAKKIL-NH₂), has good in vitro activity against both colistin-susceptible and colistin-resistant A. baumannii [20]. Therefore, the aim of this manuscript was to study the stability of mastoparan and some of its analogues as well as elucidate the mechanism of action of these peptides.

Paper

European Journal of Medicinal Chemistry

Volume 101, 28 August 2015, Pages 34–40

Research paper

Sequence-activity relationship, and mechanism of action of mastoparan analogues against extended-drug resistantAcinetobacter baumannii

^a ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
^b Biomedical Institute of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville, Seville, Spain
^c Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
^d Department of Clinical Microbiology, CDB, Hospital Clinic, School of Medicine, University of Barcelona, Barcelona, Spain
^e Department of Organic Chemistry, University of Barcelona, Barcelona, Spain

http://www.sciencedirect.com/science/article/pii/S0223523415300933

doi:10.1016/j.ejmech.2015.06.016

Highlights

•The most susceptible position of mastoparan is the peptide bond between isoleucine and asparagine.
•The positive charge present in the N-terminal play an important role in the antimicrobial activity of the peptides.
•Mastoparan and its enantiomer version exhibit a mechanism of action related to the membrane disruption of bacteria.
•Three of the mastoparan analogues synthesized have good activity against highly resistant Acinetobacter baumannii.
•Two of the active analogues showed a significant increase in the human serum stability compared to mastoparan.

Abstract

The treatment of some infectious diseases can currently be very challenging since the spread of multi-, extended- or pan-resistant bacteria has considerably increased over time. On the other hand, the number of new antibiotics approved by the FDA has decreased drastically over the last 30 years. The main objective of this study was to investigate the activity of wasp peptides, specifically mastoparan and some of its derivatives against extended-resistant Acinetobacter baumannii. We optimized the stability of mastoparan in human serum since the specie obtained after the action of the enzymes present in human serum is not active. Thus, 10 derivatives of mastoparan were synthetized. Mastoparan analogues (guanidilated at the N-terminal, enantiomeric version and mastoparan with an extra positive charge at the C-terminal) showed the same activity against Acinetobacter baumannii as the original peptide (2.7 μM) and maintained their stability to more than 24 h in the presence of human serum compared to the original compound. The mechanism of action of all the peptides was carried out using a leakage assay. It was shown that mastoparan and the abovementioned analogues were those that released more carboxyfluorescein. In addition, the effect of mastoparan and its enantiomer against A. baumannii was studied using transmission electron microscopy (TEM). These results suggested that several analogues of mastoparan could be good candidates in the battle against highly resistant A. baumannii infections since they showed good activity and high stability.

Graphical abstract

References

PDB: 2CZP; Todokoro Y, Yumen I, Fukushima K, Kang SW, Park JS, Kohno T, Wakamatsu K, Akutsu H, Fujiwara T (August 2006). “Structure of Tightly Membrane-Bound Mastoparan-X, a G-Protein-Activating Peptide, Determined by Solid-State NMR”. Biophys. J. 91 (4): 1368–79. doi:10.1529/biophysj.106.082735. PMC 1518647. PMID 16714348.
Higashijima T, Uzu S, Nakajima T, Ross EM (May 1988). “Mastoparan, a peptide toxin from wasp venom, mimics receptors by activating GTP-binding regulatory proteins (G proteins)”. J. Biol. Chem. 263 (14): 6491–4. PMID 3129426.

Reference

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- An increasing threat in hospitals: multidrug resistant Acinetobacter baumannii
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- Therapeutic options for Acinetobacter baumannii infections: an update
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- In vitro activity of 18 antimicrobial agents against clinical isolates of Acinetobacter spp. Multicenternational study GEIH-REIPI-Ab 2010
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- Structure, membrane orientation, mechanism, and function of pexiganan–a highly potent antimicrobial peptide designed from magainin
- Biochim. Biophys. Acta, 1788 (2009), pp. 1680–1686
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- Efficacy of six frog skin-derived antimicrobial peptides against colistin-resistant strains of theAcinetobacter baumannii group
- Int. J. Antimicrob. Agents, 39 (2012), pp. 317–320
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- Antimicrobial activity and protease stability of peptides containing fluorinated amino acids
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- Bad bugs, no drugs: no ESKAPE! An update from the infectious diseases Society of Ame
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- L.M. Gottler, R. de la Salud Bea, C.E. Shelburne, A. Ramamoorthy, E.N. Marsh
- Using fluorous amino acids to probe the effects of changing hydrophobicity on the physical and biological properties of the beta-hairpin antimicrobial peptide protegrin-1
- Biochemistry, 47 (2008), pp. 9243–9250
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- Small cationic antimicrobial peptides delocalize peripheral membrane proteins
- Proc. Natl. Acad. Sci. U. S. A., 111 (2014), pp. E1409–E1418
- D.K. Lee, J.R. Brender, M.F. Sciacca, J. Krishnamoorthy, C. Yu, A. Ramamoorthy
- A. Lipid composition-dependent membrane fragmentation and pore-forming mechanisms of membrane disruption by pexiganan (MSI-78)
- Biochemistry, 52 (2013), pp. 3254–3263
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- Detergent-type membrane fragmentation by MSI-78, MSI-367, MSI-594, and MSI-843 antimicrobial peptides and inhibition by cholesterol: a solid-state nuclear magnetic resonance study
- Biochemistry, 54 (2015), pp. 1897–1907
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- Probing the “charge cluster mechanism” in amphipathic helical cationic antimicrobial peptides
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- Clin. Microbiol. Infect., 18 (2012), pp. 383–387

Patent IDDatePatent TitleUS20160672612016-03-10SERCA INHIBITOR AND CALMODULIN ANTAGONIST COMBINATION

Mastoparan
Solution structure of mastoparan from Vespa simillima xanthoptera.^[1]
Identifiers
Symbol	Mastoparan_2
Pfam	PF08251
InterPro	IPR013214
TCDB	1.C.32
OPM superfamily	160
OPM protein	2czp

///////Peptide, Antimicrobial peptide, Mastoparan, Acinetobacter baumannii, NSC351907, 72093-21-1, NSC 351907

CCC(C)C(C(=O)NC(CC(=O)N)C(=O)NC(CC(C)C)C(=O)NC(CCCCN)C(=O)NC(C)C(=O)NC(CC(C)C)C(=O)NC(C)C(=O)NC(C)C(=O)NC(CC(C)C)C(=O)NC(C)C(=O)NC(CCCCN)C(=O)NC(CCCCN)C(=O)NC(C(C)CC)C(=O)NC(CC(C)C)C(=O)N)N

Eldecalcitol, an active vitamin D3 analog used to treat osteoporosis

Uncategorized Comments Off

Jul 072016

Eldecalcitol

(1S,2S,3S,5Z)-5-[(2E)-2-[(1R,3aS,7aR)-1-[(2R)-6-hydroxy-6-methylheptan-2-yl]-7a-methyl-2,3,3a,5,6,7-hexahydro-1H-inden-4-ylidene]ethylidene]-2-(3-hydroxypropoxy)-4-methylidenecyclohexane-1,3-diol

(1R,2R,3R,5Z,7E)-2-(3-Hydroxypropyloxy)-9,10-secocholesta-5,7,10(19)-triene-1,3,25-triol

AC1O5QQ2; CAS 104121-92-8; AN-3697; ED 71, Edirol^®
Molecular Formula:	C₃₀H₅₀O₅
Molecular Weight:	490.715 g/mol

APPROVED JAPAN , 2011-01-21, Chugai (Originator) , Roche,Taisho Toyama

Eldecalcitol was approved by Pharmaceuticals and Medicals Devices Agency of Japan (PMDA) on January 21, 2011. It was developed by Chugai Pharmaceutical (a member of Roche) and marketed as Edirol^® by Chugai Pharmaceutical and Taisho.

Eldecalcitol is an orally active vitamin D analogue leading to greater absorption of bind calcium. It is usually used to treat osteoporosis.

Edirol^® is available as capsule for oral use, containing 0.5 μg or 0.75 μg of free Eldecalcitol, and the recommended dose is 0.75 μg once daily.

ED-71, a vitamin D analog, is a more potent inhibitor of bone resorption than alfacalcidol in an estrogen-deficient rat model of osteoporosis. ED-71, effectively and safely increased lumbar and hip bone mineral density (BMD) in osteoporotic patients who also received vitamin D3 supplementation.

Eldecalcitol is a drug used in Japan for the treatment of osteoporosis.^[1] It is an analog of vitamin D.^[2] Osteoporosis is a common bone disease among the older generation, with an estimated prevalence of over 200 million people.^[1] This condition often results in bone fractures due to abnormally low bone mass density, and is a leading cause of disability, especially among developed countries with longer average life spans. Osteoporosis is more common in women than with men.

Eldecalcitol

Discovery

Chugai Pharmaceutical/Roche are the originators of the medicinal drug eldecalcitol through Taisho Pharmaceutical Holdings and Chugai Pharmaceutical. The trade name of eldecalcitol is Edirol, and its Chemical Abstracts Service (CAS) registry number is 104121-92-8. Eldecalcitol was approved for use in Japan on January 2011. The approval came from the Japanese Ministry of Health, Labor, and Welfare for the objective of a treatment for osteoporosis.^[3]

Effects

Clinical trials have suggested that eldecalcitol, a vitamin D analog, has strong effects to reduce calcium reabsorption into the body from bones, therefore increasing bone mineral density, and to increase calcium absorption in intestines.^[4] In animals, eldecalcitol inhibits the activity of osteoclasts for the function to reduce bone degradation for calcium, while still able to maintain osteoblast function so as to not hinder bone formation.^[5] Unlike other vitamin D analogs, eldecalcitol does not significantly suppress parathyroid hormone levels, promising a better treatment for osteoporosis in comparison to other medications.^[6] Bone mineral density increases with eldecalcitol use, in addition to strengthening bone structure. This occurs due to the function of the eldecalcitol drug, which decreases bone reabsorption as observed through a bone reabsorption marker. Bone geometry assessments show that eldecalcitol increases cortical bone area in patients with osteoporosis more so than other vitamin D analogs, such as alfacalcidol. There was also the maintenance of thickness of cortical bone mass, strongly indicating that eldecalcitol improves the strength and mass of bone, specifically cortical bone structure.^[7] Adverse effects of eldecalcitol include an increase in blood and urinary calcium levels. Abnormally high levels of calcium can lead to problems associated with hypercalcemia.

Treatment for Osteoporosis

Eldecalcitol can be used for the treatment of hypocalcaemia or osteoporosis. Calcium absorption increases with the presence of eldecalcitol by the body, occurring in the intestines, which is useful for those who have low calcium levels. Eldecalcitol is more often used due to its effects to treat osteoporosis. In the aging population, the bone matrix becomes weakened through untreated osteoporosis. This leads to an increased risk of severe fractures that include spinal and hip fractures in addition to vertebral and wrist fractures. This creates a burden on the health care system due to a decline in the quality of life for the individuals that suffer from this condition. Some risk factors leading to the predisposition of developing osteoporosis are previous incidents of bone fractures and a reduction in bone mineral density.^[1] These factors expectantly increase as age increases. Bone health is reliant on maintaining physiologically needed levels of calcium, where the body constantly maintains this calcium homeostasis through osteoblast and osteoclast activity. Osteoblast activity serves this function of maintaining appropriate calcium levels by depositing calcium in bones when blood calcium levels are above normal. In contrast, osteoclasts break down bone tissue to increase blood calcium levels if they are low.^[8] This activity is performed after absorption of calcium by the body, which requires the actions of vitamin D. The active metabolite of vitamin D, calcitriol, performs its function through interactions with the calcitriol receptor. This nuclear hormone receptor is responsible for calcium absorption which, in turn, is involving in bone depletion and formation. The new analogs of vitamin D, such as eldecalcitol, are observed to have stronger effects in preventing bone loss, fractures, and falls in comparison to calcitriol.^[9] Eldecalcitol is even more effective than its counterpart alfacalcidol, another vitamin D analog. Studies have shown eldecalcitol is more effective than alfacalcidol in preventing vertebral and wrist fractures, and even falls, with osteoporotic patients with vitamin D insufficiencies.^[10] Eldecalcitol is also more effective at preventing fractures than vitamin D and calcium supplements.^[1] Eldecalcitol increases calcium absorption for vitamin D deficient patients, and therefore could be used for osteoporosis treatment for all age groups.

Pharmacology

Analogs of vitamin D are being explored intensely for their regulatory effects on calcium metabolism with the purpose of treating osteoporosis, a skeletal disease associated with low bone mass and deterioration of bone tissue. Vitamin D is imperative for absorption of calcium to maintain bone strength.

Mechanism of Action

Eldecalcitol is an orally administered drug to patients, which binds to vitamin D receptors and binding protein for the goal of achieving greater specificity to bind calcium for its absorption. This greater affinity is 2.7-fold that of the active vitamin D form of calcitriol. Eldecalcitol is readily absorbed into the body, with a long elimination half-life of over eight hours, reaching maximum absorption in 3.4 hours.^[1]

Dosage

Eldecalcitol is present in the form of pills for oral administration. In preclinical models with healthy male volunteers, oral doses of eldecalcitol ranged from 0.1 to 1.0 micrograms once daily to show an increase in bone mineral density.^[11] Preclinical trials show improvements for doses at 0.5 and 0.75 micrograms, which are the recommended dosage amounts for the Edirol product as approved by the Japanese Ministry of Health, Labor, and Welfare for treating osteoporosis.^[3]

Chemistry

The class of eldecalcitol is a vitamin D3 derivative. This molecule has a molecular weight of 490.71 grams per mole. The eldecalcitol analog of calcitriol, contains a hydroxypropyl group in the lower cyclohexane ring. The synthesis of eldecalcitol incorporates two units assembled together. The IUPAC names include (3S, 4S, 5R)-oct-1-en-7-yne-3,4,5-triol that is fused to a bicyclic system, (R)-6-((1R, 3aR, 7aR, E)-4-(bromomethylene)-7a-methyloctahydro-1H-inden-1-yl)-2-methylheptan-2-ol. The assembly process includes a Diels-Alder reaction to give the fully protected eldecalcitol. In order to get the parent molecule, the hydroxyl groups have to be deprotected. The chemistry of eldecalcitol allows for its binding 2.7-fold more potently than calcitriol. In addition, some vitamin D derivatives have been known to inhibit the serum parathyroid hormone. Eldecalcitol only weakly inhibits the serum parathyroid hormone, making it an even more appealing medicinal drug for its physiological uses in the treatment of osteoporosis.^[3] Animal studies of eldecalcitol, in ovariectomized rats, show improvements in bone mass while lowering bone reabsorption to demonstrate its effectiveness in osteoporosis treatment.^[5]

PAPER

Heterocycles, Vol 92, No. 6, 2016, pp.1013-1029
Published online, 22nd March, 2016

DOI: 10.3987/REV-16-840

https://www.heterocycles.jp/newlibrary/payments/form/24714/fulltext

■ Diverse and Important Contributions by Medicinal Chemists to the Development of Pharmaceuticals: An Example of Active Vitamin D3 Analog, Eldecalcitol

Noboru Kubodera*

*International Institute of Active Vitamin D Analogs, 35-6, Sankeidai, Mishima, Shizuoka 411-0017, Japan

Abstract

Presented herein are diverse and important contributions by medicinal chemists to different stages of pharmaceutical development. The conceptual elements reviewed, which are intended for young chemists who engage in drug discovery research, draw upon the author’s experience in developing eldecalcitol, an active vitamin D3 analog used to treat osteoporosis. The review covers exploratory research for a lead candidate compound; process development for practical manufacturing; and synthesis of other compounds relevant to the program, such as tritiated compounds, postulated metabolites, and miscellaneous analogs for mode of action studies.

PAPER

Eldecalcitol [1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D₃], an analog of calcitriol (1α,25-dihydroxyvitamin D₃), possesses a hydroxypropoxy substituent at the 2β-position of calcitriol. Eldecalcitol has potent biological effects on bone disease such as osteoporosis. The marketing of eldecalcitol has very recently started in Japan. In consideration of this, we have been investigating practical synthesis of eldecalcitol for industrial-scale production. Eldecalcitol was initially synthesized in a linear manner. The 27-step linear sequence was, however, suboptimal due to its lengthiness and low overall yield (ca. 0.03%). Next, we developed a convergent approach based on the Trost coupling reaction, in which the A-ring fragment (ene-yne part obtained in 10.4% overall yield) and the C/D-ring fragment (bromomethylene part obtained in 27.1% overall yield) are coupled to produce the triene system of eldecalcitol (15.6%). Although the overall yield of the convergent synthesis was better than that of the linear synthesis, significant improvements were still necessary. Therefore, additional biomimetic studies were investigated. Process development for the practical production of eldecalcitol is described herein.

http://ar.iiarjournals.org/content/32/1/303/F3.expansion.html

Convergent synthesis of eldecalcitol (5) by coupling A-ring fragment 37 with C/D-ring fragment 40. Reagents and conditions: a: HO(CH₂)₃OH/t-BuOK, 120°C. b: t-BuCOCl/pyridine/CH₂Cl₂, rt. c: H₂/Pd(OH)₂/MeOH, rt. d: Me₂C(OMe)₂/TsOH/acetone, rt. e: DMSO/(COCl)₂/CH₂Cl₂, −60°C. f: CH₂=CHMgBr/THF, −60°C. g: t-BuCOCl/Et₃N/DMAP/CH₂Cl₂, rt. h: 1 M HCl/MeOH, rt. i: Ph₃P/DEAD/benzene, reflux. j: LiC ≡ CTMS/BF₃-OEt₂, −78°C. k: 10 N NaOH/MeOH, rt. l: TBSOTf/Et₃N/CH₂Cl₂, 0°C. m: TESOTf/Et₃N/CH₂Cl₂, 0°C. n: O₃/CH₂Cl₂/MeOH, −78°C then NaBH₄/MeOH, −78°C. o: NMO/TPAP/4Ams/CH₂Cl₂, rt. p: Ph₃P⁺CH₂BrBr⁻/NaHMDS/ THF, −60°C to rt. q: (dba)₃Pd₂-CHCl₃/PPh₃/Et₃N/toluene, reflux. r: TBAF/THF/toluene, reflux.

Industrial synthesis of alfacalcidol (4) and biomimetic synthesis of eldecalcitol (5) from cholesterol (42). Reagents and conditions: a: [Al(Oi-Pr)₃]/cyclohexanone. b: DDQ/AcOEt. c: NaOEt/EtOH. d: NaBH₄/MeOH/THF. e: Ac₂O/DMPA/pyridine, rt. f: NBS/AIBN/n-hexane, reflux. g: γ-collidine/toluene, reflux. h: KOH/MeOH, rt. i: PTAD/CH₂Cl₂, rt. j: TBSCl/imidazole. k: MCPBA/CH₂Cl₂. l: DMI, 140°C. m: TBAF/THF. n: NaBH₄/EtOH. o: 400 W high pressure mercury lamp/THF, 0°C then reflux without mercury lamp. p: HO(CH₂)₃OH/t-BuOK, 110°C. q: Microbial 25-hydroxylation.

ROUTE1

Reference：1. US4666634A / EP184206A2.

2. Chem. Pharm. Bull. 1993, 41, 1111-1113.

3. Drug Evaluation Research 2011, 34, 224-229.

Route 2

Reference：1. Anticancer. Res. 2012, 32, 303-310.

2. Drugs. Fut. 2005, 30, 450-461.

Route 3

Reference：1. J. Am. Chem. Soc. 2001, 123, 3716-3722.

Route 4

Reference：1. Bioorg. Med. Chem. Lett. 1997, 7, 2871-2874.

2. Anticance. Res. 2009, 29, 3571-3578.

3. Heterocycles 2009, 77, 323-331.

4. Heterocycles 2006, 70, 295-307.

Route 5

Reference：1. EP0503630A1.

2. Drugs Fut. 2005, 30, 450-461.

Route 6

Reference：1. Bioorg. Med. Chem. 1998, 6, 2517-2523.

References

Sanford, M; McCormack, PL (2011). “Eldecalcitol: A review of its use in the treatment of osteoporosis”. Drugs 71 (13): 1755–70. doi:10.2165/11206790-000000000-00000. PMID 21902297.
Hatakeyama, S; Yoshino, M (2010). “Synthesis and preliminary biological evaluation of 20-epieldecalcitol [20-epi-1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D3: 20-epi-ED-71]”. The Journal of Steroid Biochemistry and Molecular Biology 121 (1–2): 25–28.doi:10.1016/j.jsbmb.2010.03.041. PMID 20304058.
Robichaud; Stamford; Weinstein; McAlpine; Primeau; Lowe; Bernstein; Bronson; Manoj, Desai (2012). Annual Reports in Medicinal Chemistry 47 (1st ed.). San Diego: Elsevier Inc. pp. 529–531. ISBN 9780123964922.
Nogachi, Y; Kawate, H; Nomura, M; Takayanagi, R (2013). “Eldecalcitol for the treatment of osteoporosis”. Europe PubMed Central 8: 1313–1321. doi:10.2147/CIA.S49825.
Smith, S; Doyle, N; Boyer, M; Chouinard, L; Saito, H (2013). “Eldecalcitol, a vitamin D analog, reduces bone turnover and increases trabecular an cortical bone mass, density, and strength in ovariectomized cynomolgus monkeys”. Bone 57 (1): 116–122.doi:10.1016/j.bone.2013.06.005. PMID 23774444.
Harada, S; Uno, S; Takahashi, F; Saito, H (2010). “Eldecalcitol is less effective in suppressing parathyroid hormone compared to calcitriol in vivo“. The Journal of Steroid Biochemistry and Molecular Biology 121 (1–2): 281–283.doi:10.1016/j.jsbmb.2010.04.001. PMID 20398764.
Nakamura, T; Takano, T; Fukunaga, M; Shiraki, M; Matsumoto, T (2013). “Eldecalcitol is more effective for the prevention of osteoporotic fractures than alfacalcidol”. Journal of Bone and Mineral Metabolism 31 (4): 417–422. doi:10.1007/s00774-012-0418-5.PMC 3709079. PMID 23575909.
Matsuo, K; Irie, N (2008). “Osteoclast-osteoblast communication”. Archives of Biochemistry and Biophysics 473 (2): 201–209. doi:10.1016/j.abb.2008.03.027.PMID 18406338.
Saito, H; Takeda, S; Amizuka, N (2013). “Eldecalcitol and calcitriol stimulates ‘bone minimodeling,’ focal bone formation without prior bone resorption, in rat trabecular bone”.The Journal of Steroid Biochemistry and Molecular Biology 136 (1): 178–182.doi:10.1016/j.jsbmb.2012.10.004.
Matsumoto, T; Ito, M; Hayashi, Y; Hirota, T; Tanigawara, Y; Sone, T; Fukunaga, M; Shiraki, M; Nakamura, T (2011). “A new active vitamin D3 analog, eldecalcitol, prevents the risk of osteoporotic fractures—A randomized, active comparator, double-blind study”. Bone49 (4): 605–612. doi:10.1016/j.bone.2011.07.011. PMID 21784190.
Harada, S; Mizoguchi, T; Kobayashi, Y; Nakamichi, Y; Takeda, S; Sakai, S; Takahashi, F; Saito, H; Yasuda, H; Udagawa, N; Suda, T; Takahashi, N (2012). “Daily administration of eldecalcitol (ED-71), an active vitamin D analog, increases bone mineral density by suppressing RANKL expression in mouse trabecular bone”. Journal of Bone and Mineral Research 27 (1): 461–473. doi:10.1002/jbmr.555.

No.	Major Technical Classification	Publication No.	Patent No.	Legal Status	Filling Date	Estimated Expiry Date
1	Preparation	CN85108857A	CN1008368B	Granted/expired	1985/12/4	2005/12/4
2	Crystal	CN1223639A	CN1216861C	Granted	1997/6/16	2017/6/16
3	Preparation	CN1637017A	CN1276927C

Patent ID	Date	Patent Title
US7927613	2011-04-19	Pharmaceutical co-crystal compositions
US7323580	2008-01-29	CRYSTALS OF A VITAMIN D DERIVATIVE AND A METHOD FOR THE PREPARATION THEREOF
US7235679	2007-06-26	Crystals of a vitamin D derivative and a method for the preparation thereof
EP0924199	2006-05-10	CRYSTALS OF VITAMIN D DERIVATIVES AND PROCESS FOR THE PREPARATION THEREOF
US2005009794	2005-01-13	Crystals of a vitamin D derivative and a method for the preparation thereof
US6831183	2004-12-14	Crystals of a vitamin D derivative and a method for the preparation thereof
US6448421	2002-09-10	CRYSTALS OF VITAMIN D DERIVATIVES AND PROCESS FOR THE PREPARATION THEREOF

Eldecalcitol
Systematic (IUPAC) name

(1S,2S,3S,5Z,7E)-2-(3-Hydroxypropoxy)-9,10-secocholesta-5,7,10-triene-1,3,25-triol
Clinical data
Trade names	Edirol
Identifiers
CAS Number	104121-92-8
ATC code	None
PubChem	CID 6438982
ChemSpider	4943418
Chemical data
Formula	C₃₀H₅₀O₅
Molar mass	490.715 g/mol

///////////eldecalcitol, active vitamin D3 analog, treat osteoporosis, AC1O5QQ2, 104121-92-8, AN-3697, ED 71, ED-71, Edirol^{®, PMDA, JAPAN}

O[C@H]1CC(\C(=C)[C@H](O)[C@H]1OCCCO)=C\C=C2/CCC[C@]3([C@H]2CC[C@@H]3[C@H](C)CCCC(O)(C)C)C

CC(CCCC(C)(C)O)C1CCC2C1(CCCC2=CC=C3CC(C(C(C3=C)O)OCCCO)O)C

Discovery and development of natural product oridonin-inspired anticancer agents

Uncategorized Comments Off

Jul 072016

Natural products have historically been, and continue to be, an invaluable source for the discovery of various therapeutic agents. Oridonin, a natural diterpenoid widely applied in traditional Chinese medicines, exhibits a broad range of biological effects including anticancer and anti-inflammatory activities. To further improve its potency, aqueous solubility and bioavailability, the oridonin template serves as an exciting platform for drug discovery to yield better candidates with unique targets and enhanced drug properties. A number of oridonin derivatives (e.g. HAO472) have been designed and synthesized, and have contributed to substantial progress in the identification of new agents and relevant molecular mechanistic studies toward the treatment of human cancers and other diseases. This review summarizes the recent advances in medicinal chemistry on the explorations of novel oridonin analogues as potential anticancer therapeutics, and provides a detailed discussion of future directions for the development and progression of this class of molecules into the clinic.

Highlights

Oridonin displays significant anticancer activities via multi-signaling pathways.

Recent advances in medicinal chemistry of oridonin-like compounds are presented.

The article summarizes the SAR and mechanism studies of relevant drug candidates.

The milestones and future direction of oridonin-based drug discovery are discussed.

European Journal of Medicinal Chemistry

Volume 122, 21 October 2016, Pages 102–117

Review article

Discovery and development of natural product oridonin-inspired anticancer agents

^a Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, 77555, United States
^b Department of Clinical Cancer Prevention, Division of Cancer Prevention and Population Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, United States

SEE http://www.sciencedirect.com/science/article/pii/S0223523416304937

doi:10.1016/j.ejmech.2016.06.015

Major milestones achieved in oridonin-inspired drug discovery and development.

////////Natural product, Oridonin, Diterpenoids, Anticancer agents, Drug discovery, Chemical biology,

Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): A review

Uncategorized Comments Off

Jul 062016

Highlights

Modification of BHT has a significant multivariate effect on antioxidant efficiency.

BDE is the key to rational design and development of antioxidants.
Antioxidant performance of BHT is mainly depending on 13 very crucial parameters.
MPAO is a promising way to increase antioxidant and pharmacological activities.

Abstract

Hindered phenols find a wide variety of applications across many different industry sectors. Butylated hydroxytoluene (BHT) is a most commonly used antioxidant recognized as safe for use in foods containing fats, pharmaceuticals, petroleum products, rubber and oil industries. In the past two decades, there has been growing interest in finding novel antioxidants to meet the requirements of these industries. To accelerate the antioxidant discovery process, researchers have designed and synthesized a series of BHT derivatives targeting to improve its antioxidant properties to be having a wide range of antioxidant activities markedly enhanced radical scavenging ability and other physical properties. Accordingly, some structure–activity relationships and rational design strategies for antioxidants based on BHT structure have been suggested and applied in practice. We have identified 14 very sensitive parameters, which may play a major role on the antioxidant performance of BHT. In this review, we attempt to summarize the current knowledge on this topic, which is of significance in selecting and designing novel antioxidants using a well-known antioxidant BHT as a building-block molecule. Our strategy involved investigation on understanding the chemistry behind the antioxidant activities of BHT, whether through hydrogen or electron transfer mechanism to enable promising anti-oxidant candidates to be synthesized.

European Journal of Medicinal Chemistry

Volume 101, 28 August 2015, Pages 295–312

Review article

Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): A review

^aNanotechnology & Catalysis Research Centre, (NANOCAT), University of Malaya, Block 3A, Institute of Postgraduate Studies Building, 50603 Kuala Lumpur, Malaysia
^bDepartment of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
^cDivision of Human Biology, Faculty of Medicine, International Medical University, 57000 Kuala Lumpur, Malaysia
^dDrug Design and Development Research Group, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
http://www.sciencedirect.com/science/article/pii/S022352341530101X

doi:10.1016/j.ejmech.2015.06.026

1st Wageeh Yehye

University of Malaya
2nd Noor Rahman

University of Malaya
3rd Azhar Ariffin

University of Malaya
4th Sharifah Bee Abd Hamid

University of Malaya
5th Abeer Abdulhadi Abdulqader

University of Malaya
6th Farkaad A Kadir

International Medical University (IMU)
7th Marzieh Yaeghoobi

University of Malaya

SEE

https://www.researchgate.net/publication/278050005_ChemInform_Abstract_Understanding_the_Chemistry_Behind_the_Antioxidant_Activities_of_Butylated_Hydroxytoluene_BHT_A_Review/figures

///////////Antioxidant, Butylated hydroxytoluene, Free radical, Reactive oxygen species, Phenol

Kinetics of Rh(II)-Catalyzed α-Diazo-β-ketoester Decomposition and Application to the [3+6+3+6] Synthesis of Macrocycles on a Large Scale and at Low Catalyst Loadings

Uncategorized Comments Off

Jul 062016

Kinetics of Rh(II)-Catalyzed α-Diazo-β-ketoester Decomposition and Application to the [3+6+3+6] Synthesis of Macrocycles on a Large Scale and at Low Catalyst Loadings

Daniele Poggiali†, Alexandre Homberg†, Timothée Lathion‡, Claude Piguet‡, and Jérôme Lacour^*†

^†Department of Organic Chemistry and ^‡Department of Inorganic and Analytical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland

ACS Catal., 2016, 6, pp 4877–4881

DOI: 10.1021/acscatal.6b01283

*E-mail: jerome.lacour@unige.ch

http://pubs.acs.org/doi/full/10.1021/acscatal.6b01283

In the context of [3+6+3+6] macrocyclization reactions, precise kinetics of α-diazo-β-ketoester decomposition were measured by in situ infrared (IR) monitoring. Dirhodium complexes of Ikegami–Hashimoto type—and perchlorinated phthalimido derivatives in particular—performed better than classical achiral complexes. Clear correlations were found between speciation among dirhodium species and catalytic activity. With these results, novel cyclohexyl-derived catalysts were developed, affording good yields of macrocycles (up to 78%), at low catalyst loadings (from 0.01 mol % to 0.001 mol %) and on a large scale (from 1 g to 20 g).

///////acceptor-acceptor diazo reagents, dirhodium complexes, in situ IR monitoring, kinetics, low catalyst loading, multigram synthesis, speciation, ylides

Supporting Info

C–H Arylation of Heterocyclic N-Oxides Through in Situ Diazotisation Of Anilines without Added Promoters: A Green And Selective Coupling Process

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Jul 062016

A green and selective method for the generation of biaryl compounds through C–H arylation of heterocyclic N-oxides, in which the addition of ascorbic acid as a promoter is not required for either the generation of an aryldiazonium species or the subsequent arylation, is presented. Reaction conditions were optimized through multivariate data analysis, including orthogonal projections to latent structures (OPLS) and design of experiments (DoE) methodologies, resulting in further sustainability improvements, and were then applied to a range of substrates to establish the scope and limitations of the process. The reaction was studied using in situ infrared spectroscopy and a mechanism is presented that accounts for the available data from this and previous studies. The reaction was also performed on a multigram scale, with calorimetry studies to support further scale-up of this promoter-free transformation.

C–H Arylation of Heterocyclic N-Oxides Through in Situ Diazotisation Of Anilines without Added Promoters: A Green And Selective Coupling Process

Aymeric P. Colleville^†^‡, Richard A. J. Horan^*^†, Sandrine Olazabal^†, and Nicholas C. O. Tomkinson^‡

^† API Chemistry, GlaxoSmithKline Research and Development Ltd., Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K.

^‡ WestCHEM, Department of Pure and Applied Chemistry, Thomas Graham Building, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, U.K.

Org. Process Res. Dev., Article ASAP

DOI: 10.1021/acs.oprd.6b00117

http://pubs.acs.org/doi/full/10.1021/acs.oprd.6b00117

2-(4-(Ethoxycarbonyl)phenyl)pyridine N-Oxide

Orange solid (81 mg, 22% yield), mp 119–120 °C.

¹H NMR (DMSO-d₆, 400 MHz): δ 8.39–8.38 (m, 1H), 8.07 (d, 2H, J = 8.6 Hz), 8.00 (d, 2H, J = 8.6 Hz), 7.72–7.67 (m, 1H), 7.45–7.48 (m, 2H), 4.37 (q, 2H, J = 7.1 Hz), 1.36 (t, 3H, J = 7.1 Hz) ppm.

¹³C NMR (DMSO-d₆, 100 MHz): δ 165.3 (C_IV), 146.6 (C_IV), 140.2, 137.2 (C_IV), 130.2 (C_IV), 129.6, 128.7, 127.7, 126.1, 125.5, 60.9, 14.1 ppm.

HRMS (ESI⁺): calculated for C₁₄H₁₄NO₃ [M+H]⁺ 244.0960, found 244.0968.

//////C–H Arylation of Heterocyclic N-Oxides, Situ Diazotisation Of Anilines, Promoters, Green And Selective Coupling Process

Supporting Info

Rifaximin

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Jul 062016

Rifaximin;

Rifaxidin; Rifacol; Xifaxan; Normix; Rifamycin L 105;L 105 (ansamacrolide antibiotic), L 105SV

(2S,16Z,18E,20S,21S,22R,23R,24R,25S,26S,27S,28E)-5,6,21,23,25-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-á]-benzimidazole-1,15(2H)-dione,25-acetate

CAS 80621-81-4, 4-Deoxy-4-methylpyrido[1,2-1,2]imidazo[5,4-c]rifamycin SV,

4-Deoxy-4′-methylpyrido[1′,2′-1,2]imidazo[5,4-c]rifamycin SV, Rifacol

C₄₃H₅₁N₃O₁₁
Molecular Weight:	785.87854 g/mol

XIFAXAN tablets for oral administration are film-coated and contain 200 mg or 550 mg of rifaximin.

Rifaximin is an orally administered, semi-synthetic, nonsystemic antibiotic derived from rifamycin SV with antibacterial activity. Rifaximin binds to the beta-subunit of bacterial DNA-dependent RNA polymerase, inhibiting bacterial RNA synthesis and bacterial cell growth. As rifaximin is not well absorbed, its antibacterial activity is largely localized to the gastrointestinal tract.

Rifaximin (trade names:RCIFAX, Rifagut, Xifaxan, Zaxine) is a semisynthetic antibiotic based on rifamycin. It has poor oral bioavailability, meaning that very little of the drug will be absorbed into the blood stream when it is taken orally. Rifaximin is used in the treatment of traveler’s diarrhea, irritable bowel syndrome, and hepatic encephalopathy, for which it receivedorphan drug status from the U.S. Food and Drug Administration in 1998.

Rifaximin is a rifamycin that was launched in 1988 by Alfa Wasserman for the treatment of bacterial infection, and was commercialized in 2004 by Salix for the treatment of Clostridium difficile-associated diarrhea. In 2008, the product was launched in Germany for the treatment of travelers’ diarrhea caused by non-invasive enteropathogenic bacteria in adults. In 2015, Xifaxan was approved in the U.S. for the treatment of abdominal pain and diarrhea in adult men and women with irritable bowel syndrome with diarrhea. At the same year, Aska filed an application for approval of the product in Japan for the treatment of hepatic encephalopathy.

Rifaximin is licensed by the U.S. Food and Drug Administration to treat traveler’s diarrhea caused by E. coli.^[1] Clinical trials have shown that rifaximin is highly effective at preventing and treating traveler’s diarrhea among travelers to Mexico, with fewside effects and low risk of developing antibiotic resistance.^[2]^[3]^[4] It is not effective against Campylobacter jejuni, and there is no evidence of efficacy against Shigella or Salmonella species.

Launched – 1988	Alfa Wassermann	Infection, bacterial
Launched – 2004	Salix	Traveler’s diarrhea
Launched – 2010	Salix	Encephalopathy, hepatic
Launched – 2015	Salix	Irritable bowel syndrome (Diarrhea predominant)
Launched	Alfa Wassermann Merck & Co.	Hyperammonemia

The drug is also at Salix in phase II trials for the treatment of Crohn’s disease. Alfa Wasserman is also conducting phase II trials for Crohn’s disease. The product was approved and launched in the U.S. for the maintenance of remission of hepatic encephalopathy in 2010. Mayo Clinic is conducting phase II clinical trials in the U.S. for the treatment of primary sclerosing cholangitis and the University of Hong Kong is also conducting Phase II trials for the treatment of functional dyspepsia.

It may be efficacious in relieving chronic functional symptoms of bloating and flatulence that are common in irritable bowel syndrome (IBS),^[5]^[6] especially IBS-D.

In February 1998, Salix was granted orphan drug designation by the FDA for the use of rifaximin to treat hepatic encephalopathy. In 2009, a codevelopment agreement was established between Lupin and Salix in the U.S. for the development of a new formulation using Lupin’s bioadhesive drug delivery technology.

There was recentlya pilot-study done on the efficacy of rifaximin as a means of treatment for rosacea, according to the study, induced by the co-presence of small intestinal bacterial overgrowth.^[7]

In the United States, rifaximin has orphan drug status for the treatment of hepatic encephalopathy.^[8] Although high-quality evidence is still lacking, rifaximin appears to be as effective as or more effective than other available treatments for hepatic encephalopathy (such as lactulose), is better tolerated, and may work faster.^[9] Hepatic encephalopathy is a debilitating condition for those with liver disease. Rifaximin is an oral medication taken twice daily that helps patients to avoid reoccurring hepatic encephalopathy. It has minimal side effects, prevents reoccurring encephalopathy and high patient satisfaction. Patients are more compliant and satisfied to take this medication than any other due to minimal side effects, prolong remission, and overall cost.^[10] Rifaximin helps patients avoid multiple readmissions from hospitals along with less time missed from work as well. Rifaximin should be considered a standard prescribed medication for those whom have episodes of hepatic encephalopathy.

The drawbacks to rifaximin are increased cost and lack of robust clinical trials for HE without combination lactulose therapy.

Also treats hyperammonemia by eradicating ammoniagenic bacteria.

Mechanism of action

Rifaximin interferes with transcription by binding to the β-subunit of bacterial RNA polymerase.^[11] This results in the blockage of the translocation step that normally follows the formation of the first phosphodiester bond, which occurs in the transcription process.^[12]

Efficacy

A 2011 study in patients with IBS (sans constipation) indicated 11% showed benefits over a placebo.^[13] The study was supported by Salix Pharmaceuticals, the patent holder.^[13] A 2010 study in patients treated for Hepatic Cirrhosis with hospitalization involving Hepatic encephalopathy resulted in 22% of the rifaxmin treated group experiencing a breakthrough episode of Hepatic encephalopathy as compared to 46% of the placebo group. The majority patients were also receivingLactulose therapy for prevention of hepatic encephalopathy in addition to Rifaximin.^[14] Rifaximin shows promising results, causing remission in up to 59% of people with Crohn’s disease and up to 76% of people with Ulcerative Colitis.^[15]

Availability

In the United States, Salix Pharmaceuticals holds a US Patent for rifaximin and markets the drug under the name Xifaxan, available in tablets of 200 mg and 550 mg.^[16]^[17] In addition to receiving FDA approval for traveler’s diarrhea and (marketing approved for)^[17] hepatic encephalopathy, Xifaxan received FDA approval for IBS in May 2015.^[18] No generic formulation is available in the US and none has appeared due to the fact that the FDA approval process was ongoing. If Xifaxan receives full FDA approval for hepatic encephalopathy it is likely that Salix will maintain marketing exclusivity and be protected from generic formulations until March 24, 2017.^[17] Price quotes received on February 21, 2013 for Xifaxan 550 mg in the Denver Metro area were between $23.57 and $26.72 per tablet. A price quote received on June 24, 2016 for Xifaxan 550 mg was $31.37 per tablet.

Rifaximin is approved in 33 countries for GI disorders.^[19]^[20] On August 13, 2013, Health Canada issued a Notice of Compliance to Salix Pharmaceuticals Inc. for the drug product Zaxine.^[21] In India it is available under the brand names Ciboz and Xifapill.^[

SPECTRA

LINK IS CLICK

APT 13C NMR RIFAXIMIN

1H NMR PARTIAL

Direct infusion mass analysis ESI (+)

IH NMR

[-]ESI FRAG PATHWAY

Synthesis

Rifaximin is a broad-spectrum antibiotic belonging to the family of Rifamycins and shows its antibacterial activity, in the gastrointestinal tract against localized bacteria that cause infectious diarrhoea, irritable bowel syndrome, small intestinal bacterial overgrowth, Crohn’s disease, and/or pancreatic insufficiency.

Rifaximin is sold under the brand name Xifaxan® in US for the treatment of Travellers’ diarrhoea and Hepatic Encephalopathy. The chemical name of Rifaximin is (2S , 16Z, 18E,20S ,21 S ,22R,23R,24R,25S ,26S ,27S ,28E)-5,6,21 ,23 ,25-pentahydroxy-27-methoxy-2,4,1 l,16,20,22,24,26-octamethyl-2,7(epoxypentadeca-[l,l l,13]trienimino) benzofuro[4,5-e]pyrido[l,2-a]-benzimidazole-l,15(2H)-dione,25-acetate and the molecular formula is G^HsiNsOn with a molecular weight of 785.9. The structural formula of Rifaximin is:

Formula I

Rifaximin was first described and claimed in Italian patent IT 1154655 and U.S. Pat. No.4,341,785. These patents disclose a process for the preparation of Rifaximin and a method for the crystallisation thereof. The process for the preparation of Rifaximin is as depicted in scheme I given below:

Scheme -I

U.S. Pat. No. 4,179,438 discloses a process for the preparation of 3-bromorifamycin S which comprises reaction of rifamycin S with at least two equivalents of bromine, per one mole of rifamycin S in the presence of at least one mole of pyridine per each equivalent of bromine and in the presence of ethanol, methanol or mixtures thereof with water at a

temperature not above the room temperature. The process is shown in the scheme given below:

Rifamycin S 3-Bromo-Rifamycin-S

U.S. Patent No.4,557, 866 discloses a process for one step synthesis of Rifaximin from Rifamycin O, which is shown in scheme II given below:

Rifamycin O Rifaximin

Scheme -II

US ‘866 patent also discloses purification of Rifaximin by performing crystallization of crude Rifaximin from a 7:3 mixture of ethyl alcohol/water followed by drying both under atmospheric pressure and under vacuum. The crystalline form which is obtained has not been characterized.

U.S. Patent No. 7,045,620 describes three polymorphic forms α, β and γ of Rifaximin. Form a and β show pure crystalline characteristics while the γ form is poorly crystalline. These polymorphic forms are differentiated on the basis of water content and PXRD. This patent also discloses processes for preparation of these polymorphs which involve use of specific reaction conditions during crystallization like dissolving Rifaximin in ethyl alcohol at 45-65°C, precipitation by adding water to form a suspension, filtering suspension and washing the resulted solid with demineralized water, followed by drying at room temperature under vacuum for a period of time between 2 and 72 hours. Crystalline forms a and β are obtained by immediate filtration of suspension when temperature of reaction mixture is brought to 0°C and poorly crystalline form γ is obtained when the reaction mixture is stirred for 5-6 hours at 0°C and then filtered the suspension. In addition to above these forms are also characterized by specific water content. For a form water content should be lower than 4.5%, for β form it should be higher than 4.5% and to obtain γ form, water content should be below 2%.

U.S. Patent No. 7,709,634 describes an amorphous form of Rifaximin which is prepared by dissolving Rifaximin in solvents such as alkyl esters, alkanols and ketones and precipitating by addition of anti-solvents selected from hydrocarbons, ethers or mixtures thereof.

U.S. Patent No. 8,193,196 describes two polymorphic forms of Rifaximin, designated δ and ε respectively. Form δ has water content within the range from 2.5 to 6% by weight (preferably from 3 to 4.5%).

U.S. Patent No 8,067,429 describes a-dry, β-1, β-2, ε-dry and amorphous forms of Rifaximin.

U.S. Patent No. 8,227,482 describes polymorphs Form μ, Form π, Form Omicron, Form Zeta, Form Eta, Form Iota and Form Xi of Rifaximin.

International application publications WO 2008/035109, WO 2008/155728, WO 2012/035544, WO 2012/060675, and WO 2012/156533 describes various amorphous or poorly crystalline forms of Rifaximin.

These polymorphic forms are obtained under different experimental conditions and are characterized by XRPD pattern.

The polymorphic forms of Rifaximin obtained from the prior art methods have specific water content. Transition between different polymorphic forms of Rifaximin occurs by drying or wetting of the synthesized Rifaximin. Hence, it is evident from above that Rifaximin can exist in number of polymorphic forms, formation of these polymorphic forms depends upon specific reaction conditions applied during crystallization and drying.

Rifaximin is a semi-synthetic, rifamycin-based non-systematic antibiotic. It is chemically termed as (2S,16Z,18E,20S,21S,22R,23R,24R,25S,26 S,27S, 28E)-5,6,21,23,255-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-a]-benzimida-zole-1,15(2H)-dione,25-acetate (I).

Rifaximin is used for treatment of travelers’ diarrhea caused by noninvasive strains of Escherichia coli.

Rifaximin was first disclosed in US4341785 which also discloses a process for its preparation and a method for crystallization of rifaximin using suitable solvents or mixture of solvents. However, this patent does not mention the polymorphism of rifaximin.

Canadian patent CA1215976 discloses a process for the synthesis of imidazo rifamycins which comprises reacting rifamycin S with 2-amino-4-methyl pyridine.

US4557866 discloses a process for preparation of rifaximin, but does not mention the polymorphs of rifaximin.

US7045620 discloses crystalline polymorphic forms of rifaximin which are termed as rifaximin α, rifaximin β and rifaximin γ. These polymorphic forms are characterized using X-ray powder diffraction. Further this patent mentions that γ form is poorly crystalline with a high content of amorphous component. This patent also discloses processes for preparation of these polymorphs which involve use of processes of crystallization and drying as disclosed in US4557866along with control of temperature at which the product is crystallized, drying process, water content thereof. Further, according to this patent, crystal formation depends upon the presence of water within the crystallization solvent.

The above patent discloses rifaximin α which is characterized by water content lower than 4.5% & powder X-ray diffractogram having significant peaks are at values of diffraction angles 2θ of 6.6°; 7.4°; 7.9°, 8.8°, 10.5°, 11.1 °, 11.8°, 12.9°, 17.6°, 18.5°, 19.7°, 21.0°, 21.4°, 22.1°; rifaximin β which is characterized by water content higher than 4.5% & powder X-ray diffractogram having significant peaks are at values of diffraction angles 2θ of 5.4°; 6.4°; 7.0°, 7.8°, 9.0°, 10.4°, 13.1°, 14.4°, 17.1°, 17.9°, 18.3°, 20.9° and rifaximin γ which is characterized by poorer powder X-ray diffractogram because of poor crystallinity. The significant peaks are at values of diffraction angles 2θ of 5.0°; 7.1°; 8.4°.

US2005/0272754 also discloses polymorphs of rifaximin namely rifaximin α form, rifaximin β form & rifaximin γ form characterized by powder X-ray diffractogram, intrinsic dissolution rates and processes of preparation of polymorphic forms of rifaximin. However, none of the above patents disclose a wholly amorphous form of rifaximin.

It is a well known fact that different polymorphic forms of the same drug may have substantial differences in certain pharmaceutically important properties. The amorphous form of a drug may exhibit different dissolution characteristics and in some case different bioavailability patterns compared to crystalline forms.

Further, amorphous and crystalline forms of a drug may have different handling properties, dissolution rates, solubility, and stability.

Furthermore, different physical forms may have different particle size, hardness and glass transition temperatures. Amorphous materials do not exhibit the three-dimensional long-range orders found in crystalline materials, but are structurally more similar to liquids where the arrangement of molecules is random.

Amorphous solids do not give a definitive x-ray diffraction pattern (XRD). In addition, amorphous solids do not give rise to a specific melting point and tend to liquefy at some point beyond the glass transition temperature. Because amorphous solids do not have lattice energy, they usually dissolve in a solvent more rapidly and consequently may provide enhanced bioavailability characteristics such as a higher rate and extent of absorption of the compound from the gastrointestinal tract. Also, amorphous forms of a drug may offer significant advantages over crystalline forms of the same drug in the manufacturing process of solid dosage form such as compressibility.

Drugs Fut 1982,7(4),260

The reaction of rifamycin S (I) with pyridine perbromide (II) in 2-propanol/chloroform (70/30) mixture at 0 C gives 3-bromorifamicin S (III), which is then condensed with 2-amino-4-methyl-pyridine (IV) at 10 C. The o-quinoniminic compound (V) is then obtained. This compound is finally reduced with ascorbic acid.


	US 262123

The reaction of rifamycin S (I) with pyridine perbromide (II) in 2-propanol/chloroform (70/30) mixture at 0 C gives 3-bromorifamicin S (III), which is then condensed with 2-amino-4-methyl-pyridine (IV) at 10 C. The o-quinoniminic compound (V) is then obtained. This compound is finally reduced with ascorbic acid.

PATENT

https://www.google.com/patents/EP2069363B1?cl=e

The schematic representation for preparation of amorphous rifaximin is as follows :

Amorphous rifaximin according to the present invention can be characterized by various parameters like solubility, intrinsic dissolution, bulk density, tapped density.

Rifaximin is known to exist in 3 polymorphic Forms namely α Form, β Form & γ Form of which the α Form is thermodynamically the most stable. Hence, the amorphous form of rifaximin was studied in comparison with α Form.

Further, when intrinsic dissolution of amorphous rifaximin is carried out against the α Form, it is observed that the amorphous rifaximin has better dissolution profile than α Form which is shown in table below (this data is also shown graphically in Figure 3):

Dissolution medium : 1000 ml of 0.1M Sodium dihydrogen phosphate monohydrate + 4.5g of sodium lauryl sulphate

Temperature : 37±0.5°C

Rotation speed : 100 rpm

Particle size : Amorphous rifaximin – 11 microns

α Form of rifaximin – 13 microns

Time in minutes	% Release of Amorphous Rifaximin	% Release of α Form of Rifaximin
15	1.1	0.8
30	1.9	1.8
45	2.9	3.0
60	3.7	4.4
120	8.1	11.0
180	12.6	18.0
240	16.6	24.6
360	24.7	38.7
480	32.0	47.5
600	39.5	52.7
720	46.4	56.4
960	60.4	62.9
1200	72.9	67.8
1400	83.0	72.7

Amorphous rifaximin exhibits bulk density in the range of 0.3 – 0.4 g/ml and tapped density is in the range of 0.4 – 0.5 g/ml while the α Form rifaximin exhibits bulk density in the range of 0.2 – 0.3 g/ml & tapped density is in the range of 0.3 – 0.4 g/ml. These higher densities of amorphous rifaximin are advantageous in formulation specifically in tablet formulation, for example, it gives better compressibility.

CLIP

Rifaximin (CAS NO.: 80621-81-4), with other name of 4-Deoxy-4-methylpyrido[1,2-1,2]imidazo[5,4-c]rifamycin SV, could be produced through many synthetic methods.

Following is one of the reaction routes:

The reaction of rifamycin S (I) with pyridine perbromide (II) in 2-propanol/chloroform (70/30) mixture at 0 C gives 3-bromorifamicin S (III), which is then condensed with 2-amino-4-methyl-pyridine (IV) at 10 C. The o-quinoniminic compound (V) is then obtained. This compound is finally reduced with ascorbic acid.

POLYMORPHISM

Rifaximin (INN; see The Merck Index, XIII Ed., 8304) is an antibiotic belonging to the rifamycin class, exactly it is a pyrido-imidazo rifamycin described and claimed in Italian Patent IT 1154655, while European Patent EP 0161534 describes and claims a process for its production starting from rifamycin O (The Merck Index, XIII Ed., 8301).

Both these patents describe the purification of rifaximin in a generic way stating that crystallization can be carried out in suitable solvents or solvent systems and summarily showing in some examples that the reaction product can be crystallized from the 7:3 mixture of ethyl alcohol/water and can be dried both under atmospheric pressure and under vacuum without specifying in any way either the experimental conditions of crystallization and drying, or any distinctive crystallographic characteristic of the obtained product.

The presence of different polymorphs had just not been noticed and therefore the experimental conditions described in both patents had been developed with the goal to get a homogeneous product having a suitable purity from the chemical point of view, independent from the crystallographic aspects of the product itself.

It has now been found, unexpectedly, that there are several polymorphous forms whose formation, besides the solvent, depends on time and temperature conditions under which both crystallization and drying are carried out.

In the present application, these orderly polymorphous forms will be, later on, conventionally identified as rifaximin α (FIG. 1) and rifaximin β (FIG. 2) on the basis of their respective specific diffractograms, while the poorly crystalline form with a high content of amorphous component will be identified as rifaximin γ (FIG. 3).

Rifaximin polymorphous forms have been characterized through the technique of the powder X-ray diffraction.

The identification and characterization of these polymorphous forms and, simultaneously, the definition of the experimental conditions for obtaining them is very important for a compound endowed with pharmacological activity which, like rifaximin, is marketed as medicinal preparation, both for human and veterinary use. In fact it is known that the polymorphism of a compound that can be used as active ingredient contained in a medicinal preparation can influence the pharmaco-toxicologic properties of the drug. Different polymorphous forms of an active ingredient administered as drug under oral or topical form can modify many properties thereof like bioavailability, solubility, stability, colour, compressibility, flowability and workability with consequent modification of the profiles of toxicological safety, clinical effectiveness and productive efficiency.

What mentioned above is confirmed by the fact that the authorities that regulate the grant of marketing authorization of the drugs market require that the manufacturing methods of the active ingredients are standardized and controlled in such a way that they give homogeneous and sound results in terms of polymorphism of production batches (CPMP/QWP/96, 2003—Note for Guidance on Chemistry of new Active Substance; CPMP/ICH/367/96—Note for guidance specifications: test procedures and acceptance criteria for new drug substances and new drug products: chemical substances; Date for coming into operation: May 2000).

The need for the above-mentioned standardization has further been strengthened in the field of the rifamycin antibiotics by Henwood S. Q., de Villiers M. M., Liebenberg W. and Lotter A. P., Drug Development and Industrial Pharmacy, 26 (4), 403-408, (2000), who have ascertained that different production batches of the rifampicin (INN) made from different manufacturers differ from each other in that they show different polymorphous characteristics, and as a consequence they show different dissolution profiles, along with a consequent alteration of the respective pharmacological properties.

By applying the crystallization and drying processes generically disclosed in the previous patents IT 1154655 and EP 0161534 it has been found that under some experimental conditions a poorly crystalline form of rifaximin is obtained, while under other experimental conditions other polymorphic crystalline forms of Rifaximin are obtained. Moreover it has been found that some parameters, absolutely not disclosed in the above-mentioned patents, like for instance preservation conditions and the relative ambient humidity, have the surprising effect to determine the polymorph form.

The polymorphous forms of rifaximin object of the present patent application were never seen or hypothesized, while thinking that, whichever method was used within the range of the described condition, a sole homogeneous product would always have been obtained, irrespective of crystallizing, drying and preserving conditions. It has now been found that the formation of α, β and γ forms depends both on the presence of water within the crystallization solvent, on the temperature at which the product is crystallized and on the amount of water present in the product at the end of the drying phase. Form α, form β and form γ of rifaximin have then been synthesized and they are the object of the invention.

Moreover it has been found that the presence of water in rifaximin in the solid state is reversible, so that water absorption and/or release can take place in time in presence of suitable ambient conditions; consequently rifaximin is susceptible of transition from one form to another, also remaining in the solid state, without need to be again dissolved and crystallized. For instance polymorph α, getting water by hydration up to a content higher than 4.5%, turns into polymorph β, which in its turn, losing water by drying up to a content lower than 4.5%, turns into polymorph α.

These results have a remarkable importance as they determine the conditions of industrial manufacturing of some steps of working which could not be considered critical for the determination of the polymorphism of a product, like for instance the washing of a crystallized product, or the preservation conditions of the end product, or the characteristics of the container in which the product is preserved.

The above-mentioned α, β and γ forms can be advantageously used as pure and homogeneous products in the manufacture of medicinal preparations containing rifaximin.

As already said, the process for manufacturing rifaximin from rifamycin O disclosed and claimed in EP 0161534 is deficient from the point of view of the purification and identification of the product obtained; it shows some limits also from the synthetic point of view as regards, for instance, the very long reaction times, from 16 to 72 hours, not very suitable to an industrial use and moreover because it does not provide for the in situ reduction of rifaximin oxidized that may be formed within the reaction mixture.

Therefore, a further object of the present invention is an improved process for the industrial manufacturing of the α, β and γ forms of rifaximin, herein claimed as products and usable as defined and homogeneous active ingredients in the manufacture of the medicinal preparations containing such active ingredient.

PATENT

https://www.google.com/patents/US20090234114

FIG. 1 is a powder X-ray diffractogram of rifaximin polymorphic form α.

FIG. 2 is a powder X-ray diffractogram of rifaximin polymorphic form β.

FIG. 3 is a powder X-ray diffractogram of rifaximin polymorphic form γ.

PATENT

Patent US20130004576

Rifaximin (INN; see The Merck Index, XIII Ed., 8304, CAS no. 80621-81-4), IUPAC nomenclature (2S,16Z,18E,20S,21S,22R,23R,24R,25S,26S,27S,28E)-5,6,21,23,25 pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-(1,11,13)trienimino)benzofuro(4,5-e)pyrido(1,2,-a)benzimidazole-1,15(2H)-dione,25-acetate) is a semi-synthetic antibiotic belonging to the rifamycin class of antibiotics. More precisely rifaximin is a pyrido-imidazo rifamycin described in the Italian patent IT 1154655, whereas the European patent EP 0161534 discloses a process for rifaximin production using rifamycin O as starting material (The Merck Index, XIII Ed., 8301).

U.S. Pat. No. 7,045,620, US 2008/0262220, US 7,612,199, US 2009/0130201 and Cryst. Eng. Comm., 2008, 10 1074-1081 (2008) disclose new forms of rifaximin.

WO 2008/035109 A1 discloses a process to prepare amorphous rifaximin, which comprises reaction of rifamycin S with 2-amino-4 picoline in presence of organic solvent like dichloromethane, ethylacetate, dichloroethylene, chloroform, in an inert atmosphere. When water is added to the reaction mixture, a solid precipitate corresponding to amorphous rifaximin is obtained.

The process described in this document can be assimilated to a crash precipitation, wherein the use of an anti-solvent causes the precipitation of rifaximin without giving any information about the chemical physical and biological characteristics of the rifaximin obtained.

WO 2009/108730 A2 describes different polymorphous forms of rifaximin and also amorphous forms of rifaximin. Amorphous forms are prepared by milling and crash precipitation and with these two different methods the amorphous rifaximin obtained from these two different processes has the same properties.

FIG. 4: ¹³C-NMR spectrum of rifaximin obtained by spray drying process.

FIG. 5: FT-IR spectrum of rifaximin obtained by spray drying process.

Patent

WO 2015014984

Rifaximin, lUPAC name:

(2S,16Z,18E,20S,21 S,22H,23H,24H,25S,26S,27S,28£)-5,6,21 ,23,25-pentahydroxy- 27-methoxy-2,4,1 1 ,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1 ,1 1 ,13]-trienimmino)-benzofuro-[4,5-e]-pirido-[1 ,2-oc]-benzimidazol-1 , 15(2 -/)-dione,25-acetate, is the compound of formula (I):

Rifaximin is a broad-spectrum antibiotic belonging to the family of rifamycins, devoid of systemic activity. In view of its physicochemical properties, it is not adsorbed in the gastrointestinal tract and therefore exerts its antimicrobial action inside the gastrointestinal tract. Rifaximin therefore has applications in the treatment of diarrhoea and of microbial infections of the gastrointestinal tract typically caused by E. coli, a microorganism which, being incapable of passing through the mucosa of the gastrointestinal tract, remains in contact with the gastrointestinal fluids. Rifaximin also has applications for the treatment of irritable bowel syndrome, Crohn’s disease, diverticulitis and for antibiotic prophylaxis preceding surgical operations on the intestines.

Rifaximin was obtained and described for the first time in the EP161534 starting from rifamycin O and 2-amino-4-picoline in the presence of ethanol/water and

ascorbic acid/HCI to obtain raw rifaximin which is then treated with Ethanol/water to obtain crystallized rifaximin.

Polymorphic forms of rifaximin, and processes for their synthesis and purification, are described in various documents of the known art.

Rifaximin K was firstly described in WO2012/156951 . Such a crystalline form resulted to be more stable in the presence of humidity than the other known crystalline forms of rifaximin, thus enabling the storage, even for prolonged periods. Such a polymorph was obtained by a process starting from rifaximin comprising the following steps: -suspending or dissolving rifaximin in a 1 ,2-dimethoxyethane based solvent, recovering the product and drying to remove said 1 ,2-dimethoxyethane based solvent. In one of the embodiments of the invention 1 ,2-dimethoxyethane is used as the unique solvent of rifaximin, in other 1 ,2-dimethoxyethane is described as used in combination of n-heptane, methanol, acetonitrile, R-COO-R¹ esters wherein R and R¹ are independently C₃-C₆ alkyl radicals, and C₃-C₇ alkyl ketones, ethanol, isopropanol and water.

Paper

The synthesis of 4-deoxypyrido(1′,2′-1,2)imidazo(5,4-c)rifamycin SV derivatives
J Antibiot 1984, 37(12): 1611

LAST STEP DEPICTED AGAIN

Treatment of rifamycin S (I) with Pyr·Br2 in 2-PrOH/CHCl3 gives 3-bromorifamycin S (II) (1), which upon cyclocondensation with 2-amino-4-methyl-pyridine (III) (1,2,3) in CHCl3 (2) or EtOH (3) yields imine derivative (IV). Finally, reduction of (IV) with L-(+)- ascorbic acid (1,2,3) in MeOH (2) or EtOH (3) provides the target rifaximin (1,2,3).

PATENT

WO 2005044823, WO 2012035544, WO 2015014984

Rifaximin is prepared by the cyclocondensation of rifamycin-O with 2-amino-4-picoline in a solvent mixture such as acetone, acetonitrile, EtOH, MIBK, propylene glycol, i-PrOH or t-BuOH and H2O at 50 °C or EtOH/aceone/H2O or optionally in the presence of I2 in CH2Cl2

PATENT

WO 2015159275

The process is shown in the scheme given below:

Rifamycin-S

3-halo-Rifamycin-S

Examples

Example 1;

5g of Rifamycin S, 3.1 gms of 2-amino-4-methyl pyridine, 0.45 g of iodine, 1.65 ml of acetic acid and 20ml of acetonitrile were charged in a clean and dry round bottom flask followed by stirring the resultant reaction mixture at about 30°C for about 30 hours. The reaction progress was monitored by TLC, after completion of reaction, the reaction mass was quenched by adding a mixture of 4.0g of ascorbic acid dissolved in 20 ml of water. The resultant reaction suspension was stirred at about 25°C for about 15mins. 25 ml of dichloromethane was charged and stirred for about 15mins. followed by separation of organic and aqueous phases. The aqueous phase was extracted with 25 ml of dichloromethane followed by separation of organic and aqueous phases. The organic phases were combined and distilled at below about 50°C to yield Rifaximin as residue. 11.25ml of purified water and 11.25ml of ethanol were charged to the residue and stirred at about 30°C for about 15 mins. The resultant reaction

suspension was heated to about 75°C and stirred for about 30mins. The resultant reaction solution further cooled to about 25 °C and stirred for about 2 hours followed by further cooling to about 5°C for about 3 hours. The solid precipitated was filtered and the solid was washed with a mixture of 2.5ml of ethanol and 2.5 ml of purified water. The solid obtained was dried at about 50°C for about 10 hours to afford 3 g. of Rifaximin as crystalline form. Purity by HPLC: 99.85 area %.

PAPER

European journal of medicinal chemistry (2015), 103, 551-62

Patent

https://www.google.com/patents/WO2013027227A1?cl=en

Examples

Example 1 : Purification of Rifamycin S

Rifamycin S (500g) and Ethanol (1.5L) were stirred and refluxed for 1 hour. The reaction mixture was then cooled slowly to ambience, stirred at this temperature for 2 hour and filtered. The product dried in vacuum oven at 40 ^°C to obtain 475g of pure Rifamycin S showing the des acetyl impurity below to 0.6%.

Example 2: Preparation of rifaximin

Rifamycin S (300 g) was stirred in dichloromethane (900 ml) at room temperature for 15 minutes to get a clear solution and then 2-Amino-4-methyl pyridine (139.2g) was added at room temperature under nitrogen atmosphere. Iodine (57. Og) dissolved in dichloromethane (2100ml), was added drop wise in 30-45 minutes at room temperature. The reaction mass was stirred for 22-24 hours at 25-30 ^°C. After completion of the reaction, a 20% solution of L(-) ascorbic acid in water (300 ml) was added. The reaction mixture was stirred for 45-60 minutes at room temperature and then cooled to 10-15 ^°C. The pH of the resulting solution was adjusted to 1.5-2.0 with slow addition of dilute hydrochloric acid under stirring. The reaction mass was stirred for 15-20 minutes and layers were separated. The organic layer was washed with demineralized water (1500 ml), 10% sodium thiosulfate solution (1500 ml) and with demineralized water till pH was neutral. The solvent was distilled off under vacuum at 40-45 °C to get a residue which was taken in cyclohexane (1500 ml) and stirred for 1 hour. The resulting solid was filtered, washed with cyclohexane (300 ml) crystallized from a mixture of ethyl alcohol and water (600ml; 420ml ethyl alcohol and 180 ml water) to get 240g of crude rifaximin having purity 99.3% by HPLC.

Example 3: Preparation of rifaximin

Step-1: Preparation of crude rifaximin

Rifamycin S (300 g) was stirred in dichloromethane (900 ml) at room temperature for 15 minutes to get a clear solution and then 2-amino-4-methyl pyridine (139.2g) was added at room temperature under nitrogen atmosphere. Iodine (57. Og) dissolved in dichloromethane (2100ml), was added drop wise in 30-45 minutes at room temperature and was stirred for 22-24 hours. After completion of the reaction, a 20% solution of L (-) ascorbic acid in water (300 ml) was added and stirred for 45-60 minutes. The reaction mass was cooled to 10-15 ^°C and pH of the resulting solution was adjusted to 1.5-2.0 with slow addition of dilute hydrochloric acid under stirring. The reaction mass was stirred for 15-20 minutes and layers were separated and the organic layer was washed with demineralized water (1500 ml), with 10% sodium thiosulfate solution (1500 ml) and demineralized water till pH was neutral. The solvent was distilled off under vacuum at 40-45 °C to obtain a residue which was crystallized from a mixture of ethyl alcohol and water (378ml ethyl alcohol and 162 ml water) and dried at 35-40 °C to obtain 240g crude rifaximin having purity 98.8% by HPLC. Step-2: Purification of crude rifaximin

Crude rifaximin (240g) was stirred in dichloromethane (2400ml) at room temperature, a neutral alumina (240g) was added, stirred for 1 hour and filtered. The solvent was then distilled off and residue was treated with ethyl acetate (2400ml) and stirred to dissolution. The resulting residue was crystallized from a mixture of ethyl alcohol and water (302ml ethyl alcohol and 130ml water) and dried at 35-40 “C to obtain 192g of rifaximin having purity 99.8% by HPLC.

PATENT

https://www.google.com/patents/US9018225

PAPER

https://www.researchgate.net/profile/Miriam_Barbanti/publication/245268795_Viscomi_G_C_et_al_Crystal_forms_of_rifaximin_and_their_effect_on_pharmaceutical_properties_Cryst_Eng_Comm_10_1074-1081/links/556ec70d08aefcb861dba679.pdf

PATENTS

US4341785	May 11, 1981	Jul 27, 1982	Alfa Farmaceutici S.P.A.	Imidazo-rifamycin derivatives with antibacterial utility
US4557866	Apr 26, 1985	Dec 10, 1985	Alfa Farmaceutici S.P.A.	Process for the synthesis of pyrido-imidazo rifamycins
US7045620	Dec 5, 2003	May 16, 2006	Alfa Wassermann, S.P.A.	Polymorphous forms of rifaximin, processes for their production and use thereof in medicinal preparations
US7612199	Jun 4, 2009	Nov 3, 2009	Alfa Wassermann, S.P.A.	Polymorphic forms α, β, and γ of rifaximin
US7902206		Mar 8, 2011	Alfa Wassermann, S.P.A.	Polymorphic forms α, β and γ of rifaximin
US7906542	May 13, 2008	Mar 15, 2011	Alfa Wassermann, S.P.A.	Pharmaceutical compositions comprising polymorphic forms α, β, and γ of rifaximin
US7915275		Mar 29, 2011	Alfa Wassermann, S.P.A.	Use of polymorphic forms of rifaximin for medical preparations
US7923553		Apr 12, 2011	Alfa Wassermann, S.P.A.	Processes for the production of polymorphic forms of rifaximin
US7928115		Apr 19, 2011	Salix Pharmaceuticals, Ltd.	Methods of treating travelers diarrhea and hepatic encephalopathy
US8158644		Apr 17, 2012	Alfa Wassermann, S.P.A.	Pharmaceutical compositions comprising polymorphic forms α, β, and γ of rifaximin
US8158781	Mar 4, 2011	Apr 17, 2012	Alfa Wassermann, S.P.A.	Polymorphic forms α, β and γ of rifaximin
US8193196	Feb 27, 2006	Jun 5, 2012	Alfa Wassermann, S.P.A.	Polymorphous forms of rifaximin, processes for their production and use thereof in the medicinal preparations
US20050272754 *	May 24, 2005	Dec 8, 2005	Alfa Wassermann S.P.A.	Polymorphic forms of rifaximin, processes for their production and uses thereof

Reference
1		Viscomi, G. C., et al., “Crystal forms of rifaximin and their effect on pharmaceutical properties“, Cryst Eng Comm, 2008, 10, 1074-1081, (May 28, 2008), 1074-1081.

Citing Patent	Filing date	Publication date	Applicant	Title
US9186355	Mar 30, 2015	Nov 17, 2015	Novel Laboratories	Rifaximin crystalline forms and methods of preparation thereof

WO2008035109A1 *	Sep 24, 2007	Mar 27, 2008	Cipla Limited	Rifaximin
WO2009108730A2 *	Feb 25, 2009	Sep 3, 2009	Salix Pharmaceuticals, Ltd.	Forms of rifaximin and uses thereof
WO2011080691A1 *	Dec 27, 2010	Jul 7, 2011	Silvio Massimo Lavagna	Method for the production of amorphous rifaximin
EP1698630A1 *	Mar 3, 2005	Sep 6, 2006	ALFA WASSERMANN S.p.A.	New polymorphous forms of rifaximin, processes for their production and use thereof in the medicinal preparations
US20080262220 *	May 13, 2008	Oct 23, 2008	Giuseppe Claudio Viscomi	Polymorphic forms alpha, beta and gamma of rifaximin
US20090082558 *	Sep 20, 2007	Mar 26, 2009	Apotex Pharmachem Inc.	Amorphous form of rifaximin and processes for its preparation

* Cited by examiner

REFERENCED BY

Citing Patent	Filing date	Publication date	Applicant	Title
WO2015014984A1 *	Aug 1, 2014	Feb 5, 2015	Clarochem Ireland Ltd.	A process for preparing rifaximin k
CN103360357A *	Aug 7, 2013	Oct 23, 2013	中国药科大学	A simvastatin-gliclazide co-amorphous compound
US9359374	Jun 13, 2013	Jun 7, 2016	Apotex Pharmachem Inc.	Polymorphic forms of rifaximin

US4341785 *	May 11, 1981	Jul 27, 1982	Alfa Farmaceutici S.P.A.	Imidazo-rifamycin derivatives with antibacterial utility
US4557866 *	Apr 26, 1985	Dec 10, 1985	Alfa Farmaceutici S.P.A.	Process for the synthesis of pyrido-imidazo rifamycins
US7045620 *	Dec 5, 2003	May 16, 2006	Alfa Wassermann, S.P.A.	Polymorphous forms of rifaximin, processes for their production and use thereof in medicinal preparations

Citing Patent	Filing date	Publication date	Applicant	Title
US8518949	Jun 4, 2012	Aug 27, 2013	Alfa Wassermann S.P.A.	Polymorphous forms of rifaximin, processes for their production and use thereof in the medicinal preparations
US20140079783 *	Jul 3, 2013	Mar 20, 2014	Alfa Wassermann Spa	Pharmaceutical Compositions Comprising Rifaximin and Amino acids, Preparation Methods and Use Thereof
CN101836959A *	May 20, 2010	Sep 22, 2010	山东达因海洋生物制药股份有限公司	Method for preparing almost bitterless rifaximin dry suspension
CN103269587A *	Jun 3, 2011	Aug 28, 2013	萨利克斯药品有限公司	New forms of rifaximin and uses thereof
WO2011153444A1 *	Jun 3, 2011	Dec 8, 2011	Salix Pharmaceuticals, Ltd	New forms of rifaximin and uses thereof

References

Xifaxan label information PDF Retrieved November 15, 2008.
DuPont, H (2007). “Therapy for and Prevention of Traveler’s Diarrhea”. Clinical Infectious Diseases 45 (45 (Suppl 1)): S78–S84. doi:10.1086/518155. PMID 17582576.
Ruiz J, Mensa L, Pons MJ, Vila J, Gascon J (May 2008). “Development of Escherichia coli rifaximin-resistant mutants: frequency of selection and stability”. Journal of antimicrobial chemotherapy 61 (5): 1016–9. doi:10.1093/jac/dkn078. PMID 18325895.
Martinez-Sandoval F, Ericsson CD, Jiang ZD, Okhuysen PC, Romero JH, Hernandez N, Forbes WP, Shaw A, Bortey E, DuPont HL (Mar–Apr 2010). “Prevention of travelers’ diarrhea with rifaximin in US travelers to Mexico.”. J Travel Med. 17 (2): 111–7.doi:10.1111/j.1708-8305.2009.00385.x. PMID 20412178.
Sharara A, Aoun E, Abdul-Baki H, Mounzer R, Sidani S, ElHajj I (2006). “A randomized double-blind placebo-controlled trial of rifaximin in patients with abdominal bloating and flatulence”. Am J Gastroenterol 101 (2): 326–33. doi:10.1111/j.1572-0241.2006.00458.x.PMID 16454838.
Antibiotic May Help Ease Irritable Bowel, Businessweek, January 05, 2011
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http://www.hc-sc.gc.ca/dhp-mps/prodpharma/sbd-smd/drug-med/sbd_smd_2013_zaxine_161256-eng.php

External links

FDA label approved for Xifaxan (PDF warning)
Xifaxan200 (manufacturer’s website)

Patents

Patent Number	Pediatric Extension	Approved	Expires (estimated)
US6861053	No	1999-08-11	2019-08-11
US7045620	No	2004-06-19	2024-06-19
US7452857	No	1999-08-11	2019-08-11
US7605240	No	1999-08-11	2019-08-11
US7612199	No	2004-06-19	2024-06-19
US7718608	No	1999-08-11	2019-08-11
US7902206	No	2004-06-19	2024-06-19
US7906542	No	2005-06-01	2025-06-01
US7915275	No	2005-02-23	2025-02-23
US7928115	No	2009-07-24	2029-07-24
US7935799	No	1999-08-11	2019-08-11
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US8158781	No	2004-06-19	2024-06-19
US8193196	No	2007-09-02	2027-09-02
US8309569	No	2009-07-18	2029-07-18
US8518949	No	2006-02-27	2026-02-27
US8642573	No	2009-10-02	2029-10-02
US8741904	No	2006-02-27	2026-02-27
US8829017	No	2009-07-24	2029-07-24
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Properties

Rifaximin
Systematic (IUPAC) name


(2S,16Z,18E,20S,21S,22R,23R,24R,25S,26S,27S,28E)-5,6,21,23,25-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino)benzofuro [4,5-e]pyrido[1,2-a]-benzimida-zole-1,15(2H)-dione,25-acetate
Clinical data
Trade names	Xifaxan, Xifaxanta, Normix, Rifagut
AHFS/Drugs.com	Monograph
MedlinePlus	a604027
Pregnancy category	US: C (Risk not ruled out)
Routes of administration	Oral
Legal status
Legal status	℞ (Prescription only)
Pharmacokinetic data
Bioavailability	< 0.4%
Metabolism	Hepatic
Biological half-life	6 hours
Excretion	Fecal (97%)
Identifiers
CAS Number	80621-81-4
ATC code	A07AA11 (WHO) D06AX11(WHO) QG51AA06 (WHO)QJ51XX01 (WHO)
PubChem	CID 6436173
DrugBank	DB01220
ChemSpider	10482302
UNII	L36O5T016N
KEGG	D02554
ChEBI	CHEBI:75246
ChEMBL	CHEMBL1617
Chemical data
Formula	C₄₃H₅₁N₃O₁₁
Molar mass	785.879 g/mol

Giuseppe Viscomi, Manuela Campana, Dario Braga, Donatella Confortini, Vincenzo Cannata, Paolo Righi, Goffredo Rosini, “Polymorphic forms of rifaximin, processes for their production and uses thereof.” U.S. Patent US20050272754, issued December 08, 2005.

US20050272754

Title: Rifaximin

CAS Registry Number: 80621-81-4

CAS Name: (2S,16Z,18E,20S,21S,22R,23R,24R,25S,26R,27S,28E)-25-(Acetyloxy)-5,6,21,23-tetrahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-a]benzimidazole-1,15(2H)-dione

Additional Names: 4-deoxy-4¢-methylpyrido[1¢,2¢-1,2]imidazo[5,4-c]rifamycin SV; rifamycin L 105; rifaxidin

Manufacturers’ Codes: L-105

Trademarks: Fatroximin (Fatro); Flonorm (Schering-Plough); Normix (Alfa); Rifacol (Formenti); Xifaxan (Salix)

Molecular Formula: C43H51N3O11

Molecular Weight: 785.88

Percent Composition: C 65.72%, H 6.54%, N 5.35%, O 22.39%

Literature References: Nonabsorbable semisynthetic rifamycin antibiotic. Prepn: BE 888895; E. Marchi, L. Montecchi, US4341785 (1981, 1982 both to Alfa); E. Marchi et al., J. Med. Chem. 28, 960 (1985); and NMR study: M. Brufani et al., J. Antibiot.37, 1611 (1984). X-ray crystal structure: idem et al., ibid. 1623. In vitro and in vivo antibacterial activity: A. P. Venturini, E. Marchi,Chemioterapia 5, 257 (1986). Toxicological study: G. Borelli, D. Bertoli, ibid. 263. Clinical trial in travelers’ diarrhea: R. Steffen et al., Am. J. Gastroenterol. 98, 1073 (2003). Review of activity, pharmacokinetics and clinical experience in gastrointestinal infections: J. C. Gillis, R. N. Brogden, Drugs 49, 467-484 (1995); D. B. Huang, H. L. DuPont, J. Infection 50, 97-106 (2005).

Properties: Red orange powder, mp 200-205° (dec). uv max: 232, 260, 292, 320, 370, 450 nm (E1%1cm 489, 339, 295, 216, 119, 159). Sol in alcohols, ethyl acetate, chloroform, toluene. Insol in water. LD50 orally in rats: >2000 mg/kg (Borelli, Bertoli).

Melting point: mp 200-205° (dec)

Absorption maximum: uv max: 232, 260, 292, 320, 370, 450 nm (E1%1cm 489, 339, 295, 216, 119, 159)

Toxicity data: LD50 orally in rats: >2000 mg/kg (Borelli, Bertoli)

Therap-Cat: Antibacterial.

Therap-Cat-Vet: Antibacterial.

Keywords: Antibacterial (Antibiotics); Ansamycins.

MORE…….

Rifaximin, alpha-0817185, L-105, Xifaxan, Lumenax, Flonorm, RedActiv, Rifacol, Normix

Drug Name	XIFAXAN
Application Number	021 361	Number	001
Active ingredients	RIFAXIMIN	Market Status	prescription
Dosage form or route of administration	TABLET; ORAL	specification	200MG
Treatment equivalent code		Drug Reference	Yes
Date of approval	2004/05/25	The applicant	SALIX PHARMACEUTICALS INC
Chemistry	New molecular entity (NME)	Review Categories	Standard review drug

Patents related to this product information (from the Orange Book Orange Book)
Patent No	Patent expiration date	Whether the compound patent	Whether or not product patents	Patents purpose code	Patent Download
7928115	2029/07/24			U-1121	PDF format
8741904	2026/02/27	Y		U-1526	PDF format
7612199	2024/06/19	Y	Y		PDF format
8853231	2024/06/19		Y		PDF format
9271968	2026/02/27		Y		PDF format
8158644	2024/06/19		Y		PDF format
8193196	2027/09/02	Y	Y		PDF format
7906542	2025/06/01	Y	Y		PDF format
8158781	2024/06/19	Y			PDF format
7045620	2024/06/19	Y	Y		PDF format
8518949	2026/02/27		Y		PDF format
8835452	2024/06/19	Y	Y		PDF format
7902206	2024/06/19	Y	Y		PDF format
History Patent Information
7045620	2024/05/22	Y			PDF format
8642573	2029/10/02			U-1481	PDF format

Related to this product market exclusivity protection information
Exclusivity Code	Expiration date
no
Historical market exclusivity protection information
NCE	2009/05/25

And information related to drug registration
Application Number	Amendment No.	Approval Conclusion	Disclosure Document Type	Document creation time	Obtaining Documentation
021 361	013	AP	Label	2014/03/13	download
021 361	013	AP	Letter	2014/03/14	download
021 361	012	AP	Letter	2015/05/28	download
021 361	012	AP	Label	2015/05/29	download
021 361	011	AP	Label	2010/03/05	download
021 361	011	AP	Letter	2010/03/08	download
021 361	009	AP	Label	2010/11/17	download
021 361	009	AP	Letter	2010/11/18	download
021 361	006	AP	Label	2007/02/02	download
021 361	006	AP	Letter	2007/02/12	download
021 361	000	AP	Letter	2004/06/01	download
021 361	000	AP	Label	2004/06/01	download
021 361	000	AP	Review	2004/08/27	download

Regulatory approval history information
Application Number	Amendment No.	Approval Conclusion	Approval Date	Approval of the content
021 361	016	AP	2015/10/15	Manufacturing Change or Addition
021 361	015	AP	2016/06/16	Manufacturing Change or Addition
021 361	014	AP	2015/04/23	Manufacturing Change or Addition
021 361	013	AP	2014/03/12	Labeling Revision
021 361	012	AP	2015/05/27	Efficacy Supplement with Clinical Data to Support
021 361	011	AP	2010/03/03	Labeling Revision
021 361	009	AP	11/15/2010	Labeling Revision
021 361	006	AP	2007/01/30	Labeling Revision
021 361	000	AP	2004/05/25	Approval

///////Rifaximin, Rifaxidin, Rifacol, Xifaxan, Normix, Rifamycin L 105, 80621-81-4, Rifaximin, alpha-0817185, L-105, Xifaxan, Lumenax, Flonorm, RedActiv, Rifacol, Normix

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