Tout sur les médicaments הכל על תרופות كل شيئ عن الأدوية Все о наркотиках 关于药品的一切 డ్రగ్స్ గురించి అన్ని 마약에 관한 모든 것 Όλα για τα Ναρκωτικά Complete Tracking of Drugs Across the World by Dr Anthony Melvin Crasto, Worldpeacepeaker, worlddrugtracker, PH.D (ICT), MUMBAI, INDIA, Worlddrugtracker, Helping millions, 9 million hits on google on all websites, 2.5 lakh connections on all networks, “ALL FOR DRUGS” CATERS TO EDUCATION GLOBALLY, No commercial exploits are done or advertisements added by me. This is a compilation for educational purposes only. P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent
This industry standard encyclopedia on pharmaceutical manufacturing processes has been completely updated to include FDA drugs approved up to the summer of 2004. The encyclopedia gives details for the manufacture of 2226 pharmaceuticals that are being marketed as a trade-named product somewhere in the world. Each entry includes:
ò Therapeutic function
ò Chemical and common name
ò Structural Formula
ò Chemical Abstracts Registry no.
ò Trade name, manufacturer, country, and year introduced
ò Raw Materials
ò Manufacturing Process
In addition, references are also cited under each drug’s entry to major pharmaceutical works where additional information can be obtained on synthesis and the pharmacology of the individual products.
Miconazole is an imidazoleantifungal agent, developed by Janssen Pharmaceutica, commonly applied topically to the skin or tomucous membranes to cure fungal infections. It works by inhibiting the synthesis of ergosterol, a critical component of fungal cell membranes. It can also be used against certain species of Leishmaniaprotozoa which are a type of unicellular parasites that also contain ergosterol in their cell membranes. In addition to its antifungal and antiparasitic actions, it also has some antibacterialproperties. It is marketed in various formulations under various brand names.
Miconazole is also used in Ektachrome film developing in the final rinse of the KodakE-6 process and similar Fuji CR-56 process, replacing formaldehyde. Fuji Hunt also includes miconazole as a final rinse additive in their formulation of the C-41RA rapid access color negative developing process.
ALTERNATIVE ROUTESbeginning with the racemic raw material will likely be more costly or more time-consuming to develop, Cox says. Crystallization might be tricky because the stereogenic center does not have a group that can readily undergo acid-base chemistry. Catalytic asymmetric chemistry will necessitate converting the raw material to an appropriate substrate and identifying effective, as well as usable, chemical catalysts or biocatalysts.
What happens to the unwanted enantiomer also depends on the economics. Reracemizing and feeding the racemate back into the process is ideal but not always practical. In the miconazole case, the raw material costs $32 per kg. It is unlikely that reracemizing would be less costly in this example, Cox explains.
People should not forget that the goal of chiral technologies–enantiopure product–also may be achieved with chemistry that already exists, notes David R. Dodds, founder of Dodds & Associates LLC, Manlius, N.Y., a consulting service for biotechnology and chemical companies. Process chemists seek the most robust, most productive, and least expensive synthetic route and aim to find it as fast as possible. Any reaction that can help reach this goal is useful. It is the overall process cost that will dictate which reactions will be used. And that cost covers not only reagents but also waste streams, utilities, equipment use, unit operations, and downstream requirements. Thus, it may be more commercially attractive to replace an elegant but expensive single reaction with several more mundane ones that have a lower total cost, he says. Such a situation is likely to arise when an asymmetric step requires an expensive chiral catalyst or chiral auxiliary.
DAS 1,940,388 (Janssen; appl 8.8.1969;. USA-prior 19.8.1968, 23.7.1969.).
US 3,717,655 (Janssen; 20.2.1973; appl 19.8.1968.).
US 3,839,574 (Janssen; 1.10.1974; prior 23.7.1969.).
Miconazole nitrate was prepared by Godefori et
al [5–7]. Imidazole 1 was coupled with
brominated 2,4‑dichloroacetophenone 2 and the resulting ketonic product 3
was reduced with sodium borohydride to its corresponding alcohol 4. The
latter compound 4 was then coupled with 2,4-dichlorotoluene by sodium borohydride
in hexamethylphosphoramide (an aprotic solvent) which was then extracted with
nitric acid to give miconazole nitrate.
2- Miconazole was also
prepared by Molina Caprile [8] as follows:
Phenyl methyl ketone 1 was brominated to give
1-phenyl-2-bromoethanone 2. Compound 2 was treated with
methylsulfonic acid to yield the corresponding methylsulfonate 3.
Etherification of 3 gave the a‑benzyloxy derivative 4 and compound 4 was
then chlorinated to give the 2,4‑dichlorinated derivative in both aromatic ring
systems 5. Compound 5 reacted with imidazole in dimethylformamide
to give miconazole 6 [7] which is converted to miconazole nitrate.
3- Ye et al reported that the reduction of 2,4-dichlorophenyl-2-chloroethanone 1 with potassium borohydride in dimethylformamide to give 90% a‑chloromethyl-2,4-dichlorobenzyl
alcohol 2. Alkylation of imidazole with compound 2 in dimethylformamide
in the presence of sodium hydroxide and triethylbenzyl ammonium chloride, gave
1-(2,4‑dichlorophenyl-2-imidazolyl)ethanol 3 and etherification of 3
with 2,4-dichlorobenzyl chloride under the same condition, 62% yield of
miconazole [9].
4- Liao
and Li enantioselectively synthesized and studied the antifungal activity of
optically active miconazole and econazole. The key step was the
enantioselective reduction of 2‑chloro-1-(2,4-dichlorophenyl)ethanone catalyzed
by chiral oxazaborolidine [10].
5- Yanez et al reported the synthesiz of miconazole and analogs through a
carbenoid intermediate. The process involves the intermolecular insertion of
carbenoid species to imidazole from a‑diazoketones with copper acetylacetonate as the key
reaction of the synthetic route [11].
5-11 as 1-7
1.E.F. Godefori and J. Heeres, Ger. Pat. 1,940,388
(1970).
2. E.F. Godefori and J. Heeres, U.S. Pat. 3,717,655
(1973).
3. E.F. Godefori, J. Heeres, J. van Cutsem and P.A.J.
Janssen, J. Med. Chem., 12, 784 (1969).
4. F. Molina Caprile, Spanish Patent ES 510870 A1
(1983).
5. B. Ye, K. Yu and Q. Huang, Zhongguo Yiyao Gongye
Zazhi, 21, 56 (1990).
Percent Composition: C 51.95%, H 3.39%, Cl 34.08%, N 6.73%, O 3.84%
Literature References: Prepn: E. F. Godefroi et al.,J. Med. Chem.12, 784 (1969); E. F. Godefroi, J. Heeres, DE1940388;eidem,US3717655 (1970, 1973 to Janssen). Clinical evaluation: Brugmans et al.,Arch. Dermatol.102, 428 (1970); Godts et al.,Arzneim.-Forsch.21, 256 (1971). Review: P. Janssen, W. Van Bever, in Pharmacological and Biochemical Properties of Drug Substancesvol. 2, M. E. Goldberg, Ed. (Am. Pharm. Assoc., Washington, DC, 1979) pp 333-354; R. C. Heel et al.,Drugs19, 7-30 (1980).
Jump up^Duret C, Daujat-Chavanieu M, Pascussi JM, Pichard-Garcia L, Balaguer P, Fabre JM, Vilarem MJ, Maurel P, Gerbal-Chaloin S (2006). “Ketoconazole and miconazole are antagonists of the human glucocorticoid receptor: consequences on the expression and function of the constitutive androstane receptor and the pregnane X receptor”. Mol. Pharmacol. 70 (1): 329–39. doi:10.1124/mol.105.022046. PMID16608920.
The primary uses of lovastatin is for the treatment of dyslipidemia and the prevention of cardiovascular disease.[5] It is recommended to be used only after other measures, such as diet, exercise, and weight reduction, have not improved cholesterol levels.[5]
Pleurotus ostreatus, the oyster mushroom, naturally contains up to 2.8% lovastatin on a dry weight basis.[15]
Structure
History
Compactin and lovastatin, natural products with a powerful inhibitory effect on HMG-CoA reductase, were discovered in the 1970s, and taken into clinical development as potential drugs for lowering LDL cholesterol.
However, in 1980, trials with compactin were suspended for undisclosed reasons (rumoured to be related to serious animal toxicity). Because of the close structural similarity between compactin and lovastatin, clinical studies with lovastatin were also suspended, and additional animal safety studies initiated.
In 1982 some small-scale clinical investigations of lovastatin, a polyketide derived natural product isolated from Aspergillus terrus, in very high-risk patients were undertaken, in which dramatic reductions in LDL cholesterol were observed, with very few adverse effects. After the additional animal safety studies with lovastatin revealed no toxicity of the type thought to be associated with compactin, clinical studies resumed.
Large-scale trials confirmed the effectiveness of lovastatin. Observed tolerability continued to be excellent, and lovastatin was approved by the US FDA in 1987.
Lovastatin at its maximal recommended dose of 80 mg daily produced a mean reduction in LDL cholesterol of 40%, a far greater reduction than could be obtained with any of the treatments available at the time. Equally important, the drug produced very few adverse effects, was easy for patients to take, and so was rapidly accepted by prescribers and patients. The only important adverse effect is myopathy/rhabdomyolysis. This is rare and occurs with all HMG-CoA reductase inhibitors.
Mechanism of action
Lovastatin is an inhibitor of 3-hydroxy-3methylglutaryl-coenzyme A reductase (HMG-CoA reductase), an enzyme which catalyzes the conversion of HMG-CoA to mevalonate. Mevalonate is a required building block for cholesterol biosynthesis and lovastatin interferes with its production by acting as a competitive inhibitor for HMG-CoA which binds to the HMG-CoA reductase. Lovastatin, being inactive in the native form, the form in which it is administered, is hydrolysed to the β-hydroxy acid form in the body and it is this form which is active. Presumably, the reductase acts on the hydrolyzed lovastatin to reduce the carboxylic acid moiety.
Discovery, Biochemistry and Biology
It is now generally accepted that a major risk factor for the development of coronary heart disease is an elevated concentration of plasma cholesterol, especially lowdensity lipoprotein (LDL) cholesterol. The objective is to decrease excess levels of cholesterol to an amount consistent with maintainence of normal body function. Cholesterol is biosynthesized in a series of more than 25 separate enzymatic reactions that initially involves 3 successive condensations of acetyl-CoA units to form a 6-carbon compound, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA). This is reduced to mevalonate and then converted in a series of reactions to the isoprenes that are building blocks of squalene, the immediate precursor to sterols, which cyclizes to lanosterol (a methylated sterol) and further metabolized to cholesterol. A number of early attempts to block the synthesis of cholesterol resulted in agents that inhibited late in the biosynthetic pathway between lanosterol and cholesterol. A major rate limiting step in the pathway is at the level of the microsomal enzyme which catalyzes the conversion of HMG CoA to mevalonic acd and which has been considered to be a prime target for pharmacologic intervention for several years.
HMG CoA reductase occurs early in the biosynthetic pathway and is among the first commited steps to cholesterol formulation. Inhibition of this enzyme could lead to accumulation of HMG CoA, a water-soluble intermediate that is then capable of being readily metabolized that is then capable of being readily metabolized to simpler molecules. This inhibition of reductase would nto lead to accumulation of lipophylic intermediates having a formal sterol ring.
Lovastatin is the first specific inhibitor of HMG CoA reductase to receive approval for the treatment of hypercholesterolemia. The first breakthrough in efforts to find a potent, specific, competitive inhibitor of HMG CoA reductase occurred in 1976 when Endo et al reported discovery of mevastatin, a highly functionalized fungal metabolite, isolated from cultures of Penicillium citrium. Mevastatin was demonstrated to be an unusually potent inhibitor of the target enzyme and of cholesterol biosynthesis. Subsequent to the first reports describing mevastatin, efforts were initiated to search for other naturally occurring inhibitors oh HMG CoA reductase. This led to the discovery of a novel fungal metabolite – Lovastatin. The structure of Lovastatin was determined to be different from that of mevastatin by the presence of a 6 alphamethyl group in the hexahydronaphthalene ring.
Key points from the study of the Biosynthesis of Lovastatin :-
– Lovastatin is comprised of 2 polyketide chains derived from acetate that are 8- and 4-
carbons long coupled in head to tail fashion.
– 6 alphamethyl group and the methyl group on the 4-carbon side chain are derived from
the methyl group of methionine, and
– 6 alphamethyl group is added before closure of the rings.
This implies that lovastatin is a unique compound synthesized by A. terreus and that mevastatin is not an intermediate in its fornmation.
Cholesterol Biosynthetic Pathway
The HMG CoA reductase reaction
Biosynthesis — Diels-Alder Catalyzed Cyclization
In vitro formation of a triketide lactone using a genetically-modified protein derived from 6-deoxyerythronolide B synthase has been demonstrated. The stereochemistry of the molecule supports the intriguing idea that an enzyme-catalyzed Diels-Alder reaction may occur during assembly of the polyketide chain. It thus appears that biological Diels-Alder reactions may be triggered by generation of reactive triene systems on an enzyme surface.
Biosynthesis – Using Broadly specific Acyltransferase
It has been found that a dedicated acyltransferase, LovD, is encoded in the lovastatin biosynthetic pathway. LovD has a broad substrate specificity towards the acyl carrier, the acyl substrate and the decalin acyl acceptor. It efficiently catalyzes the acyl transfer from coenzyme A thoesters or N-acetylcysteamine (SNAC) thioesters to monacolin J.
The biosynthesis of Lovastatin is coordinated by two iterative type I polyketide synthases and numerous accessory enzymes. Nonketide, the intermediate biosynthetic precursor of Lovastatin, is assembeled by the upstream megasynthase LovB (also known as lovastatin nonaketide synthase), enoylreductase LovC, and CYP450 oxygenases. The five carbon unit side chain is synthesized by LovF (also known as lovastatin diketide synthase) through a single condensation diketide undergoes methylation and reductive tailoring by the individual LovF catalytic domains to yield an α-S-methylbutyryl thioester covalently attached to the phosphopantetheine arm on the acyl carrier protein (ACP) domain of LovF. Encoded in the gene cluster is a 46kDa protein, LovD, which was initially identified as an esterase homolog. LovD, which was initially identified as an esterase homolog. LovD was suggested to catalyze the last step of lovastatin biosynthesis that regioselectively transacylates the acyl group from LovF to the C8 hydroxyl group of the Nonaketide to yield Lovastatin.
K. Auclair, A. Sutherland, J. Kennedy, D. J. Witter, J. P. Van den Heever, C. R. Hutchinson and J. C. Vederas, Lovastatin Nonaketide Synthase Catalyses An Intramolecular Diels-Alder Reaction Of A Substrate Analogue, J. Am. Chem. Soc., 2000, 122, 11519-11520. DOI: 10.1021/ja003216+
Z. Jia, X. Zhang, Y. Zhao, and X. Cao, “Enhancement of lovastatin production by supplementing polyketide antibiotics to the submerged culture of Aspergillus terreus,” Applied Biochemistry and Biotechnology, vol. 160, no. 7, pp. 2014–2025, 2010.
A major bulk of work in the synthesis of Lovastatin was done by M. Hirama in the 1980’s. Hirama synthesized Compactin and used one of the intermediates to follow a different path to get to Lovastatin. The synthetic sequence is shown in the schemes below. The γ-lactone was synthesized using Yamada methodology starting with aspartic acid. Lactone opening was done using lithium methoxide in methanol and then silylation to give a separable mixture of the starting lactone and the silyl ether. The silyl ether on hydrogenolysis followed by Collins oxidation gave the aldehyde. Stereoselective preparation of (E,E)-diene was accomplished by addition of trans-crotyl phenyl sulfone anion, followed by quenching with Ac2O and subsequent reductive elimination of sulfone acetate. Condensation of this with Lithium anion of dimethyl methylphosphonate gave compound 1.Compound 2 was synthesized as shown in the scheme in the synthetic procedure. Compounds 1 and 2 were then combined together using 1.3eq sodium hydride in THF followed by reflux in chlorobenzene for 82 hrs under nitrogen to get the enone 3.
Simple organic reactions were used to get to Lovastatin as shown in the scheme.
Pharmacopoeia Information
Lovastatin tablets are preserved in well closed, light resistant containers. Protected from light and stored either in a cool place or at controlled room temperature.
Lovastatin tablets are tested for Dissolution and Assay as per the USP.
Limit for Dissolution – Not less than 80% (Q) of the labeled amount of Lovastatin is dissolved in 30 mins.
Limit for Assay – Each tablet contains not less than 90% and not more than 110% of the labeled amount of Lovastatin, tested by HPLC analysis.
Lovastatin raw material contains 5 impurities – A, B, C, D and E (as shown below).
Market brands and other analogues
There are other derivatives of Lovastatin which possess cholesterol reducing activity. Simvastatin (Zocor®) is another statin closely related to Lovastatin, differing only by the presence of a methyl group in the butanoyl ester moiety. Both effective in lowering total cholesterol.
Another statin having vastly different structure but a popular drug – Atorvastatin (Lipitor®), administered as a calcium salt is a pyrrole derivative and a synthetic compound rather than a natural product.
NMR
1 H NMR spectrum of lovastatin, 300 MHz, solvent CDCl 3 .
UV LOVASTATIN
Figure 6. The mean FT-IR spectra (the calibration set) and variables selected after application of UVE-PLS for modelling lovastatin (triangles) and wavenumbers for characteristic peaks for lovastatin IR spectrum (dots).
Lovastatin is produced as a secondary metabolite of the fungusAspergillus terreus (US 4,231,938) deposited in American Type Culture Collection under Nos. ATCC 20541, ATCC 20542, and Monascus ruberdeposited in Fermentation Research Institute Agency of Industrial Science and Technology, Ministry of International Trade and Industry, Japan (DE 30 06 216 A1) under No. Ferm 4822. Other kinds of microorganisms producing lovastatin are known as well, e.g. a mutant of the microorganism Aspergillus terreus andAspergillus oryzae marked ATCC 74135.
Lovastatin is chemically 1′,2′,6′,7′,8a’-hexahydro-3,5-dihydroxy-2′,6′-dimethyl-8′-2″-methyl-1″-oxobutoxy)-1-naphtalene heptanoic acid-5-lactone (Stubbs et al., 1986) of the formula (EP 0 033 537 A1)
An active form of lovastatin is also an acid, which is chemically 1,2,6,8,8a-hexahydro-β,δ-dihydroxy-1-naphtalene heptanoic acid (Alberts et al., 1980) of the formula (EP 0 022 478 A1)
The lactone form of lovastatin is used as an agent for reducing cholesterol level in blood (Scott M.G. and Vega G.L, 1985). It inhibits the biosynthesis of mevalonic acid by inhibition of 3-hydroxy-3-methylglutaryl A reductase coenzyme (HMG-CoA reductase, E.C. 1.1.1.34) (Zubay et al., 1984).
Prior Art
After the completed fermentation, lovastatin is present in the broth in the lactone form (compound I) and in the acid form (compound II). In the isolation process as disclosed in EP 0 033 536 A2, lovastatin is extracted from the broth with ethyl acetate. The extract is concentrated by vacuum distillation. Since lovastatin is present in the lactone form as well as in the acid form and only the lactone is of commercial interest, the acid form should be converted into the lactone. The lactonisation is carried out by the reflux of the concentrate in toluene at 106 °C for 2 hours. After the lactonisation is complete, the solution is concentrated to a small volume. A pure substance is obtained by means of purifying the concentrate on columns packed with silica gel, in the presence of solvents such as ethyl acetate or n-hexane. The collected fractions are again concentrated in vacuo and then pure lovastatin crystallizes in the lactone form.
Due to the sophisticated multi-step procedure and vigorous conditions applied during the isolation, the yields of lovastatin are generally low. Different solvents, which in part exhibit toxicity, are used such as benzene, toluene, acetonitrile or ethyl acetate. Hence working with these solvents endangers the health of the persons involved and poses a problem with respect to the environment.
Literature References: Fungal metabolite; potent inhibitor of HMG-CoA reductase, the rate controlling enzyme in cholesterol biosynthesis. Isoln from Monascus ruber: A. Endo, J. Antibiot.32, 852 (1979); from Aspergillus terreus: R. L. Monaghan et al.,US4231938 (1980 to Merck & Co.). Structure and biochemical properties: A. W. Alberts et al.,Proc. Natl. Acad. Sci. USA77, 3957 (1980). Total synthesis: M. Hirama, M. Iwashita, Tetrahedron Lett.24, 1811 (1983). Review of syntheses: T. Rosen, C. H. Heathcock, Tetrahedron42, 4909-4951 (1986). Biosynthesis: M. D. Greenspan, J. B. Yudkovitz, J. Bacteriol.162, 704 (1985); R. N. Moore et al.,J. Am. Chem. Soc.107, 3694 (1985). HPLC determn in plasma and bile: R. J. Stubbs et al.,J. Chromatogr.383,438 (1986). Clinical pharmacology: S. M. Grundy, G. L. Vega, J. Lipid Res.26, 1464 (1985). Clinical comparison with gemfibrozil,q.v.: M. J. Tikkanen et al.,Am. J. Cardiol.62, 35J (1988). Review of clinical experience: J. A. Tobert, Am. J. Cardiol.62, 28J-34J (1988). Comprehensive description: G. S. Brenner et al.,Anal. Profiles Drug Subs. Excip.21, 277-305 (1992). Prevention of acute coronary events in men and women with average cholesterol levels: J. R. Downs et al.,J. Am. Med. Ass
References
Neuvonen, PJ; Backman, JT; Niemi, M (2008). “Pharmacokinetic comparison of the potential over-the-counter statins simvastatin, lovastatin, fluvastatin and pravastatin.”. Clinical Pharmacokinetics. 47 (7): 463–74. doi:10.2165/00003088-200847070-00003. PMID18563955.
. Gunde-Cimerman N; Cimerman A. (Mar 1995). “Pleurotus fruiting bodies contain the inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase-lovastatin.”. Exp Mycol. 19 (1): 1–6.doi:10.1006/emyc.1995.1001. PMID7614366.
Jump up^Katz MS (2005). “Therapy insight: Potential of statins for cancer chemoprevention and therapy”. Nature Clinical Practice Oncology. 2(2): 82–9. doi:10.1038/ncponc0097. PMID16264880.
Jump up^Alarcón J, Aguila S, Arancibia-Avila P, Fuentes O, Zamorano-Ponce E, Hernández M (Jan–Feb 2003). “Production and purification of statins from Pleurotus ostreatus (Basidiomycetes) strains”. Z Naturforsch C. 58 (1–2): 62–4. doi:10.1515/znc-2003-1-211.PMID12622228.
Jump up^Vederas JC, Moore RN, Bigam G, Chan KJ (1985). “Biosynthesis of the hypocholesterolemic agent mevinolin by Aspergillus terreus. Determination of the origin of carbon, hydrogen and oxygen by 13C NMR and mass spectrometry”. J Am Chem Soc. 107 (12): 3694–701.doi:10.1021/ja00298a046.
Jump up^Opletal L, Jahodár L, Chobot V, et al. (December 1997). “Evidence for the anti-hyperlipidaemic activity of the edible fungus Pleurotus ostreatus”. Br. J. Biomed. Sci. 54 (4): 240–3. PMID9624732.
Jump up^Bajaj M, Vadhera S, Brar AP, Soni GL (October 1997). “Role of oyster mushroom (Pleurotus florida) as hypocholesterolemic/antiatherogenic agent”. Indian J. Exp. Biol. 35(10): 1070–5. PMID9475042.
Jump up^Bobek P, Ozdín L, Kuniak L, Hromadová M (March 1997). “[Regulation of cholesterol metabolism with dietary addition of oyster mushrooms (Pleurotus ostreatus) in rats with hypercholesterolemia]”.Cas. Lek. Cesk. (in Slovak). 136 (6): 186–90. PMID9221192.
Jump up^Bobek P, Ozdín L, Kuniak L (August 1996). “Effect of oyster mushroom (Pleurotus Ostreatus) and its ethanolic extract in diet on absorption and turnover of cholesterol in hypercholesterolemic rat”.Nahrung. 40 (4): 222–4. doi:10.1002/food.19960400413.PMID8810086.
Jump up^Bobek P, Ozdín O, Mikus M (1995). “Dietary oyster mushroom (Pleurotus ostreatus) accelerates plasma cholesterol turnover in hypercholesterolaemic rat”. Physiol Res. 44 (5): 287–91.PMID8869262.
Jump up^Bobek P, Ozdin L, Kuniak L (1995). “The effect of oyster mushroom (Pleurotus ostreatus), its ethanolic extract and extraction residues on cholesterol levels in serum, lipoproteins and liver of rat”. Nahrung. 39(1): 98–9. doi:10.1002/food.19950390113. PMID7898579.
Jump up^Bobek P, Ozdin L, Kuniak L (March 1994). “Mechanism of hypocholesterolemic effect of oyster mushroom (Pleurotus ostreatus) in rats: reduction of cholesterol absorption and increase of plasma cholesterol removal”. Z Ernahrungswiss. 33 (1): 44–50.doi:10.1007/BF01610577. PMID8197787.
Jump up^Chorváthová V, Bobek P, Ginter E, Klvanová J (1993). “Effect of the oyster fungus on glycaemia and cholesterolaemia in rats with insulin-dependent diabetes”. Physiol Res. 42 (3): 175–9.PMID8218150.
Jump up^Bobek P, Ginter E, Jurcovicová M, Kuniak L (1991). “Cholesterol-lowering effect of the mushroom Pleurotus ostreatus in hereditary hypercholesterolemic rats”. Ann. Nutr. Metab. 35 (4): 191–5.doi:10.1159/000177644. PMID1897899.
Jump up^Khatun K, Mahtab H, Khanam PA, Sayeed MA, Khan KA (January 2007). “Oyster mushroom reduced blood glucose and cholesterol in diabetic subjects”. Mymensingh Med J. 16 (1): 94–9.doi:10.3329/mmj.v16i1.261. PMID17344789.
Jump up^“FDA bans red yeast rice product” by Michael McCarthy, The Lancet, Volume 351, Issue 9116, Page 1637, 30 May 1998
Jump up^Endo, Akira; Kuroda M.; Tsujita Y. (December 1976). “ML-236A, ML-236B, and ML-236C, new inhibitors of cholesterogenesis produced by Penicillium citrinium”. Journal of Antibiotics (Tokyo). 29(12): 1346–8. doi:10.7164/antibiotics.29.1346. PMID1010803.
Jump up^Hirama M, Vet M (1982). “A chiral total synthesis of compactin”. J. Am. Chem. Soc. 104 (15): 4251. doi:10.1021/ja00379a037.
Jump up^Hirama M, Iwashita; Iwashita, Mitsuko (1983). “Synthesis of (+)-Mevinolin starting from Naturally occurring building blocks and using an asymmetry inducing reaction”. Tetrahedron Lett. 24 (17): 1811–1812. doi:10.1016/S0040-4039(00)81777-3.
Jump up^Javernik S, Kreft S, Strukelj B, Vrecer F (2001). “Oxidation of lovastatin in the solid state and its stabilization with natural antioxidants”. Die Pharmazie. 56 (9): 738–40. PMID11593996.
Jump up^Hartig K, Beck E (2005). “Assessment of lovastatin application as tool in probing cytokinin-mediated cell cycle regulation”. Physiologia Plantarum. 125 (2): 260–267. doi:10.1111/j.1399-3054.2005.00556.x.
Pazopanib is a small molecule inhibitor of multiple protein tyrosine kinases with potential antineoplastic activity. It is developed by GlaxoSmithKline and was FDA approved on October 19, 2009.
Pazopanib is a potent and selective multi-targeted receptor tyrosine kinase inhibitor of VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-a/b, and c-kit that blocks tumor growth and inhibits angiogenesis. It was approved for renal cell carcinoma by the U.S. Food and Drug Administration in 2009 and is marketed under the trade name Votrient by the drug’s manufacturer, GlaxoSmithKline.
Pazopanib (Votrient®; GlaxoSmithKline, Brentford, U.K.) is currently approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency for the treatment of patients with metastatic renal cell carcinoma (mRCC)
Medical uses
It is approved by numerous regulatory administrations worldwide (including the FDA (19 October 2009), EMA (14 June 2010), MHRA(14 June 2010) and TGA (30 June 2010)) for use as a treatment for advanced/metastatic renal cell carcinoma and advanced soft tissue sarcomas.[1][2][3][4][5] In Australia and New Zealand, it is subsidised under the PBS and by Pharmac respectively, under a number of conditions, including:[6][7]
The medication is used to treat clear cell variant renal cell carcinoma.
The treatment phase is continuing treatment beyond 3-months.
The patient has been issued an authority prescription for pazopanib
The patient must have stable or responding disease according to the Response Evaluation Criteria In Solid Tumours (RECIST)
This treatment must be the sole tyrosine kinase inhibitor subsidised for this condition.
It has also demonstrated initial therapeutic properties in patients with ovarian and non-small cell lung cancer,[8] though plans to apply to the EMA for a variation to include advanced ovarian cancer have been withdrawn and a license will not be sought in any country.[9][10]
SYNTHESIS
Pazopanib hydrochloride drug substance is manufactured by Glaxo Wellcome Manufacturing Pte. Limited, Jurong, Singapore
NDA 22-465 was submitted by GlaxoSmithKline (GSK) for VOTRIENT™ (pazopanib), an immediate release tablet for oral administration containing either 200 mg or 400 mg of pazopanib free base (GW786034X) as the hydrochloride salt (GW786034B). Pazopanib is a new molecular entity and is submitted for review pursuant to Section 505(b)(1) of the Food, Drug and Cosmetic Act. Reference is made to one active Investigational New Drug application, IND 65,747.
Quality by Design (QbD) approach and risk management to increase their understanding of the process and drug substance properties. A number of Critical Quality Attributes (CQAs) were identified. These are: Identity by IR, Chloride Identity, Crystalline Form, Content by HPLC, Drug-related Impurities (including named impurities and genotoxic (b) (4) (b) (4) (b) (4) (b) (4) Executive Summary Section CMC Review #1 Page 9 of 262 CMC REVIEW OF NDA 22-465 impurities content), Residue on Ignition, Particle Size, Residual Solvents, Water Content by Karl Fischer, Description, Pd Content, and Heavy Metals.
CQA are mainly controlled by controlling starting material attributes, intermediate attributes (e.g. specifications of GW786034 quality process parameters, and by following the manufacturing process. A risk based method (e.g. failure mode and effects analysis (FMEA)) was used to identify the Quality Critical Process Parameters (QCPPs), Quality Process Parameters (QPPs), CQAs and Quality Attributes (QAs) for the pazopanib hydrochloride manufacturing process. The inputs to the FMEA were knowledge gained through the work to develop the impurity fate map, spiking and purging studies, the Design of Experiments (DOE) work to establish potential QCPPs/QPPs, one factor at a time experiments to establish parameter proven acceptable ranges, and 6 years of plant experience preparing over batches of pazopanib hydrochloride in 3 plants throughout the GSK network. It was concluded from this risk assessment that there are no QCPP but a few QPP in the drug substance (DS) manufacturing process. Stages 1 and 2 had no QPP, the few were only present in stages 3 and 4. All the QPP were scale invariant. A combination of multivariate DOE and univariate experimentation was used to determine the Proven acceptable Ranges (PAR) for the variables. The risks for combining univariate and multivariate experimentation were found to be minimal, on the basis of outcome from the robustness study. For this study, all the process parameters were all set at the lower limit of the PARs to create a worst-case scenario for impurity purging. Neither new impurities nor elevated levels of known impurities were detected. This data demonstrated that multivariate interactions will not lead to elevated levels of impurities.
Drug Product Pazopanib Tablets, 200 mg and 400 mg are film-coated IR oral tablets. The two strengths contain 216.7 mg and 433.4 mg pazopanib hydrochloride, respectively, which are equivalent to 200 mg and 400 mg pazopanib (free base), respectively. Excipients in the tablet core are: microcrystalline cellulose, sodium starch glycolate, povidone, and magnesium stearate. Pazopanib Tablets, 200 mg are modified capsule-shaped, gray film-coated tablets, one side plain and the opposite side debossed with an identifying code of ‘GS JT’. Pazopanib Tablets, 400 mg are modified capsule-shaped, yellow film-coated tablets, one side plain and the opposite side debossed with an identifying code of ‘GS UHL’. The tablets are manufactured at Glaxo Operations UK Limited, Priory Street, Ware, Hertfordshire SG12 0DJ, United Kingdom. Primary packaging of tablets will be performed by either Glaxo Operations UK Limited, Priory Street, Ware, Hertfordshire SG12 0DJ, United Kingdom or GlaxoSmithKline Inc, 1011 North Arendell Avenue, Zebulon, North Carolina 27597, USA.
Pazopanib hydrochloride is a new molecular entity of Biopharmaceutics Classification System (BCS) Class 2 (poor solubility, high permeability) and a crystalline solid. Its solubility in pH 1.1 is 0.65 mg/mL. The conjugate acids of the basic nitrogens have the following acidity constants: pKa – pK1 = 2.1 (indazole), pK2 = 6.4 (pyrimidine), pK3 = 10.2 (sulfonamide).
“Synthetic approaches to the 2009 new drugs”
Kevin K.-C. Liua, Subas M. Sakyab, Christopher J. O’Donnellb, Andrew C. Flickb, Jin Lic,
Bioorganic & Medicinal Chemistry, Volume 19, Issue 3, Pages 1136–1154
“An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals”., Beilstein J. Org. Chem., 2011, 7, 442–495.
Pazopanib is marketed as hydrochloride salt by Glaxoshiithkline under the trade name VOTRIENT® is tyrosine kinase inhibitor and indicated for the treatment of patients with advanced renal cell carcinoma (RCC) and treatment of patients with advanced soft tissue sarcoma (STS) who have received prior chemotherapy.
U.S. Patent No (s). US 7105530 (“the ‘530 patent”), US7262203 (“the ‘203 patent”) and US8114885 (“the ‘885 patent”) discloses a variety of pyrimidineamines and their derivatives such as Pazopanib, processes for their preparation, pharmaceutical compositions comprising the derivatives, and method of use thereof.
The process disclosed in the ‘530 patent is schematically represented as follows:
Patent publication No. WO 2011/050159 (“the Ί59 publication”) disclosed process for preparation of Pazopanib hydrochloride, which involves condensation of 2,3-dimethyl-2H-indazol-6-amine of Formula A and 2,4-dicMoropyrimidine of Formula B in a solvent like industrial methylated sprit and specific reaction conditions like, in presence of a base, sodium bicarbonate having a particle size distribution of > 250μηι or 50 to 150μηι selected to ensure that the pH of the reaction mixture is less than 7 for the reaction time period not more than 300 min to obtain N-(2-c oropyrimidin-4-yl)- 2,3-dimethyl-2H-indazol-6-amine of Formula II. The compound of Formula Π was methylated in presence of a methylating agent in an organic solvent like dimethylformamide by using specific reaction conditions like, in presence of a base i.e. Potassium carbonate having a particle size distribution D99 of > 300μηι or D99 of < 200μηι selected to ensure that the reaction time needs to reduce the starting material to less than 2% in less than 8 his to obtain N-(2-cMoropyrimidin-4-yl)-N-2,3-trimemyl-2H-mdazol-6-amine of Formula III. The resultant methylated compound was condensed with 5-amino-2-methylbenzenesulfonamide of Formula C in presence of 4M HC1 and methanol to yield Pazopanib hydrochloride.
WO Ί59 publication disclosed that use of sodium bicarbonate with specific particle size distribution of > 250μπι or 50 to 150μηι is key element in condensation of compound of Formula A and Formula B to niinimize the formation of Impurity of Formula 1 within
WO Ί59 publication also disclosed that use of potassium carbonate with specific particle size distribution D99 of > 300μπι or D99 of < 200μηι is key element in methylation of compound of Formula II to reduce the formation of Impurities of Formula 2, Formula 3 and Formula 4 within the range of about 0.05-3%.
Patent publication No. WO 2012/073254 (“the ‘254 publication”) disclosed a process for preparation of pazopanib hydrochloride, which involves condensation of 2,4-dicMoropyrimidine of Formula B with 5-amino-2-methylbenzenesulfonamide of Formula C in presence of a base like sodium bicarbonate and a solvent like ethanol to yield 5-(4-chloropyrimidm-2-yl-ammo)-2-memylbenzenesulfonamide The resultant compound was condensed with N-2,3-1rimethyl-2H-indazole-6-amine of Formula D in an alcoholic solvent like ethanol. WO ‘254 publication also discloses process for purification of pazopanib hydrochloride from alcoholic solvent and water. The process disclosed in the ‘254 publication is schematically represented as follows:
Patent publication No. IN 2505/CHE/2011 disclosed a process for preparation of pazopanib, which involves condensation of 2,3-dimethyl-2H-indazol-6-amine of Formula A and 2,4-dichloropyrimidine of Formula B in presence of sodium bicarbonate and a phase transfer catalyst like tetrabutyl ammonium bromide in a solvent like methanol to obtain N-(2-chloropyrimidin-4-yl)-2,3 -dimethyl -2H-indazol-6-amine of Formula II. The resultant compound was methylated in presence of methyl iodide, potassium carbonate in a solvent like dimethylformamide to obtain compound of Formula III. The obtained Formula III was condensed with 5-amino-2-methylbenzenesulfonamide of Formula C in presence of dimethylformamide and concentrated HC1 to yield pazopanib hydrochloride.
Patent publication No. CN 103373989 (“the ‘989 publication”) disclosed a process for preparation of Pazopanib intermediate of Formula III by condensation of N-2,3-trimethyl-2H-indazole-6-amine of Formula D with 2,4-dicWoropyrimidine of Formula B in
Patent publication No. WO 2014/97152 (“the Ί52 publication”) disclosed a process for preparation of Pazopanib hydrochloride starting from 2,3-dimethyl-6-nitro-2H-indazole.
The processes for preparation of pazopanib described in the above literature have certain drawbacks as it involves: a) use of specific predefined particles of bases like sodium bicarbonate and potassium carbonate, which involves additional process steps like milling, grinding etc, b) use of expensive phase transfer catalysts and c) multiple steps making the process quite expensive, particularly on large scale.
European Medicines Agency (EMA) public assessment report disclosed that pazopanib hydrochloride is a white to slightly yellow, non-hygroscopic, crystalline substance and the manufacturing process consistently produces pazopanib hydrochloride Form 1. However, the EMEA does not describe any particular characterization data for the disclosed polymorph Form 1.
PCT Publication No. WO 2011/058179 (“the Ί79 publication”) discloses pazopanib base crystalline Forms such as Form-I and Form-II and a process for its preparation; also disclosed characterization data of Form-I and Form-II by XRD, IR and melting point. –
PCT Publication No. WO 2011/069053 (“the ‘053 publication”) discloses crystalline pazopanib base and crystalline pazopanib hydrochloride Forms such as Form-II, Form-Ill, Form-TV, Form-V, Form- VI, Form- VIII, Form-IX, Form-X, Form-XI, Form-XII, Form-XIII, Form-A, Form-G and also discloses crystalline Pazopanib dihydrochloride Forms such as Form-I, Form-XIV, Form-XV. The crystalline Forms reported in the PCT publication characterized by its XRD pattern.
IN Publication No. 3023/CHE/2010 discloses crystalline pazopanib dihydrochloride Form-I and crystalline pazopanib mono hydrochloride, process for it preparation and characterization by XRD of the same.
IN Publication No. 1535/CHE/2012 discloses crystalline pazopanib hydrochloride Form-SP and a process for its preparation; also disclosed characterization data, of Form-SP by XRD, DSC and TR.
PCT Publication No (s): WO 2007/143483, WO 2007/064753, WO 2006/20564 and WO 2005/105094 as well as US Publication No. US 2008/0293691 disclose anhydrous and hydrated Forms of pazopanib hydrochloride and their process for preparation thereof. ‘
IP. Com journal disclosure Number IPCOM000207426D discloses crystalline Form of pazopanib hydrochloride Form-R, which is characterized by XRD pattern.
Further, IP.Com journal disclosure Number IPCOM000193076D discloses crystalline Forms of N-(2-cUoropyrirnidin-4-yl)-N-2,3-trimethyl-2H-indazol-6-amine of
Formula III such as Form I and Form II along with characteristic data of XRD pattern
Preparation of 5-(4-chloropyrimidin-2ylamino)-2-methyIbenzenesulfonamide
To a mixture of 5-amino-2-methylbenzenesulfonamide (20 gm) in ethanol (208 ml) and tetrahydrofuran (52 ml) was added 2,4-dichloropryrimidine (44 gm) and sodium bicarbonate (36 gm) at room temperature. The contents were heated to 70 to 75°C and maintained for 13 hours. The reaction mass was then cooled to 10°C and maintained for 2 hours. The reaction mass was filtered and the solvent was distilled off under vacuum at below 50 to 55°C to obtain a residual mass. To the residual mass was added ethyl acetate (100 ml) and stirred for 1 hour, filtered. The solid obtained was dried to give 15.5 gm of 5-(4-chloropyrimidin-2ylamino)-2-methylbenzenesulfonamide. Example 2:
Preparation of N,2,3-trimethyI-2H-indazol-6-amine
Sodium methoxide (19 gm) was dissolved in methanol (610 ml) and then added 2,3-dimethyl-2H-indazol-6-amine (13 gm). The reaction mixture was stirred for 15 minutes and then added paraformaldehyde (3.9 gm). The contents were heated to 60°C and stirred for 10 hours. The reaction mass was then cooled to room temperature and maintained for 4 hours 30 minutes. Sodium borohydride (2.8 gm) was added to the reaction mass slowly at room temperature and then heated to reflux. The reaction mass was maintained for 2 hours at reflux and then cooled to room temperature. The reaction mass was stirred for 14 hours at room temperature and then added sodium hydroxide solution (1M, 100 ml). The pH of the reaction mass was adjusted to 8.0 to 8.5 with hydrochloric acid solution (40 ml) and then added ethyl acetate (400 ml). Then the layers were separated and the aqueous layer was extracted with ethyl acetate. The organic layer was dried with sodium sulfate and treated with carbon. The combined organic layers were washed with sodium chloride solution and dried with sodium sulfate. The organic layer was treated with carbon and filtered through hi-flow bed. The solvent was distilled off under vacuum at below 50°C to obtain a residual mass. To the residual mass was added diisopropyl ether (75 ml) and stirred for 1 hour, filtered. The solid obtained was dried to give 10 gm of N,2,3-trimethyl-2H-indazol-6-amine.
Example 3:
Preparation of pazopanib hydrochloride
5-(4-Chloropyrimidin-2ylamino)-2-methylbenzenesulfonamide (17 gm) as obtained in example 1, N,2,3-trimethyl-2H-indazol-6-amine (10 gm) as obtained in example 2 and ethanol (166 ml) were added at room temperature and then heated to reflux. The reaction mass was maintained for 3 hours at reflux and then added concentrated hydrochloric acid (1 ml). The reaction mass was maintained for 10 hours at reflux and then cooled to room temperature. The separated solid was filtered and dried to obtain 17 gm of pazopanib hydrochloride (HPLC Purity: 97.5%). Example 4:
Purification of pazopanib hydrochloride
Pazopanib hydrochloride (5 gm; HPLC Purity: 97.5%) as obtained in example 3 was dissolved in a mixture of methanol (100 ml) and water (10 ml) at room temperature and then heated to reflux. The reaction mass was maintained for 30 minutes at reflux and filtered. The filtrate obtained was cooled to room temperature and maintained for 2 hours at room temperature. The solid obtained was collected by filtration and dried to obtain 3.5 gm of pazopanib hydrochloride (HPLC Purity: 99.9%). Example 5:
Purification of pazopanib hydrochloride
Pazopanib hydrochloride (22 gm; HPLC Purity: 98%), methanol (528 ml), water (55 ml) and concentrated hydrochloric acid (0.2 ml) were added at room temperature. The contents were heated to reflux and maintained for 30 minutes, filtered. Take the filtrate and the solvent was distilled off under vacuum to obtain a residual mass. The residual mass was then cooled to room temperature and stirred for 30 minutes at room temperature. The contents were further cooled to 0 to 5°C, stirred for 1 hour and filtered. The solid obtained was dried to give 19 gm of pazopanib hydrochloride (HPLC Purity: 99.85%).
Example 6:
Purification of pazopanib hydrochloride
Pazopanib hydrochloride (10 gm; HPLC Purity: 96%), methanol (250 ml), water (25 ml) and concentrated hydrochloric acid (0.1 ml) were added at room temperature. The contents were heated to reflux and maintained for 30 minutes, filtered. The filtrate obtained was then cooled to room temperature and stirred for 30 minutes at room temperature. The contents further cooled to 0 to 10°C and stirred for 1 hour. The separated solid was filtered and dried to obtain 6.6 gm of pazopanib hydrochloride (HPLC Purity: 99.8%).
Example 7: Purification of pazopanib hydrochloride
Pazopanib hydrochloride (22 gm; HPLC Purity: 97%) was dissolved in a mixture of isopropanol (132 ml) and water (20 ml) at room temperature and then heated to reflux. The reaction mass was maintained for 1 hour at reflux and then cooled to room temperature. The reaction mass was stirred for 1 hour at room temperature and filtered. The solid obtained was dried to give 18 gm of pazopanib hydrochloride (HPLC Purity: 99.8%).
The recently developed semiquantitative assessment tool for the evaluation of carryover potential of mutagenic impurities (MIs) into the final API was applied to the five identified MIs within pazopanib hydrochloride (dimethyl sulfate (DMS) and compounds II, III, VI, and VIII). The theoretical and predicted purge factors were compared. The tool accurately predicted the purging capacity for the most reactive MI, DMS, giving a theoretical purge factor of 30000 versus an actual value of 29411 (for spiking at stage 1). For the other less reactive MIs, both measured and predicted values agreed reasonably well, and the high values for the purging factors were indicative of an effective process capability that could significantly reduce observed MI levels. The only exception was for compound VI, where although the measured and theoretical purge factors were in agreement, they were significantly lower (<200) than for the other MIs. In this case, a strategy was implemented including a requirement for control of this MI on API specification. The purge-factor assessment tool has the potential to play a key role in GRA (genotoxic risk assessment) processes and subsequent regulatory submissions. This tool could provide regulators with additional confidence to accept these purging arguments without resorting to testing. This could potentially significantly reduce the analytical testing burden for early clinical candidates.
PATENT
WO 2011058179
The compound 5-(4-(N-(2,3-dimethyl-2H-indazole-6-yl)-N-methylamino)pyrimidine-2- ylamino)-2-methylbenzenesulfonamide, also known as Pazopanib, is useful in the treatment of disorders associated with inappropriate or pathological angiogenesis, such as cancer, in mammals. Pazopanib has the following formula (I):
H CH,
NH2
In WO 02/059110 the preparation of 5-(4-(N-(2,3-dimethyl-2H-indazole-6-yl)-N- methylamino)pyrimidine-2-ylamino)-2-methylbenzenesulfonamide hydrochloride as well as the uses of this compound have been disclosed. In particular, this compound is an inhibitor of tyrosine kinase enzymes, namely vascular endothelial growth factor receptors, and can be used for the treatment and/or prevention of diseases which are associated with tyrosine kinase enzymes such as vascular endothelial growth factor receptors, such as cancer, particularly breast cancer and colon cancer.
Alternative methods for the preparation of 5-(4-(N-(2,3-dimethyl-2H-indazole-6-yl)-N- methylamino)pyrimidine-2-ylamino)-2-methylbenzenesulfonamide hydrochloride are disclosed in WO 03/106416.
In WO 2007/064752 the use of Pazopanib for the treatment of age related macula degeneration is disclosed. WO 2007/064753 further discloses Pazopanib for the treatment of various types of cancer, e.g. brain cancer, glioblastoma multiforme, neuroendocrine cancer, prostate cancer, myeloma, lung cancer, liver cancer, gallbladder cancer or skin cancer.
Typically Pazopanib is administered orally, as this route provides great comfort and convenience of dosing. Although the hydrochloride form of Pazopanib is known in the art, as described above, this form is not optimal in regard to bioavailability, inter-patient variability, and safety. Further, the known form of Pazopanib hydrochloride is not optimal with regard to mechanical and chemical stability, which is in particular necessary for manufacturing tablets, as well as not optimal in regard to flow properties, compressibility, dissolution rate. Additionally, it is at least to some extent hygroscopic and shows electrostatic charging. These properties constitute disadvantages in the preparation of pharmaceutical compositions
A series of novel pazopanib derivatives, 7a–m, were designed and synthesized by modification of terminal benzene and indazole rings in pazopanib. The structures of all the synthesized compounds were confirmed by 1H NMR and MS. Their inhibitory activity against VEGFR-2, PDGFR-α and c-kit tyrosine kinases were evaluated. All the compounds exhibited definite kinase inhibition, in which compound 7l was most potent with IC50 values of 12 nM against VEGFR-2. Furthermore, compounds 7c, 7d and 7mdemonstrated comparable inhibitory activity against three tyrosine kinases to pazopanib, and compound 7f showed superior inhibitory effects than that of pazopanib.
To a solution of Intermediate Example 13 (200 mg, 0.695 mmol) and 5-amino-2- ethylbenzenesulfonamide (129.4 mg, 0.695 mmol) in isopropanol (6 ml) was added 4 drops of cone. HCI. The mixture was heated to reflux overnight. The mixture was cooled to rt and diluted with ether (6 ml). Precipitate was collected via filtration and washed with ether. HCI salt of 5-({4-[(2,3-dimethyl-2H-indazol-6-yl)(methyl)amino]-pyrimidin-2- yl}amino)-2-methylbenzenesulfonamide was isolated as an off-white solid. Y\ NMR (400 MHz, deDMSO+NaHCOa) δ 9.50 (br s, 1 H), 8.55 (br s, 1 H), 7.81 (d, J = 6.2 Hz, 1 H), 7.75 (d, J = 8.7 Hz, 1 H), 7.69 (m, 1 H), 7.43 (s, 1 H), 7.23 (s, 2H), 7.15 (d, J = 8.4 Hz, 1 H), 6.86 (m, 1 H), 5.74 (d, J = 6.1 Hz, 1 H), 4.04 (s, 3H), 3.48 (s, 3H), 2.61 (s, 3H), 2.48 (s, 3H). MS (ES+, m/z) 438 (M+H).
Example 13
Preparation of Λ/-(2-chloropyrimidin-4-yl)-Λ/,2,3-trimethyl-2r/-indazol-6-amine
To a stirred solution of the Intermediate 12 (7.37 g) in DMF (50 ml) was added CS2CO3 (7.44 g, 2 eqv.) and Mel (1.84 ml, 1.1 eqv.) at room temperature. Mixture was stirred at rt for overnight The reaction mixture was poured into ice-water bath, and the precipitate was collected via filtration and washed with water. The precipitate was air- dried to afford Λ/-(2-chloropyrimidin-4-yl)-Λ/,2,3-trimethyl-2r/-indazol-6-amine as an off-white solid (6.43 g, 83%). ‘H NMR (400 MHz, dsDMSO) δ 7.94 (d, J = 6.0 Hz, 1 H), 7.80 (d, J = 7.0 Hz, 1 H), 7.50 (d, J = 1.0 Hz, 1 H), 6.88 (m, 1 H), 6.24 (d, J = 6.2 Hz, 1 H), 4.06 (s, 3H), 3.42 (s, 3H), 2.62 (s, 3H). MS (ES+, m/z) 288 (M+H).
Intermediate Example 12 Preparation of Λ/-(2-chloropyrimidin-4-yl)-2,3-dimethyl-2H-indazol-6-amine
to a stirred solution of Intermediate Example 11 (2.97 g, .015 mol) and NaHCOs (5.05 g, .06 mol) in THF (15 mL) and ethanol (60 mL) was added 2,4-dichloropyrimidine (6.70 g, .045 mol) at room temperature. After the reaction was stirred for four hours at 85 °C, the suspension was cooled to rt, filtered and washed thoroughly with ethyl acetate. The filtrate was concentrated under reduced pressure, and the resulting solid was triturated with ethyl acetate to yield 3.84 g (89 % yield) of Λ/-(2-chloropyrimidin-4-yl)- 2,3-dimethyl-2tf-indazol-6-amine. 1H NMR (400 MHz, deDMSO) δ 7.28 (d, J = 9.0 Hz, 1 H), 6.42 (d, J = 8.8 Hz, 1 H), 6.37 (s, 1 H), 5.18 (br s, 1 H), 3.84 (s, 3H), 2.43 (s, 3H). MS (ES+, m/z) 274 (M+H).
Intermediate Example 11
Preparation of 2,3-dimethyl-2r/-indazol-6-amine
To a stirred solution of 18.5 g (0.11 mol) of 3-methyl-6-nitro- 7W-indazole in 350 ml acetone, at room temperature, was added 20 g (0.14 mol) of trimethyloxonium tetraflouroborate. After the solution was allowed to stir under argon for 3 hours, the solvent was removed under reduced pressure. To the resulting solid was added saturated aqueous NaHC03 (600 ml) and a 4:1 mixture of chloroform-isopropanol (200 ml), and the mixture was agitated and the layers were separated. The aqueous phase was washed with additional chloroform: isopropanol (4 x 200 ml) and the combined organic phase was dried (Na2S04). Filtration and removal of solvent gave a tan solid. The solid was washed with ether (200 ml) to afford 2,3-dimethyl-6-nitro-2r/-indazole as a yellow solid (15.85 g, 73 o/o). 1H NMR (300 MHz, dβDMSO) δ 8.51 (s, I H), 7.94 (d, J = 9.1 Hz, 1 H), 7.73 (d, J = 8.9 Hz, 1 H), 4.14 (s, 3H), 2.67 (s, 3H). MS (ES+, m/z) 192 (M+H).
To a stirred solution of 2,3-dimethyl-6-nitro-2V-indazole (1.13 g) in 2- methoxyethyl ether (12 ml), at 0 °C, was added a solution of 4.48 g of tin(ll) chloride in 8.9 ml of concentrated HCI dropwise over 5 min. After the addition was complete, the ice bath was removed and the solution was allowed to stir for an additional 30 min. Approximately 40 ml of diethyl ether was added to reaction, resulting in precipitate formation. The resulting precipitate was isolated by filtration and washed with diethyl ether, and afforded a yellow solid (1.1 g, 95 %), the HCI salt 2,3-dimethyl-2/7-indazol-6- amine. 1H NMR (300 MHz, deDMSO) δ 7.77 (d, J = 8.9 Hz, 1 H), 7.18 (s, 1 H), 7.88 (m, 1 H), 4.04 (s, 3H), 2.61 (s, 3H). MS (ES+, m/z) 162 (M+H).
Affiliation: Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing, Jiangsu 210009, P.R. China.
Abstract:
This paper reports a novel approach to synthesize pazopanib. In our synthetic route, the potently mutagenic alkylating agents such as dimethyl sulfate and methyl iodide are avoided. A novel regioselective methylation of the 2- position of 3-methyl-6-nitro-1H-indazole was reported. This novel route is one step shorter than the previously reported route.
Pazopanib is a tyrosine kinase inhibitor of Formula la.
Formula la
Pazopanib is marketed as the hydrochloride salt, with the chemical name 5-[[4- [(2,3-dimethyl-2H-indazol-6-yl)methylamino]-2-pyrimidinyl]amino]-2- methylbenzenesulfonamide monohydrochloride, having the structure as depicted in Formula I:
Formula I
U.S. Patent No. 7,105,530 provides a process for the preparation of a hydrochloride salt of a compound of Formula II
Formula II involving the reduction of 2,3-dimethyl-6-nitro-2H-indazole with tin (II) chloride in concentrated hydrochloric acid in the presence of 2-methoxyethyl ether at 0°C. It also describes the preparation of a compound of Formula III
Formula III involving the reaction of a hydrochloride salt of compound of Formula II with 2,4- dichloropyrimidine in the presence of a base and solvent mixture of
tetrahydrofuran/ethanol followed by stirring for 4 hours at 85°C.
PCT Publication No. WO 2007/064752 provides a process for the preparation of a compound of Formula II comprising reducing 2,3-dimethyl-6-nitro-2H-indazole with 10% Palladium-carbon (50% wet) in the presence of methanol, followed by the addition of ammonium formate at a rate that ensures the reaction temperature is maintained at or between 25°C and 30°C. It also discloses the preparation of a compound of Formula III comprising heating the compound of Formula II with sodium bicarbonate in presence of tetrahydrofuran and ethanol at or between 75°C and 80°C followed by cooling to 20°C to
25°C.
The present invention provides a process for the preparation of a compound of Formula II which offers recycling of the Raney nickel catalyst used in the process, and an easy filtration work-up procedure. Further, the present invention offers selective reduction under mild conditions that is economical to use at an industrial scale.
The present invention also provides a process for the preparation of compound of Formula III which avoids the use of two or more solvents, and additionally, also circumvents heating and cooling procedures during the reaction. The aforesaid advantages yield a compound of Formula III with a lesser amount of N-(4-chloropyrimidin-2-yl)-2,3- dimethyl-2H-indazol-6-amine (CPDMI) impurity.
The compounds of Formula II and Formula III prepared by the present invention yield a compound of Formula la or its salts in comparable yield and suitable purity required for medicinal preparations.
EXAMPLES
Step 1: Synthesis of 2,3-dimcthyl-6-nitro-2H-indazole
Example 1 :
Trimethyloxonium tetrafluoroborate (125.2 g, 0.85 mol) was added to a stirred suspension of 3-methyl-6-nitro-indazole (100 g, 0.56 mol) in ethyl acetate (2000 mL) over a period of 4 hours in four equal lots at 1 hour time intervals. The reaction mixture was stirred at 25 °C to 30°C for 16 hours. The solvent was recovered under reduced pressure. A saturated sodium bicarbonate solution (3240 mL) was added to the mixture slowly, and the reaction mixture was extracted with 4: 1 mixture of dichloromethane:isopropyl alcohol (1080 mL x 5). The solvent was recovered under reduced pressure. Methyl fert-butyl ether (800 mL) was added to the residue, and the reaction mixture was stirred for 30 minutes at 45 °C to 50°C. The reaction mixture was cooled to 25 °C to 30°C and was stirred at this temperature for 30 minutes. The solid was filtered, washed with methyl tert- butyl ether (100 mL x 2), and dried in an air oven at 50°C for 12 hours to afford 2,3- dimethyl-6-nitro-2H-indazole as a yellow solid.
Yield: 82.4% w/w
Step 2: Synthesis of 2,3-dimethyl-2H-indazol-6-amine
Example 2a:
Raney nickel ( 12.50 g) was added to a suspension of 2,3-dimethyl-6-nitro-2H- indazole (50 g, 0.26 mol) in methanol (500 mL). The reaction mixture was stirred in an autoclave under hydrogen pressure of 3.5 kg/cm2 – 4.0 kg/cm2 at 25°C to 30°C for 5 hours. Further, the reaction mixture was filtered through a hyflo bed, and the catalyst was washed with methanol (100 mL x 2). The filtrates were combined, and the solvent was recovered completely. «-Heptane (250 mL) and dichloromethane (50 mL) were added to the residue, and the reaction mixture was stirred for 1 hour at 25°C to 30°C. The solid was collected by filtration, washed with n-heptane (50 mL x 2), and dried under vacuum at 40°C to 45 °C to afford 2,3-dimethyl-2H-indazol-6-amine as a light brown solid.
Yield: 95% w/w
Example 2b:
Raney nickel (21.25 g) was added to a suspension of 2,3-dimethyl-6-nitro-2H- indazole (85 g, 0.45 mol) in methanol (850 mL). The reaction mixture was stirred in an autoclave under hydrogen pressure of 3.5 kg/cm2 – 4.0 kg/cm2 at 25°C to 30°C for 5 hours. Further, the reaction mixture was filtered through a hyflo bed, and the catalyst was washed with methanol (85 mL x 3). The filtrates were combined, and the solvent was recovered up to the volume of 850 mL. The 2,3-dimethyl-2H-indazol-6-amine in methanol was used as such in the next step. Step 3: Synthesis of N-(2-chloropyrimidin-4-yl)-2,3-dimethyl-2H-indazol-6-amine
Example 3 :
Sodium bicarbonate ( 112 g, 1.34 mol) was added to a stirred solution of 2,3- dimethyl-2H-indazol-6-amine (as obtained from step 2; Examples 2a and 2b) in methanol. 2,4-Dichloropyrimidine (99.35 g, 0.67 mol) was added to the reaction mixture followed by stirring of the reaction mixture for 24 hours at 25°C to 30°C. De-ionized water (850 mL) was added to the reaction mixture followed by stirring of the reaction mixture at 25 °C to 30°C for 1 hour. The solid was filtered. The wet solid was washed with de-ionized water (170 mL x 2) to obtain a wet material. De-ionized water (850 mL) was added to the wet material to obtain a slurry, and the slurry was stirred at 25°C to 30°C for 30 minutes. The solid was filtered, then washed with de-ionized water (170 mL x 2). The wet material obtained was treated with ethyl acetate (340 mL) to obtain a slurry. The slurry was stirred at 35°C to 40°C for 30 minutes and then cooled to 0°C to 5°C. The slurry was further stirred at 0°C to 5°C for 30 minutes. The solid was collected by filtration, then washed with cold ethyl acetate (170 mL x 2). The solid was dried in an air oven at 50°C for 16 hours to afford N-(2-chloropyrimidin-4-yl)-2,3 -dimethyl -2H-indazol-6-amine as an off- white solid.
Yield: 86.7% w/w
Step 4: Synthesis of pazopanib hydrochloride
Example 4a: Synthesis of N-(2-Chloropyrimidin-4-yl)-N.2.3-trimethyl-2H-indazol-6- amine
Cesium carbonate (238 g, 0.73 mol) and iodomethane (57 g, 0.40 mol) were added to a stirred suspension of N-(2-chloropyrimidin-4-yl)-2,3-dimethyl-2H-indazol-6-amine (lOOg, 0.37 mol) in N,N-dimethylformamide (300 mL) at 25°C to 30°C. The reaction mixture was further stirred at 25 °C to 30°C for 6 hours followed by cooling of the reaction mixture to 0°C to 5°C. De-ionized water (300 mL) was added drop-wise to the reaction mixture, then the reaction mixture was stirred at 5°C to 10°C for 30 minutes. The solid was collected by filtration, and washed with de-ionized water (100 mL x 2). The wet material so obtained was dried in an air oven at 50°C for 12 hours to obtain the title compound.
Yield: 90.4% w/w Example 4b: Synthesis of pazopanib hydrochloride
To a suspension of N-(2-chloropyrimidin-4-yl)-N-2,3-trimethyl-2H-indazol-6- amine (90 g, 0.312 mol) and 5-amino-2-methyl benzene sulfonamide (64.07 g, 0.344 mol) in isopropyl alcohol (900 mL) was added 4M hydrochloric acid solution in isopropyl alcohol (1.56 mL, 6.25 mol). The reaction mixture was heated to reflux temperature for 10 hours to 12 hours. The reaction mixture was cooled to 25°C. The reaction mixture was further stirred at 25°C to 30°C for 30 minutes, then the solid was filtered. The wet solid was washed with isopropyl alcohol (180 mL x 2), and then dried under vacuum at 45 °C to 50°C for 12 hours to afford the hydrochloride salt of 5-({4-[(2,3-dimethyl-21-I-indazol-6- yl)(methyl) amino] pyrimidin-2-yl} amino-Z-methylbenzene sulfonamide as a light brown solid.
In the reaction flask pazopanib hydrochloride crude 100g, 700ml of acetonitrile was added under stirring and purified water 200ml, feeding is completed, begin heating to 75~80 ° C, until clear solvent filtration system, slowly dropped 10~20 ° C, keep stirring lh, filtered, and the filter cake washed with purified water and acetonitrile respectively, drained and the filter cake was dried at 60 ° C blast 5h, have pazopanib hydrochloride monohydrate solid 84g, yield 80.9%.For example, crystalline form pazopanib hydrochloride prepared the following examples.
pazopanib hydrochloride polymorph of preparation:
Example 1:
In the reaction flask pazopanib hydrochloride monohydrate 8. 0g, ethanol 50ml and purified water 0.Iml (the volume of water accounted for a mixed solution of 2% of the total volume of the square, ethanol – water mixture total volume was 6.26 times pazopanib hydrochloride monohydrate quality), heated to 75 ° C, stirred at reflux for about 5h, after cooling to 10~20 ° C, keep stirring lh, the filter cake washed with ethanol, then blast drying at 105 ° C 5h, to obtain ultrafine powder solid 6. 8g, yield of 81. 9%, HPLC purity was 99.8%, as measured crystal X- ray powder diffraction pattern of FIG. 1 the basic consistent, as measured with a DSC thermogram consistent FIG. 2, the particle size distribution measurement is basically the same as Fig 3 (D90 <10ym).
CLIP
Pazopanib is a highly bio-available, multi- tyrosine kinase inhibitor of vascular endothelial growth factor receptor (VEGFR)-l, -2, -3, platelet-derived factor receptor (PDGFR) -α, -β, cytokine receptor (cKit), interleukin-2 receptor inducible T-cell kinase (Itk), leukocyte-specific protein tyrosine kinase (Lck), and transmembrane glycoprotein receptor tyrosine kinase (c-Fms). Pazopanib was recently approved by the Food and Drug Administration (FDA) for the treatment of patients with advanced renal cell carcinoma; thus adding to the other FDA-approved VEGF pathway inhibitors, sunitinib, bevacizumab (in combination with interferon) and sorafinib for this same indication.
Processes by which pazopanib and its intermediates can be synthesized have been described in US Patent No. 7,105,530 as well as in the published PCT application WO03/106416.
U.S. patent no. 7,105,530 disclosed pyrimidineamines and their derivatives thereof. These compounds are antineoplastic agents, and are useful in the treatment of various cancers and renal cell carcinoma. Among them pazopanib hydrochloride, chemically 5-[4-[N-(2,3-Dimethyl-2H-indazol-6-yl)-N-methylamino]pyrimidin-2- ylamino]-2-methylbenzenesulfonamide hydrochloride. Pazopanib hydrochloride is represented by the following structure:
Pazopanib hydrochloride is a potent and selective multi-targeted receptor tyrosine kinase inhibitor of VEGFR (Vascular endothelial growth factor receptors)- 1, VEGFR-2, VEGFR-3, PDGFR (Platelet-derived growth factor receptors )-a/p, and c-kit that blocks tumor growth and inhibits angiogenesis. It has been approved for renal cell carcinoma by the U.S. Food and Drug Administration. Pazopanib hydrochloride may also be active in ovarian cancer and soft tissue sarcoma. Pazopanib hydrochloride also appears effective in the treatment of non-small cell lung carcinoma. Pazopanib hydrochloride is marketed under the brand name Votrient® by Glaxosmithkline in the form of tablet.
Processes for the preparation of pazopanib hydrochloride and related compounds were disclosed in U.S. patent no. 7,105,530 and U.S. patent no. 7,262,203.
According to U.S. patent no. 7,105,530, pazopanib hydrochloride can be prepared by reacting the N-(2-chloropyrimidin-4-yl)-N,2,3-trimethyl-2H-indazol-6-amine with 5- amino-2-methylbenzenesulfonamide in the presence of hydrochloric acid in isopropanol and ether.
U.S. patent application publication no. 2006/0252943 disclosed a process for the preparation of pazopanib hydrochloride. According to this patent, pazopanib hydrochloride can be prepared by reacting the N-(2-chloropyrimidin-4-yl)-N,2,3- trimethyl-2H-indazol-6-amine with 5-amino-2-methylbenzenesulfonamide in the presence of hydrochloric acid in ethanol or methanol or tetrahydrofuran or acetonitrile and dioxane.
Drugs of the Future, 2006, 31 (7): 585-589
WO0306416
Marcus Baumann, Ian R. Baxendale, Steven V. Ley and Nikzad Nikbin
Innovative Technology Centre, Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, UK
Corresponding author email
Editor-in-Chief: J. Clayden
Beilstein J. Org. Chem.2011,7, 442–495.
Pazopanib (246, Votrient) is a new potent multi-target tyrosine kinase inhibitor for various human cancer cell lines. Pazopanib is considered a promising replacement treatment to imatinib and sunitinib and was approved for renal cell carcinoma by the FDA in late 2009. The indazole system is built up via diazotisation and spontaneous cyclisation of 2-ethyl-5-nitroaniline (247) using tert-butyl nitrite. The resulting indazole structure 249 can be methylated entirely regioselectively with either Meerwein’s salt, trimethyl orthoformate or dimethyl sulfate. A tin-mediated reduction of the nitro group unmasks the aniline which undergoes nucleophilic aromatic substitution to introduce the pyrimidine system with the formation of 253. Methylation of the secondary amine function with methyl iodide prior to a second SNAr reaction with a sulfonamide-derived aniline affords pazopanib .
Synthesis of pazopanib.
Pandite, A. N.; Whitehead, B. F.; Ho, P. T. C.; Suttle, A. B. Cancer Treatment Method. WO Patent 2007/064753, June 7, 2007.
Harris, P. A.; Boloor, A.; Cheung, M.; Kumar, R.; Crosby, R. M.; Davis-Ward, R. G.; Epperly, A. H.; Hinkle, K. W.; Hunter, R. N., III; Johnson, J. H.; Knick, V. B.; Laudeman, C. P.; Luttrell, D. K.; Mook, R. A.; Nolte, R. T.; Rudolph, S. K.; Szewczyk, J. R.; Truesdale, A. T.; Veal, J. M.; Wang, L.; Stafford, J. A. J. Med. Chem.2008,51,4632–4640. doi:10.1021/jm800566m
CLIP
Pazopanib hydrochloride (Votrient)
Pazopanib is a potent and selective multi-targeted receptor tyrosine kinase inhibitor of VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-a/b, and c-kit that blocks tumor growth and inhibits angiogenesis. It was approved for renal cell carcinoma by the U.S. Food
and Drug Administration in 2009 and is marketed under the trade name Votrient by the drug’s manufacturer, GlaxoSmithKline. The
synthesis of pazopanib begins with methylation of 3-methyl-6-nitroindazole (82) with trimethyl orthoformate in the presence of BF3OEt to give indazole 83 in 65% yield (Scheme 14).65 Reduction of the nitro group was achieved via transfer hydrogenation to give 84 in 97% yield, and this was followed by coupling the aniline with 2,4-dichloropyrimidine in a THF-ethanol mixture at elevated
temperature to provide diarylamine 85 in 90% yield. The aniline nitrogen was then methylated using methyl iodide to give 86 in
83% yield prior to coupling with 5-amino-2-methylbenzenesulfonamide (87) and salt formation using an alcoholic solution of
HCl to furnish pazopanib hydrochloride (XIV) in 81% yield.
VOTRIENT (pazopanib) is a tyrosine kinase inhibitor (TKI). Pazopanib is presented as the hydrochloride salt, with the chemical name 5-[[4-[(2,3-dimethyl-2H-indazol-6- yl)methylamino]-2-pyrimidinyl]amino]-2-methylbenzenesulfonamide monohydrochloride. It has the molecular formula C21H23N7O2S•HCl and a molecular weight of 473.99. Pazopanib hydrochloride has the following chemical structure:
Pazopanib hydrochloride is a white to slightly yellow solid. It is very slightly soluble at pH 1 and practically insoluble above pH 4 in aqueous media.
Tablets of VOTRIENT are for oral administration. Each 200 mg tablet of VOTRIENT contains 216.7 mg of pazopanib hydrochloride, equivalent to 200 mg of pazopanib free base. The inactive ingredients of VOTRIENT are:Tablet Core: Magnesium stearate, microcrystalline cellulose, povidone, sodium starch glycolate. Coating: Gray film-coat: Hypromellose, iron oxide black, macrogol/polyethylene glycol 400 (PEG 400), polysorbate 80, titanium dioxide.
FierceBiotech. 2008-09-15. Retrieved 2010-08-10.
Country
Patent Number
Approved
Expires (estimated)
United States
7105530
2009-10-19
2023-10-19
United States
7262203
2009-10-19
2021-12-19
United States
8114885
2009-10-19
2021-12-19
JUNE 4 2013 old article cut paste
GlaxoSmithKline’s (GSK) Votrient (pazopanib) has met the primary objective of a statistically significant improvement in the time to disease progression or death that is the progression-free survival (PFS) against placebo in Phase III ovarian cancer..
Pazopanib is an angiogenesis inhibitor targeting vascular endothelial growth factor receptors (VEGFR)-1, -2, and -3, platelet-derived growth factor receptors (PDGFR)-α/-β, and c-Kit. The hydrochloride salt of pazopanib (5-[[4-[(2,3-dimethyl-2H-indazol-6-yl)methylamino]-2-pyrimidinyl]amino]-2-methylbenzenesulfonamide) is marketed by GlaxoSmithKline as Votrient®, which is approved in the United States and other countries for the treatment of renal cell carcinoma (RCC).
Votrient® is currently prescribed to adults in the form of 200 mg tablets for oral administration, with each 200 mg tablet containing an amount of pazopanib hydrochloride equivalent to 200 mg of pazopanib free base.
Though the current tablets are acceptable of use in adults, the tablets are not preferred for use in potential future use for administering pazopanib to children. In pediatric populations, it is often desired that drug be available as a powder for reconstitution to an oral suspension. Manufacture of such a powder requires dry blending of various excipients with the active substance to provide good flow properties and content uniformity of the powder blend.
Several additional challenges exist concerning the use of pazopanib in a pediatric formulation. For instance, the nature of the drug substance favors conversion from the hydrochloride salt to the free base and hydrate forms in an aqueous environment such that standard formulations fail to provide adequate suspension stability at long term storage conditions of 25° C./65% RH or room temperature. Further, the drug has been found to have a bitter taste and, therefore, taste masking is critical.It is desired to invent a pediatric formulation of pazopanib hydrochloride suitable for administration to a pediatric population
Zivi, A; Cerbone, L; Recine, F; Sternberg, CN (September 2012). “Safety and tolerability of pazopanib in the treatment of renal cell carcinoma”. Expert Opinion on Drug Safety. 11 (5): 851–859. doi:10.1517/14740338.2012.712108. PMID22861374.
Khurana V, Minocha M, Pal D, Mitra AK (March 2014). “Role of OATP-1B1 and/or OATP-1B3 in hepatic disposition of tyrosine kinase inhibitors.”. Drug Metabol Drug Interact. 0 (0): 1–11. doi:10.1515/dmdi-2013-0062. PMID24643910.
Khurana V, Minocha M, Pal D, Mitra AK (May 2014). “Inhibition of OATP-1B1 and OATP-1B3 by tyrosine kinase inhibitors.”. Drug Metabol Drug Interact. 0 (0): 1–11.doi:10.1515/dmdi-2014-0014. PMID24807167.
Verweij, J; Sleijfer, S (May 2013). “Pazopanib, a new therapy for metastatic soft tissue sarcoma”. Expert Opinion on Pharmacotherapy. 14 (7): 929–935.doi:10.1517/14656566.2013.780030. PMID23488774.
Schöffski, P (June 2012). “Pazopanib in the treatment of soft tissue sarcoma”. Expert Review of Anticancer Therapy. 12 (6): 711–723. doi:10.1586/era.12.41.PMID22716487.
Pick, AM; Nystrom, KK (March 2012). “Pazopanib for the treatment of metastatic renal cell carcinoma”. Clinical Therapeutics. 34 (3): 511–520.doi:10.1016/j.clinthera.2012.01.014. PMID22341567.
Novel 2,4-Dianilinopyrimidine Derivatives, the Preparation Thereof, Their Use as Medicaments, Pharmaceutical Compositions and, in Particular, as IKK Inhibitors
Eribulin mesylate is the mesylate salt of a synthetic analogue of halichondrin B, a substance derived from a marine sponge (Lissodendoryx sp.) with antineoplastic activity.
E7389 is the mesylate salt of a synthetic analogue of halichondrin B, a substance derived from a marine sponge (Lissodendoryx sp.) with antineoplastic activity. Eribulin binds to the vinca domain of tubulin and inhibits the polymerization of tubulin and the assembly of microtubules, resulting in inhibition of mitotic spindle assembly, induction of cell cycle arrest at G2/M phase, and, potentially, tumor regression.
Halichondrin B, a large polyether macrolide, was isolated 25 years ago from the marine sponge Halichondria okadai
ERBULIN
The anti-cancer drug made from a sea-spongeEribulin is an anticancer drug marketed by Eisai Co. under the trade name Halaven. Eribulin mesylate was approved by the U.S. Food and Drug Administration on November 15, 2010, to treat patients with metastatic breast cancer who have received at least two prior chemotherapy regimens for late-stage disease, including both anthracycline– and taxane-based chemotherapies.[1] It was approved by Health Canada on December 14, 2011 for treatment of patients with metastatic breast cancer who have previously received at least two chemotherapeutic regimens for the treatment of metastatic disease. [2]
Eribulin has been previously known as E7389 and ER-086526, and also carries the US NCI designation NSC-707389.
Eribulin mesylate is an analogue of halichondrin B, which in 1986 was isolated from the marine sponge Halichondria okadai toxic Pacific.Halichondrin B has a significant anti-tumor activity. The Eribulin synthetically obtained has a simpler but still complex molecular structure.Taxanes such as to inhibit the spindle apparatus of the cell, but it is engaged in other ways.
Drug substance, eribulin mesylate, is a It is a structurally simplified synthetic analogue of halichondrin B, a natural product isolated from the marine sponge Halichondira okadai. Eribulin mesylate is a white powder which is freely soluble in water, methanol, ethanol, 1-octanol, benzyl alcohol, dichloromethane, dimethylsulfoxide, N-methylpyrrolidone and ethyl acetate. It is soluble in acetone, sparingly soluble in acetonitrile, and practically insoluble in tertbutyl methyl ether, n-heptane and n-pentane. Eribulin mesylate is characterized by ion chromatography for counter ion content, and spectroscopic analyses (mass, ultraviolet, nuclear magnetic resonance, single crystal X-ray crystallography, and circular dichroism) for molecular structure and absolute configuration. Bulk drug substance is hygroscopic and sensitive to light, heat, and acid hydrolysis,,,,,,……..http://www.accessdata.fda.gov/drugsatfda_docs/nda/2010/201532orig1s000chemr.pdf
Melvin Yu received his B.S. from MIT, and both his M.A. and Ph.D. degrees from Harvard University while studying under Professor Yoshito Kishi. In 1985, he joined Eli Lilly, and in 1993 he relocated to Eisai Inc. where he led the chemistry team that discovered Halaven. He was then responsible for the initial route nding and synthesis scale-up effort that ultimately provided the rst multi-gram batch of eribulin mesylate. Mel retains a strong interest in natural products as the inspiration of new chemotherapeutic agents, and in this context recently expanded his area of research to include cheminformatics and compound library design.
Wanjun Zheng received a Ph.D. in organic chemistry from Wesleyan University in 1994 under the direction of Professor Peter A. Jacobi working on synthetic methodology development and its application in natural product synthesis. He spent over two years as a postdoctoral research fellow in Harvard University under Professor Yoshito Kishi working on the complete structure determination of maitotoxin. He joined Eisai in 1996 and has since been contributing and leading many drug discovery projects including project in the discovery of Halaven.
Boris M. Seletsky earned his PhD in 1987 from Shemyakin Institute of Bioorganic Chemistry in Moscow, Russia working on new methods in steroid synthesis under direction of Dr George Segal and Professor Igor Torgov. Aer several years of natural product research at the same Institute, he moved on to postdoctoral studies in stereoselective synthesis with Professor Wolfgang Oppolzer at the University of Geneva, Switzerland, and Professor James A. Marshall at the University of South Carolina. Boris joined Eisai in 1994, and has contributed to many oncology drug discovery projects with considerable focus on natural products as chemical leads, culminating in the discovery of Halaven.
The synthesis of eribulin mesylate from microgram to multi-gram scale is described in thisHighlight. Key coupling reactions include formation of the C30a to C1 carbon–carbon bond and macrocyclic ring closure through an intramolecular Nozaki–Hiyama–Kishi reaction.
The synthesis of the C27–C35 tetrahydrofuran fragment.
The synthesis of the C14–C21 aldehyde subfragment.
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In 1986, two Japanese chemists Hirata and Uemura [Y. Hirata, D. Uemura, Pure Appl. Chem. 58 (1986) 701.] isolated a naturally-occurring compound from the marine sponge Halichondria okadai (picture above, right). The compound was named Halichondrin B, and it immediately began to generate great excitement when it was realised that it was extremely potent at killing certain types of cancer cells in small-scale tests. As a result of this discovery, it was immediately given top priority to be tested against a wide range of other cancers, and became one of the first compounds to be evaluated using the novel 60-cell line method developed by the US National Cancer Institute (NCI). In this technique, 60 different types of human tumor cells (including leukemia, melanoma and cancers of the lung, colon, brain, ovary, breast, prostate, and kidney) are tested with the potential anti-cancer molecule delivered at a single dose of 10 μM concentration. This process can be run in parallel, with dozens of different molecules being tested against all 60 cancer cell lines at the same time in a huge array. Any molecules which exhibit significant growth inhibition are prioritised, and the test repeated on them, but this time at five different concentration levels.
Halichondrin B – the part of the molecule used to make Eribulin is shown in blue.
Unfortunately, the concentration of Halichondrin B in the sea sponge wasn’t enough to enable commercial production for use in chemotherapy. For example, a ton of sea sponges could only produce 300 mg of Halichondrin B! The race was on to try to synthesise Halichondrin B in the lab, which wasn’t easy due to its large size (molecular weight 1110) and complex structure. However, only 6 years later, chemists at Harvard University published the complete chemical synthesis of this molecule………..T.D. Aicher, K.R. Buszek, F.G. Fang, C.J. Forsyth, S.H. Jung, Y. Kishi, M.C. Matelich, P.M. Scola, D.M. Spero, S.K. Yoon, J. Am. Chem. Soc. 114 (1992) 3162
Although this was a great achievement, Halichondrin B was still far too complex and the sythesis route too expensive to do on a large scale. The molecule needed to be stripped down to its essential components, while keeping, or even improving, its anti-cancer efficacy. Many tests were performed, but eventually the work led to te development of the structurally-simplified and pharmaceutically-optimized analog, which was named Eribulin [3,4]. Eribulin mesylate was approved by the U.S. Food and Drug Administration in 2010, to treat patients with metastatic breast cancer [5], and it is currently being marketed by Eisai Co. under the trade nameHalaven . It is also being investigated for use in a variety of other solid tumors, including lung cancer, prostate cancer and sarcoma .
ERIBULIN
M.J. Towle, K.A. Salvato, J. Budrow, B.F. Wels, G. Kuznetsov, K.K. Aalfs, S. Welsh, W. Zheng, B.M. Seletsk, M.H. Palme, G.J. Habgood, L.A. Singer, L.V. Dipietro, Y. Wang, J.J. Chen, D.A. Quincy, A. Davis, K. Yoshimatsu, Y. Kishi, M.J. Yu, B.A. Littlefield, Cancer Res.61 (2001) 1013.
M.J. Yu, Y. Kishi, B.A. Littlefield, in D.J. Newman, D.G.I. Kingston, G.M. Cragg, Anticancer agents from natural products, Washington, DC, Taylor and Francis (2005).
The substance inhibits the polymerization of tubulin into microtubules and encapsulates tubulin molecules in non-productive aggregates from. The lack of training of the spindle apparatus blocks the mitosis and ultimately induces apoptosis of the cell. Eribulin differs from known microtubule inhibitors such as taxanes and vinca alkaloids by the binding site on microtubules, also it does not affect the shortening. This explains the effectiveness of the new cytostatic agent in taxane-resistant tumor cell lines with specific tubulin mutations.
Structure and mechanism
Structurally, eribulin is a fully synthetic macrocyclic ketone analogue of the marine sponge natural product halichondrin B,[4][5] the latter being a potent naturally-occurring mitotic inhibitor with a unique mechanism of action found in the Halichondria genus of sponges.[6][7] Eribulin is a mechanistically-unique inhibitor of microtubule dynamics,[8][9] binding predominantly to a small number of high affinity sites at the plus ends of existing microtubules.[10] Eribulin exerts its anticancer effects by triggering apoptosis of cancer cells following prolonged and irreversible mitotic blockade.[11][12]
A new synthetic route to E7389 was published in 2009.[13]
Halaven is a novel anticancer agent discovered and developed in-house by Eisai and is currently approved in more than 50 countries, including Japan, the United States and in Europe. In Russia, Halaven was approved in July 2012 for the treatment of locally advanced or metastatic breast cancer previously treated with at least two chemotherapy regimens including an anthracycline and a taxane. Approximately 50,000 women in Russia are newly diagnosed with breast cancer each year, with this type of cancer being the leading cause of death in women aged 45 to 55 years. read all at…………………….
Eribulin mesylate (Halaven; Eisai) — a synthetic analogue of the marine natural product halichondrin B that interferes with microtubule dynamics — was approved in November 2010 by the US Food and Drug Administration for the treatment of metastatic breast cancer.
Family members of the product patent, WO9965894, have SPC protection in the EU until 2024 and one of its Orange Book listed filings, US8097648, has US154 extension till January 2021.
The drug also has NCE exclusivity till November 2015.
HALAVEN (eribulin mesylate) Injection is a non-taxane microtubule dynamics inhibitor. Eribulin mesylate is a synthetic analogue of halichondrin B, a product isolated from the marine sponge Halichondria okadai. The chemical name for eribulin mesylate is 11,15:18,21:24,28-Triepoxy-7,9-ethano12,15-methano-9H,15H-furo[3,2-i]furo[2′,3′:5,6]pyrano[4,3-b][1,4]dioxacyclopentacosin-5(4H)-one, 2[(2S)-3-amino-2-hydroxypropyl]hexacosahydro-3-methoxy-26-methyl-20,27-bis(methylene)-, (2R,3R,3aS,7R,8aS,9S,10aR,11S,12R,13aR,13bS,15S,18S,21S,24S,26R,28R,29aS)-, methanesulfonate (salt).
It has a molecular weight of 826.0 (729.9 for free base). The empirical formula is C40H59NO11 •CH4O3S. Eribulin mesylate has the following structural formula:
HALAVEN is a clear, colorless, sterile solution for intravenous administration. Each vial contains 1 mg of eribulin mesylate as a 0.5 mg/mL solution in ethanol: water (5:95).
Nitrogen: dark blue, oxygen: red, hydrogen: light blue
graphics: Wurglics, Frankfurt am Main
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Macrocyclization process for preparing a macrocyclic intermediate of halichondrin B analogs, in particular eribulin, from a non-macrocyclic compound, using a carbon-carbon bond-forming reaction.
Eisai has developed and launched eribulin mesylate for treating breast cancer. Follows on from WO2014208774, claiming use of a combination comprising eribulin mesylate and lenvatinib mesylate, for treating cancer.
Macrocyclization reactions and intermediates useful in the synthesis of analogs of halichondrin B
By: Fang, Francis G.; Kim, Dae-Shik; Choi, Hyeong-Wook; Chase, Charles E.; Lee, Jaemoon
Assignee: Eisai R&D Management Co., Ltd., Japan
The invention provides methods for the synthesis of eribulin or a pharmaceutically acceptable salt thereof (e.g., eribulin mesylate) through a macrocyclization strategy. The macrocyclization strategy of the present invention involves subjecting a non-macrocyclic intermediate to a carbon-carbon bond-forming reaction (e.g., an olefination reaction (e.g., Horner-Wadsworth-Emmons olefination), Dieckmann reaction, catalytic Ring-Closing Olefin Metathesis, or Nozaki-Hiyama-Kishi reaction) to afford a macrocyclic intermediate. The invention also provides compds. useful as intermediates in the synthesis of eribulin or a pharmaceutically acceptable salt thereof and methods for prepg. the same.
In a recent discussion (Nicolau), about the suggested move of Prof. NicoIau from Scripps, the issue of the practicality of natural product total synthesis was raised. Here is a wonderful example of just that very usefulness, a wonderful piece of science extending over many years. It concerns the journey from Halichondrin B to Eribulin (E7389) a novel anti-cancer drug. The two compounds have the following structures:
I think you can see the relationship and as a development chemist I am glad they managed to simplify things (a bit).
Both compounds have an enormous number of possible isomers: Halichondrin B, with 32 stereocenters has 232possible isomers; Eribulin has 19 with 219 isomers (if I have counted correctly, it does not really matter, there are lots of isomers). Remarkable is the fact that only one of these isomers is active in the given area of anti-cancer agents.
An excellent review of the biology and chemistry of these compounds has been published by Phillips etal1. This review is an excellent read and is to be commended. Another one written by Kishi2, is also full of information about the discovery of E7389 and I hope you will all get a chance to read this chapter.
The history of Halichondrin B goes back to 1987 when Blunt2-5 isolated it with other similar compounds from extraction of 200Kg of a sponge. Independently Pettit isolated the same compound from a different species4. The appearance of this compound in different species of sponge may indicate that it is produced by a symbiote.
The biological activity of Halichondrin B is amazing. When evaluated against B-16 melanoma cells it was found to have an IC50 of 0.093ng/mL. Against various cancers, generated in mice, it was shown to be affective at a daily dose of 5ug/kg, which resulted in a doubling of the survival rate. It has also been demonstrated that Halichondrin acts as a microtubule destabiliser and mitoitic spindle poison. It was proven that it is has tremendous in vivo activity against a variety of drug resistant cancers, lung, colon, breast, ovarian to mention a few. Consequently the National Cancer Institute selected it for pre-clinical trials and it’s here that the problems began. According to reference 1 the entire clinical development would require some 10g, and if successful the annual production amount would be between 1-5 kg. Blunt and co-workers managed to isolate 310mg from 1000kg-harvested sponge therefore, the only way to obtain the amounts required is total chemical synthesis. But synthesising 1-5 kg of such a compound would indeed be a mammoth task.
Kishi synthesised this compound7 in 1992 starting from carbohydrate precursors employing the Nozaki-Hiyama-Kishi Ni/Cr reaction, several times, in the long synthetic sequence8, 9. Now as an aside I have used this reaction on scale several times and although it works well its success is very dependant upon the quality of the chromium source and also the presence of other trace transition metals.
In collaboration with Eisai work on the SAR of Halichondrin began. They had a good start: Thanks to the total syntheses of Kishi several advanced intermediates were available for biological screening and one popped out of the screen as being very active:
The first active lead compound
As one can see the complete left hand side of Halichondrin has gone! However, this compound was not active in vivo. Many derivatives and analogues of this compound were prepared: furans, diols, ketones and so on and a lead emerged from this complex SAR study, ER-076349. The vicinal diol was used as a handle for further refinement and lead ultimately to E7389, the clinical candidate.
It can be synthesised in around 35 steps from simple starting materials.
Going through all this work in a few sentences really belittles the tremendous amount of effort that went into discovery and development of this compound and the people involved are to be applauded for their dedication.
Kishi continues to optimise the synthesis of Eribulin as judged by a recent publication10. Where he describes an approach to the amino-alcohol-tetrahydrofuran part of Eribulin (top left fragment, compound 1 below). The retro-synthetic analysis is shown below. The numbering corresponds to that of Eribulin.
The first generation synthesis consisted of 20 steps and delivered compound 1 about 5% yield, the second-generation route was completed in 12 steps with a yield of 48%. One of the highlights includes a remarkable asymmetric hydrogenation11 with Crabtree’s catalyst12:
This selectivity was not just luck; it seems to quite general, at least in this system. I always wonder how long it took them to stumble across this catalyst, but then I suppose that Eisai like most of the large pharma. companies has a hydrogenation group that probably indulges in catalyst screening.
The C34-C35 diol was obtained by a Sharpless asymmetric hydroxylation, here the diastereoisomeric ratio was not very high, only about 3:1 in favour of the desired isomer. Fortunately the undesired isomer could be removedcompletely by crystallisation.
This is a remarkable story and references 1 and 2 are worth reading to obtain the complete picture and learn lots of new chemistry as well. Eisai filed a NDA and the FDA approved the compound in 2010 for the treatment of metastatic breast cancer.
[00120] Compound E-12A (133 mg, 160 μηιοΙ, 1.0 eq) was dissolved in anhydrous dichloromethane (20 mL) and cooled to 0 °C. To this solution was sequentially added 2,6-lutidine (0.09 m L, 0.8 mmol, 5.0 eq), and trimethyl silyl triflate (TMSOTf) (0.12 m L, 0.64 mmol, 4.0 eq) and the cooling bath was removed . The reaction was stirred at room temperature for 1.5 hours and another portion of 2,6-lutidine (5.0 eq) and TMSOTf (4.0 eq) were added at room temperature. The reaction was further stirred for 1 hour and quenched with water (10 m L). The layers were separated and the organic phase was washed with additional water (2x 10 m L), brine (10 m L), dried over MgS04 and concentrated under reduced pressure. The residue was dissolved in MeOH (10 m L), a catalytic amount of K2C03 was added at room temperature and the resulting mixture was stirred for 2 hours. The reaction was diluted with dichloromethane and quenched with water (10 mL). The layers were separated and the aqueous phase was further extracted with dichloromethane (5 x 10 m L). The combined organic layers were washed with brine (20 m L), dried over MgS04, filtered and concentrated. The residue was dissolved in dichloromethane and purified by column chromatography on silica gel, using 1 : 9 MeOH : CH2CI2 to 1 : 9 : 90 N H4OH : MeOH : CH2CI2 as eluent. The product was afforded as a white amorphous solid (103 mg, 88%) . [00121] EXAMPLE 23 : Preparation of compound of formula 4a
D-Gulonolactone 4a
[00122] The compound of formula 4a was prepared from D-Gulonolactone according to the conditions described in PCT publication number WO 2005/118565. [00123] EXAMPLE 24: Preparation of Eribulin mesylate (3)
[00124] Eribulin mesylate (3) was prepared from Eribulin according to the conditions described in US patent application publication number US
Halichondrin B analogs, e.g., eribulin or pharmaceutically acceptable salts thereof, can be synthesized from the C14-C35 fragment as described in U.S. Patent No. 6,214,865 and International Publication No. WO 2005/118565. In one example described in these references, the C14-C35 portion, e.g., ER- 804028, of the molecule is coupled to the C1-C13 portion, e.g., ER-803896, to produce ER-804029, and additional reactions are carried out to produce eribulin (Scheme 1):
Scheme 1
eribulin, eribulin mesylate
Scheme 2
ER-804028
Compound AE (280 mg, 0.281 mmol, 1 eq) was dissolved in CH2C12 and cooled to 0 °C. Pyridine (0.045 ml, 0.56 mmol, 2.0 eq) was added followed by Ms20 (58.8 mg, 0.338 mmol, 1.20 eq). The reaction was allowed to warm to room temperature, and stirring was continued for an additional 1 h. The reaction mixture was cooled to 0 °C, diluted with MTBE (5.6 ml), washed with saturated NaHC03 (0.84 g), and concentrated to give crude product as colorless film. The crude was azeotropically dried with heptane (3 ml χ 2) and re-dissolved in THF (7.0 ml). The mixture was cooled to 0 °C and treated with 25 wt% NaOMe (0.13 ml). After 10 min, the reaction was allowed to warm to room temperature, and stirring was continued for an additional 30 min. The mixture was treated with additional 25 wt% NaOMe (0.045 ml), and stirring was continued for an additional 20 min. The reaction mixture was diluted with heptane (7.0 ml) and washed with water (1.4 ml). The organic layer was separated, sequentially washed with: 1) 20 wt% NH4C1 (0.84 g) and 2) 20 wt% NaCl (3 g), and concentrated to give crude product as brownish oil. The crude was purified by Biotage (Uppsala, Sweden) 12M (heptane-MTBE 2:3 v/v) to give ER-804028 (209 mg, 0.245 mmol, 87%) as pale yellow oil. 1H NMR (400 MHz, CDC13): δ 7.89 (2H, m), 7.64 (IH, m), 7.56 (2H, m), 4.85 (IH, d, J= 1.6 Hz), 4.80 (IH, s), 4.72 (IH, s), 4.61 (IH, d, J= 1.6 Hz), 4.23 (IH, br), 3.91 (IH, m), 3.79 (IH, m), 3.76 (2H, m), 3.63 (IH, m), 3.50-3.60 (4H, m), 3.43 (IH, dd, J= 5.6 Hz, 10.0 Hz), 3.38 (3H, s), 3.32 (IH, m), 2.98 (2H, m), 2.61 (IH, br), 2.56 (IH, m), 2.50 (IH, m), 2.08-2.22 (3H, m), 1.96 (IH, m), 1.84 (IH, m), 1.78 (IH, m), 1.70 (IH, m), 1.42-1.63 (6H, m), 1.28-1.42 (2H, m), 1.01 (3H, d, J= 6.8 Hz), 0.84 (18H, s), 0.05 (3H, s), 0.04 (3H, s), 0.00 (3H, s), -0.01 (3H, s); and 13C NMR (100 MHz, CDC13): δ 150.34, 150.75, 139.91, 134.18, 129.73 (2C), 128.14 (2C), 105.10, 85.97, 80.92, 79.72, 78.50, 77.45, 77.09, 75.53, 71.59, 68.04, 62.88, 58.27, 57.73, 43.51, 42.82, 39.16, 37.68, 35.69, 33.31, 32.41, 31.89, 31.48, 29.79, 26.21 (3C), 26.17 (3C), 18.58, 18.38, 18.13, -3.85, – 4.71, -5.12 (2C).
CLIP
Eribulin mesylate (Halaven)
Eribulin is a highly potent cytotoxic agent approved in the US for the treatment of metastatic breast cancer for patients who have
received at least two previous chemotherapeutic regimens.30 Eribulin was discovered and developed by Eisai and it is currently
undergoing clinical evaluation for the treatment of sarcoma (PhIII) and non-small cell lung cancer which shows progression after platinum-based chemotherapy and for the treatment of prostate cancer (PhII). Early stage clinical trials are also underway to evaluate
eribulin’s efficacy against a number of additional cancers. Eribulin is a structural analog of the marine natural product halichondrin B.
Its mechanism of action involves the disruption of mitotic spindle formation and inhibition of tubulin polymerization which results
in the induction of cell cycle blockade in the G2/M phase and apoptosis.31 Several synthetic routes for the preparation of eribulin have
been disclosed,32–35 each of which utilizes the same strategy described by Kishi and co-workers for the total synthesis of halichondrin B.36 Although the scales of these routes were not disclosed in all cases, this review attempts to highlight what appears to be the production-scale route based on patent literature.37,38 Nonetheless, the synthesis of eribulin represents a significant accomplishment in the field of total synthesis and brings a novel chemotherapeutic option to cancer patients.
The strategy to prepare eribulin mesylate (V) employs a convergent synthesis featuring the following: the late stage coupling of
sulfone 22 and aldehyde 23 followed by macrocyclization under Nozaki–Hiyami–Kishi coupling conditions, formation of a challenging
cyclic ketal, and installation of the primary amine (Scheme 5).Sulfone 22 was further simplified to aldehyde 24 and vinyl triflate 25 which were coupled through a Nozaki–Hiyami–Kishi reaction.
The schemes that follow will describe the preparation of fragments 23, 24 and 25 along with how the entire molecule was assembled.
The synthesis of the C1–C13 aldehyde fragment 23 is described in Scheme 6. L-Mannonic acid-lactone 26 was reacted with cyclohexanone in p-toluene sulfonic acid (p-TSA) to give the biscyclohexylidene ketal 27 in 84% yield. Lactone 27 was reduced with
diisobutylaluminum hydride (DIBAL-H) to give lactol 28 followed by condensation with the ylide generated from the reaction of
methoxymethylene triphenylphosphorane with potassium tertbutoxide to give a mixture of E and Z vinyl ethers 29 in 81% yield.
Dihydroxylation of the vinyl ether of 29 using catalytic osmium teteroxide and N-methylmorpholine-N-oxide (NMO) with concomitant cyclization produced diol 30 in 52% yield. Bis-acetonide 30 was then reacted with acetic anhydride in acetic acid in the presence of ZnCl2 which resulted in selective removal of the pendant ketal protecting group. These conditions also affected peracylation, giving rise to tetraacetate 31 in 84% yield. Condensation of 31 with methyl 3-(trimethylsilyl)pent-4-enoate in the presence of boron trifluoride etherate in acetonitrile provided alkene 32. Saponification conditions using Triton B(OH) removed the acetate protecting groups within 32 and presumably induced isomerization of the alkene into conjugation with the terminal ester, triggering an intramolecular Michael attack of the 2-hydroxyl group, ultimately resulting in the bicylic-bispyranyl diol methyl ester 33 as a crystalline solid in 38% yield over two steps. Oxidative cleavage of the vicinal diol of 33 with sodium periodate gave aldehyde 34 which was coupled to (2-bromovinyl)trimethylsilane under Nozaki–Hiyami–Kishi conditions to give an 8.3:1 mixture of allyl alcohols 35 in 65% yield over two steps. Hydrolysis of the cyclohexylidine ketal 35 with aqueous acetic acid followed by recrystallization gave diastereomerically pure triol 36 which was reacted with tert-butyldimethylsilyl triflate (TBSOTf) to afford the tris-TBS ether 37 in good yield. Vinyl silane 37 was treated with NIS and catalytic tert-butyldimethylsilyl chloride (TBSCl) to give vinyl iodide 38 in 90% yield.
Reduction of the ester with DIBAL-H produced the key C1–C14 fragment 23 in 93% yield.
The preparation of the tetra-substituted tetrahydrofuran intermediate 24 is described in Scheme 7. D-Glucurono-6,3-lactone
39 was reacted with acetone and sulfuric acid to give the corresponding acetonide and the 5-hydroxyl group was then removed by converting it to its corresponding chloride through reaction with sulfuryl chloride (SO2Cl2) followed by hydrogenolysis
to give lactone 40 in good overall yield. Reduction of the lactone 40 with DIBAL-H gave the corresponding lactol which was condensed
with (trimethylsilyl)methylmagnesium chloride to afford silane 41. Elimination of the silyl alcohol of 41 was accomplished
under Peterson conditions with potassium hexamethyldisilazide (KHMDS) to afford the corresponding terminal alkene in 94% yield.
The secondary alcohol of this intermediate was alkylated with benzyl bromide to afford ether 42 in 95% yield. Asymmetric dihydroxylation of the alkene of 42 under modified Sharpless conditions using potassium osmate (VI) dehydrate (K2OsO4), potassium
ferricyanide (K3Fe(CN)6) and the (DHQ)2AQN ligand produced the vicinal diol which was then reacted with benzoyl chloride,
N-methylmorpholine, and DMAP to give di-benzoate 43 in excellent yield as a 3:1 mixture of diastereomeric alcohols. Allyl trimethylsilane was added to the acetal of 43 using TiCl3(OiPr) as the Lewis acid to give 44 in 83% yield. Re-crystallization of 44 from
isopropanol and n-heptane afforded 44 in >99.5% de in 71% yield.
Oxidation of the secondary alcohol of 44 under the modified Swern conditions generated the corresponding ketone which was condensed with the lithium anion of methyl phenyl sulfone to give a mixture of E and Z vinyl sulfones 45. Debenzylation of 45 using iodotrimethylsilane (TMSI) followed by chelation-controlled reduction of the vinyl sulfone through reaction with NaBH(OAc)3, and
then basic hydrolysis of the benzoate esters using K2CO3 in MeOH resulted in triol 46 as a white crystalline solid in 57% yield over the
five steps after re-crystallization. The vicinal diol of 46 was protected as the corresponding acetonide through reaction with 2,2-
dimethoxypropane and sulfuric acid and this was followed by methyl iodide-mediated methylation of the remaining hydroxyl
group to give methyl ether 47. The protecting groups within acetonide 47 were then converted to the corresponding bis-tert-butyldimethylsilyl ether by first acidic removal of the acetonide with aqueous HCl and reaction with TBSCl in the presence of imidazole to give bis-TBS ether 48. Then, ozonolysis of the olefin of 48 followed by hydrogenolysis in the presence of Lindlar catalyst afforded the key aldehyde intermediate 24 in 68% yield over the previous five steps after re-crystallization from heptane.
Two routes to the C14–C26 fragment 25 will be described as both are potentially used to prepare clinical supplies of eribulin.
The first route features a convergent and relatively efficient synthesis of 25, however it is limited by the need to separate enantiomers
and mixture of diastereomers via chromatographic methods throughout the synthesis.37 The second route to 25 is a
much lengthier synthesis from a step-counting perspective; however it takes full advantage of the chiral pool of starting materials
and requires no chromatographic separations and all of the products were carried on as crude oils until they could be isolated as
crystalline solids.38 The first route to fragment 25 is described in Scheme 8 and was initiated by the hydration of 2,3-dihydrofuran (49) using an aqueous suspension of Amberlyst 15 to generate the intermediate tetrahydro-2-furanol (50) which was then immediately reacted with 2,3-dibromopropene in the presence of tin and catalytic HBr to afford diol 51 in 45% for the two steps.
The primary alcohol of 51 was selectively protected as its tert-butyldiphenylsilyl ether using TBDPSCl and imidazole and the racemate was then separated using simulated moving bed (SMB) chromatography to give enantiopure 52 in 45% yield over the two steps. The secondary alcohol of 52 was reacted with p-toluenesulfonyl chloride and DMAP to give tosylate 53 in 78% yield which was used as a coupling partner later in the synthesis of this fragment. The synthesis of the appropriate coupling partner was initiated by condensing diethylmalonate with (R)-2-(3-butenyl)oxirane (54), followed by decarboxylation to give lactone 55 in 71% yield for the two step process. Methylation of the lactone with LHMDS and MeI provided 56 in 68% yield as a 6:1 mixture of diastereomers. The lactone 56 was reacted with the aluminum amide generated by the reaction of AlMe3 and N,O-dimethylhydroxylamine to give the corresponding Weinreb amide which was protected as its tert-butyldimethylsilyl ether upon reaction with TBSCl and imidazole to give 57 in 91% yield over the two steps. Dihydroxylation of the olefin of 57 by reaction with OsO4 and NMO followed by oxidative cleavage with NaIO4 gave the desired coupling partner aldehyde 58 in 93% yield. Aldehyde 58 was coupled with vinyl bromide 53 using an asymmetric Nozaki–Hiyami– Kishi reaction using CrCl2, NiCl2, Et3N and chiral ligand 66 (described in Scheme 9 below). The reaction mixture was treated with ethylene diamine to remove the heavy metals and give the secondary alcohol 59. This alcohol was stirred with silica gel in isopropanol to affect intramolecular cyclization to give the tetrahydrofuran 60 in 48% yield over the three step process. The Weinreb amide of 60 was reacted with methyl magnesium chloride to generate the corresponding methyl ketone which was converted to vinyl triflate 61 upon reaction with KHMDS and Tf2NPh. De-silylation of the primary and secondary silyl ethers with methanolic HCl gave the corresponding diol in 85% yield over two steps and the resulting mixture of diastereomers was separated using preparative HPLC to provide the desired diastereomer in 56% yield. The primary alcohol was protected as its pivalate ester with the use of pivaloyl chloride, DMAP and collidine; the secondary alcohol was converted to a mesylate upon treatment with methanesulfonyl chloride (MsCl) and Et3N to give the C15–C27 fragment 25 in high yield.
The preparations of the chiral ligand 66 used in the coupling reaction in Scheme 8 along with the chiral ligand 67 utilized later
in the synthesis are described in Scheme 9. 2-Amino-3-methylbenzoic acid (62) was reacted with triphosgene to give benzoxazine
dione 63 in 97% yield, which then was reacted with either D- or L-valinol in DMF followed by aqueous LiOH to give alcohols 64
and 65, respectively in 65–75% yield for the two steps. Reaction of alcohol 64 or 65 with MsCl in the presence of DMAP effected formation of the dihydrooxazole ring and mesylation of the aniline to give the corresponding (R)-ligand 66 derived from D-valinol or the (S)-ligand 67 derived from L-valinol, respectively in high yield.
An alternative route to intermediate 25 is described in Scheme 10 and although much lengthier than the route described in
Scheme 8, it avoids chromatographic purifications as all of the products are carried on crude until a crystalline intermediate
was isolated and purified by re-crystallization. Quinic acid (68) was reacted with cyclohexanone in sulfuric acid to generate a protected
bicyclic lactone in 73% yield and the resulting tertiary alcohol was protected as its trimethylsilyl ether 69. Reduction of the
lactone 69 was accomplished with DIBAL-H and the resulting lactol was treated with acetic acid to remove the TMS group and the resulting compound was reacted with acetic anhydride, DMAP and Et3N to give bis-acetate 70 in 65% yield for the three steps after re-crystallization. Methyl 3-(trimethylsilyl)pent-4-enoate was coupled to the acetylated lactol 70 in the presence of boron trifluoride etherate and trifluoroacetic anhydride to give adduct 71 in 62% yield. The acetate of 71 was removed upon reaction with sodium methoxide in methanol and the resulting tertiary alcohol cyclized on to the isomerized enone alkene to give the fused pyran ring. Reduction of the methyl ester with lithium aluminum hydride provided pyranyl alcohol 72. Mesylation of the primary alcohol was followed by displacement with cyanide anion to give nitrile 73.
The nitrile was methylated upon reaction with KHMDS and MeI and the resulting product was purified by re-crystallization
to provide nitrile 74 in 66% over the previous five steps in a 34:1 diastereomeric ratio. Acid hydrolysis of the ketal of 74 liberated
the corresponding diol in 72% yield and this was reacted with 2-acetoxy-2-methylpropionyl bromide to give bromo acetate 75.
Elimination of the bromide was accomplished upon treatment with 1,8-diazabicycloundec-7-ene (DBU) to give alkene 76 in 63%
yield for two steps. Ozonolysis of the cyclohexene ring followed by reductive work-up with NaBH4 and basic hydrolysis of the acetate
produced a triol which upon reaction with NaIO4 underwent oxidative cleavage to give cyclic hemiacetal 77 in 75% yield over
the previous four steps. Wittig condensation with carbomethoxymethylene triphenylphosphorane gave the homologated unsaturated
ester 78. Catalytic hydrogenation of the alkene using PtO2 as the catalyst was followed by converting the primary alcohol to the
corresponding triflate prior to displacement with sodium iodide resulted in iodide 79 in 75% yield over four steps. The ester of 79
was reduced to the corresponding primary alcohol upon reaction with LiBH4 in 89% yield and the resulting iodoalcohol was treated
with Zn dust to affect reductive elimination of the iodide and decomposition of the pyran ring system to give the tetrahydrofuran
diol 80 in 90% yield. This diol was treated with methanolic HCl to affect an intramolecular Pinner reaction and this was followed
by protection of the primary alcohol as its tert-butyldiphenylsilyl ether to give lactone 81 The lactone was reacted with the
aluminum amide generated from AlMe3 and N,O-dimethylhydroxylamine and the resulting secondary alcohol was protected as
its tert-butyldimethylsilyl ether to give Weinreb amide 82 in 99% crude yield over four steps. Compound 82 is the diastereomerically
pure version of compound 60 and can be converted to compound 25 by the methods described in Scheme 8 absent the required
HPLC separation of diastereomers. With the three key fragments completed, the next step was to assemble them and complete the synthesis of eribulin. Aldehyde 24 was coupled to vinyl triflate 25 using an asymmetric Nozaki– Hiyami–Kishi reaction using CrCl2, NiCl2, Et3 N and chiral ligand 67 (Scheme 9) to give alcohol 83 (Scheme 11).
Formation of the THP ring was accomplished by reaction with KHMDS which allowed for displacement of the mesylate with the secondary alcohol and provided the THP containing product in 72% yield for the three steps. The pivalate ester group was removed with DIBAL-H to give the western fragment 22 in 92% yield.
The completion of the synthesis of eribulin is illustrated in Scheme 12. The lithium anion of sulfone 22 generated upon reaction
with nBuLi was coupled to aldehyde 23 to give diol 84 in 84% yield. Both of the alcohol functional groups of 84 were oxidized
using a Dess–Martin oxidation in 90% yield and the resulting sulfone was removed via a reductive cleavage upon reaction with
SmI2 to give keto-aldehyde 85 in 85% yield. Macrocyclization of 85 was accomplished via an asymmetric Nozaki–Hiyami–Kishi
reaction using CrCl2, NiCl2, Et3N and chiral ligand 67 to give alcohol 86 in 70% yield. Modified Swern oxidation of the alcohol provided the corresponding ketone in 91% yield and this was followed by removal of the five silyl ether protecting groups upon reaction with TBAF and subsequent cyclization to provide ketone 87. Compound 87 was treated with PPTS to provide the ‘caged’ cyclic ketal 88 in 79% over two steps. The vicinal diol of 88 was reacted with Ts2O in collidine to affect selective tosylation of the primary alcohol and this crude product was reacted with ammonium hydroxide to install the primary amine to give eribulin which was treated
with methanesulfonic acid in aqueous ammonium hydroxide to give eribulin mesylate (V) in 84% yield over the final three steps.
30. Zheng, W.; Seletsky, B. M.; Palme, M. H.; Lydon, P. J.; Singer, L. A.; Chase, C. E.;
Lemelin, C. A.; Shen, Y.; Davis, H.; Tremblay, L.; Towle, M. J.; Salvato, K. A.;
Wels, B. F.; Aalfs, K. K.; Kishi, Y.; Littlefield, B. A.; Yu, M. J. Bioorg. Med. Chem.
Lett. 2004, 14, 5551.
31. Wang, Y.; Serradell, N.; Bolós, J.; Rosa, E. Drugs Future 2007, 32, 681.
32. Chiba, H.; Tagami, K. J. Synth. Org. Chem. Jpn. 2011, 69, 600.
33. Choi, H.; Demeke, D.; Kang, F.-A.; Kishi, Y.; Nakajima, K.; Nowak, P.; Wan, Z.-
K.; Xie, C. Pure Appl. Chem. 2003, 75, 1.
34. Kishi, Y.; Fang, F.; Forsyth, C. J.; Scola, P. M.; Yoon, S. K. WO 9317690 A1, 1993.
35. Littlefield, B. A.; Palme, M.; Seletsky, B. M.; Towle, M. J.; Yu, M. J.; Zheng, W.
WO 9965894 A1, 1999.
36. Aicher, T. D.; Buszek, K. R.; Fang, F. G.; Forsyth, C. J.; Jung, S. H.; Kishi, Y.;
Matelich, M. C.; Scola, P. M.; Spero, D. M.; Yoon, S. K. J. Am. Chem. Soc. 1992,
114, 3162.
37. Austad, B.; Chase, C. E.; Fang, F. G. WO 2005118565 A1, 2005.
38. Chase, C.; Endo, A.; Fang, F. G.; Li, J. WO 2009046308 A1, 2009.
Halichondrin B is a wicked molecule. In tests in mice, it is an extremely potent cancer cell killer, active at around 80 picomolar concentration. It also possesses a fiendish macrocyclic polyketide structure, with 32 stereocentres meaning that it could adopt over four billion different isomers – with just one that fights cancer.
Eribulin is a cut-down derivative of halichondrin B, which maintains most of its activity with significantly reduced complexity
Its power is therefore inherently hard to harness. Halichondrin B was found in various sea sponge species in the 1980s, but getting 400mg of the compound from a tonne of sponge was doing well. Clinical development required at least 10g, and annual production takes kilograms.
Although developing a synthetic route to halichondrin B looked just as tough as trying to extract it from sponges, Yoshito Kishi’s group at Harvard University in the US accepted the challenge. Frank Fang, one of the team, recalls how the Nozaki–Hiyama–Kishi (NHK) coupling reaction would prove critical. ‘Another feature that was impressed upon me was the importance of crystalline intermediates,’ Fang adds. These allowed simple purification by recrystallisation, rather than expensive and time-consuming chromatography.
Published in 1992, their method used several NHK couplings, forming carbon–carbon bonds between multifunctional vinyl halides and aldehydes via a nickel-catalysed, chromium-mediated process.4 The sprawling convergent synthesis, whose longest linear sequence involved 47 steps, prompted Japanese pharmaceutical company Eisai to collaborate with Kishi in exploring halichondrin B’s structure–activity relationship. On screening the team’s intermediates, one featuring the macrocyclic half of halichondrin B proved especially active. A series of medicinal chemistry refinements led to what would eventually becomeeribulin (marketed by Eisai as Halaven), promising a slightly simpler synthesis. It has ‘just’ 19 stereocentres, which along with other structural restrictions cuts the possible number of isomers to a mere 16,384.
Fang joined Eisai in 1998 as it selected eribulin for further development, and worked to develop a production process for a route that produced it from three fragments. He again strove to exploit recrystallisation and use the NHK reaction, although making it reliable enough for manufacturing was challenging. ‘There was an appreciation for the somewhat sensitive nature of the reaction, particularly the asymmetric variant,’ he recalls.
The Eisai researchers therefore studied the NHK procedure as they applied it to redesigning the synthesis for part of the eribulin molecule they refer to as the C14–C26 fragment. Featuring just one ring, this fragment isn’t the most structurally complex of the three, but is still very difficult to make. That’s because it is a long chain with several stereocentres, whose stereochemistry is hard to link together.
Fang’s team initially broke this section down into two sub-fragments, C14–C19 and C20–C26, using asymmetric NHK reactions on each, learning about the reaction’s parameters as they did so.5 They then used what they’d found out to devise NHK reactions linking the two sub-fragments and attaching the two fragments on either side, which included closing the eribulin macrocycle. ‘We gained knowledge through our studies on the C19–C20 NHK coupling and were ultimately able to utilise that knowledge to try to execute an asymmetric NHK reaction in fixed equipment on multi-kilogram scale and construct the C19–C20, C26–C27, and C13–C14 bonds,’ Fang explains.
Synthesis of eribulin relies heavily on Nozaki–Hiyama–Kishi (NHK) coupling reactions to make key C–C bonds
Halaven was approved in the US in 2010 to treat breast cancer and earned ¥2.89 billion in sales (£159 million) in 2014. The commercial route initially took 62 steps across a convergent synthesis bringing together three fragments, with a longest linear sequence of 30 steps. Fang’s team has since added seven steps to the C14–C26 fragment route, which counterintuitively cuts costs and waste by 80% by eliminating chromatography.6 ‘I am hopeful that we can find the lessons applicable in future work,’ Fang says.
Cheaper synthesis would appear welcome, given that Halaven’s price tag has been criticised. In the UK it currently costs £2,000 per 21 day treatment cycle according to data from the British National Formularyand the country’s National Institute for Health and Clinical Excellence (Nice). As a result, Nice refused to cover the drug, and in January 2015 the remaining funding in England looked set to be closed off with Halaven being taken off the Cancer Drugs Fund (CDF)’s list. But Eisai was told in March that the drug would stay on the list, pending reconsideration, after an appeal against the decision.
In defence, Fang claims that Halaven is actually one of the most affordable breast cancer treatments on the CDF. ‘Eisai was given no opportunity to lower the price of Halaven before NHS England announced that the treatment would be removed from the fund, despite this being something we were, and still are, very willing to do,’ he adds.
Synthetic process for preparation of macrocyclic c1-keto analogs of halichondrin b and intermediates useful therein including intermediates containing -so2-(p-tolyl) groups
2-((2S,3S,4R,5R)-5-((S)-3-amino-2-hydroxyprop-1-yl)-4-methoxy-3-(phenylsulfonylmethyl)tetrahydrofuran-2-yl)acetaldehyde derivatives and process for their preparation
^ Towle MJ, Salvato KA, Budrow J, Wels BF, Kuznetsov G, Aalfs KK, Welsh S, Zheng W, Seletsky BM, Palme MH, Habgood GJ, Singer LA, Dipietro LV, Wang Y, Chen JJ, Quincy DA, Davis A, Yoshimatsu K, Kishi Y, Yu MJ, Littlefield BA (February 2001). “In vitro and in vivo anticancer activities of synthetic macrocyclic ketone analogues of halichondrin B”. Cancer Res.61 (3): 1013–21. PMID11221827.
^ Yu MJ, Kishi Y, Littlefield BA (2005). “Discovery of E7389, a fully synthetic macrocyclic ketone analogue of halichondrin B”. In Newman DJ, Kingston DGI, Cragg, GM. Anticancer agents from natural products. Washington, DC: Taylor & Francis. ISBN0-8493-1863-7.
^ Hirata Y, Uemura D (1986). “Halichondrins – antitumor polyether macrolides from a marine sponge”. Pure Appl. Chem.58 (5): 701–710. doi:10.1351/pac198658050701.
^ Bai RL, Paull KD, Herald CL, Malspeis L, Pettit GR, Hamel E (August 1991). “Halichondrin B and homohalichondrin B, marine natural products binding in the vinca domain of tubulin. Discovery of tubulin-based mechanism of action by analysis of differential cytotoxicity data”. J. Biol. Chem.266 (24): 15882–9. PMID1874739.
Jordan MA, Kamath K, Manna T, Okouneva T, Miller HP, Davis C, Littlefield BA, Wilson L (July 2005). “The primary antimitotic mechanism of action of the synthetic halichondrin E7389 is suppression of microtubule growth”. Mol. Cancer Ther.4 (7): 1086–95. doi:10.1158/1535-7163.MCT-04-0345. PMID16020666.
Kuznetsov G, Towle MJ, Cheng H, Kawamura T, TenDyke K, Liu D, Kishi Y, Yu MJ, Littlefield BA (August 2004). “Induction of morphological and biochemical apoptosis following prolonged mitotic blockage by halichondrin B macrocyclic ketone analog E7389”. Cancer Res.64 (16): 5760–6. doi:10.1158/0008-5472.CAN-04-1169. PMID15313917.
^ Towle MJ, Salvato KA, Wels BF, Aalfs KK, Zheng W, Seletsky BM, Zhu X, Lewis BM, Kishi Y, Yu MJ, Littlefield BA (January 2011). “Eribulin induces irreversible mitotic blockade: implications of cell-based pharmacodynamics for in vivo efficacy under intermittent dosing conditions”. Cancer Res.71 (2): 496–505. doi:10.1158/0008-5472.CAN-10-1874. PMID21127197.
^ Kim DS, Dong CG, Kim JT, Guo H, Huang J, Tiseni PS, Kishi Y (November 2009). “New syntheses of E7389 C14-C35 and halichondrin C14-C38 building blocks: double-inversion approach”. J. Am. Chem. Soc.131 (43): 15636–41. doi:10.1021/ja9058475. PMID19807076.
Arformoterol inhalation solution, a long-acting beta2-adrenoceptor agonist, was launched in the U.S. in 2007 for the long-term twice-daily (morning and evening) treatment of bronchospasm in patients with chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema. The product, known as Brovana(TM), for use by nebulization only, is the first long-acting beta2-agonist to be approved as an inhalation solution for use with a nebulizer. The product was developed and is being commercialized by Sunovion Pharmaceuticals (formerly Sepracor)
Arformoterol ball-and-stick model
Bronchodilators, in particular β2-adrenoceptor agonists, are recognized as very effective drugs to treat asthma and other bronchospastic conditions. Important characteristics for these drugs are activity, selectivity, duration of action, and onset. While the first-generation drugs (e.g., isoprenaline or terbutaline) were relatively unselective and short-acting, the current drugs have either a fast onset but only a short duration of action of about 4 h (albuterol) or a slow onset (20 min) with a longer duration of action (salmeterol). Formoterol (IUPAC name: 3-formamido-4-hydroxy-α-[[N-(p-methoxy-α-methylphenethyl)amino]methyl]benzyl alcohol) is unique in that it not only is extremely potent and selective but also has a duration of up to 12 h and a rapid onset of 1−5 min. Most β2-adrenoceptor agonists are currently marketed as racemates despite regulatory preference and different biological activity of pure enantiomers. In the case of formoterol it has been shown that the (R,R)-isomer is 1000 times more active than the (S,S)-isomer
Arformoterol is a bronchodilator. It works by relaxing muscles in the airways to improve breathing. Arformoterol inhalation is used to prevent bronchoconstriction in people with chronic obstructive pulmonary disease, including chronic bronchitis and emphysema. The use of arformoterol is pending revision due to safety concerns in regards to an increased risk of severe exacerbation of asthma symptoms, leading to hospitalization as well as death in some patients using long acting beta agonists for the treatment of asthma.
Arformoterol is an ADRENERGIC BETA-2 RECEPTOR AGONIST with a prolonged duration of action. It is used to manage ASTHMA and in the treatment of CHRONIC OBSTRUCTIVE PULMONARY DISEASE.
Arformoterol (Brovana)
Arformoterol is a beta2-Adrenergic Agonist. The mechanism of action of arformoterol is as an Adrenergic beta2-Agonist.
Arformoterol is a long-acting beta-2 adrenergic agonist and isomer of formoterol with bronchodilator activity. Arformoterol selectively binds to and activates beta-2 adrenergic receptors in bronchiolar smooth muscle, thereby causing stimulation of adenyl cyclase, the enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3′,5′-adenosine monophosphate (cAMP). Increased intracellular cAMP levels cause relaxation of bronchial smooth muscle and lead to a reduced release of inflammatory mediators from mast cells. This may eventually lead to an improvement of airway function.
Formoterol (Foradil) is a long acting β2-agonist used as a bronchodilator in the therapy of asthma and chronic bronchitis. The (R,R)-enantiomer has been shown to be more active than the other stereoisomers (R,S; S,R; and S,S) of formoterol. (R,R)-Formoterol is extremely potent and selective, having rapid onset (1−5 min) and long duration, and is 1000 times more active than the (S,S) isomer
Arformoterol tartrate
Molecular FormulaC23H30N2O10
Average mass494.492
cas 200815-49-2
183-185°C
Butanedioic acid, 2,3-dihydroxy-, (2R,3R)-, compd. with formamide, N-[2-hydroxy-5-[(1R)-1-hydroxy-2-[[(1R)-2-(4-methoxyphenyl)-1-methylethyl]amino]ethyl]phenyl]- (1:1)[ACD/Index Name]
Arformoterol Tartrate, can be used in the synthesis of Omeprazole (O635000), which is a proton pump inhibitor, that inhibits gasteric secretion, also used in the treatment of dyspepsia, peptic ulcer disease, etc. Itis also the impurity of Esomeprazole Magnesium (E668300), which is the S-form of Omeprazole, and is a gastric proton-pump inhibitor. Also, It can be used for the preparation of olodaterol, a novel inhaled β2-adrenoceptor agonist with a 24h bronchodilatory efficacy.
SYNTHESIS
PATENT
US-9309186
Example 1
Synthesis of (R,R)-Formoterol-L-tartrate Form D
A solution containing 3.9 g (26 mmol) of L-tartaric acid and 36 mL of methanol was added to a solution of 9 g (26 mmol) of arformoterol base and 144 mL methanol at 23.degree. C. Afterwards, the resulting mixture was seeded with form D and stirred at 23.degree. C. for 1 hour. It was then further cooled to 0-5.degree. C. for 1 hour and the product collected by filtration and dried under inlet air (atmospheric pressure) for 16 hours to provide 11.1 g (86% yield) (99.7% chemical purity, containing 0.14% of the degradation impurity (R)-1-(3-amino-4-hydroxyphenyl)-2-[[(1R)-2-(4-methoxyphenyl)-1-methylethy- l]amino]ethanol) of (R,R)-formoterol L-tartrate form D, as an off white powder. .sup.1H-NMR (200 MHz, d.sub.6-DMSO) .delta.: 1.03 (d, 3H); 2.50-2.67 (m, 5H); 3.72 (s, 3H); 3.99 (s, 2H); 4.65-4.85 (m, 1H); 6.82-7.15 (m, 5H); 8.02 (s, 1H); 8.28 (s, 1H); 9.60 (s, NH). No residual solvent was detected (.sup.1H-NMR).
PSD: d.sub.50=2.3 .mu.m.
PAPER
Tetrahedron Letters, Vol. 38, No. 7, pp. 1125-1128, 1997
Enantio- and Diastereoselective Synthesis of all Four Stereoisomers of Formoterol
PAPER
Taking Advantage of Polymorphism To Effect an Impurity Removal: Development of a Thermodynamic Crystal Form of (R,R)-FormoterolTartrate
The development and large-scale implementation of a novel technology utilizing polymorphic interconversion and crystalline intermediate formation of (R,R)-formoteroll-tartrate ((R,R)-FmTA, 1) as a tool for the removal of impurities from the final product and generation of the most thermodynamically stable crystal form is reported. The crude product was generated by precipitation of the free base as the l-tartrate salt in a unique polymorphic form, form B. Warming the resultant slurry effected the formation of a partially hydrated stable crystalline intermediate, form C, with a concomitant decrease in the impurity levels in the solid. Isolation and recrystallization of form C provided 1 in the thermodynamically most stable polymorph, form A.
Formoterol, (+/-)N-[2-hydroxy-5-[1-hydroxy-2-[[2-(p-methoxyphenyl)-2-propylamino]ethyl]phenyl]-formamide, is a highly potent and β2-selective adrenoceptor agonist having a long lasting bronchodilating effect when inhaled. Its chemical structure is depicted below:
Formoterol has two chiral centres, each of which can exist into two different configurations. This results into four different combinations, (R,R), (S,S), (S,R) and (R,S). Formoterol is commercially available as a racemic mixture of 2 diasteromers (R,R) and (S,S) in a 1:1 ratio. The generic name Formoterol always refers to its racemic mixture. Trofast et al. (Chirality, 1, 443, 1991) reported on the potency of these isomers, showing a decrease in the order of (R,R)>(R,S)≥(S,R)>(S,S). The (R,R) isomer, also known as Arformoterol, being 1000 fold more potent than the (S,S) isomer. Arformoterol is commercialised by Sepracor as Brovana
Formoterol was first disclosed in Japanese patent application (Application N° 13121 ) whereby Formoterol is synthesised by N-alkylation using a phenacyl bromide as described in the scheme below:
Afterwards, a small number of methods have been reported so far, regarding the synthesis of the (R,R) isomer, also referred as (R,R)-Formoterol and Arformoterol.
Murase et al. [Chem. Pharm. Bull. 26(4) 1123-1129(1978)] reported the preparation of (R,R)-Formoterol from a racemic mixture of the (R,R) and (S,S) isomers by optical resolution using optically active tartaric acid. Trofast et al. described a method in which 4-benzyloxy-3-nitrostyrene oxide was coupled with a optically pure (R,R)- or (S,S)-N-phenylethyl-N-(1-p-methoxyphenyl)-2-(propyl)amine to give a diastereomeric mixture of Formoterol precursors. These precursors were further separated by HPLC in order to obtain pure Formoterol isomers. Both synthetic processes undergo long synthetic procedures and low yields.
Patent publication EP0938467 describes a method in which Arformoterol is prepared via the reaction of the optically pure (R) N-benzyl-2-(4-methoxyphenyl)-1-(methylethylamine) with an optically pure (R)-4-benzyloxy-3-nitrostyrene oxide or (R)-4-benzyloxy-3-formamidostyrene oxide followed by formylation of the amino group. This method requires relatively severe reaction conditions, 24 h at a temperature of from 110 up to 130 °C as well as a further purification step using tartaric acid in order to eliminate diastereomer impurities formed during the process.
WO2009/147383 discloses a process for the preparation of intermediates of Formoterol and Arformoterol which comprises a reduction of a ketone intermediate of formula:
Using chiral reductive agent with an enantiomeric excess of about 98% which requires further purification steps to obtain a product of desired optical purity.
R,R)-Formoterol (Arformoterol) or a salt thereof from optically pure and stable intermediate (R)-2-(4-Benzyloxy-3-nitro-phenyl)-oxirane (compound II), suitable for industrial use, in combination with optically pure amine in higher yields, as depicted in the scheme below:
Compound (R, R)-1-(4-Benzyloxy-3-nitro-phenyl)-2-[[2-(4-methoxy-phenyl)-1-methylethyl]-(1-phenyl-ethyl)-amino]-ethanol (compound VI), having the configuration represented by the following formula:
Examples(R)-2-(4-Benzyloxy-3-nitro-phenyl)-oxirane (II)
A solution of 90 g (0.25 mol) of (R)-1-(4-Benzyloxy-3-nitro-phenyl)-2-bromo-ethanol (compound I) in 320 mL of toluene and 50 mL of MeOH was added to a stirred suspension of 46 g (0.33 mol) of K2CO3 in 130 mL of toluene and 130 mL of MeOH. The mixture was stirred at 40°C for 20 h and washed with water (400 mL). The organic phase was concentrated under reduced pressure to a volume of 100 mL and stirred at 25 °C for 30 min. It was then further cooled to 0-5°C for 30 min. and the product collected by filtration and dried at 40 °C to provide 67.1 g (97% yield) (98% chemical purity, 100% e.e.) of compound II as an off-white solid. 1H-NMR (200 MHz, CDCl3) δ: 2.80-2.90 (m, 2H); 3.11-3.20 (m, 2H), 3.80-3.90 (m, 1H); 5.23 (s, 2H); 7.11 (d, 2H); 7.41 (m, 5H), 7.76 (d, 2H).
Preparation of (R,R)-[2-(4-Methoxy-phenyl)-1-methyl-ethyl]-(1-phenyl-ethyl)-amine (III)
A solution of 13 g (78.6 mmol) of 1-(4-Methoxy-phenyl)-propan-2-one and 8.3 g (78.6 mmol) of (R)-1-Phenylethylamine in 60 mL MeOH was hydrogenated in the presence of 1.7 g of Pt/C 5% at 10 atm. and 30 °C for 20 h. The mixture was filtered though a pad of diatomaceous earth and concentrated under reduced pressure to give compound III as an oil. The obtained oil was dissolved in 175 mL of acetone, followed by addition of 6.7 mL (80.9 mmol) of a 12M HCl solution. The mixture was stirred at 23 °C for 30 min and at 0-5 °C for 30 min. The product collected by filtration and dried at 40 °C to provide 13.8 g of the hydrochloride derivate as a white solid. The obtained solid was stirred in 100 mL of acetone at 23 °C for 1h and at 0-5 °C for 30 min, collected by filtration and dried at 40 °C to provide 13.2 g of the hydrochloride derivate as a white solid. This compound was dissolved in 100 mL of water and 100 mL of toluene followed by addition of 54 mL (54 mmol) of 1N NaOH solution. The organic phase was concentrated to give 11.7 g (55% yield) (99% chemical purity and 100% e.e) of compound III as an oil.1H-NMR (200 MHz, CDCl3) δ: 0.88 (d, 3H); 1.31 (d, 3H), 2.40-2.50 (m, 1H); 2.60-2.80 (m, 2H); 3.74 (s, 3H); 3.90-4.10 (m, 1H); 6.77- 6.98 (m, 4H), 7.31 (s, 5H).
Synthesis of (R,R)-1-(4-Benzyloxy-3-nitro-phenyl)-2-[[2-(4-methoxy-phenyl)-1-methyl-ethyl]-(1-phenyl-ethyl)-amino]-ethanol (IV)
A 1-liter flask was charged with 50g (0.18 mol) of II and 50g (0.18 mol) of III and stirred under nitrogen atmosphere at 140 °C for 20 h. To the hot mixture was added 200 mL of toluene to obtain a solution, which was washed with 200 mL of 1N HCl and 200 mL of water. The organic phase was concentrated under reduced pressure to give 99 g (99% yield) (88% chemical purity) of compound IV as an oil. Enantiomeric purity 100%. 1H-NMR (200 MHz, CDCl3) δ: 0.98 (d, 3H); 1.41 (d, 3H), 2.60-2.90 (m, 4H); 3.20-3.30 (m, 1H); 3.74 (s, 3H); 4.10-4.20 (m, 1H); 4.30-4.40 (m, 1H), 5.19 (s, 2H); 6.69-7.42 (m, 16H); 7.77 (s, 1H).
Synthesis of (R, R)-1-(3-Amino-4-benzyloxy-phenyl)-2-[[2-(4-methoxy-phenyl)-1-methyl-ethyl]-(1-phenyl-ethyl)-amino]-ethanol (V)
A solution of 99 g (0.18 mol) of IV in 270 mL IPA and 270 mL toluene was hydrogenated in the presence of 10 g of Ni-Raney at 18 atm and 40 °C for 20 h. The mixture was filtered though a pad of diatomaceous earth and the filtrate was concentrated under reduced pressure to give 87 g (92% yield) (83% chemical purity, 100 % e.e.) of compound V as an oil. 1H-NMR (200 MHz, CDCl3) δ: 0.97 (d, 3H); 1.44 (d, 3H), 2.60-2.90 (m, 4H); 3.20-3.30 (m, 1H); 3.74 (s, 3H); 4.10-4.20 (m, 1H); 4.30-4.40 (m, 1H), 5.07 (s, 2H); 6.67-6.84 (m, 7H); 7.25-7.42 (m, 10H).
Synthesis of (R,R)-N-(2-Benzyloxy-5-{1-hydroxy-2-[[2-(4-methoxy-phenyl)-1-methyl-ethyl]-(1-phenyl-ethyl)-amino]-ethyl)-phenyl)-formamide (VI)
24 mL (0.63 mol) of formic acid was added to 27 mL (0.28 mol) of acetic anhydride and stirred at 50 °C for 2 h under nitrogen atmosphere. The resulting mixture was diluted with 100 mL of CH2Cl2 and cooled to 0 °C. A solution of 78 g (0.15 mol) of V in 300 mL de CH2Cl2 was slowly added and stirred for 1h at 0 °C. Then, 150 mL of 10% K2CO3 aqueous solution were added and stirred at 0 °C for 15 min. The organic phase was washed twice with 400 mL of 10% K2CO3 aqueous solution and concentrated under reduced pressure to give 80 g (97% yield, 100% e.e.) (75% chemical purity) of compound VI as an oil. 1H-NMR (200 MHz, CDCl3) δ: 0.98 (d, 3H); 1.42 (d, 3H), 2.60-2.90 (m, 4H); 3.20-3.30 (m, 1H); 3.75 (s, 3H); 4.10-4.20 (m, 1H); 4.30-4.40 (m, 1H), 5.09 (s, 2H); 6.67-7.41 (m, 17H); 8.4 (d, 1H).
A solution of 8.5 g (16 mmol) of VI, previous purified by column chromatography on silica gel (AcOEt/heptane, 2:3), in 60 mL ethanol was hydrogenated in the presence of 0.14 g of Pd/C 5% at 10 atm. and 40 °C for 20 h. The mixture was filtered though a pad of diatomaceous earth and concentrated under reduced pressure to give 5 g (93% yield) (91% chemical purity, 100% e.e.) of compound VII as foam. m. p.= 58-60 °C. 1H-NMR (200 MHz, d6-DMSO) δ: 0.98 (d, 3H); 2.42-2.65 (m, 5H); 3.20-3.40 (m, 1H); 3.71 (s, 3H); 4.43-4.45 (m, 1H); 6.77-7.05 (m, 5H); 8.02 (s, 1H), 8.26 (s, 1H).
A solution of 46 g (0.08 mol) of VI, crude product, was dissolved in 460 mL ethanol and hydrogenated in the presence of 0.74 g of Pd/C 5% at 10 atm. and 40 ° C for 28 h. The mixture was filtered though a pad of diatomaceous earth and the filtrate was concentrated under reduced pressure to give 24 g (83% yield) (77% chemical purity, 100% e.e.) of compound VII as a foam. m. p. = 58-60 °C. 1H-NMR (200 MHz, d6-DMSO) δ: 0.98 (d, 3H); 2.42-2.65 (m, 5H); 3.20-3.40 (m, 1H); 3.71 (s, 3H); 4.43-4.45 (m, 1H); 6.77-7.05 (m, 5H); 8.02 (s, 1H), 8.26 (s, 1H).
The HPLC conditions used for the determination of the Chemical purity % are described in the table below:
HPLC Column
Kromasil 100 C-18
Dimensions
0.15 m x 4.6 mm x 5 µm
Buffer
2.8 ml TEA (triethylamine) pH=3.00 H3PO4 (85%) in 1 L of H2O
Phase B
Acetonitrile
Flow rate
1.5 ml miN-1
Temperature
40 °C
Wavelength
230 nm
The HPLC conditions used for the determination of the enantiomeric purity % are described in the table below:
HPLC Column
Chiralpak AD-H
Dimensions
0.25 m x 4.6 mm
Buffer
n-hexane : IPA : DEA (diethyl amine) : H2O 85:15:0.1:0.1
(R) -2- (4- benzyloxy-3-nitrophenyl) oxirane (I) (9. 86g, 36mmol) and (R) -I- (4- methoxybenzene yl) -N – [(R) -I- phenyl-ethyl] -2-amino-propane (II) (10. 8g, 40mmol) and toluene 100ml, 110 ° C0-flow reactor 36 hours, the solvent was distilled off succeeded intermediates (III) (16. 8g, yield 85%).
Example 3
(R) -2- (4- benzyloxy-3-nitrophenyl) oxirane (I) (9. 86g, 36mmol) and (R) -I- (4- methoxybenzene After [(R) -I- phenyl-ethyl] -2-amino-propane (II) (10. 8g, 40mmol) and dichloromethane 100ml, 30 ° C for 48 hours, and the solvent was distilled off – yl) -N succeeded intermediates (III) (15. Sg, yield 80%).
Example 4
(R) -2- (4- benzyloxy-3-nitrophenyl) oxirane (I) (9. 86g, 36mmol) and (R) -I- (4- methoxybenzene yl) -N – [(R) -I- phenyl-ethyl] -2-amino-propane (II) (8. 75g, 32mmol) cast in the reaction flask, the reaction 20 hours at 140 ° C, the chiral intermediate form (III) (16. 3g, 83% yield).
Example 5
(R) -2- (4- benzyloxy-3-nitrophenyl) oxirane (I) (9. 86g, 36mmol) and (R) -I- (4- methoxybenzene yl) -N – [(R) -I- phenyl-ethyl] -2-amino-propane (II) (14. 6g, 54mmol) cast in the reaction flask, the reaction 20 hours at 140 ° C, the chiral intermediate form (III) (17. 5g, 89% yield).
Scheme
chirality 1991, 3, 443-50
Fumaric acid (0.138 mmol, 16 mg) was added to the residue dissolved in methanol. Evaporation of the solvent gave the
product (SS) W semifumarate (109 mg) characterized by ‘HNMR (4-D MSO) 6 (ppm) 1.00 (d, 3H, CHCH,), 4.624.70 (m, lH,
CHOH), 3.73 (s, 3H, OCH,), 6.M.9 (m, 3H, aromatic), 7.00 (dd,4H, aromatic), 6.49 (s, 1@ CH = CH fumarate). MS of disilylated
(SS) W: 473 (M +<H3,7%); 367 (M ‘<8H90, 45%); 310 61%). The (RSS) fraction was treated in the same manner
giving the product (R;S) W semifumarate, which was characterized by ‘H-NMR (4-DMSO) 6 (ppm) 1.01 (d, 3H, CHCH,),
3.76 (s, 3H, OC&), 6.49 (s, lH, CH=CH, fumarate) 6.M.9 (m, 3H, aromatic), 7.0 (dd, 4H, aromatic). MS of disilylated (R;S)
(M’X~~HIGNO1,7 %); 178 ( C I ~H~ ~N95O%,) ; 121 (CsH90, W. 473 (M’4H3, 5%); 367 (M’4gH90, 48%); 310
(M +–CI~HIGNO18, %); 178 (CIIHIGNO, 95%); 121 (CsH90, 52%). The structural data for the (RR) and (S;R) enantiomers
were in accordance with the proposed structures. The enantiomeric purity obtained for the enantiomers in each batch is
shown in Table 1.
Scheme
The enantioselective reduction of phenacyl bromide (I) with BH3.S(CH3)2 in THF catalyzed by the chiral borolidine (II) (obtained by reaction of (1R,2S)-1-amino-2-indanol (III) with BH3.S(CH3)2 in THF) gives the (R)-2-bromo-1-(4-benzyloxy-3-nitrophenyl)ethanol (IV), which is reduced with H2 over PtO2 in THF/toluene yielding the corresponding amino derivative (V). The reaction of (V) with formic acid and Ac2O affords the formamide (VI), which is condensed with the chiral (R)-N-benzyl-N-[2-(4-methoxyphenyl)-1-methylethyl]amine (VII) in THF/methanol providing the protected target compound (VIII). Finally, this compound is debenzylated by hydrogenation with H2 over Pd/C in ethanol. The intermediate the chiral (R)-N-benzyl-N-[2-(4-methoxyphenyl)-1-methylethyl]amine (VII) has been obtained by reductocondensation of 1-(4-methoxyphenyl)-2-propanone (IX) and benzylamine by hydrogenation with H2 over Pd/C in methanol yielding racemic N-benzyl-N-[2-(4-methoxyphenyl)-1-methylethyl]amine (X), which is submitted to optical resolution with (S)-mandelic acid to obtain the desired (R)-enantiomer (VII).
Org Process Res Dev1998,2,(2):96
Large-Scale Synthesis of Enantio- and Diastereomerically Pure (R,R)-Formoterol†
(R,R)-Formoterol (1) is a long-acting, very potent β2-agonist, which is used as a bronchodilator in the therapy of asthma and chronic bronchitis. Highly convergent synthesis of enantio- and diastereomerically pure (R,R)-formoterol fumarate is achieved by a chromatography-free process with an overall yield of 44%. Asymmetric catalytic reduction of bromoketone 4 using as catalyst oxazaborolidine derived from (1R, 2S)-1-amino-2-indanol and resolution of chiral amine 3 are the origins of chirality in this process. Further enrichment of enantio- and diastereomeric purity is accomplished by crystallizations of the isolated intermediates throughout the process to give (R,R)-formoterol (1) as the pure stereoisomer (ee, de >99.5%).
Anal. Calcd for C42H52N4O12: C, 62.67; H, 6.51; N, 6.96. Found: C, 62.34; H, 6.57; N, 6.85.
Scheme
The intermediate N-benzyl-N-[1(R)-methyl-2-(4-methoxyphenyl)ethyl]amine (IV) has been obtained as follows: The reductocondensation of 1-(4-methoxyphenyl)-2-propanone (I) with benzylamine (II) by H2 over Pd/C gives the N-benzyl-N-[1-methyl-2-(4-methoxyphenyl)ethyl]amine (III) as a racemic mixture, which is submitted to optical resolution with L-mandelic acid in methanol to obtain the desired (R)-enantiomer (IV). The reaction of cis-(1R,2S)-1-aminoindan-2-ol (V) with trimethylboroxine in toluene gives the (1R,2S)-oxazaborolidine (VI), which is used as chiral catalyst in the enantioselective reduction of 4-benzyloxy-3-nitrophenacyl bromide (VII) by means of BH3/THF, yielding the chiral bromoethanol derivative (VIII). The reaction of (VIII) with NaOH in aqueous methanol affords the epoxide (IX), which is condensed with the intermediate amine (IV) by heating the mixture at 90 C to provide the adduct (X). The reduction of the nitro group of (X) with H2 over PtO2 gives the corresponding amino derivative (XI), which is acylated with formic acid to afford the formamide compound (XII). Finally, this compound is debenzylated by hydrogenation with H2 over Pd/C in ethanol, providing the target compound.
The synthesis of the chiral borolidine catalyst (II) starting from indoline (I), as well as the enantioselective reduction of 4′-(benzyloxy)-3′-nitrophenacyl bromide (III), catalyzed by borolidine (II), and using various borane complexes (borane/dimethylsulfide, borane/THF and borane/diethylaniline), has been studied in order to solve the problems presented in large-scale synthesis. The conclusions of the study are that the complex borane/diethylaniline (DEANB) is the most suitable reagent for large-scale reduction of phenacyl bromide (III) since the chemical hazards and inconsistent reagent quality of the borane/THF and borane/dimethylsulfide complexes disqualified their use in large-scale processes. The best reaction conditions of the reduction with this complex are presented.
Formoterol is a long-acting β2-adrenoceptor agonist and has a long duration of action of up to 12 hours. Chemically it is termed as Λ/-[2-hydroxy-5-[1-hydroxy-2-[[2-(4- methoxyphenyl)propan-2-yl]amino]ethyl]phenyl]-formamide. The structure of formoterol is as shown below.
The asterisks indicate that formoterol has two chiral centers in the molecule, each of which can exist in two possible configurations. This gives rise to four diastereomers which have the following configurations: (R,R), (S1S), (S1R) and (R1S).
(R1R) and (S1S) are mirror images of each other and are therefore enantiomers. Similarly (S1R) and (R1S) form other enatiomeric pair.
The commercially-available formoterol is a 50:50 mixture of the (R1R)- and (S1S)- enantiomers. (R,R)-formoterol is an extremely potent full agonist at the β2-adrenoceptor and is responsible for bronchodilation and has anti-inflammatory properties. On the other hand (S,S)-enantiomer, has no bronchodilatory activity and is proinflammatory.
Murase et al. [Chem.Pharm.Bull., .26(4)1123-1129(1978)] synthesized all four isomers of formoterol and examined for β-stimulant activity. In the process, racemic formoterol was subjected to optical resolution with tartaric acid.
In another attempt by Trofast et al. [Chirality, 3:443-450(1991 )], racemic 4-benzyloxy-3- nitrostryrene oxide was coupled with optically pure N-[(R)-1-phenylethyl]-2-(4- methoxyphenyl)-(R)1-methylethylamine to give diastereomeric mixtures of intermediates, which were separated by column chromatography and converted to the optically pure formoterol.
In yet another attempt, racemic formoterol was subjected to separation by using a chiral compound [International publication WO 1995/018094].
WO 98/21175 discloses a process for preparing optically pure formoterol using optically pure intermediates (R)-N-benzyl-2-(4-methoxyphenyl)-1-methylethyl amine and (R)-4- benzyloxy-3-formamidostyrene oxide.
Preparation of optically pure formoterol is also disclosed in IE 000138 and GB2380996.
Example 7
Preparation of Arformoterol
4-benzyloxy-3-formylamino-α-[N-benzyl-N-(1-methyl-2-p- methoxyphenylethyl)aminomethyl]benzyl alcohol (120gms, 0.23M), 10% Pd/C (12 gms) and denatured spirit (0.6 lit) were introduced in an autoclave. The reaction mass was hydrogenated by applying 4 kg hydrogen pressure at 25-300C for 3 hrs. The catalyst was removed by filtration and the, clear filtrate concentrated under reduced pressure below 400C to yield the title compound. (63 gms, 80%).
Example 8
Preparation of Arformoterol Tartrate
Arformoterol base (60 gms, 0.17M), 480 ml IPA , 120 ml toluene and a solution of l_(+)- tartaric acid (25.6 gms, 0.17M) in 60 ml distilled water were stirred at 25-300C for 2 hrs and further at 40°- 45°C for 3 hrs. The reaction mass was cooled to 25-300C and further chilled to 200C for 30 mins. The solid obtained was isolated by filtration to yield the title compound. (60 gms, 70%),
The tartrate salt was dissolved in hot 50% IPA-water (0.3 lit), cooled as before and filtered to provide arformoterol tartrate. (30 gms, 50 % w/w). having enantiomeric purity greater than 99%.
PAPER
Organic Process Research & Development 2000, 4, 567-570
Modulation of Catalyst Reactivity for the Chemoselective Hydrogenation of a Functionalized Nitroarene: Preparation of a Key Intermediate in the Synthesis of (R,R)-Formoterol Tartrate………..http://pubs.acs.org/doi/abs/10.1021/op000287k
Modulation of Catalyst Reactivity for the Chemoselective Hydrogenation of a Functionalized Nitroarene: Preparation of a Key Intermediate in the Synthesis of (R,R)-Formoterol Tartrate
Chemical Research and Development, Sepracor Inc., 111 Locke Drive, Marlborough, Massachusetts 01752, U.S.A.
Org. Proc. Res. Dev., 2000, 4 (6), pp 567–570
DOI: 10.1021/op000287k
In the synthesis of the β2-adrenoceptor agonist (R,R)-formterol, a key step in the synthesis was the development of a highly chemoselective reduction of (1R)-2-bromo-1-[3-nitro-4-(phenylmethoxy)phenyl]ethan-1-ol to give (1R)-1-[3-amino-4-(phenylmethoxy)phenyl]-2-bromoethan-1-ol. The aniline product was isolated as the corresponding formamide. The reaction required reduction of the nitro moiety in the presence of a phenyl benzyl ether, a secondary benzylic hydroxyl group, and a primary bromide, and with no racemization at the stereogenic carbinol carbon atom. The development of a synthetic methodology using heterogeneous catalytic hydrogenation to perform the required reduction was successful when a sulfur-based poison was added. The chemistry of sulfur-based poisons to temper the reacitivty of catalyst was studied in depth. The data show that the type of hydrogenation catalyst, the oxidation state of the poison, and the substituents on the sulfur atom had a dramatic effect on the chemoselectivity of the reaction. Dimethyl sulfide was the poison of choice, possessing all of the required characteristics for providing a highly chemoselective and high yielding reaction. The practicality and robustness of the process was demonstrated by preparing the final formamide product with high chemoselectivity, chemical yield, and product purity on a multi-kilogram scale.
PAPER
Tetrahedron: Asymmetry 11 (2000) 2705±2717
An ecient enantioselective synthesis of (R,R)-formoterol, a potent bronchodilator, using lipases
Francisco Campos, M. Pilar Bosch and Angel Guerrero*
formoterol (R,R)-1 as amorphous solid. Rf: 0.27 (SiO2, AcOEt:MeOH, 1:1). 20D=-41.5 (CHCl3, c 0.53).
The tartrate salt was prepared by dissolving 13.8 mg (0.04 mmol) of(R,R)-1 and 6.0 mg (0.04 mmol) of (l)-(+)-tartaric acid in 150 mL of 85% aqueous isopropanol.
The solution was left standing overnight and the resulting crystalline solid (7.6 mg) puri®ed on areverse-phase column (1 g, Isolute SPE C18) using mixtures of MeOH±H2O as eluent. The solventwas removed under vacuum and the aqueous solution lyophilized (^35C, 0.6 bar) overnight. The(l)-(+)-tartrate salt of (R,R)-1 showed an 20D=-29.4 (H2O, c 0.61) (>99% ee based on the
reported value 34). 34=Hett, R.; Senanayake, C. H.; Wald, S. A. Tetrahedron Lett. 1998, 39, 1705.
PAPER
Diethylanilineborane: A Practical, Safe, and Consistent-Quality Borane Source for the Large-Scale Enantioselective Reduction of a Ketone Intermediate in the Synthesis of (R,R)-Formoterol
The development of a process for the use of N,N-diethylaniline−borane (DEANB) as a borane source for the enantioselective preparation of a key intermediate in the synthesis of (R,R)-formoterol l-tartrate, bromohydrin 2, from ketone 3 on kilogram scale is described. DEANB was found to be a more practical, safer, and higher-quality reagent when compared to other more conventional borane sources: borane−THF and borane−DMS.
Sepracor in the US is developing arformoterol [R,R-formoterol], a single isomer form of the beta(2)-adrenoceptor agonist formoterol [eformoterol]. This isomer contains two chiral centres and is being developed as an inhaled preparation for the treatment of respiratory disorders. Sepracor believes that arformoterol has the potential to be a once-daily therapy with a rapid onset of action and a duration of effect exceeding 12 hours. In 1995, Sepracor acquired New England Pharmaceuticals, a manufacturer of metered-dose and dry powder inhalers, for the purpose of preparing formulations of levosalbutamol and arformoterol. Phase II dose-ranging clinical studies of arformoterol as a longer-acting, complementary bronchodilator were completed successfully in the fourth quarter of 2000. Phase III trials of arformoterol began in September 2001. The indications for the drug appeared to be asthma and chronic obstructive pulmonary disease (COPD). However, an update of the pharmaceutical product information on the Sepracor website in September 2003 listed COPD maintenance therapy as the only indication for arformoterol. In October 2002, Sepracor stated that two pivotal phase III studies were ongoing in 1600 patients. Sepracor estimates that its NDA submission for arformoterol, which is projected for the first half of 2004, will include approximately 3000 adult subjects. Sepracor stated in July 2003 that it had completed more than 100 preclinical studies and initiated or completed 15 clinical studies for arformoterol inhalation solution for the treatment of bronchospasm in patients with COPD. In addition, Sepracor stated that the two pivotal phase III studies in 1600 patients were still progressing. In 1995, European patents were granted to Sepracor for the use of arformoterol in the treatment of asthma, and the US patent application was pending.
Key Laboratory of Drug Targeting Education Ministry, West China School of Pharmacy, Sichuan University, Chengdu 610041, China\
Abstract
(R)-1-(4-Methoxyphenyl)propan-2-amine 2a, an optical active intermediate for (R,R)-formoterol, was synthesized from d-alanine in 65% overall yield by using a simple route, which contained protecting amino group, cyclization, coupling with Grignard reagent, reduction and deprotection.
IR spectra of (a) (R,R)-formoterol tartrate/form A, (b) (R,R)-formoterol tartrate/form B, (c) (R,R)-formoterol tartrate/form C.
References
Muller, P., et al.: Arzneimittel-Forsch., 33, 1685 (1983); Wallmark, B., et al.: Biochim. Biophys. Acta., 778, 549 (1984); Morii, M., et al.: J. Biol. chem., 268, 21553 (1993); Ritter, M., et al.: Br. J. Pharmacol., 124, 627 (1998); Stenhoff, H., et al.: J. Chromatogr., 734, 191 (1999), Johnson, D.A., et al.: Expert Opin. Pharmacother., 4, 253 (2003); Bouyssou, T., et al.: Bio. Med. Chem. Lett. 20, 1410, (2010);
Percent Composition: C 66.26%, H 7.02%, N 8.13%, O 18.58%
Literature References: Selective b2-adrenergic receptor agonist. Mixture of R,R (-) and S,S (+) enantiomers. Prepn: M. Murakamiet al.,DE2305092; eidem,US3994974 (1973, 1976 both to Yamanouchi); K. Murase et al.,Chem. Pharm. Bull.25, 1368 (1977). Absolute configuration and activity of isomers: eidem,ibid.26, 1123 (1978). Toxicity studies: T. Yoshida et al.,Pharmacometrics26, 811 (1983). HPLC determn in plasma: J. Campestrini et al.,J. Chromatogr. B704, 221 (1997). Review of pharmacology: G. P. Anderson, Life Sci.52, 2145-2160 (1993); and clinical efficacy: R. A. Bartow, R. N. Brogden, Drugs55, 303-322 (1998).
Percent Composition: C 55.86%, H 6.12%, N 5.67%, O 32.36%
Literature References: Prepn: Y. Gao et al.,WO9821175; eidem,US6040344 (1998, 2000 both to Sepracor). Pharmacology: D. A. Handley et al.,Pulm. Pharmacol. Ther.15, 135 (2002).
USFDA approves Indoco’s Allopurinol ANDA… Indoco Remedies Limited (India)’s … Indoco Remedies Limited (India) added a new photo
Allopurinol, sold under the brand name Zyloprim and generics, is a medication used primarily to treat excess uric acid in the bloodand its complications, including chronic gout.It is a xanthine oxidase inhibitor and is administered orally.
Allopurinol has been marketed in the United States since August 19, 1966, when it was first approved by FDA under the trade name Zyloprim. Allopurinol was marketed at the time by Burroughs-Wellcome. Allopurinol is now a generic drug sold under a variety of brand names, including Allohexal, Allosig, Milurit, Alloril, Progout, Ürikoliz, Zyloprim, Zyloric, Zyrik, and Aluron
Generic drugmakers submitting abbreviated new drug applications (ANDAs) and prior approval supplements (PAS) will see their US Food and Drug Administration (FDA) fee rates drop in 2017, though all other rates, including those for drug master files (DMF) and facility fees will increase when compared to 2016.
For FY 2017, the generic drug fee rates are: ANDA ($70,480, down from $76,030 in 2016), PAS ($35,240, down from $38,020 in 2016), DMF ($51,140, up from $42,170 in 2016), domestic active pharmaceutical ingredient (API) facility ($44,234, up from $40,867 in 2016), foreign API facility ($59,234, up from $55,867 in 2016), domestic finished dose formulation (FDF) facility ($258,646, up from $243,905), and foreign FDF facility ($273,646, up from $258,905 in 2016).
The new fees are effective 1 October 2016 and will remain in effect through 30 September 2017.
FDA explained the increases and decreases in fees, noting that for ANDA and PAS fees, the agency is expecting an increase in the number of submissions estimated to be submitted in FY 2017 when compared to 2016. For 2017, the agency estimates that approximately 891 new original ANDAs and 439 PASs will be submitted and incur filing fees.
Fees for DMFs will increase, meanwhile, because of an expected decrease in the number of submissions estimated to be submitted in 2017 (FDA is estimating 379 fee-paying DMFs for 2017), when compared to the estimated submissions from 2016.
And all facility fees will increase in 2017 when compared to the previous year because of a decrease in the number of facilities that self-identified (the total number of FDF facilities identified through self-identification was 675, of which 255 were domestic facilities and 420 foreign facilities; while the total number of API facilities self-identified was 789, of which 101 were domestic facilities and 688 were foreign facilities), FDA said.
How FDA Calculates the Fees
In order to calculate the ANDA fee, FDA estimated the number of full application equivalents (FAEs) that will be submitted in FY 2017, which is done by assuming ANDAs count as one FAE and PASs (supplements) count as one-half of an FAE, since the fee for a PAS is one half of the fee for an ANDA.
The Generic Drug User Fee Act (GDUFA) also requires that 75% of the fee paid for an ANDA or PAS filing be refunded if either application is refused due to issues other than a failure to pay the fees.
And since this is the last year of this iteration of GDUFA (the next version is still in the works), the agency is allowed to further increase the fee revenues and fees established if such an adjustment is necessary to provide for not more than three months of operating reserves for the first three months of FY 2018, though FDA estimates that the GDUFA program will have carryover balances for such activities in excess of three months of such operating reserves, so FDA will not be performing a final year adjustment.
To pay the fees, companies must complete a Generic Drug User Fee Cover Sheet, available at http://www.fda.gov/gdufa and generate a user fee identification (ID) number. Payment must be made in US currency drawn on a US bank by electronic check, check, bank draft, US postal money order or wire transfer.
“Brilliant Course, learn lots of tips and tricks” Vertex “First incursion into Chemical Development has been very, very educational. John’s way of explaining the material has been wonderful.” Almirall
“Very clear and interesting sessions with a lot of relevant examples and not only theory.” Oribase Pharma
Gemfibrozil is classified as a fibric acid derivative and is used in the treatment of hyperlipidaemias. It has effects on plasma-lipid concentrations similar to those described under bezafibrate. The major effects of gemfibrozil have been a reduction in plasma-triglyceride concentrations and an increase in high-density lipoprotein (HDL) cholesterol concentrations. A reduction in very-low-density lipoprotein (VLDL)-triglyceride appears to be largely responsible for the fall in plasma triglyceride although reductions in HDL and low-density lipoprotein (LDL)-triglycerides have also been reported.
The effects of gemfibrozil on total cholesterol have been more variable: in general, LDL-cholesterol may be decreased in patients with pre-existing high concentrations and raised in those with low concentrations. The increase in HDL-cholesterol concentrations has resulted in complementary changes to the ratios of HDL-cholesterol to LDL-cholesterol and to total cholesterol. Gemfibrozil has successfully raised HDL-cholesterol concentrations in patients with isolated low levels of HDL-cholesterol but otherwise normal cholesterol concentrations.The Helsinki heart study assessed gemfibrozil for the primary prevention of ischaemic heart disease in middle-aged men with hyperlipidaemia. The usual dose, by mouth, is 1.2 g daily in two divided doses given 30 min before the morning and evening meals. Gemfibrozil is available as tablets for oral administration (Lopid: USP).
Gemfibrozil is the generic name for an oral drug used to lower lipid levels. It belongs to a group of drugs known as fibrates. It is most commonly sold as the brand name, Lopid. Other brand names include Jezil and Gen-Fibro.
history
Gemfibrozil was selected from a series of related compounds synthesized in the laboratories of the American company Parke Davisin the late 1970s. It came from research for compounds that lower plasma lipid levels in humans and in animals.[1]
Gemfibrozil should not be given to these patients:
Hepatic dysfunction
Gemfibrozil should be used with caution in these higher risk categories:
Biliary tract disease
Renal dysfunction
Pregnant women
Obese patients
Drug interactions
Anticoagulants: Gemfibrozil potentiates the action of warfarin and indanedione anticoagulants.[citation needed]
Statin drugs: Concomitant administration of fibrates (including gemfibrozil) with statin drugs increases the risk of muscle cramping, myopathy, andrhabdomyolysis.
Gemfibrozil inhibits the activation of the liver’s Cytochrome P450 system, reducing hepatic metabolism of many drugs, and prolonging their half lives and duration of action.
Drugs metabolized by the Cytochrome P450 system include:
Gemfibrozil has been detected in biosolids (the solids remaining after wastewater treatment) at concentrations up to 2650 ng/g wet weight.[3] This indicates that it survives the wastewater treatment process.
SYNTHESIS
The sodium isobutyrate (I) is metallated with lithium diisopropylamide, and the resulting compound is alkylated with 3- (2,5-dimethylphenoxy) propyl bromide.
PATENT
Paul, L. C.2,2-Dimethyl-ω-aryloxy alkanoic acids and salts and ester thereof. U.S. 3,674,836, 1972.
Production of Gemfibrozil (1)2,5-Dimethylphenol and 1-Bromo-3-chloropropane reaction of 1-(2,5-dimethylphenoxy)-3-chloropropane. The reaction is carried out in toluene, adding new clean off reflux 5h. Just as follows:
(2)N/A can be used to manufacture Gemfibrozil.
PAPER
Improved Process for Preparation of Gemfibrozil, an Antihypolipidemic
† Chemical Research and Development, Aurobindo Pharma Ltd., Survey No. 71 and 72, Indrakaran (V), Sangareddy (M), Medak District-502329, Andhra Pradesh, India
‡ Engineering Chemistry Department, AU College of Engineering, Andhra University, Visakhapatnam-530003, Andhra Pradesh, India
An improved process for the preparation of gemfibrozil, an antihypolipodimic drug substance, with an overall yield of 80% and ∼99.9% purity (including three chemical reactions) is reported. Formation and control of possible impurities are also described. Finally, gemfibrozil is isolated from water without any additional solvent purification.
Literature References:
Serum lipid regulating agent. Prepn: P. L. Creger, DE1925423; eidem,US3674836 (1969, 1972, both to Parke, Davis).
Production: O. P. Goel, US4126637 (1978 to Warner-Lambert).
Pharmacology: A. H. Kissebach et al.,Atherosclerosis24, 199 (1976); M. T. Kahonen et al.,ibid.32, 47 (1979).
Series of articles on metabolism, clinical pharmacology, kinetics and toxicology: Proc. R. Soc. Med.69, Suppl 2, 1-120 (1976).
Toxicity data: S. M. Kurtz et al.,ibid. 15.
Clinical trial in hyperlipidemia: J. E. Lewis et al.,Pract. Cardiol.9, 99 (1983).
Clinical reduction of cardiovascular risk in patients with low HDL levels: H. B. Rubins et al.,N. Engl. J. Med.341, 410 (1999).
LOPID® (gemfibrozil tablets, USP) is a lipid regulating agent. It is available as tablets for oral administration. Each tablet contains 600 mg gemfibrozil. Each tablet also contains calcium stearate, NF; candelilla wax, FCC; microcrystalline cellulose, NF; hydroxypropyl cellulose, NF; hypromellose, USP; methylparaben, NF; Opaspray white; polyethylene glycol, NF; polysorbate 80, NF; propylparaben, NF; colloidal silicon dioxide, NF; pregelatinized starch, NF. The chemical name is 5-(2,5-dimethylphenoxy)2,2-dimethylpentanoic acid, with the following structural formula:
The empirical formula is C15H22O3 and the molecular weight is 250.35; the solubility in water and acid is 0.0019% and in dilute base it is greater than 1%. The melting point is 58° –61°C. Gemfibrozil is a white solid which is stable under ordinary conditions.
![2D [1H,1H]-TOCSY, n/a spectrum for Miconazole](http://www.bmrb.wisc.edu/metabolomics/standards/miconazole/nmr/bmse000924/spectra_png/HH_TOCSY/00.png)
![2D [1H,13C]-HSQC, n/a spectrum for Miconazole](http://www.bmrb.wisc.edu/metabolomics/standards/miconazole/nmr/bmse000924/spectra_png/1H_13C_HSQC/00.png)
![2D [1H,13C]-HMBC, n/a spectrum for Miconazole](http://www.bmrb.wisc.edu/metabolomics/standards/miconazole/nmr/bmse000924/spectra_png/1H_13C_HMBC/00.png)
![2D [1H,1H]-COSY, n/a spectrum for Miconazole](http://www.bmrb.wisc.edu/metabolomics/standards/miconazole/nmr/bmse000924/spectra_png/HH_COSY/00.png)
![2D [1H,13C]-HMQC, n/a spectrum for Miconazole](http://www.bmrb.wisc.edu/metabolomics/standards/miconazole/nmr/bmse000924/spectra_png/1H_13C_HMQC/00.png)
Title:
IR spectrum of lovastatin.
.
![[1860-5397-7-57-i50]](http://beilstein-journals.org/bjoc/content/inline/1860-5397-7-57-i50.png?scale=2.0&max-width=1024&background=FFFFFF)
The synthesis of the C27–C35 tetrahydrofuran fragment.
The synthesis of the C14–C21 aldehyde subfragment.
Eribulin is a cut-down derivative of halichondrin B, which maintains most of its activity with significantly reduced complexity
Synthesis of eribulin relies heavily on Nozaki–Hiyama–Kishi (NHK) coupling reactions to make key C–C bonds
3D STRUCTURE
Arformoterol ball-and-stick model
Arformoterol (Brovana)
.
