MK 8876
CAS 1426960-33-9

2-(4-Fluorophenyl)-5-(11-fluoro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indol-2-yl)-N-methyl-6-(N-methylmethanesulfonamido)-1-benzofuran-3-carboxamide

2-(4-Fluorophenyl)-5-(11-fluoro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indol-2-yl)-N-methyl-6-[methyl(methylsulfonyl)amino]-3-benzofurancarboxamide

Molecular Formula		C32H24F2N4O5S
Molecular Weight		614.62

• Originator Merck & Co
• Class Antivirals

• Phase I Hepatitis C

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DATA

2-(4-Fluorophenyl)-5-(11-fluoro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indol-2-yl)-N-methyl-6-(N-methylmethanesulfonamido)-1-benzofuran-3-carboxamide

MK-8876 off-white solid

¹H NMR (500 MHz, DMSO-d₆) δ 8.56 (q, J = 4.7 Hz, 1H), 8.06–8.01 (m, 2H), 8.05 (s, 1H), 7.86 (s, 1H), 7.71 (d, J = 8.5 Hz, 1H), 7.62 (d, J = 8.5 Hz, 1H), 7.52 (d, J = 8.3 Hz, 1H), 7.46–7.40 (m, 2H), 7.29–7.22 (m, 1H), 7.11 (s, 1H), 6.94 (dd, J = 10.6, 7.9 Hz, 1H), 6.27 (s, 2H), 3.31 (s, 3H), 2.96 (s, 3H), 2.85 (d, J = 4.7 Hz, 3H);

¹³C NMR (125.7 MHz, DMSO-d₆) δ 162.86, 162.82 (d, J_C–F = 248.5 Hz), 155.74 (d, J_C–F = 246.1 Hz), 153.80, 152.43, 152.28, 147.20, 137.08, 137.00 (d, J_C–F = 10.8 Hz), 136.36, 136.20, 132.37, 129.50 (d, J_C–F = 8.6 Hz), 127.17, 125.45 (d, J_C–F = 3.1 Hz), 125.08, 125.02, 123.70 (d, J_C–F = 7.7 Hz), 122.28, 117.23 (d, J_C–F = 22.4 Hz), 116.01 (d, J_C–F = 21.9 Hz), 113.65, 111.76, 106.90 (d,J_C–F = 3.5 Hz), 105.32 (d, J_C–F = 18.5 Hz), 94.16, 73.57, 39.39, 37.24, 26.16;

HR-ESI-MS m/zcalcd for C₃₂H₂₅N₄O₅SF₂⁺ [M + H]⁺ 615.1514, found 615.1500.

HPLC Method
column	Ascentis Express C18 2.7 μm (fused core), 100 mm × 4.6 mm
detection	UV at 210 nm
column temperature	40 °C
flow rate	1.8 mL/min
injection volume	5.0 μL
gradient	90% A to 5% A over 11 min, hold at 5% A for 2 min, 5% A back to 90% A over the next 0.1 min, and then hold at 90% A for 2.9 min
run time	16 min
data collection	acquisition for the first 13 min
mobile phases	solvent A: water with 0.1% H3PO4
	solvent B: acetonitrile

Retention Time Data
identity	tR (min)
boronic acid 27	4.24
desbromoarene 28	5.33
MK-8876 (1)	7.89
chloropyridine starting material 2	8.03
BHT	10.22

SYNTHESIS 

CONTD……………

 

 

MK 8876

MK 8876

Patent

WO 2013033900

Scheme 1

 

Scheme 2

 

Scheme 3

Q

 

Scheme 4

 

EXAMPLES

Example 1

Preparation of Compound 1

Step 1 – Synthesis of 2,6-dichloropyridin-3-ol

Η₂0₂ (1.60 g, 47.12 mmol) was added slowly to the solution of compound 2,6- dichloropyridin-3-ylboronic acid (3 g, 15.71 mmol) in CH₂CI₂ (30 mL) at 0 °C. After stirred at room temperature for about 15 hours, the mixture was quenched with sat. Na₂S203 aqueous (50 mL) and adjusted to pH < 7 with IN HC1. The mixture was extracted with EtOAc (40 mL x 3). The organic layer was washed with brine (100 mL), dried over Na₂S0₄, filtered and the solvent was evaporated to provide2,6-dichloropyridin-3-ol (2.34 g, yield: 91.4%). 1H-NMR (CDC1₃, 400 MHz) δ 7.30 (d, / = 8.4 Hz, 1H), 7.19 (d, / = 8.4 Hz, 1H), 5.70 (br, 1H).

– Synthesis of 2,6-dichloro- -methoxypyridine

To a solution of 2,6-dichloropyridin-3-ol (16.3 g, 0.1 mol) and K₂C0₃ (41.4 g, 0.3 mol) in DMF (200 mL) were added Mel (21.3 g, 0.15 mol). The mixture was allowed to stir at 80 °C for 2 hours. The mixture was then diluted with water (200 mL) and extracted with EtOAc (200 mL x 3). The organic layer was washed with brine (200 mL x 3), dried over Na₂S0₄, filtered and the solvent was evaporated to provide 2,6-dichloro-3-methoxypyridine (17.0 g, yield: 96.0%). 1H-NMR (CDC1₃, 400 MHz) δ 7.12-7.18 (m, 2H), 3.86 (s, 3H). Step 3 – Synthesis of2-(6-chloro-3-methoxypyridin-2-yl)-lH-indole

To a degassed solution of compound 2,6-dichloro-3-methoxypyridine (8.9 g, 0.05 mol), (l-(tert-butoxycarbonyl)-lH-indol-2-yl)boronic acid (13 g, 0.05 mol) and K₃PO₄ (31.8 g, 3.0 mol) in DMF (100 mL) was added Pd(dppf)Cl₂ (3.65 g, 0.005 mol) under N₂. The mixture was heated at 60 °C for about 15 hours. The reaction mixture was cooled to room temperature, diluted with EtOAc and filtered. The filtrate was washed with H₂0, brine, dried over Na₂S0₄. After being concentrated in vacuo, the resulting residue was purified using prep-HPLC to provide the desired product of 2-(6-chloro-3-methoxypyridin-2-yl)-lH-indole (9.0 g, yield:

69.8%). 1H-NMR (CDC1₃, 400 MHz) δ 9.52 (s, 1H), 7.65 (d, / = 7.6 Hz, 1H), 7.38-7.43 (m, 2H), 7.07-7.26 (m, 4H), 4.03 (s, 3H).

Step 4 – Synthesis of6-chlor -2-(lH-indol-2-yl)pyridin-3-ol

BBr₃ (0.4 mL, 0.39 mmol) was added to the solution of 2-(6-chloro-3- methoxypyridin-2-yl)-lH-indole (50 mg, 0.194 mmol) in CH₂C1₂ (0.5 mL) at -78 °C under N₂. The mixture was allowed to stir at room temperature for 3 hours. The mixture was then quenched with CH₃OH (10 mL) at -78 °C. After being concentrated in vacuo, the resulting residue was purified using prep-TLC (PE : EtOAc = 2.5 : 1) to afford the desired product of 6- chloro-2-(lH-indol-2-yl)pyridin-3-ol (40 mg, yield: 85.1%). 1H-NMR (CDC1₃, 400 MHz) δ 10.09 (s, 1H), 9.72 (s, 1H), 7.50 (d, / = 7.9 Hz, 1H), 7.17-7.32 (m, 3H), 7.08-7.14 (m, 1H), 6.87-6.96 (m, 2H).

Step 5 – Synthesis of 2-chlo -6H-pyrido[2′ ,3′ : 5 ,6] [ 1 ,3]oxazino[3 ,4-a]indole

To a solution of chloroiodomethane (3.51 g, 20.0 mmol) and K₂CO₃ (1.38 g, 10.0 mmol) in DMF (50 mL) was allowed to stir at 100 °C, 6-chloro-2-(lH-indol-2-yl)pyridin-3-ol (480 mg, 2.0 mmol) in DMF (50 mL) was added dropwise. After addition, the mixture was allowed to stir for another 0.5 hours. The mixture was then diluted with water (100 mL) and extracted with EtOAc (100 mL x 3). The organic layer was washed with brine (100 mL x 3), dried over Na₂S0₄ and concentrated. The residue was purified using prep-TLC (PE : EtOAc = 3 1) to afford the desired product of 2-chloro-6H-pyrido[2′,3′:5,6][l,3]oxazino[3,4-a]indole (260 mg, yield: 50.7%). 1H-NMR (CDC1₃, 400 MHz) δ 7.63 (d, / = 8.0 Hz, 1H), 7.22-7.27 (m, 3H), 7.19 (d, / = 2.4 Hz, 1H), 7.08-7.12 (m, 2H), 5.86 (s, 2H).

Step 6 – Synthesis of2-(4-fluowphenyl)-N-methyl-6-(N-methylmethylsulfonamido)-5-(6H- pyridol 2 ‘,3’:5,6][ l, mpound 1 )

To a degassed solution of 2-(4-fluorophenyl)-N-methyl-6-(N- methylmethylsulfonamido)-5-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)benzofuran-3- carboxamide (502 mg, 1.0 mmol), 2-chloro-6H-pyrido[2′,3′:5,6][l,3]oxazino[3,4-a]indole (256 mg, 1.0 mmol) and K₃PO₄ (636 mg, 3.0 mmol) in dioxane : H₂0 (1.5 mL : 0.4 mL) was added Pd₂(dba)₃ (91 mg, 0.1 mmol) and X-phos (91 mg, 0.2 mmol) under N₂. The mixture was heated to 110 °C for 3 hours. The reaction mixture was cooled to room temperature, diluted with EtOAc and filtered. The filtrate was washed with H₂0, brine, dried over Na₂S0₄. After being concentrated in vacuo, the resulting residue was purified using prep-HPLC to provide the desired product of Compound 1 (275 mg, yield: 46.1%). 1H-NMR (CDC1₃, 400 MHz) δ 7.88-7.94 (m, 3H), 7.61-7.63 (m, 2H), 7.40 (s, 2H), 7.09-7.28 (m, 6H), 5.94 (s, 2H), 5.86 (d, / = 4.4 Hz, 1H), 3.29 (s, 3H), 2.92 (d, / = 5.2 Hz, 3H), 2.65 (s, 3H). MS (M+H)⁺: 596.

Compounds 2-15, depicted in the table below, were prepared using the method described above.

COMPD 2 IS MK 8876

PATENT

WO 2013033971

Example 81

Preparation of Compound 2

Synthesis of ethyl 3- 4-fluorophenyl)-3-oxopropanoate

Diethyl carbonate (130 g, 1.1 mol) was dissolved in a suspension ofNaH (60% in oil, 50.2 g, 1.3 mol) in anhydrous tetrahydrofuran (1.5 L), and then l-(4-fluorophenyl)ethanone (150 g, 1.09 mol) was added dropwise at 70 °C. The resulting mixture was stirred at 70 °C for 3 hours. After the reaction mixture was cooled to room temperature and poured into HCl (1 N). The mixture was extracted with EtOAc, the organic phase was dried with anhydrous NaS0₄ and concentrated in vacuo. The resulting residue was purified using column chromatography (eluted with petroleum ether / EtOAc = 50 / 1) to provide ethyl 3-(4-fluorophenyl)-3-oxopropanoate (217 g, yield: 95%). 1H-NMR (CDC1₃, 400 MHz) δ 7.92-7.97 (m, 2H), 7.07-7.13 (m, 2H), 4.14-4.20 (m, 2H), 3.93 (s, 2H), 1.22 (d, J= 7.2 Hz, 3H). MS (M+H)⁺: 211. Step 2 – Synthesis of ethyl 5-bromo-2-(4-fluorophenyl)benzofuran-3-carboxylate

A solution of ethyl 3-(4-fluorophenyl)-3-oxopropanoate (130 g, 0.6 mol), 4- bromophenol (311 g, 1.8 mol) and FeCl₃-6H₂0 (19.5 g, 0.09 mol) in DCE (700 mL) was heated to reflux, and then 2-(tert-butylperoxy)-2-methylpropane (193 g, 1.32 mol) was added dropwise under nitrogen. After 6 hours of refluxing, the mixture was cooled to RT, quenched with saturated NaHS0₃ and extracted with dichloromethane. The organic phases were washed with water, brine and dried over Na₂S0₄, filtered and concentrated in vacuo. The resulting residue was purified using column chromatography (petroleum ether / dichloromethane = 15 / 1) to provide the crude product, which was crystallized from cold MeOH to provde ethyl 5-bromo-2- (4-fluorophenyl)benzofuran-3-carboxylate (37 g, yield: 14.3%) as solid. 1H- MR (CDC1₃, 400 MHz) δ 8.12 (s, 1H), 7.97-8.01 (m, 2H), 7.37 (d, J= 4.0 Hz, 1H), 7.32 (d, J= 8.0 Hz, 1H), 7.11 (t, J= 8.0 Hz, 2H), 4.32-4.38 (m, 2H), 1.36 (t, J= 8.0 Hz, 3H). MS (M+H)⁺: 363 / 365.

Step 3 – Synthesis of eth l 5-bromo-2-(4-fluorophen -6-nitrobenzofuran-3-carboxylate

To a solution of ethyl 5-bromo-2-(4-fluorophenyl)benzofuran-3-carboxylate (50 g,

137.6 mmol) in CHC1₃ (500 mL), fuming HN0₃ (50 mL) was added dropwise at -15 °C and the mixture was stirred for 0.5 hour. The reaction mixture was poured into ice water and extracted with CH₂C1₂. The organic layer was washed with a.q. sat. NaHC0₃ and brine, after removed the most of solvent, the resulting residue was crystallized with petroleum ether / dichloromethane = 20 / 1 to provide product of ethyl 5-bromo-2-(4-fluorophenyl)-6-nitrobenzofuran-3-carboxylate (35 g, yield: 66%). 1H- MR (CDC1₃, 400 MHz) δ 8.36 (s, 1H), 8.02-8.04 (m, 3H), 7.13-7.18 (m, 2H), 4.36-4.41 (m, 2H), 1.37 (t, J= 4.0 Hz, 3H). MS (M+H)⁺: 408 / 410.

Step 4 – Synthesis of ethyl 6-amino-5-bromo-2-(4-fluorophenyl)benzofuran-3-carboxylate

A mixture of ethyl 5-bromo-2-(4-fluorophenyl)-6-nitrobenzofuran-3-carboxylate (52 g, 127 mmol), iron filings (21.3 g, 382.2 mmol) and H₄C1 (41 g, 764.4 mmol) in MeOH / THF / H₂0 (2 / 2 / 1, 500 mL) was stirred at reflux for 3 hour. After filtered and concentrated, the resulting residue was purified using column chromatography (petroleum ether / EtOAc / dichloromethane = 20 : 1 : 20) to provide ethyl 6-amino-5-bromo-2-(4-fluorophenyl) benzofuran-3-carboxylate (40 g, yield: 82%). 1H- MR (CDC1₃, 400 MHz) δ 8.01 (s, 1H), 7.94-7.98 (m, 2H), 7.08 (t, J= 8.0 Hz, 2H), 6.83 (s, 1H), 4.32-4.36 (m, 2H), 4.18 (s, 2H), 1.35 (t, J= 8.0 Hz, 3H). MS (M+H)⁺: 378 / 380.

Step 5 – Synthesis of 5-Bromo-2-(4-fluoro-phenyl)-6-methanesulfonylamino-benzofuran-3- carboxylic acid eth l ester

MsCI (31.7 g, 277.5 mmol) was added to a solution of ethyl 6-amino-5-bromo-2- (4-fluorophenyl)benzofuran-3-carboxylate (35 g, 92.5 mmol) and pyridine (60 mL) in

dichloromethane (300 mL) at 0 °C. After stirred overnight at room temperature, the mixture was diluted with water and extracted with dichloromethane. The organic layer was washed with brine, dried over Na₂S0₄, filtered and concentrated in vacuo, the resulting residue was purified using crystallized with EtOAc to provde the pure product of ethyl 5-bromo-2-(4-fluorophenyl)-6- (methylsulfonamido)benzofuran-3-carboxylate (35 g, yield: 82%). 1H- MR (CDC1₃, 400 MHz) δ 8.27 (s, 1H), 8.01-8.05 (m, 2H), 7.87 (s, 1H), 7.15-7.19 (m, 2H), 6.87 (s, 1H), 4.38-4.43 (m, 2H), 3.00 (s, 3H), 1.40 (t, J= 40 Hz, 3H). MS (M+H)⁺: 456 / 458.

Step 6 – Synthesis of 5-Bromo-2-(4-fluoro-phenyl)-6-methanesulfonylamino-benzofuran-3- carboxylic acid

To a solution of ethyl 5-bromo-2-(4-fluorophenyl)-6-(methylsulfonamido) benzofuran-3-carboxylate (53 g, 0.23 mol) in dioxane / H₂0 (5 / 1, 600 mL) was added

LiOH-H₂0 (25 g, 1.17 mol), and the mixture was stirred at 100 °C for 3 hours. After

concentrated, the resulting residue was dissolved in H₂0, 1 N HCl was added until pH reached 3, and the mixture was extracted with EtOAc. The organic layer was washed with brine, dried over Na₂S0₄ and filtered. The solvent was removed to provide the product of 5-bromo-2-(4- fluorophenyl)-6-(methylsulfonamido)benzofuran-3-carboxylic acid (48 g, yield: 96%).¹H- MR (DMSO- e, 400 MHz) δ 13.49 (s, 1H), 9.67 (s, 1H), 8.30 (s, 1H), 8.12-8.17 (m, 2H), 7.87 (s, 1H), 7.45-7.50 (m, 2H), 3.16 (s, 3H). MS (M+H)⁺: 428 / 430. Step 7 – Synthesis of 5-Bromo-2-(4-fluoro-phenyl)-6-methanesulfonylamino-benzofuran-3- carboxylic acid methylamide

A solution of 5-bromo-2-(4-fluorophenyl)-6-(methylsulfonamido) benzofuran-3- carboxylic acid (33 g, 77 mmol), HOBT (15.6 g, 115.5 mmol) and EDCI (22.2 g, 115.5 mmol) in DMF (250 mL) was stirred at room temperature. After 2 hours, Et₃N (50 mL) and CH₃ H₂ (HC1 salt, 17.7 g, 231 mmol) was added to the mixture, and the mixture was stirred overnight. After the solvent was removed, H₂0 was added and the mixture was extracted with ethyl acetate. The combined organic layer was washed with H₂0, brine and concentrated in vacuo. The resulting residue was washed with EtOAc to provide the product of 5-bromo-2-(4-fluorophenyl)-N- methyl-6-(methylsulfonamido)benzofuran-3-carboxamide (32 g, yield: 94%). 1H- MR (DMSO- ck, 400 MHz) δ 9.55 (br s, 1H), 8.46-8.48 (m, 1H), 8.12-8.17 (m, 2H), 7.96 (s, 1H), 7.87 (s, 1H), 7.45-7.50 (m, 2H), 3.16 (s, 3H), 2.93 (d, J= 8.4 Hz, 3H). MS (M+H)⁺: 441 / 443.

Step 8 – Synthesis of 5-bromo-2-(4-fluorophenyl)-N-methyl-6-(N- methylmethylsulfonamido benzofuran-3-carboxamide

CH₃I (31.6 g, 223 mmol) was added to a mixture of 5-bromo-2-(4-fluorophenyl)- N-methyl-6-(methylsulfonamido)benzofuran-3-carboxamide (32 g, 74 mmol), K₂C0₃ (25.6 g, 186 mmol) and KI (246 mg, 1.5 mmol) in DMF (150 mL) under N₂ protection. The mixture was stirred at 80-90 °C overnight. After concentrated in vacuo, the resulting residue was washed with water (200 mL) and EtOAc (200 mL) to provide the product of 5-bromo-2-(4- fluorophenyl)-N-methyl-6-(N-methylmethylsulfonamido)benzofuran-3-carboxamide (31.5 g, 94%). 1H- MR (CDCI₃, 400 MHz) δ 8.16 (s, 1H), 7.88-7.92 (m, 2H), 7.70 (s, 1H), 7.18-7.23 (m, 2H), 5.78 (br s, 1H), 3.34 (s, 3H), 3.09 (s, 3H), 3.00 (d, J= 4.8 Hz, 3H). MS (M+H)⁺: 455 / 457. Step 9 – Synthesis of 2-(4-fluorophenyl)-N-methyl-6-(N-methylmethylsulfonamido)-5-(4, 4, 5, 5- tetramethyl-1 -dioxaborolan-2-yl)benzofuran-3-carboxamide

a degassed solution of 5-bromo-2-(4-fluorophenyl)-N-methyl-6-(N- methylmethylsulfonamido)benzofuran-3-carboxamide (1.0 g, 2.2 mmol) and pinacol diborane (2.79 g, 11.0 mmol) in 1,4-Dioxane (25 mL) was added KOAc (647 mg, 6.6 mmol) under N₂ and stirred for 4 hours at room temperature. Then Pd(dppf)Cl₂ (60 mg) was added, and the mixture was stirred for another 30 minutes. Then the mixture was put into a pre-heated oil-bath at 130 °C and stirred for another 1 hour under N₂. The reaction mixture was cooled to room

temperatureand concentrated and extracted with EtOAc. The organic layers were washed with brine, dried over Na₂S0₄. After concentrated, the crude product of the boronic ester was purified using column chromatography (petroleum ether / EtOAc = 5 / 1 to 2 / 1) to obtain 2-(4- fluorophenyl)-N-methyl-6-(N-methylmethylsulfonamido)-5-(4,4,5,5-tetramethyl-l,3,2- dioxaborolan-2-yl)benzofuran-3-carboxamide as white solid (700 mg, yield: 64%). ¹H- MR (CDCI₃, 400 ΜΗζ) δ 8.17 (s, 1H), 7.87-7.91 (m, 2H), 7.52 (s, 1H), 7.11 (t, 7= 7.6 Hz, 2H), 5.81 (d, 7= 2.8 Hz, 1H), 3.30 (s, 3H), 2.97 (d, 7= 5.2 Hz, 3H), 2.90 (s, 3H), 1.31 (s, 12H). MS (M+H)⁺: 503.

Step 10 – Synthesis of tert-butyl 4-fluoro-lH-indole-l -car boxy late

To a solution of 4-fluoro-lH-indole (5 g, 0.11 mol) and DMAP (150 mg, 3%Wt) in THF (50 mL) was added (Boc)₂0 (8.5 g, 0.04 mol) dropwise. The mixture was stirred at room temperature for 2 hours. The organic solvent was removed in vacuo, and the resulting residue was purified using column chromatography (pure petroleum ether) to provide tert-butyl 4-fluoro- lH-indole-l-carboxylate (8.3 g, yield: 96%). 1H- MR (CDC1₃, 400 MHz) δ 7.92 (d, J= 8.4 Hz, 1H), 7.55 (d, J= 3.6 Hz, 1H), 7.23 (m, 1H), 6.90 (m, 1H), 6.66 (d, J= 3.6 Hz, 1H), 1.67 (s, 9H). MS (M+H)⁺: 236.

Step 11 – Synthesis of (l-(tert-butoxycarbonyl)-4-fluoro-lH-indol-2-yl)boronic acid

To a solution of diisopropylamine (7.5 mL, 0.11 mol) in THF (35 mL) at 0 °C was added «-BuLi (21 mL, 0.055 mol) dropwise. The mixture was stirred at 0 °C for 40 minutes. Then the mixture was cooled to -78 °C. Tert-butyl 4-fluoro-lH-indole-l-carboxylate (5 g, 0.02 mol) in THF (13 mL) was added dropwise slowly. After addition, the mixture was stirred at -78 °C for 2 hours. Then triisopropyl borate (3.29 g, 0.03 mol) was added. The mixture was stirred at -78 °C for another 40 minutes. The reaction was monitored using TLC. When the reaction was completed, the mixture was adjusted to pH = 6 with 1 N HC1. After extracted with EtOAc (25 mL x 3), the combined organic layers were washed with brine (50 mL), dried over Na₂S0₄, filtered and concentrated in vacuo. The obtained solid was recrystallized with EtOAc and petroleum ether to provide (l-(tert-butoxycarbonyl)-4-fluoro-lH-indol-2-yl)boronic acid (4.5 g, yield: 76.7%, which might be unstable at high temp, work up, store in fridge). ¹H- MR (CDC1₃, 400 MHz) δ 7.77 (d, J= 8.4 Hz, 1H), 7.57 (s, 1H), 7.44 (s, 2H), 7.24 (m, 1H), 6.90 (m, 1H), 1.66 (s, 9H). MS (M+H)⁺: 280.

Step 12 – Synthesis of 6-chloro-2-iodopyridin-3-ol

6-chloropyridin-3-ol (5.0 g, 38.6 mmol) was dissolved in water (50 mL) and placed under an N₂ atmosphere. Na₂C0₃ (8.2 g, 77.4 mmol) was added followed by iodine (9.8 g, 38.8 mmol). The reaction mixture was stirred at room temperature for 2 hours. The mixture was poured into 1M Na₂S₂0₃ and extracted with EtOAc. The combined organic phases were washed with brine, dried over Na₂S0₄ and concentrated to provide the product of 6-chloro-2- iodopyridin-3-ol (7.0 g, yield: 70.9%). 1H- MR (CDC1₃, 400 MHz) δ 7.17 (d, J= 8.4 Hz, 1H), 7.06 (d, J= 8.4 Hz, 1H). MS (M+H)⁺: 256 / 258.

Step 13 – Synthesis of 6-chloro-2-(4-fluoro-lH-indol-2-yl)pyridin-3-ol

A mixture of (l-(tert-butoxycarbonyl)-4-fluoro-lH-indol-2-yl)boronic acid (5 g, 18.0 mmol), 6-chloro-2-iodopyridin-3-ol (3.82 g, 15.0 mol) and NaHC0₃ (3.78 g, 45.0 mol) in 1, 4-dioxane (76 mL) and water (7 mL) was stirred at room temperature for 15 minutes. Then Pd(PPh₃)₂Cl₂ (527 mg, 0.75 mmol) was added under nitrogen atmosphere, and the mixture was heated at 100 °C under N₂ for 16 hours. The reaction mixture was cooled to room temperature, diluted with EtOAc (50 mL), filtered and concentrated in vacuo. The resulting residue was diluted with H₂0 (60 mL) and EtOAc (30 mL), and the layer was separated, the aqueous layer was extracted with EtOAc (3*30 mL). The combined organic layers were washed with brine (50 mL), dried over Na₂S0₄, filtered and concentrated in vacuo. The resulting residue was purified using column chromatography (petroleum ether / EtOAc = 20 / 1 ~ 3 / 1) to provide 6-chloro-2- (4-fluoro-lH-indol-2-yl)pyridin-3-ol (3 g, yield: 76.5%). 1H- MR (MeOD, 400 MHz) δ 7.36 (s, 1H), 7.23-7.27 (m, 2H), 7.03-7.11 (m, 2H), 6.63-6.68 (m, 1H). MS (M+H)⁺: 263 / 265.

Ste 14 – Synthesis of 2-chloro-ll-fluoro-6H-pyrido[2′,3′:5, 6][l,3]oxazino[3,4-a]indole

A solution of 6-chloro-2-(4-fluoro-lH-indol-2-yl)pyridin-3-ol (2 g, 7.6 mmol) and Cs₂C0₃ (7.46 g, 22.89 mmol) in DMF (100 mL) was stirred at 100 °C (internal temperature) for 15 min, and then chloroiodomethane (2.85 g, 15.3 mmol) in DMF (2 mL) was added dropwise. After the reaction was completed, the mixture was filtered and concentrated in vacuo. The resulting residue was diluted with water (50 mL) and extracted with ethyl acetate (30 mL x 3). The organic layer was washed with brine, dried over Na₂S0₄ and concentrated in vacuo. The resulting residue was purified using column chromatography (petroleum ether:EA=10: l) to provde 2-chloro-l l-fluoro-6H-pyrido[2′,3′:5,6][l,3]oxazino[3,4-a]indole (1.8 g, yield: 86.1%). 1H- MR (DMSO-i¾, 400 MHz) δ 7.64 (d, J= 8.8 Hz, 1H), 7.39-7.46 (m, 2H), 7.21-7.25 (m, 1H), 7.06 (s, 1H), 6.88-6.92 (m, 1H), 6.18 (s, 2H). MS (M+H)⁺: 275 / 277. Step 15 – Synthesis of5-(ll-fluoro-6H-pyrido[2 3′:5, 6][l,3]oxazino[3,4-a]indol-2-yl)-2-(4- fluorophenyl)-N-methyl-6-(N-methylmethylsulfonamido)benzofuran-3-carboxam

To a degassed solution of 2-(4-fluorophenyl)-N-methyl-6-(N- methylmethylsulfonamido)-5-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)benzofuran-3- carboxamide (100 mg, 0.199 mmol), 2-chloro-l l-fluoro-6H-pyrido[2′,3′:5,6][l,3]oxazino[3,4- a]indole (56 mg, 0.199 mmol) and Κ₃Ρ0₄·3Η₂0 (159 mg, 0.597 mmol) in dioxane / H₂0 (0.8 mL / 0.2 mL) was added Pd₂(dba)₃ (9 mg, 0.01 mmol) and X-Phos (9 mg, 0.02 mmol) under N₂. The mixture was heated at 80 °C for 1 hour. The mixture was then diluted with water (30 mL) and extracted with EtOAc (15 mL x 3). The organic layer was washed with brine (20 mL), dried over Na₂S0₄ and concentrated in vacuo. The resulting residue was purified using prep-TLC (petroleum ether / EtOAc = 1 : 1.5) to provde the pure product of 5-(l l-fluoro-6H- pyrido [2′, 3 ‘ : 5 , 6] [ 1 , 3 ]oxazino [3 ,4-a]indol-2-yl)-2-(4-fluorophenyl)-N-methyl-6-(N- methylmethylsulfonamido)benzofuran-3-carboxamide (60 mg, 48.8%). 1H- MR (CDC1₃, 400 MHz) δ: 7.99 (s, 1H), 7.93-7.96 (m, 2H), 7.65 (s, 1H), 7.45-7.50 (m, 2H), 7.17-7.21 (m, 4H), 7.10 (d, J= 8.0 Hz, 1H), 6.81-6.85 (m, 1H), 5.98 (s, 3H), 3.35 (s, 3H), 2.98 (d, J= 4.8 Hz, 3H), 2.72 (s, 3H). MS (M+H)⁺: 615.

 

Paper

Process Development of the HCV NS5B Site D Inhibitor MK-8876

http://pubs.acs.org/doi/abs/10.1021/acs.oprd.5b00405

PAPER

Evaluation and Control of Mutagenic Impurities in a Development Compound: Purge Factor Estimates vs Measured Amounts

http://pubs.acs.org/doi/abs/10.1021/acs.oprd.5b00263?journalCode=oprdfk

WO2004041201A2 *	Oct 31, 2003	May 21, 2004	Viropharma Incorporated	Benzofuran compounds, compositions and methods for treatment and prophylaxis of hepatitis c viral infections and associated diseases
WO2011106992A1 *	Mar 2, 2011	Sep 9, 2011	Merck Sharp & Dohme Corp.	Inhibitors of hepatitis c virus ns5b polymerase

//////MK-8876, 1426960-33-9, Merck & Co, Antivirals, Phase I,  Hepatitis C

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