Methanol → 2-Methoxy-5-pyridinecarbonitrile

Participants

Reaction Steps

To a solution of 4-aminomethylphenylboronic acid hydrochloride (2.0 g, 13.2 mmol) in methanol (20 ml) was added di-tert-butyl dicarbonate (3.16 g, 15.5 mmol) and sodium bicarbonate (3.32 g, 19.8 mmol). The mixture was sonicated for 4 h then concentrated under reduced pressure. The residue was partitioned between ethyl acetate and water. The organic phase was washed with brine, dried over anhydrous magnesium sulfate and the solvent evaporated to give (4-bromo-benzyl)-carbamic acid tert-butyl ester (1.8 g, 13.2 mmol, 100%) as a white solid. To 6-chloro-nicotinonitrile (15 g, 0.11 mol) under argon atmosphere was added 25% sodium methoxide in methanol (11.7 g, 0.22 mol) and the mixture heated under reflux for 20 h. The methanol was evaporated and the residue partitioned between ethyl acetate and water. The aqueous phase was extracted with ethyl acetate. The combined organic extracts were washed with water, brine, dried over anhydrous magnesium sulfate and the solvent evaporated to give 6-methoxy-nicotinonitrile (17.0 g, 0.13 mol, 117%) as a white solid. To 6-methoxy-nicotinonitrile (13.2 g, 99 mmol) in acetic acid (32 ml) was added sodium acetate (8.1 g, 99 mmol). The mixture was stirred and a solution of bromine (31.5 g, 197 mmol) in acetic acid (32 ml) added. The mixture was heated to 80° C. for 48 h. The reaction mixture was poured into water and extracted with diethyl ether. The organic phase was washed with 4M aqueous sodium hydroxide solution, 5% sodium thiosulfate solution, dried over anhydrous potassium carbonate and the solvent was evaporated to give 5-bromo-6-methoxy-nicotinonitrile (11.9 g, 56 mmol, 57%). To a solution of 2-methoxy-5-cyanopyridine-3-boronic acid (1.0 g, 4.0 mmol) in 1,2-dimethoxyethane (10 ml) was added (4-bromo-benzyl)-carbamic acid tert-butyl ester (0.42 g, 2.0 mmol), tetrakis(triphenylphosphine)palladium (0) (114 mg, 0.1 mmol) and 2M aqueous sodium carbonate (1 ml, 2.0 mmol). The reaction was heated to 150° C. for 10 min in a microwave over. The mixture was concentrated under reduced pressure and partitioned between ethyl acetate and water. The organic phase was washed with water, then brine, dried over anhydrous magnesium sulfate and the solvent evaporated. The residue was purified on silica gel eluting with 5:1 heptane/ethyl acetate to give [4-(5-cyano-2-methoxy-pyridin-3-yl)-benzyl]-carbamic acid tert-butyl ester as a white solid (0.5 g, 1.47 mmol, 37%). To a solution of [4-(5-cyano-2-methoxy-pyridin-3-yl)-benzyl]-carbamic acid tert-butyl ester (0.5 g, 1.5 mmol) in dichloromethane (5 ml) at 0° C. was added trifluoroacetic acid (5 ml, 28 mmol). The reaction mixture was stirred for 30 min at 0° C. before the solvent was evaporated and the residue purified on a SCX column (eluted with 2M ammonia in methanol) to give 5-(4-aminomethyl-phenyl)-6-methoxy-nicotinonitrile as a clear glass (0.39 g, 1.6 mmol, 107%). To a solution of 5-(4-aminomethyl-phenyl)-6-methoxy-nicotinonitrile (57.3 mg, 0.24 mmol) in dichloromethane (2 ml) was added triethylamine (73.0 mg, 0.72 mmol) and 2-(trifluoromethoxy)benzenesulfonyl chloride. The reaction mixture was agitated for 20 hours and the solvent evaporated under reduced pressure. The crude product was taken up in dimethyl sulfoxide (1 ml) and purified by preparatory LCMS. The solvent was evaporated under reduced pressure to give the title compound (19.1 mg, 0.04 mmol, 17%). 1H NMR (400 MHz, DMSO-d6): δ 8.68 (d, 1H), 8.47 (t, 1H), 8.15 (d, 1H), 7.90 (m, 1H), 7.73 (m, 1H), 7.45-7.55 (m, 4H), 7.31 (d, 2H), 4.19 (d, 2H), 3.96 (s, 3H) ppm; MS (ESI) m/z: 464.3 [M+H]+.

Provenance & Evidence