Hydrochloric Acid → 2'-Methyl-2-oxo-1,2-dihydro-3,4'-bipyridine-6-carboxylic acid, hydrochloride salt

Synthesis of methyl 5-bromo-6-methoxypyridine-2-carboxylate (C30). A stirred solution of methyl 5-bromo-6-methoxypyridine-2-carboximidoate (C29) (9.42 g, 38.4 mmol) in methanol (66 mL) and concentrated hydrochloric acid (6.6 mL) was heated under reflux for 18 hours. The reaction was concentrated to dryness under reduced pressure. The resulting solid was dissolved in dichloromethane (500 mL) and washed with saturated aqueous sodium bicarbonate solution (250 mL). The aqueous phase was extracted with dichloromethane (200 mL), and the combined organics were washed with water (250 mL), with saturated aqueous sodium chloride solution (250 mL), dried over magnesium sulfate and concentrated under reduced pressure to provide the title compound. The reaction was repeated on additional material (1.65 g, 6.73 mmol), worked up in a similar manner, combined with the first reaction, and purified by silica gel chromatography (Eluant: 10% ethyl acetate in heptane) to provide the title compound as a yellow solid. Yield: 4.48 g, 18.2 mmol, 40%. LCMS m/z 246.1 (M+1). 1H NMR (400 MHz, CDCl3) δ 3.97 (s, 3H), 4.11 (s, 3H), 7.59 (d, J=7.8 Hz, 1H), 7.93 (d, J=7.8 Hz, 1H).