General procedure for the synthesis of methyl 5-bromo-1-methyl-6-oxo-1,6-dihydropyridine-3-carboxylate from 5-bromo-6-hydroxynicotinic acid methyl ester and iodomethane: Methyl 5-bromo-6-hydroxynicotinic acid methyl ester (3.0 g, 1.0 eq.) and potassium carbonate (3.6 g, 2.0 eq.) were dissolved in N,N-dimethylformamide, and iodomethane (1.5 eq.) was added dropwise at room temperature. The reaction mixture was stirred at 35°C for 3 hours. After completion of the reaction, the reaction solution was diluted with ethyl acetate, washed with water, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The concentrated residue was dissolved in dichloromethane and hexane was added for crystallization to afford methyl 5-bromo-1-methyl-6-oxo-1,6-dihydropyridine-3-carboxylate as a white solid (2.5 g, 79% yield).
