GENERAL STEPS: Methyl 1-methyl-2-oxo-1,2-dihydropyridine-4-carboxylate (1 g, 1.0 eq.) was dissolved in 25 mL of methanol and 5 mL of an aqueous solution of lithium hydroxide monohydrate (755 mg, 3.0 eq.) was added with stirring. The reaction mixture was stirred at room temperature for 2 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. An appropriate amount of water was added to the residue and the pH was adjusted to 1~3 with aqueous 3N hydrochloric acid. the resulting white solid product was collected by filtration, washed with water and dried to afford 1-methyl-2-oxo-1,2-dihydro-4-pyridinecarboxylic acid (540 mg, 60% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 13.56 (brs, 1H), 7.80 (d, J=1.2 Hz, 1H), 6.83 (d, J=1.6 Hz, 1H), 6.53 (d, J=6.8 Hz, 1H), 3.46 (s, 3H).
