Under nitrogen atmosphere, 2-hydroxyisonicotinic acid (500 g, 3.59 mol) was dissolved in methanol (10 L) and palladium hydroxide (150 g) was added to a 20 L autoclave. The reaction mixture was stirred at room temperature and 5 kg/cm2 hydrogen pressure for 18 hours. After confirming complete consumption of the feedstock by LCMS monitoring, the reaction mixture was filtered through a diatomaceous earth pad and the filtrate was concentrated under reduced pressure. The resulting residue was ground with ether (2.5 L) and dried under vacuum to afford 2-oxopiperidine-4-carboxylic acid (450 g, 85% yield) as an off-white solid.1H NMR (500 MHz, DMSO-d6): δ 12.37 (s, 1H), 7.44 (s, 1H), 3.16-3.12 (m, 2H), 2.78-2.71 (m, 1H), 2.33-2.71 (m, 1H), 2.33-2.71 (m, 1H). 1H), 2.33-2.21 (m, 2H), 1.98-1.92 (m, 1H), 1.74-1.63 (m, 1H). LCMS (m/z): 144.2 [M++1].
