General procedure for the synthesis of 1-(benzyloxy)-6-oxo-1,6-dihydropyridine-2-carboxylic acid from benzyl chloride and 1-hydroxy-6-oxo-1,6-dihydropyridine-2-carboxylic acid: 1-hydroxy-6-carboxy-2(1H)-pyridinone (15.5 g, 0.1 mol) and anhydrous potassium carbonate (27.6 g, 0.2 mol) were mixed with benzyl chloride (15.2 g, 0.12 mol) were mixed in methanol (250 mL) and reacted at reflux for 16 hours. After completion of the reaction, the mixture was filtered and the filtrate was evaporated to dryness. The residue was dissolved in water (50 mL) and acidified with 6N HCl to pH 2. A white precipitate was isolated by filtration, washed with cold water, and dried under vacuum to give 22.3 g (91% yield) of 1-benzyloxy-6-carboxy-2(1H)-pyridinone with a melting point of 176-177 °C. The product was purified by 1H NMR (1H NMR) (1H NMR) and dried under vacuum. The product was characterized by 1H NMR (300 MHz, CDCl3) and 13C NMR (75 MHz, DMSO-d6) with the following data: 1H NMR δ 5.269 (s, 2H), 6.546 (dd, J = 16 Hz, J = 6.7 Hz, 1H), 6.726 (dd, J = 16 Hz, J = 9.2 Hz, 1H), 7.39 -7.51 (m, 6H); 13C NMR δ 77.9, 106.0, 124.1, 128.5, 129.1, 129.6, 133.8, 138.7, 140.5, 157.7, 161.7. Elemental analysis (C13H11NO4) calculated values: C, 63.66 (63.75); H, 4.53 (4.55) N, 5.71 (5.52).
