To a solution of 4-methyl-2-(4-(benzyloxy)-2-oxopyridin-1(2H)-yl)thiazole-5-carboxylic acid (0.10 g, 0.29 mmol) and 4-methylmorpholine (0.032 mL, 0.29 mmol) in anhydrous dichloromethane (6 mL) was added isobutylchloroformate (0.044 mL, 0.34 mmol) dropwise at 0° C. After stirring at ambient temperature for 2 hours, the reaction mixture was cooled to 0° C. and benzylamine (0.032 mL, 0.29 mmol) was added dropwise. Stirring at ambient temperature was continued for 18 hours, then the reaction mixture was diluted with ethyl acetate (30 mL) and washed with saturated aqueous sodium bicarbonate (10 mL) and brine (10 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The residue was triturated with a mixture of ethyl acetate/dichloromethane 1/1 (10 mL) to afford the title compound as a white solid (0.055 g, 44%): mp 219-220° C. (ethyl acetate/dichloromethane); 1H NMR (300 MHz, CDCl3) δ 8.67 (d, J=8.1 Hz, 1H), 7.47-7.15 (m, 10H), 6.22 (dd, J=8.1, 2.6 Hz, 1H), 6.14 (t, J=5.6 Hz, 1H), 6.05 (d, J=2.6 Hz, 1H), 5.03 (s, 2H), 4.58 (d, J=5.6 Hz, 2H), 2.68 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 167.4, 162.3, 162.0, 153.5, 152.2, 137.8, 134.6, 131.6, 128.9, 128.8, 127.9, 127.8, 127.7, 122.4, 104.1, 97.4, 70.8, 44.1, 17.3; (ES+) m/z 432.2 (M+1).
