62259-92-1

124-42-5

52763-21-0

62259-92-1

To a mixed solution containing sodium methanolate (25 wt% methanol solution, 67.6 mL, 296 mmol) and methanol (70 mL) was sequentially added acetamidine hydrochloride (11.00 g, 106 mmol) and ethyl 1-benzyl-3-oxopiperidine-4-carboxylate hydrochloride (25.16 g, 84 mmol) at 25 °C. The reaction mixture was stirred continuously at 25°C for 20 hours. Upon completion of the reaction, the mixture was cooled to 0 °C, followed by the addition of water (90 mL) and the slow dropwise addition of acetic acid (6.05 mL, 106 mmol), and continued stirring at 25 °C for 3 hours. Most of the methanol was removed by distillation under reduced pressure and the reaction mixture was concentrated. The resulting suspension was filtered and the solid product was collected and washed with cold water. Finally, the solid was dried under vacuum to afford 7-benzyl-2-methyl-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-4(3H)-one (16.10 g, 79% yield) as a white solid. The product was analyzed by LC/MS showing m/z 242.06 (M+H)+ with a retention time of 0.598 min (Method 12).1H-NMR (500 MHz, CDCl3) data were as follows: δ 12.61 (broad single peak, 1H), 7.99 (single peak, 1H), 7.38-7.26 (multiple peaks, 5H), 3.73 (multiple peaks, 2H), and 3.50 (multiple peaks, 2H), 2.74 (multiple peaks, 2H), 2.66 (multiple peaks, 2H).