7-Benzyl-5,6,7,8-tetrahydro-3H-pyrido[3,4-d]pyrimidin-4-one hydrochloride

3473-63-0

52763-21-0

62458-96-2

To a mixed solution of sodium methanolate (25 wt% methanol solution, 67.6 mL, 296 mmol) and methanol (70 mL) was sequentially added formamidine acetate (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, water (90 mL) was added followed by slow dropwise addition of acetic acid (6.05 mL, 106 mmol) and stirring was continued 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, washed with water and dried under vacuum to afford 7-benzyl-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-4(3H)-one (16.10 g, 79% yield) as a white solid.LC/MS analysis showed: m/z 242.06 ([M+H]+), retention time 0.598 min (Method 12). .1H-NMR (500 MHz, CDCl3) δ 12.61 (broad single peak, 1H), 7.99 (single peak, 1H), 7.38-7.26 (multiple peaks, 5H), 3.73 (multiple peaks, 2H), 3.50 (multiple peaks, 2H), 2.74 (multiple peaks, 2H), 2.66 (multiple peaks, 2H).