62459-02-3

39514-19-7

57-13-6

62459-02-3

To a solution of ethyl 1-benzyl-3-oxa-4-piperidinecarboxylate (12.0 g, 40.4 mmol) in methanol (200 ml) at 0 °C was added sequentially urea (5.1 g, 84.8 mmol) and sodium methanolate (12.3 g, 228 mmol). The reaction mixture was stirred at 60°C for 96 hours under nitrogen protection. After completion of the reaction, the mixture was cooled to room temperature and concentrated under reduced pressure to remove the solvent. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol=10:1, v/v) to afford 7-benzyl-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine-2,4(1H,3H)-dione (6.3 g, 61% yield). lRMS (M+H+) m/z: calculated value 258.29; measured value 258.30.