6-Benzyl-5,6,7,8-tetrahydro-1H-pyrido[4,3-d]pyrimidine-2,4-dione

41276-30-6

57-13-6

135481-57-1

GENERAL STEPS: Ethyl 1-benzyl-4-piperidone-3-carboxylate (10.0 g, 33.5 mmol) was dissolved in anhydrous ethanol (150.0 mL), followed by the sequential addition of urea (10.0 g, 167.0 mmol) and sodium methanol (22.7 g, 118.0 mmol). The reaction mixture was stirred under heated reflux conditions for 24 hours. Upon completion of the reaction, the mixture was cooled to 0 °C and the precipitated solid was collected by filtration. The resulting solid was suspended in deionized water, and the pH was adjusted to 6.0 by slowly adding 6.0 mol/L hydrochloric acid solution. After continued stirring at room temperature for 1 h, the crystals were separated by filtration and dried under vacuum to afford 6-phenylmethyl-5,6,7,8-tetrahydro-1H-piperidino[4,3-D]2,4-dihydropyrimidinone (6.5 g, 75% yield), which was ready to use in the subsequent reaction without further purification. subsequent reaction without further purification. Thin-layer chromatography (TLC) analysis: Rf = 0.1 (Expanding agent: ethyl acetate/methanol=5:1); Melting point: 293 °C; 1H NMR (300 MHz, CDCl3, δ ppm): 2.43-2.45 (m, 2H), 2.51-2.52 (m, 2H), 3.01 (s, 2H), 3.53 (s, 2H), 7.23- 7.41 (m, 5H). 7.41 (m, 5H), 10.21 (s, 1H), 11.01 (s, 1H).