635698-34-9

1027-35-6

57-13-6

635698-34-9

Ethyl 1-benzyl-4-keto-3-pyrrolidinecarboxylate (9.23 g, 0.0372 mol) was dissolved in ethanol (170 mL), to which a methanolic solution of urea (11.2 g, 0.186 mol) and sodium methanolate (~28%, 25 g) was added. The reaction mixture was stirred under reflux conditions for 24 hours. Upon completion of the reaction, the reaction mixture was mixed with water (100 mL) and stirring was continued at room temperature. Subsequently, dilute hydrochloric acid (~1 mol/L, 100 mL) was added slowly and dropwise to the reaction mixture. The precipitated solid was collected by filtration and washed with water (100 mL). Finally, the resulting solid was dried under reduced pressure to afford 6-benzyl-6,7-dihydro-1H-pyrrolo[3,4-D]pyrimidine-2,4(3H,5H)-dione (3.93 g, 43% yield).