657428-42-7

157327-42-9

1280210-79-8

Tert-butyl 3-((dimethylamino)methylene)-4-oxopyrrolidine-1-carboxylate (1 g, 4.16 mmol, 1.00 eq.) was used as a raw material and dissolved in ethanol (10 mL) with hydrazine hydrate (340 mg, 6.79 mmol, 1.63 eq.). The mixed solution was stirred and reacted at room temperature for 5 hours. Upon completion of the reaction, the solvent was removed by vacuum concentration and the crude product obtained was purified by silica gel column chromatography with ethyl acetate/petroleum ether as eluent (the ratio was gradually adjusted from 1:5 to 1:2). Finally, 250 mg (29% yield) of tert-butyl 4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate was obtained and the product was a yellow oil. The product was confirmed by LC/MS (Method C, ESI) analysis: retention time RT = 1.30 min, mass-to-charge ratio m/z ~ 210.0 [M + H]+.