(Step 3) Synthesis of tert-butyl 3-(4-amino-1H-pyrazol-1-yl)pyrrolidine-1-carboxylate:[0490] 3-(4-nitro-1H-pyrazol-1-yl)pyrrolidine-1-carboxylic acid tert-butyl ester (1.25 g, 4.43 mmol) was suspended in ethanol (EtOH, 30.0 mL) and 10% palladium/carbon (Pd/C, 0.30 g) was added. The reaction mixture was stirred overnight at room temperature under hydrogen atmosphere. Upon completion of the reaction, the mixture was filtered and the filter cake was washed with methanol (MeOH, 10.0 mL). The filtrates were combined and concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography with a gradient of dichloromethane (DCM) to DCM/methanol (methanol solution containing 3M ammonia) as eluent (v/v=100/1 to 50/1) to afford the title compound as a brown viscous liquid (0.65 g, 58% yield). m/z MS (ESI, positive ion mode): 253.2 [M+H ]+; 1H NMR (400 MHz, CDCl3) δ (ppm): 7.16 (s, 1H), 7.01 (s, 1H), 4.79-4.67 (m, 1H), 3.82-3.73 (m, 1H), 3.70-3.44 (m, 3H), 2.90 (s, 2H), 2.36-2.24 (m, 2H), 1.45 (s, 9H).
