219503-74-9

219503-81-8

Step B: Preparation of tert-butyl 6-amino-1H-indazole-1-carboxylate: To a solution of tert-butyl 6-nitro-1H-indazole-1-carboxylate (0.88 g, 3.34 mmol) in methanol (20 mL) was added 10% Pd/C catalyst (0.355 g, 0.334 mmol). After displacing the air in the reaction system with nitrogen, the hydrogenation reaction was carried out under hydrogen (30 psi) atmosphere for 2 hours. After completion of the reaction, the reaction mixture was filtered through GF/F filter paper and the filtrate was concentrated to afford the target product tert-butyl 6-amino-1H-indazole-1-carboxylate (0.76 g, 98% yield). Mass spectrometry analysis (APCI-positive ion mode) showed [M+1]+ peak of 233.8.