The general procedure for the synthesis of 4-amino-1-tert-butylpyrazole from 1-(tert-butyl)-4-nitro-1H-pyrazole is as follows: to a solution of 1-tert-butyl-4-nitro-1H-pyrazole (1.10 g, 6.5 mmol) in methanol (20 mL) was added a 10% palladium-carbon catalyst (containing 50% water, 442 mg). The reaction mixture was stirred in a hydrogen atmosphere for 3 hours at room temperature. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. The resulting residue was purified by column chromatography (silica gel as stationary phase, eluent ratio hexane/ethyl acetate = 70/30 → 0/100) to give 4-amino-1-tert-butylpyrazole (838 mg, 92% yield). The structure of the product was confirmed by 1H-NMR (CDCl3, 300 MHz): δ 1.53 (9H, s), 2.86 (2H, br s), 7.15 (1H, s), 7.19 (1H, s).
