Methyl 4-nitro-1H-pyrazole-3-carboxylate (9.63 g, 56.3 mmol) was used as starting material and 10% palladium/carbon catalyst (1.00 g) and methanol (150 mL) were added. The reaction was stirred under hydrogen atmosphere at room temperature for 16 hours. After completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to afford methyl 4-amino-1H-pyrazole-3-carboxylate (7.87 g, 99% yield). The product was characterized by 1H-NMR (CDCl3): δ 3.93 (3H, s, -OCH3), 4.08 (2H, brs, -NH2), 7.25 (1H, s, pyrazole ring-H).
