5-Chloro-3-(2,5-dimethyl-1H-pyrrol-1-yl)-1-methyl-1H-pyrazole (CAS: 89088-52-8, 0.50 g, 2.38 mmol) was used as a raw material, which was dissolved in ethanol (20 mL) in a sealed tube. Subsequently, an ethanol (5 mL) solution of hydroxylamine hydrochloride (0.83 g, 12.0 mmol) was added dropwise, followed by a water (10 mL) solution of potassium hydroxide (0.30 g, 6.0 mmol) dropwise. The reaction mixture was heated at 105 °C for 2 days, during which the progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the mixture was concentrated to remove the solvent to give the crude product. The crude product was purified by silica gel column chromatography with an eluent of 0-30% ethyl acetate-hexane mixed solvent to give 5-chloro-1-methyl-1H-pyrazol-3-amine (0.29 g, 93% yield) as a yellow liquid. The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6) and mass spectrometry (MS): 1H NMR δ 5.49 (s, 1H), 4.74 (s, 2H), 3.51 (s, 3H); MS m/z: 131.94 (M + H).
