反应详情

To a solution of ethyl 4-chloro-5-methyl-1H-pyrazole-3-carboxylate (Intermediate 1A, 2.01 g, 10.7 mmol) in MeOH (8.2 mL) and THF (8.2 mL) was added 2N aq. NaOH solution (27 mL, 53.3 mmol). The reaction mixture was stirred at room temperature overnight, then cooled to 0° C. and neutralized with 1N aq. HCl solution (pH=3-4). The resulting solid was collected by filtration and washed with water to give the title compound (1.50 g, 87%) as a white solid. 1H NMR (DMSO-d6) δ 2.19 (br s, 3H); MS (ESI+) m/z 160.9 (M+H)+.

1. filtrationThe resulting solid was collected by filtration
2. washwashed with water