15366-34-4

67-56-1

1621-91-6

15366-34-4

To a stirred solution of 1H-pyrazole-3-carboxylic acid (2 g, 17.8 mmol, 1 eq.) in methanol (20 mL) was slowly added thionyl chloride (2.5 mL, 35.5 mmol, 2 eq.). The reaction mixture was stirred at 40 °C for 5 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure to remove the solvent. The resulting residue was dissolved in dichloromethane (DCM) and washed with saturated aqueous sodium bicarbonate (NaHCO3). The organic layer was separated, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (petroleum ether/ethyl acetate=1/3, v/v) to afford methyl 1H-pyrazole-3-carboxylate (1.8 g, yield 79.6%) as a white solid.