Acetyl chloride → 3-Acetylaminopyrazole

Participants

Reaction Steps

To a solution of 1H-pyrazol-5-amine (50 g, 0.602 mol) and N-methylmorpholine (160 mL, 1.44 mol) in CH2Cl2 (2 L) was added acetyl chloride (99 mL, 1.38 mol) dropwise at 0° C. under an atmosphere of nitrogen. The reaction mixture was stirred at room temperature for 1 d. Some di-acylated product was observed in an LCMS. The reaction mixture was concentrated in vacuo and the resulting solid was suspended in MeOH (2 L) and cooled to 0° C. 4 M NaOH solution (aq., 440 mL, 1.75 mol) was added slowly and the mixture allowed to warm to room temperature over 1.5 h. The MeOH was removed in vacuo and the solid was collected by filtration, washed with minimal cold water and dried in vacuo to provide the title compound as a solid (60 g).

Provenance & Evidence