Acetic Anhydride → N-(1,3-dimethylpyrazol-4-yl)acetamide

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Reaction Steps

Acetic anhydride (27.2 mL, 243.89 mmol) was dropwise added to a stirred suspension of 1,3-dimethyl-pyrazol-4-amine hydrochloride (12 g, 81.30 mmol) and potassium acetate (7.98 g, 81.30 mmol) in EtOAc (250 mL) at 25° C. The suspension was stirred for 1 hour and the insoluble was removed by filtration. After evaporation of the solvent, the resulting crude material was purified by chromatography on silica gel eluting with 0% to 10% of MeOH in DCM. After evaporation of the solvent, the residue was triturated in Et2O. The resulting precipitate was collected by filtration, washed with Et2O and dried to a constant weight to afford N-(1,3-dimethylpyrazol-4-yl)acetamide. The filtrate was concentrated and purified by flash chromatography on silica gel eluting with 0 to 10% MeOH in DCM. The solvent was evaporated to dryness to afford more N-(1,3-dimethylpyrazol-4-yl)acetamide. The two batches were combined to give N-(1,3-dimethylpyrazol-4-yl)acetamide (6.40 g, 51.4%) as a off-white solid.

Provenance & Evidence