N-bromobutanimide → 1-(4-Fluoro-3-cyanophenyl)-3-trifluoromethyl-5-bromomethylpyrazole

Participants

Reaction Steps

To a solution of 1-(4-fluoro-3-cyanophenyl)-3-trifluoromethyl-5-methylpyrazole (4.0 g, 14.9 mmol) in CCl4 (75 mL) was added NBS (5.3 g, 29.7 mmol) and benzylperoxide (0.2 g, 1.49 mmol). The reaction was brought to reflux overnight. The next day the CCl4 was evaporated and the residue was partitioned between ethyl acetate and sodium bicarbonate (sat.). The organic phase was washed with water, brine, dried over sodium sulfate, filtered and concentrated. Flash chromatography gave 1-(4-fluoro-3-cyanophenyl)-3-trifluoromethyl-5-bromomethylpyrazole (2.6 g, 50% yield) as pure compound: MS (CI): 348 (M+H)+ (100%).

Provenance & Evidence