Benzoyl Peroxide → 1-(4-Fluoro-3-cyanophenyl)-3-trifluoromethyl-5-bromomethylpyrazole

Participants

Reaction Steps

To a solution of 1-(3-cyano-4-fluorophenyl)-3-trifluoromethyl-5-methyl pyrazole(4.0 g, 14.87 mmol) in carbon tetrachloride(50 mL) was added NBS(2.65 g, 14.87 mmol) and benzoyl peroxide(0.36 g, 1.48 mmol). The reaction mixture was brought to reflux overnight. Solvent was removed on rotary evaporator under reduced pressure. Residue was partitioned between ethyl acetate(80 mL) and sodium bicarbonate(sat. 80 mL). Organic phase was separated and washed with water(60 mL); dried over sodium sulfate; filtered, concentrated and subjected to silica-gel flash chromatography (ethyl acetate : hexane, 1:10) to afford 1-(3-cyano-4-fluorophenyl)-3-trifluoromethyl-5-bromomethyl pyrazole(2.5 g). CI mass spectrum m/z (rel. intensity) 348 (M+H, 100).

Provenance & Evidence