Phosphorus tribromide → 5-Bromo-4-(bromomethyl)-1-(1,1-dimethylethyl)-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A solution of (5-bromo-1-tert-butyl-1H-pyrazol-4-yl)methanol (460 mg, 1.97 mmol) in dichloromethane (25 mL) was cooled to 0° C. and then treated with phosphorus(III)bromide (0.37 mL, 3.46 mmol), dropwise, over 5 minutes. The mixture was stirred 30 minutes at 0° C. and then 1 hour at room temp. The mixture was quenched slowly with water (50 mL), stirred 30 minutes, and then extracted with ethyl acetate (2×50 mL). The organic phase was washed with saturated aqueous sodium bicarbonate (50 mL), dried over sodium sulfate, filtered and concentrated to yield 362 mg of 5-bromo-4-(bromomethyl)-1-tert-butyl-1H-pyrazole as a clear oil. 1H NMR (400 MHz, CDCl3, δ): 7.54 (s, 1H), 4.39 (s, 2H), 1.74 (s, 9H).

Provenance & Evidence