Bromine → 3-Bromo-7-(trifluoromethyl)imidazo[1,2-a]pyrimidine

Participants

Reaction Steps

7-Trifluoromethylimidazo[1,2-α]pyrimidine (20. g, 10.7 mmol) and sodium acetate (1.1 mg, 13.4 mmol) were dissolved in methanol (30 ml) which had been saturated with potassium bromide and this mixture was cooled to −10° C. before dropwise addition of bromine (1.86 mg, 11.7 mmol) over 5 min. On complete addition the mixture was quenched by addition of 1M sodium sulfite solution (2 ml) and the solvent removed in vacuo. The residue was treated with water (100 ml) and saturated sodium hydrogencarbonate solution (100 ml) and extracted with ethyl acetate (3×100 ml). The organics were combined then washed with brine (100 ml), dried over anhydrous sodium sulfate and evaporated to give an off-white solid. This solid was purified by silica gel chromatography eluting with dichloromethane and 1% conc. ammonia on a gradient of methanol (1-2%) to give 3-bromo-7-trifluoromethylimidazo[1,2-α]pyrimidine (1.98 g) as a white solid: δH (400 MHz, CDCl3) 7.35 (1H, d, J 7), 8.02 (1H, s), 8.62 (1H, d, J 7).

Provenance & Evidence