4-Bromobenzyl bromide → Ammonium Hydroxide

A solution of 11.2 g of 1-dimethylcarbamoyl-4-(3-trimethylsilyloxypropyl)-1H-imidazole and 12.49 g of p-bromobenzyl bromide in 110 ml of acetonitrile is refluxed for 24 h. The solution is cooled to 0° and ammonia gas is bubbled through the reaction mixture for 5 min. After reacting an additional 45 min at room temperature, the solvent is evaporated. The residue is taken up in 100 ml of 1N hydrochloric acid and extracted with 50 ml of ether. The aqueous phase is adjusted to pH 8 and extracted with ethyl acetate (5×50 ml). The organic extracts are washed with water, dried over sodium sulfate and evaporated. The resulting oil is chromatographed on 530 g of silica gel with ethyl acetate:methanol:saturated NH4OH (90:5:5) to yield the title compound a) as an oil; NMR: δ5.00 (s, 2H).