Halogenated active methylene compounds are important synthetic intermediates owing to their high reactivity for the nucleophilic substitution. A number of methods have previously been described in the literature for the haloganation of active methylene compounds, however, most of them have serious disadvantage. We now report the novel chemoselective bromination of active methylene compounds using potassium bromide, hydrogen peroxide and hydrochloric acid. The monobrominated active methylene compounds were quantitatively obtained from the reaction of the active methylene compounds with potassium bromide and hydrogen peroxide in toluene and hydrochloric acid. Ester bonds, amide bonds and aromatic rings were not affected at all under the reaction conditions.
