Copper-promoted oxidative mono- and di-bromination of 8-aminoquinoline amides with HBr and DMSO

Abstract

An efficient and convenient method for oxidative mono- and di-bromination of 8-aminoquinoline amides is presented, utilizing hydrogen bromide (HBr) as the brominating reagent and dimethyl sulfoxide (DMSO) as a mild oxidant. Copper salts act as Lewis acid catalysts, facilitating the bromination process. The formation of C5-monobrominated products is promoted by copper sulfate (CuSO₄·5H₂O), whereas the generation of C5, C7-dibrominated products necessitates the participation of copper nitrate (Cu(NO₃)₂·3H₂O). A wide range of substrates bearing diverse functional groups undergo smooth transformation, resulting in brominated products with good to excellent yields.