Electrochemical bromination of cyclic and acyclic enes using biphasic electrolysis

A simple method of electrochemical bromination of a series of cyclic and acyclic enes (styrene and substituted styrenes, stilbene, indene, and cyclooctene) in a biphasic water–chloroform mixture mediated by bromide/bromine redox system is reported. Aqueous 25% NaBr/H2SO4 is used as the electrolyte. Regio- and stereoselective dibromination of enes is achieved. Moderate to excellent yields of the product (83–98%) is obtained depending on the substrate. Electrolyte reuse has also been demonstrated successfully using HBr in the dibromination of styrene.