Efficient Conversion of Olefins into Epoxides, Bromohydrins, and Dibromides with Sodium Bromide in Water-Organic Solvent Electrolysis Systems

Selective functionalizations of dimethyl 4-cyclohexene-l,2-dicarboxylate (1) and acyclic olefins 5 into the corresponding epoxides 2 and 6, bromohydrins 3 and 7, and 1,2-dibromides 4 and 8 were performed by electrolysis in a MeCN-H₂0-NaBr-(Pt) system. Lower Br^- concentration (less than 0.05 M) facilitates the formation of 2 in neutral medium and of 3 in acidic medium, whereas higher Br^- concentration (more than 1.5 M in acidic medium) produced exclusively 4. The effective C-C bond cleavage of the epoxy group of 2, leading to the corresponding diacetal 10, was also accomplished by electrolysis in a Me0H-H₂S0₄-(C) system.