Selective electrochemical dibromination of terpenes and naturally derived olefins

Abstract

A simple electrochemical protocol is established for the selective alkene dibromination of naturally derived olefins, such as terpenes. The use of hazardous Br2 or its analogues have been elegantly avoided by employing readily available, inexpensive, and harmless sodium bromide with a dual role as reagent and supporting electrolyte in combination with sustainable carbon-based electrodes. This electrochemical protocol provides the desired products with good to excellent yields up to 82 % with 10 examples. Scalability has been proved by a 5-fold scale-up. Notably, higher yields and selectivity were achieved in comparison to conventional bromination by Br2 and DMSO/HBr system and the dibrominated compound was eligible for further functionalization, such as cyanation according to the Kolbe nitrile synthesis protocol.