Oxidative homodimerization of substituted olefins by DDQ visible light photocatalysis

Abstract

A visible-light-mediated dehydrogenative homocoupling reaction of readily available mono- and disubstituted olefins to afford symmetrical di- and tetrasubstituted buta-1,3-dienes in the presence of catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been developed. The reaction proceeds for a wide range of substrates giving buta-1,3-dienes in moderate to good yields. We propose a reaction mechanism involving direct oxidative radical coupling followed by proton and hydrogen atom elimination.