In Situ Generated, Tetracoordinated Copper(II)-Quinoline Complexes as Photocatalysts for the Chlorosulfonylation of Alkenes and Alkynes

Abstract

A series of copper complexes was synthesized and studied as photocatalysts for the chlorosulfonylation of olefins. Featuring a tetradentate ligand consisting of one amino quinoline and two methyl pyridine moieties, the resulting Cu(II)-complex is effective under visible light irradiation to add sulfonyl chlorides to alkenes and alkynes, including unactivated aliphatic olefins. A weak base additive such as Na2CO3 prevents catalyst poisoning, resulting in an improvement of reaction yields and catalyst lifetime. A broad scope of sulfonyl chlorides and alkenes/alkynes as coupling partners are amenable for the title process, including examples previously reported unsuccessful with established copper-based photocatalysts.