Catalytic Hydroetherification of Unactivated Alkenes Enabled by Proton-Coupled Electron Transfer

We report a light-driven, catalytic protocol for the intramolecular hydroetherification of unactivated alkenols to furnish cyclic ether products. These reactions occur under visible light irradiation in the presence of an Ir(III)-based photosensitizer, a Brønsted base catalyst, and a hydrogen atom transfer co-catalyst. Reactive alkoxy radicals are proposed as key intermediates that are generated by direct homolytic activation of alcohol O–H bonds through a proton-coupled electron transfer mechanism. This method exhibits a broad substrate scope and high functional group tolerance, and it accommodates a diverse range of alkene substitution patterns. Results demonstrating the extension of this catalytic system to carboetherification reactions are also presented.