Visible Light-promoted C(sp³)-H α-Carbamoylation of Cyclic Ethers with Isocyanides

A protocol exploiting isocyanides as carbamoylating agents for the α-C(sp³)-H functionalization of cyclic ethers has been optimized via a combined visible light-driven hydrogen atom transfer/Lewis acid-catalyzed approach. The isocyanide substrate scope revealed an exquisite functional group compatibility (18 examples, with yields up to 99 %). Both radical and polar trapping, kinetic isotopic effect and real-time NMR studies support the mechanistic hypothesis and provide insightful details for the design of new chemical processes involving the generation of oxocarbenium ions.