Electrophotocatalytic C-H Functionalization of Ethers with High Regioselectivity

The highly regioselective electrophotocatalytic C-H functionalization of ethers is described. These reactions are catalyzed by a trisaminocyclopropenium (TAC) ion at mild electrochemical potential with visible light irradiation. Ethers undergo oxidant-free coupling with isoquinolines, alkenes, alkynes, pyrazoles, and purines with typically high regioselectivity for the less-hindered alpha-position. The reaction is proposed to operate via hydrogen atom transfer (HAT) from the substrate to the photoexcited TAC radical dication, thus demonstrating a new reactivity mode for this electrophotocatalyst.