Visible light-induced C(sp 3 )-H azolation of ethers via radical-polar crossover.

Reported herein is a photochemical strategy for C(sp 3 )-H azolation of ethers via a hydrogen-atom transfer and radical-polar crossover process, offering efficient access to valuable N -alkylated azoles under visible-light irradiation. The protocol is metal-free and photocatalyst-free, and exhibits good to excellent yields and broad substrate scope with regard to azoles. EPR experiments provide evidence for the formation of intermediates formed in situ .