Electrochemical oxidation-induced etherification via C(sp)─H/O─H cross-coupling.

Direct electrochemical construction of C─O bonds through C(sp)─H functionalization still remains fundamentally challenging. Here, electrochemical oxidation-induced benzylic and allylic C(sp)─H etherification has been developed. This protocol not only offers a practical strategy for the construction of C─O bonds using nonsolvent amounts of alcohols but also allows direct electrochemical benzylic and allylic C(sp)─H functionalization in the absence of transition metal catalysis. A series of alcohols and benzylic and allylic C(sp)─H compounds were compatible with this transformation. Mechanistically, the generation of aryl radical cation intermediates is the key to this C(sp)─H etherification, as evidenced by radical probe substrate (cyclopropane ring opening) and electron paramagnetic resonance experiments.