Photo-induced oxidant-free oxidative C–H/N–H cross-coupling between arenes and azoles

Direct cross-coupling between simple arenes and heterocyclic amines under mild conditions is undoubtedly important for C–N bonds construction. Selective C(sp 2 )-H amination is more valuable. Herein we show a selective C(sp 2 )-H amination of arenes (alkyl-substituted benzenes, biphenyl and anisole derivatives) accompanied by hydrogen evolution by using heterocyclic azoles as nitrogen sources. The reaction is selective for C(sp 2 )-H bonds, providing a mild route to N -arylazoles. The KIE (kinetic isotope effect) experiment reveals the cleavage of C–H bond is not involved in the rate-determining step. Kinetic studies indicate the first-order behaviour with respect to the arene component. It is interesting that this system works without the need for any sacrificial oxidant and is highly selective for C(sp 2 )-H activation, whereas C(sp 3 )-H bonds are unaffected. This study may have significant implications for the functionalization of methylarenes which are sensitive to oxidative conditions. Functionalization of unactivated C–H bonds is an attractive strategy to introduce functionality without the need for pre-functionalized starting materials. Here the authors combine cobalt catalysis with photoredox catalysis, allowing arene-azole cross-coupling under oxidant-free conditions.