Reversing Conventional Site-Selectivity: Electrochemically Driven C(sp2)-H/C(sp3)-H Coupling with H2 Evolution

Sustainable and site-selective C-H functionalization is still a challenge because of the comparable prop-erties of bonds of the same type. Here, an electro-chemical C(sp2)-H/C(sp3)-H coupling with aryl iodides is reported for the first time. The C(sp2)-H bond outperformed the much weaker C(sp2)-I bond participating in C(sp2)-H/C(sp3)-H coupling. This protocol features mild reaction conditions, good functional group tolerance, and scalability. Cross-coupling products with C-I bonds are versatile moi-eties for further synthetic manipulation, that can undergo Suzuki, Sonogashira, Ullmann-Ma, Catellani, Heck reactions, and so on to introduce new function-al groups into target molecules with good yields. Mechanistic investigations showed that the site selectivity of the reaction is enabled by an iodine-assisted [3,3]-sigmatropic rearrangement, and the interaction of hypervalent iodine generated in situ with an enolate is the rate-determining step.