Benzylic C(sp)-C(sp) cross-coupling of indoles enabled by oxidative radical generation and nickel catalysis

A mechanistically unique functionalization strategy for a benzylic C(sp 3 )-H bond has been developed based on the facile oxidation event of indole substrates. This novel pathway was initiated by efficient radical generation at the benzylic position of the substrate, with subsequent transition metal catalysis to complete the overall transformation. Ultimately, an aryl or an acyl group could be effectively delivered from an aryl (pseudo)halide or an acid anhydride coupling partner, respectively. The developed method utilizes mild conditions and exhibits a wide substrate scope for both substituted indoles and C(sp 2 )-based reaction counterparts. Mechanistic studies have shown that competitive hydrogen atom transfer (HAT) processes, which are frequently encountered in conventional methods, are not involved in the product formation process of the developed strategy. A mechanistically distinct Ni-catalysed benzylic functionalization of indoles is developed by the facile oxidation of arenes. The method exhibits a wide substrate scope and pronounced chemoselectivity that cannot be accessed via known protocols.