Recent advances for construction and late-stage diversification of indole core via C–H bond activation/functionalization

Abstract Indole is an important structural motif of various drugs, therapeutic leads besides its prevalence in numerous natural products, agrochemicals, perfumery, and dyes. More than 200 indole derivatives have already been marketed as drugs or are under advanced stages of clinical trials. Owing to such a huge potential, continuous efforts are being put forward to construct or diversify this scaffold. This chapter provides an overview of various recently developed methodologies for the construction of indole core via C–H bond activation/functionalization. In particular, Pd- and Ru-mediated cyclization strategies involving Csp2-H functionalization of monofunctionalized arene substrates with the unsaturated bond of alkene and alkyne are highlighted herein. Also, late-stage diversification of indole system (C4–C7 position) via direct C–H activation is covered. Furthermore, the mechanistic aspects of some of these reactions are discussed as well.