Transition Metal‐Catalyzed C–H Functionalization of Indole Benzenoid Ring

Abstract

Indole is an important heteroarene feature in many bioactive compounds, natural products, and functional materials. Hence, diversification of indoles by transition metal-catalyzed direct C-H activation has emerged as one of the most important topics in organic synthesis. Due to multiple C−H bonds with different reactive profiles in indoles, site selectivity is a long-standing challenge. The early developments focused primarily on C2-H and C3-H functionalization because of the inherent reactivity of the pyrrole ring. The recent focus on transition metal-catalyzed selective C−H functionalization on the benzenoid moiety at C4, C5, C6, and C7 positions provide direct access to diversely decorated indole compounds. This chapter describes contributions made in benzenoid ring C−H functionalization of indoles through transition metal catalysts.