Transition-Metal-Catalyzed Directing-Group-Assisted C4-H Carbon–Carbon Bond Formation of Indole

Abstract

C4-Functionalized indole scaffold is ubiquitous in natural products, bio-active compounds and pharmaceuticals. Much efforts have thus been made to develop the effective synthetic strategies for the C4 functionalization of indole core. Among them, the chelation assisted synthetic approach using transition-metal-catalysis for the C4-selective C-H functionalization of indole is attractive. This account highlights the progress of the C4-carbon-carbon bond formation of indole using directing group assisted transition-metal-catalyzed C-H functionalization (till May 2022). These studies have been performed using Ru, Rh, Pd and Ir-based catalytic systems, while attention has been devoted on the use of first-row abundant catalytic systems.