Pd/β-cyclodextrin-catalyzed C–H functionalization in water: a greener approach to regioselective arylation of (NH)-indoles with aryl bromides

Abstract

A greener and more practical strategy for the site-selective C–H arylation of (NH)-indoles via coupling of (hetero)aryl bromides was developed, in which β-cyclodextrin, acting as both a ligand for Na₂PdCl₄ and a host for indoles, enables the reactions to occur easily in water. The key advantage of this method is the ingenious merging of aqueous homogeneous catalysis and ligand mediation, leading to the highly regioselective formation of C3-arylindoles with a broad substrate scope and functional-group tolerance. Moreover, the regioselectivity can be switched from the C3 to the C2-position by varying the nature of the base without recourse to employing ArI as substrates.