Palladium Catalyzed Regioselective C4-Arylation and Olefination of Indoles and Azaindoles

A convergent strategy for the synthesis of biologically relevant C4-substituted indole scaffolds was demonstrated using Pd(II)-catalyzed remote C-H functionalization of indoles and azaindoles. The reaction displays high regioselectivity for the C4-position of indole-3-carbaldehydes using glycine as an inexpensive transient directing group. Notable features of this transformation include the selective formation of six-membered palladacyle and excellent functional group tolerance.