Intramolecular Palladium(II)-Catalyzed 6-endo C-H Alkenylation Directed by the Remote N-Protecting Group: Mechanistic Insight and Application to the Synthesis of Dihydroquinolines.

A protocol for the Pd(II)-catalyzed C-H alkenylation reaction of substituted N-allylanilines via an unusual 6-endo process has been developed. A density functional theory (DFT) study of the mechanistic pathway has shown that the coordination of the remote protecting group to the palladium center is determinant for the control of the regioselectivity in favor of the 6-endo process. The reaction would proceed via prior activation of the alkene. This procedure constitutes a mild and efficient method for the synthesis of 1,4-dihydroquinoline derivatives from simple and readily accessible substrates.