Pd(II)-Catalyzed C-H Activation of Styrylindoles: Short, Efficient, and Regioselective Synthesis of Functionalized Carbazoles.

A novel Pd(II)-catalyzed approach for the direct synthesis of highly functionalized carbazoles from unprotected styrylindoles has been developed. The reaction features a variety of olefin substrates, which are readily switchable by subtle tuning of the reaction conditions. Investigations of the mechanism suggest that the C-H activation proceeds via enamine formation.