Site-Selective Addition of Maleimide to Indole at the C-2 Position: Ru(II)-Catalyzed C-H Activation.

Synthesis of 3-(indol-2-yl)succinimide derivatives is presented using a directing group strategy. Selective functionalization of C-2 in the presence of highly reactive C-3 in indole derivatives has been achieved. A conjugate addition product instead of Heck-type product has been brought about by careful selection of the alkene partner (maleimides and maleate esters) such that a β-hydride elimination is avoided.