Cobalt(III)-Catalyzed Intramolecular Cross-Dehydrogenative C-H/X-H Coupling: Efficient Synthesis of Indoles and Benzofurans.

An efficient cobalt(III)-catalyzed intramolecular cross-dehydrogenative C-H/N-H coupling of ortho-alkenylanilines has been developed utilizing O2 as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross-dehydrogenative C-H/O-H coupling of ortho-alkenylphenols.