Rh(III)-Catalyzed Denitrogenative [4+2] Annulation of Benzamides and 3-Diazoindolin-2-imines: Expedient Access to Indolo[2,3-c] isoquinolin-5-ones.

An effective and pragmatic strategy for the synthesis of structurally diverse indolo[2,3-c]isoquinolin-5-ones has been developed via a Rh(III)-catalyzed C-H activation and [4+2] annulation reaction of N-methoxybenzamides and 3-diazoindolin-2-imines. The reaction involves the efficient formation of two new (one C-C and one C-N) bonds under operationally simple conditions and has the benefits of a broad substrate scope.