Rhodium-Catalyzed Reaction of Sulfoxonium Ylides and Anthranils toward Indoloindolones via a (4 + 1) Annulation

Abstract

A rhodium-catalyzed annulation between aroyl sulfoxonium ylides and anthranils has been developed to synthesize 10H-indolo[1,2-a]indol-10-one derivatives. This reaction started with an unpredented (4 + 1) annulation toward N-(2-formylphenyl) indolones, proceeding with the sequential ortho-amination of the C–H bond in aroyl sulfoxonium ylides by anthranils and the insertion of N–H to carbene. Finally, the Aldol condensation constructed the second indole ring. This procedure features the formation of two C–N bonds and one C═C bond in one pot.