Rhodium(III)-Catalyzed C-H Activation/Cylization of Indole-2-amides Derivatives and Terminal Alkynes

A simple and efficient Rh-catalyzed the C-H activation/cyclization reaction of indole-2-amides and alkynes was developed. A series of novel pyrido[3,4-b]indol-1-ones can be efficiently obtained with high to excellent yields using the internal oxidant at room temperature. The transformations have a wide range of substrates with various functional groups. Intermolecular competition experiment was conducted, and a plausible mechanism was proposed. The structures of all conpound were confirmed by H-1 NMR, C-13 NMR and HRMS.