Synthesis of γ-Carbolines through Annulative Cyclization between Indolyl Azines and Alkynes under Rhodium Catalysis

Functionalized carbolines play a crucial role in the discovery of bioactive compounds and functional materials. In this study, we report a Rh(III)-catalyzed annulative synthesis of γ-carbolines from indolyl azines and internal alkynes. Remarkably, indolyl azines can undergo N–N bond cleavage under the influence of a Rh(III) catalyst, yielding 2-fold ketimines, which demonstrates the atom economy of indolyl azines in catalytic C–H functionalizations. A series of post-transformations for the synthesized products are also described.