Copper-Catalyzed Tandem Imine Formation, Sonogashira Coupling and Intramolecular Hydroamination: A Facile Synthesis of 3-Aryl-gamma-carbolines

A one-pot, atom-economical multicomponent reaction of 2-bromoindole-3-carbaldehydes, alkynes and ammonia was developed in the presence of copper catalyst for the synthesis of a series of 3-aryl-gamma-carboline derivatives in good to high yields. The developed reaction involved formation of imine followed by copper-catalyzed directed Sonogashira coupling and intramolecular hydroamination sequence of reactions. This multicomponent approach features mild reaction conditions and good functional group tolerance to access variety of 3-aryl-carbolines.