Copper-Catalyzed Cascade Cyclization Reaction of Enamines and Electron-Deficient Terminal Alkynes: Synthesis of Polysubstituted Pyrido[1,2-a]indoles.

A novel copper-catalyzed cascade cyclization reaction between enamines and electron-deficient terminal alkynes has been developed. The reaction provides a new and efficient strategy for the construction of polysubstituted pyrido[1,2-a]indoles by the formation of two rings, three C-C bonds, and one C-N bond in a single step from readily available acyclic starting materials.