Synthesis of Fully Substituted Alkynyl <i>N</i> , <i>N</i> ′-Bicyclic Pyrazolidinones via a Cu(I)-Catalyzed Interrupted CuAIAC/Alkynylation Cascade Reaction

An efficient Cu(I)-catalyzed interrupted CuAIAC/alkynylation cascade reaction has been developed for the preparation of alkynyl N,N′-bicyclic pyrazolidinones utilizing various alkynes, azomethine imines, and bromoalkynes. This method exhibits excellent regioselectivity and good functional group tolerance. In addition, the complex molecule-derived alkyne and bromoalkyne substrates are compatible with the reaction system and make it a highly efficient synthetic strategy.