Enantioselective Copper-Catalyzed Azide-Alkyne Click Cycloaddition to Desymmetrization of Maleimide-Based Bis(alkynes)

A copper catalyst system derived from TaoPhos and CuF2 was used successfully for catalytic asymmetric Huisgen [3+2] cycloaddition of azides and alkynes to give optically pure products containing succinimide- and triazole-substituted quaternary carbon stereogenic centers. The desired products were obtained in good yields (60-80%) and 85:15 to >99:1 enantiomeric ratio (e.r.) in this click cycloaddition reaction.