A New Copper-Catalyzed [3 + 2] Cycloaddition:  Enantioselective Coupling of Terminal Alkynes with Azomethine Imines To Generate Five-Membered Nitrogen Heterocycles

Abstract

A copper-catalyzed method for the regioselective 1,3-dipolar cycloaddition of azomethine imines to terminal alkynes has been developed. Through the use of a chiral phosphaferrocene-oxazoline ligand, a wide range of substrates can be coupled to generate useful heterocycles in very good enantiomeric excess.