A new copper-catalyzed [3 + 2] cycloaddition: enantioselective coupling of terminal alkynes with azomethine imines to generate five-membered nitrogen heterocycles.

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.