<i>exo</i>- and Enantioselective Cycloaddition of Azomethine Ylides Generated from <i>N</i>-Alkylidene Glycine Esters Using Chiral Phosphine−Copper Complexes

Abstract

High diastereo- and enantioselectivities were obtained for the asymmetric 1,3-dipolar cycloaddition of azomethine ylides generated from N-alkylideneglycine esters with dipolarophiles using chiral phosphine−copper complexes as catalysts. Whereas the cycloaddition of azomethine ylides catalyzed by metal salts generally afforded endo-adducts as the predominant product, the present method is the first example of an exo-selective cycloaddition.