The Juliá-Colonna Asymmetric Epoxidation Reaction of Chalcone Catalyzed by Length Defined Oligo-L-leucine: Importance of the N-Terminal Functional Group and Helical Structure of the Catalyst in the Asymmetric Induction

Abstract

Abstract Catalysts, oligo-L-leucine, for the Juliá-Colonna asymmetric epoxidation of chalcone with defined degrees of polymerization were prepared by a stepwise elongation method. The yield and enantioselectivity in the epoxidation increased with the degree of polymerization of the catalyst. The presence of an unprotected amine moiety at the N-terminus proved to be essential for high asymmetric induction. The IR characteristic absorption bands (the amide I region) of the catalysts suggested that helical structure in the catalyst is related to asymmetric induction.