The Juliá-Colonna Type Asymmetric Epoxidation Reaction Catalyzed by Soluble Oligo-l-leucines Containing an α-Aminoisobutyric Acid Residue: Importance of Helical Structure of the Catalyst on Asymmetric Induction

Abstract

Abstract Length-defined organic solvent soluble oligo-l-leucines containing an Aib residue were prepared by stepwise elongation and fragment condensation methods, and were used as catalysts in the Juliá–Colonna asymmetric epoxidation reaction. The yield and enantioselectivity rose by increasing the number of amino acid units in the catalyst. The enantioselectivity was very sensitive to the reaction solvent. The IR characteristic bands (the amide I region) in CH2Cl2 indicated the soluble catalysts to be of helical structure in solution.