Conformationally flexible, chiral quaternary ammonium bromides for asymmetric phase-transfer catalysis

Abstract

A simple yet powerful strategy for the molecular design of chiral phase-transfer catalysts: Conformationally flexible, N-spiro chiral quaternary ammonium bromides of type 1 have been newly designed and are found to exert high chiral efficiency by taking advantage of the considerable difference of activity between the diastereomeric homo- and heterochiral isomers through rapid conformational interconversion.