Solid-state Vibrational Circular Dichroism as Applied for Heterogenous Asymmetric Catalysis: Copper(II) Complexes Immobilized in Montmorillonite

Abstract

Solid-state vibrational circular dichroism (SD-VCD) spectra were measured on the ion-exchange adducts of sodium montmorillonite and [Cu(RR- or SS-oxa)]2+ as prepared in the presence of a substrate in Michael additions, (E)-2-butenoyl-2-oxazolidinone. Here RR- or SS-oxa denotes RR- or SS-2,2′-isopropylidene-bis(4-phenyl-2-oxazoline), respectively. By comparing the observed and theoretical VCD spectra, it was deduced that the substrate was transformed to a chiral structure in association with the Cu(II) complex within a clay mineral.