Stereochemical study of the CD spectral differences between anomers of alkyl glucopyranosides

Abstract

Slightly different chair conformation geometries were demonstrated to be the origin of the CD spectral differences observed in anomers of alkyl glucopyranosides. The study, using methyl glucopyranoside derivatives as model compounds, showed excellent agreement between CD data, 1H NMR data, and semiempirical calculations, and the geometries found explained satisfactorily the higher amplitudes observed for the β-anomers of tetrachromophorically substituted alkyl glucopyranosides. The pairwise interactions involving the chromophore at C2, the 2/3, 2/4 and 2/6, were the most dependent on the anomeric configuration, the 2/4 interaction even showing opposite CD signs for the anomers. In addition, the 2/3 pairwise interaction was revealed to be independent of the structural nature of the aglycon.