Conformational behaviour of glycomimetics: NMR and molecular modelling studies of the C-glycoside analogue of the disaccharide methyl beta-D-galactopyranosyl-(1-->3)-beta-D-glucopyranoside.

The conformational behaviour of the C-glycoside beta-C-Gal-(1-->3)-beta-Glc-OMe (1) has been studied using a combination of molecular mechanics and NMR spectroscopy (proton-proton coupling constants and nuclear Overhauser effects). It is shown that the C-disaccharide populates two distinctive conformational families in solution, the normal syn-psi conformation, which is the predominating conformation of parent O-glycoside 2, and the anti-psi conformation, which has not been detected for the O-disaccharide.