Conformational behavior of C-glycosyl analogues of sialyl-α-(2 → 3)- galactose

The conformational behavior of the C-glycosyl analogue of sialyl-α-(2 → 3)-galactose, synthesized as a glycosidase inhibitor, has been studied using a combination of NMR spectroscopy (J and NOE data) and molecular dynamics calculations. The obtained results show that the population distribution of conformers with respect to the orientation about the pseudo- glycosidic linkages is mainly controlled by steric interactions. This is in contrast to findings made for O-glycosides. In these natural compounds, the conformational behavior about the glycosidic linkage Φ is mainly governed by the exo-anomeric effect.