Diagnostic structural criteria for the anomeric effect in carbohydrates and inferences of general significance on their scope and limitations

Abstract

A systematic analysis of 529 carbohydrate structures that contain OCO units, retrieved from the Cambridge Structural Database, was performed with regard to the bond lengths (CO) and bond (COC and OCO) angles as they depend on the dihedral angles in the sequence COCOC. This dependence was then interpreted in terms of the anomeric effect. Known and new concepts that concern the manifestations of the anomeric and exo-anomeric effects were thus reassessed. A set of structural criteria of diagnostic value was defined which, together with qualifying arguments, allow evaluation of the scope and limitations of these stereoelectronic effects in carbohydrate systems.