THE CONFIGURATION OF GLYCOSIDIC LINKAGES IN OLIGOSACCHARIDES: I. APPLICATION OF JACKSON AND HUDSON'S OXIDATION METHOD TO REDUCING DISACCHARIDES

Abstract

Use of glycol-cleavage oxidations to assist in establishing the configuration of biose linkages is considered. The approach is based on degradation of disaccharides to yield compounds of simpler structure, all disaccharides of a given class yielding the same product. Thus, 1,6-D-aldohexopyranose disaccharides on oxidation yield one of two possible trialdehydes, the reducing end-unit being converted to glycolic aldehyde and the non-reducing end-unit to a dialdehyde of a type produced from simpler glycosides. These two compounds differ only in the configuration of the carbon atom which originally constituted the glycosidic center, α-linked disaccharides giving rise to one compound, and β-linked to the other. The relative contribution of the glycosidic center to the optical activity of these oxidation products is thereby enhanced and, accordingly, is expected to promote a large rotational difference between α- and β-compounds. Correlation of a 1,6-disaccharide of unknown configuration with known ones by comparison of specific rotational values should then be possible. Disaccharides having other linkage positions, e.g., 1,2- or 1,4-, are likewise degraded to compounds having fewer asymmetric carbon atoms, which are common to all disaccharides of the same class. The results obtained with disaccharides of established structure are in accordance with the theoretical considerations presented. Experimentally, the procedures are simple and require only small quantities of material.