THE CONFIGURATION OF GLYCOSIDIC LINKAGES IN OLIGOSACCHARIDES: II. BY DEGRADATION OF REDUCING DISACCHARIDES TO 2-O-GLYCOSYL-GLYCEROLS

Reducing aldohexopyranose disaccharides are degraded by employing a series of oxidations and reductions to yield 2-O-glycosyl-glycerols, configurations of which are assigned according to Hudson's definition. Maltose, for example, treated with 2 moles of lead tetraacetate gives 2-O-α-D-glucopyranosyl-D-erythrose; the latter is reduced to the corresponding alcohol, which is oxidized in turn with 1 mole of lead tetraacetate to give 2-O-α-D-glucopyranosyl-L-glyceraldehyde, and a second reduction yields 2-O-α-D-glucopyranosyl-glycerol. Cellobiose is converted to 2-O-β-D-glucopyranosyl-glycerol by the same sequence of reactions. Other reducing disaccharides containing D-glucopyranose non-reducing end-units may also be degraded to give one or other of these anomeric glycerol-derivatives, the identity of which establishes the configuration of the glycosidic linkage in the original disaccharide. The pair of anomeric 2-O-D-galactopyranosyl-glycerols is afforded by the naturally-occurring α-anomer, and the product o...