Synthesis of 6-O-α- and β-D-xylopyranosyl-D-mannopyranose. (Glycosidation of α-and β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate))

Abstract

Crystalline β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) has been prepared by the reaction of sulfuryl chloride with D-xylose. Anomerization of β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) yielded crystalline α-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate). Both α- and β-D-xylopyranosyl chlorides gave high yields of their inversion products on methyl glycosidation (Königs–Knorr conditions) demonstrating the non-participating properties of the chlorosulfate group. Using modified Königs–Knorr conditions β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) was condensed with 1,2,3,4-tetra-O-acetyl-β-D-mannopyranose to give predominantly 6-O-α-D-xylopyranosyl-D-mannopyranose. A similar condensation using α-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) did not yield the analogous 6-O-β-D-xylopyranosyl-D-mannopyranose, therefore, for comparative purposes it was synthesized by the method of Bredereck and co-workers (1).