Solvent Effect and Anchimeric Assistance on α-Glycosylation

Abstract

The condensation reaction of 3-acetamido-2, 4, 6-tri-O-benzyl-3-deoxy-α-D-glucopyranosyl chloride, 6-acetamido-2, 3, 4-tri-O-benzyl-6-deoxy-D-glucopyranosyl chloride and 2, 3, 4, 6-tetra-O-benzyl-α-D-glucopyranosyl chloride were performed by a modified Königs-Knorr method. The rapid conversion of the benzyl halogeno derivative of 3-acetamido-3-deoxy-D-glucose to a stable intermediate caused a poor yield in the glucoside formation with complex aglycons at the presence of dioxane. For the benzyl halogeno derivative of 6-acetamido-6-deoxy-D-glucose, the C-6 acetamido group was favorable to the α-glucoside formation by its anchimeric assistance. A favorable effect of dioxane was observed for the α-glucoside formation of benzyl halogeno derivative of D-glucose.