Synthesis of 2-acetamido-2-deoxy-3- O-β- d-mannopyranosyl- d-glucose

Abstract

Condensation of 4,6-di- O-acetyl-2,3- O-carbonyl-α- d-mannopyranosyl bromide with benzyl 2-acetamido-4,6- O-benzylidene-2-deoxy-α- d-glucopyranoside (2) gave an α- d-linked disaccharide, further transformed by removal of the carbonyl and benzylidene groups and acetylation into the previously reported benzyl 2-acetamido-4,6- O-benzylidene-2-deoxy-3- O-(2,3,4,6-tetra- O-acetyl-α- d-mannopyranosyl)-α- d-glucopyranoside. Condensation of 3,4,6-tri- O-benzyl-1,2- O-(1-ethoxyethylidene)-α- d-glucopyranose or 2- O-acetyl-3,4,6-tri- O-benzyl-α- d-glucopyranosyl bromide with 2 gave benzyl 2-acetamido-3- O-(2- O-acetyl-3,4,6-tri- O-benzyl-β- d-glucopyranosyl)-4,6- O-benzylidene-2-deoxy-α- d-glucopyranoside. Removal of the acetyl group at O-2, followed by oxidation with acetic anhydride-dimethyl sulfoxide, gave the β- d- arabino-hexosid-2-ulose 14. Reduction with sodium borohydride, and removal of the protective groups, gave 2-acetamido-2-deoxy-3- O-β- d-mannopyranosyl- d-glucose, which was characterized as the heptaacetate. The anomeric configuration of the glycosidic linkage was ascertained by comparison with the α- d-linked analog.