Synthesis of the pentasaccharide related to the repeating unit of the antigen from Shigella dysenteriae type 4 in the form of its methyl ester 2-(trimethylsilyl)ethyl glycoside

Abstract

Starting from d-mannose, d-glucose and l-fucose, the pentasaccharide derivative methyl 2,3,4-tri- O-benzyl-α- l-fucopyranosyl-(1→3)-2- O-acetyl-4,6- O-benzylidene-α- d-mannopyranosyl-(1→3)-2- O-acetyl-6- O-benzyl-4- O-(2,3,4-tri- O-benzyl-α- l-fucopyranosyl)-α- d-mannopyranosyl-(1→4)-[2-(trimethylsilyl)ethyl 2,3-di- O-benzyl-β- d-glucopyranosid]uronate was synthesized. This compound with two α-mannopyranosyl units was transformed, via Walden inversion and subsequent deprotection, into the α- d-glucosamine-type target compound, namely methyl α- l-fucopyranosyl-(1→3)-2-acetamido-2-deoxy-α- d-glucopyranosyl-(1→3)-2-acetamido-2-deoxy-4- O-(α- l-fucopyranosyl)-α- d-glucopyranosyl-(1→4)-[2-(trimethylsilyl)ethyl β- d-glucopyranosid]uronate which is related to the repeating unit of the O-antigen from Shigella dysenteriae type 4.