Synthesis of a Core Trisaccharide as a Versatile Building Block for N-Glycans and Glycoconjugates

摘要

N-Linked oligosaccharides from glycoproteins (N-glycans) can be conveniently assembled with a building block approach. A protected form of the core trisaccharide (beta-mannosyl chito-biose) was identified as a key building block. The chitobiose part of the core trisaccharide was built from a glycosyl fluoride, which served as a precursor for the reducing GlcNAc azide and the inner GlcNAc moiety. beta-Mannosylation was accomplished at the trisaccharide stage by intramolecular inversion of a beta-glucosyl chitobiose. The benzylidene protection of the beta-mannoside and the azido group at the reducing end of the core trisaccharide allow modular synthesis of N-glycans and their glycocon-jugates.