A short synthesis of the trisaccharide building block of the N-linked glycans

An efficient preparation of the core trisaccharide of N-linked glycoproteins containing β-azido functionality at the reducing terminus is described. In the synthesis, triflate-mediated direct β-mannosylation was employed for the formation of the β-d-Man-(1→4)-GlcNAc linkage; the anomeric azide installation was achieved through oxazoline ring opening.