Convenient introduction of a bisecting GlcNAc residue into multiantennary N-glycans as the ultimate residue

A straightforward chemical synthesis was developed for multiantennary N-glycans of the complex-type containing a bisecting GlcNAc moiety. It was found that a bisecting GlcNAc can be introduced as the final residue despite considerable steric hindrance of the buried 4-hydroxyl group of the N-glycan acceptor. This approach circumvents the need for a temporary protecting group on the primary hydroxyl group of the central β-mannoside resulting in a shorter and more flexible synthesis. Thus the generation of N-glycans with an optional bisecting GlcNAc can be accomplished by a unified synthetic path using the same precursors and intermediates.