Convenient Synthesis of an N-Glycan Octasaccharide of theBisecting Type

摘要

Convenient synthesis of an N-glycan octasaccharide (A) of the bisecting type was described. The stableand easily prepared orthoester F, 3"-O-chloroacetyl-4",6"-O-benzylidene-α-D-glucopyranose 1",2"-(chloromethyl 3',6'-di-O-benzyl-2'-deoxy-2'-phthalimido-β-D-glucopyranosyl-( 1 →4)-3 ,6-di- O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranosylazide-4'-yl orthoacetate), was designed as the key intermediatewith two advantages: (1) distinguishing OH-2" from OH-3" in β-D-glucopyranoside to construct thecentral β-D-mannopyranoside by inverting the configuration of OH-2" in β-D-glucopyranoside and (2)distinguishing OH-4" and OH-6" from OH-3" in the β-D-mannopyranoside to introduce the bisectingGlcNAc residue.