First chemical synthesis of triglucosylated tetradecasaccharide (GlC3Man9GlcNAc2), a common precursor of asparagine-linked oligosaccharides

Triglucosylated high-mannose-type tetradeca saccharide (Glc(3)Man(9)GlcNAc(2)), the oligosaccharide part of the donor substrate of oligosaccharyl transferase (OST) complex, and diglucosylated tridecasaccharide (Glc(2)Man(9)GlcNAc(2)) were synthesized. These oligosaccharides were assembled in a convergent and stereoselective manner. Undecasaccharide 5 was employed as the common intermediate, and coupling with trisaccharide (4) and disaccharide (3) donor afforded fully protected tetradeca-(17) and tridecasaccharide (16), respectively. These oligosaccharides were deprotected to give Glc(3)Man(9)GlcNAc(2) and Glc(2)Man(9)GlcNAc(2), respectively. (c) 2005 Elsevier Ltd. All rights reserved.