Synthesis of the pentasaccharide core structure of asparagine-linked glycoprotein oligosaccharides by the glycal assembly method.

The "core" pentasaccharide region of high mannose asparagine-linked glycoproteins was synthesized using thioethyl donors and methyl triflate to promote coupling. All monosaccharide units were prepared from glycals. The central mannose residue was installed by inversion of the C2 hydroxyl of a glucosyl precursor. The protecting group scheme employed allows for the extension of the pentasaccharide through the terminal mannose units and a peptide can be coupled through transformation of the glycal.