The synthesis of linear trilactosamine

TrilactosamineGalβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ-sp, where sp = O(CH₂)₃NH₂ is a spacer, was synthesized. The tetrasaccharide fragment Galβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ-sp was obtained by successive glycosylation using elongation by one monosaccharide residue at a time; and the tetrasaccharide was then transformed into a hexasaccharide with a disaccharide glycosyl donor. A 2,2,2-trichloroethoxycarbonyl group was used for the protection of the glucosamine amino group.