Synthesis of 3-O-sulfoglucuronyl lacto-N-neotetraose 2-aminoethyl glycoside and biotinylated neoglycoconjugates thereof Original Research Article

The 2-aminoethyl glycoside of pentasaccharide 3-O-sulfo-GlcA(β-1→3)Gal(β-1→4)GlcNAc(β-1→3)Gal(β-1→4)Glc(β (1) and its conjugates with biotin and biotinylated polyacrylic acid were synthesized as molecular probes to investigate the recognition of the HNK-1 epitope containing carbohydrates by proteins. Key steps in the first of two investigated schemes for the preparation of the target compound 1 were (a) assembling of the pentasaccharide backbone (compound 10) by glycosylation of selectively substituted allyl glycoside of the trisaccharide GlcNAc(β-1→3)Gal(β-1→4)Glc(β with glucuronyl-galactose glycosyl donor, (b) transformation of the allyl aglycon in 10 into 2-azidoethyl one (to give 11), (c) selective deprotection of the OH group at C-3 of the GlcA residue in 11 via saponification, intramolecular formation of 6,3-lacton (13) and its methanolysis, and (d) subsequent O-sulfation. The alternative scheme with the use of 2-azido-ethyl glycoside of the trisaccharide GlcNAc(β-1→3)Gal(β-1→4)Glc(β instead of the allyl glycoside 6 was less effective due to smaller yield at the step of pentasaccharide synthesis. Additionally to 1 the 2-aminoethyl glycosides of the oligosaccharides GlcA(β-1→3)Gal(β-1→4)GlcNAc(β-1→3)Gal(β-1→4)Glc(β, 3-O-sulfo-GlcA(β-1→3)Gal(β, and GlcA(β-1→3)Gal(β were also synthesized.