Synthetic Studies on Sialoglycoconjugates 37: Synthesis of Sialyl-α(2→6)-D-glucopyranosyl, 2-Acetamido-2-deoxyhexopyranosyl, and Sialyl-α(2→3)-2-acetamido-2-deoxy-D-glucopyranosyl Ceramide or the Analogs at the Lipophilic Part

Sialyl-α(2→3)- or sialyl-α(2→6)-β-D-glucopyranosyl- and 2-acetamido-2-deoxy-β-D-hexopyranosyl ceramides or the analogs at the lipophilic residue were synthesized. 2-(Trimethylsilyl)ethyl sialyl-α(2→6)-β-D-gluco-, 2-acetamido-2-deoxy-β-D-gluco-, 2-acetamido-2-deoxy-β-D-galacto- and sialyl-α(2→3)-2-acetamido-2-deoxy-β-D-gluco-pyranoside derivatives (1–4) were converted into the corresponding α-trichloroacet-imidate 8 or oxazolines 14,15 and 23 which, on coupling with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-l,3-diol (5) or 2-azidoethanol, gave the corresponding β-glycosides 9,16,19 and 24, respectively. Finally, the p-glycosides 9, 16, 19 and 24 were transformed, via selective reduction of the azide group, condensation with octa-decanoic acid or 2-tetradecylhexadecanoic acid (6), O-deacylation and hydrolysis of the methyl ester group, into the title compounds.