TOTAL SYNTHESIS OF THE MOLLU-SERIES GLYCOSYL CERAMIDES α-D-Manp-(1->3)-β-D-Manp-(1->4)-β-D-Glcp-(1->1)-Cer AND α-D-Manp-(1->3)-2)>-β-D-Manp-(1->4)-β-D-Glcp-(1->1)-Cer

Article abstract of DOI:10.1016/0008-6215(90)84167-S

The mollu-series glycosphingolipids, O-α-D-mannopyranosyl-(1->3)-O-β-D-mannopyranosyl-(1->4)-O-β-D-glucopyranosyl-(1->1)-2-N-tetracosanoyl-(4E)-sphingenine and O-α-D-mannopyranosyl-(1->3)-O-<β-D-xylopyranosyl-(1->2)>-O-β-D-mannopyranosyl-(1->4)-O-β-D-glucopyranosyl-(1->1)-2-N-tetracosanoyl-(4E)-sphingenine, were synthesized for the first time by using 2,3,4-tri-O-acetyl-D-xylopyranosyl trichloroacetimidate, methyl 2,3,4,6-tetra-O-acetyl-1-thio-α-D-mannopyranoside, benzyl O-(4,6-di-O-benzyl-β-D-mannopyranosyl)-(1->4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside 9, and (2S,3R,4E)-2-azido-3-O-(tert-butyldiphenylsilyl)-4-octadecene-1,3-diol 6 as the key intermediates.The hexa-O-benzyl disaccharide 9 was prepared by coupling two monosaccharide synthons, namely, 2,3-di-O-allyl-4,6-di-O-benzyl-α-D-mannopyranosyl bromide and benzyl 2,3,6-tri-O-benzyl-β-D-glucopyranoside.It was demonstrated that azide 6 was highly efficient as a synthon for the ceramide part in the coupling with both glycotriaosyl and glycotetraosyl donors, particularly in the presence of trimethylsilyl triflate.