A total synthesis of hematoside, α-NeuGc-(2→3)-β-Gal-(1→4)-β-Glc-(1→1)-Cer

✍ Scribed by Masaaki Numata; Mamoru Sugimoto; Shohei Shibayama; Tomoya Ogawa

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 953 KB
• Volume: 174
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(88)85082-1

✦ Synopsis

Methyl (5-acetoxyacetamido-4,7,8,9-tetra-O-acetyl-3,5- dideoxy-D-glycero-beta-D-galacto-2-nonulopyranosyl chloride)onate, prepared from N-glycolyl-neuraminic acid, was used for the glycosylation of benzyl O-(2,6-di-O-benzyl-beta-D- galactopyranosyl)-(1----4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside to give benzyl O-[methyl (5-acetoxyacetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero- alpha- and beta-D-galacto-2-nonulopyranosyl)onate]-(2----3)-O-(2,6-di-O -benzyl-beta- D-galacto-pyranosyl)-(1----4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, and a regioisomer. Compounds 9 and 13 were converted into the corresponding glycotriaosyl glycosyl donors which, upon coupling with (2S,3R,4E)-3-O-tert-butyldiphenylsilyl-2-N- tetracosanoylsphingenine, afforded completely protected hematoside and a stereoisomer 26, respectively. Deprotection of 22 and 26 completed the first total synthesis of both hematoside and a stereoisomer, beta-NeuGc-(2----3)-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer.