A total synthesis of hematoside, alpha-NeuGc-(2----3)-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer.
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.
Numata
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M
RIKEN (The Institute of Physical and Chemical Research), Saitama, Japan.
Sugimoto
M
M
Shibayama
S
S
Ogawa
T
T
D002236:Carbohydrate Conformation; D005679:G(M3) Ganglioside / Q000138:chemical synthesis*; D005732:Gangliosides / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D009904:Optical Rotation; D013237:Stereoisomerism
D005679:G(M3) Ganglioside; D005732:Gangliosides; D007202:Indicators and Reagents