A facile, regio- and stereo-selective synthesis of ganglioside GM3.
Gangliosides GM3, containing three different fatty acyl groups at the ceramide moiety, have been synthesized. Coupling of 2-(trimethylsilyl)ethyl O-(6-O-benzoyl-beta-D-galactopyranosyl)-(1----4)- 2,6-di-O-benzoyl-beta-D-glucopyranoside (4), prepared from 2-(trimethylsilyl)ethyl beta-lactoside (1) by selective 3'-O-benzylation, O-benzoylation, and subsequent removal of the benzyl group, with methyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-alpha-D- galacto - 2-nonulopyranosid)onate (5) using dimethyl(methylthio)sulfonium triflate as a glycosyl promoter, gave 2-(trimethylsilyl)ethyl O-(methyl 5-acetamido-4,7,8,9-tetra-O- acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosylonate++ +)-(2----3)- O-(6-O- benzoyl-beta-D-galactopyranosyl)-(1----4)-2,6-di-O-benzoyl-beta-D- glucopyranoside (6), which was converted, via O-acetylation, selective removal of the 2-(trimethylsilyl)-ethyl group, and subsequent imidate formation, into the alpha-N-acetylneuraminyl-(2----3')-lactose trichloroacetimidate 9. Glycosylation of (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (10) with 9 afforded the beta-glycoside 11, which was converted, via selective reduction of the azide group, coupling with fatty acids, O-deacetylation, and de-esterification, into the title compounds.
Department of Applied Bioorganic Chemistry, Gifu University, Japan.
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Murase
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Ishida
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Kiso
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Hasegawa
D002236:Carbohydrate Conformation; D005679:G(M3) Ganglioside / Q000138:chemical synthesis*; D005732:Gangliosides / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D008722:Methods; D015394:Molecular Structure; D009904:Optical Rotation; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism
D005679:G(M3) Ganglioside; D005732:Gangliosides; D007202:Indicators and Reagents