A facile, regio- and stereo-selective synthesis of ganglioside GM"3 - Murase, T.; Ishida, H.; Kiso, M.; Hasegawa, A. (Elsevier)
Gangliosides GM"3, containing three different fatty acyl groups at the ceramide moiety, have been synthesized. Coupling of 2-(trimethylsilyl)ethyl O-(6-O-benzoyl-β-d-galactopyranosyl)-(1-〉4)-2,6-di-O-benzoyl-β-d-glucopyra noside (4), prepared from 2-(trimethylsilyl)ethyl β-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-α-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-α-d-galacto-2-nonu lopyranosylonate)-(2-〉3)-O-(6-O- benzoyl-β-d-galactopyranosyl)-(1-〉4)-2,6-di-O-benzoyl-β-d-glucopyranoside (6), which was converted, via O-acetylation, selective removal of the 2-(trimethylsilyl)-ethyl group, and subsequent imidate formation, into the α-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 β-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.
http://linkinghub.elsevier.com/retrieve/pii/0008-6215(89)84060-1
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