Synthesis of the trisaccharide moiety of gangliotriosylceramide (asialo GM2).
The synthesis of the trisaccharide methyl glycoside beta-D-GalNAc-(1----4)-beta-D-Gal-(1----4)-beta-D-Glc-OMe, which corresponds to the carbohydrate portion of gangliotriosylceramide (asialo GM2), was accomplished by the reaction of 4-O-acetyl-3,6-di-O-benzoyl-2-deoxy-2-phthalimido-D-galactopyranosyl bromide (18) with a benzylated derivative of methyl 4-O-beta-D-galactopyranosyl-beta-D-glucopyranoside. Comparative studies with a 6'-benzyl ether and a 6'-benzoate revealed that the substituent at O-6' is crucial to the outcome of glycosylations at O-4', the ether derivative being much the more reactive. tert-Butyl 4-O-acetyl-3,6-di-O-benzoyl-2-deoxy-2-phthalimido-D-galactopyranoside, which was readily converted into the corresponding bromide 18, was obtained from the gluco derivative via a single-step, crown ether-assisted epimerization.
D005732:Gangliosides; D006028:Glycosphingolipids / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D009844:Oligosaccharides / Q000138:chemical synthesis*; D009904:Optical Rotation; D013329:Structure-Activity Relationship
D005732:Gangliosides; D006028:Glycosphingolipids; D007202:Indicators and Reagents; D009844:Oligosaccharides; C038244:ganglio-N-triaosylceramide