Oligosaccharides through reactivity tuning: convergent synthesis of the trisaccharides of the steroid glycoside Sokodoside B isolated from marine sponge Erylus placenta

Chemical synthesis of the trisaccharide of the steroid glycoside Sokodoside B isolated from Erylus placenta is reported. Stereoselective, high-yielding glycosylation strategies through thioglycoside activation using H2SO4 immobilized on silica in conjunction with N-iodosuccinimide are used for better results. A late stage TEMPO-mediated oxidation was performed for the formation of required uronic acid moiety. An analog of the target trisaccharide is also prepared by using a bis-glycosylation approach.