olivomycins and apoptolidin

We describe here the first use of 2,3-anhydrosugars as glycosylating agents for the preparation of 2-deoxypyranosides. In particular, the methodology was used to assemble 2,6-dideoxysugar glycosides. Glycosylation of a panel of alcohols with one of two 6-deoxy-2,3-anhydrosugar thioglycosides (8 and 9) in the presence of a Lewis acid afforded 2,6-dideoxy-2-thiotolyl glycoside products in generally excellent yields with an exclusively syn relationship between the aglycon and the C-3 hydroxyl group. Removal of the 2-thiotolyl group can be achieved upon reaction with tri-n-butyltin hydride and AIBN to give the corresponding 2,6-dideoxy pyranosides. Once developed, the method was applied to the synthesis of oligosaccharide moieties in the natural products apoptolidin and olivomycin A.

Topics: Biological Products; Glycosides; Glycosylation; Macrolides; Monosaccharides; Oligosaccharides; Olivomycins