Synthesis of the Reducing-end Hexasaccharide Fragment of Marine Lipopolysaccharide Axinelloside A

Chemical synthesis of an orthogonally protected hexasaccharide relevant to the reducing-end half of axinelloside A, a highly sulfated marine lipopolysaccharide, is disclosed. The synthesis features preparation of the scyllo-inositol unit via a Ferrier-type-II rearrangement, construction of the 1,2-cis-glycosidic bonds via remote participation, and concise [2+2+2] assembly via Au(I)-catalyzed glycosylation. A properly protected hexasaccharide relevant to the reducing-end half of telomerase inhibitor axinelloside A was synthesized. Features of the synthetic approach include (1) preparation of the scyllo-inositol unit via Ferrier-type-II rearrangement, (2) formation of the 1,2-cis-glycosidic linkages via remote acyl group participation, and (3) concise [2+2+2] assembly by virtue of Au(I)-catalyzed glycosylation.+ image