Synthesis of di- and tri-saccharides with intramolecular NH-glycosidic linkages: molecules with flexible and rigid glycosidic bonds for conformational studies

摘要: Abstract Attempted dephthalimidation of the trisaccharide 1-O-acetyl-3,4-di-O-benzyl-2,6-di-O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β- d -glucopyranosyl)-α- -mannopyranose (1) and its derivatives 2 3, as well disaccharide 1-O-acetyl-3,4,6-tri-O-benzyl-2-O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β- (13), with hydrazine hydrate in ethanol at 80°C, produced trisaccharide-6-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β- -glucopyranosyl)-3,4-di-O-benzyl-β- -mannopyranose-3′,4′,6′ -tri-O-acetyl-β- -glucopyranose 1,2′-N:1′,2-O-dianhydride (4) 3,4,6-tri-O-acetyl-β- 1,2′-N: 1′,2-O-dianhydride (14), respectively, containing an intramolecular NH-glycosidic linkage. The conventional deblocking compounds 4 14 gave completely deblocked 6-O-(2-acetamido-2-deoxy-β- -glucopyranosyl)-β- β- (6) -glucopyrannose (16), intact bond. unusual intra NH-glycosyl character makes linkage rigid, therefore these should not only be useful for NMR studies but also substrates or inhibitors GlcNAc-transferases.