SYNTHESIS OF DISACCHARIDE AND TRISACCHARIDE WITH INTRAMOLECULAR NH-GLYCOSIDIC LINKAGES - MOLECULES WITH FLEXIBLE AND RIGID GLYCOSIDIC BONDSFOR CONFORMATIONAL STUDIES

Attempted dephthalimidation of the trisaccharide -O-(3,4,6-tri-O-acety l-2-deoxy-2-phthalimido-beta- D-glucopyranosyl)-alpha-D-mannopyranose (1) and its derivatives 2 and 3, as well as the disaccharide imido-bet a-D-glucopyranosyl)-alpha-D-mannopyranose (13), with hydrazine hydrate in ethanol at 80 degrees C, produced the beta-D-mannopyranose-3',4',6 '-tri-O-acetyl-beta-D- glucopyranose 1,2'-N:1',2-O-dianhydride (4) and 3,4,6-tri-O-benzyl-beta-D-mannopyranose 3',4',6'-tri-O-acetyl-beta-D- glucopyranose 1,2'-N:1',2-O-dianhydride (14), respectively, containing an intramolecular NH-glycosidic linkage. The conventional deblocking of compounds 4 and 14 gave the completely deblocked trisaccharide -deo xy-beta-D-glucopyranosyl)-beta-D-mannopyranose beta-D-glucopyranose 1, 2'-N:1',2-O-dianhydride (6) and the disaccharide beta-D-mannopyranose beta-D-glucopyrannose 1,2'-N:1',2-O-dianhydride (16), respectively, co ntaining an intact intramolecular NH-glycosidic bond. The unusual intr a NH-glycosyl character makes the linkage rigid, and therefore these c ompounds should not only be useful for NMR studies but also as substra tes or inhibitors of GlcNAc-transferases.