Ring-opening polymerization of new 3-O-branched 1, 6-anhydro glucopyranose di- and trisaccharide monomers.

New 3-O-branched 1, 6-anhydro glucopyranose disaccharide monomers, 1, 6-anhydro-2, 4-di-O- benzyl-3-O-(2', 3', 4', 6'-tetra-O-benzyl-α-D-mannopyranosyl)- (LGM 6) and -glucopyranosyl)-β-D- glucopyranose (LGG 7), and a trisaccharide monomer, 1, 6-anhydro-2, 4-di-O-benzyl-3-O-α-(2', 3', 6', 2″, 3″, 4″, 6″-hepta-O-benzyl- α-D-maltopyranosyl)-β-D-glucopyranose (LGMAL 8), were synthesized and polymerized. It was found that the 3-O-branched1, 6-anhydro disaccharide monomers were polymerized. However, the polymerizability was lower than that of the 4-O-branched disaccharide monomers reported previously, and the trisaccharide monomer was not polymerizable, probably due to the steric hindrance of the branched bulky mono and disaccharide units at the 3-O position in 1, 6-anhydro glucopyranose. Debenzylation of the resulting polymers gave 3-O-gluco- and mannopyranosidic (1 → 6)-α-D-glucopyranans in moderate yields. These results are the first reports of the polymerization of 3-O-branched 1, 6-anhydro glucopyranose disaccharide monomers to give 3-O-branched polysaccharides.