Synthesis of natural- and non-natural-type aminopolysaccharides:: 2-Acetamido-2-deoxy-β-D-glucopyranan derivatives by acid-catalyzed polymerization of 2-methyl(3,6- and 3,4-di-O-benzyl-1,2-dideoxy-α-D-glucopyrano)-[2,1-d]-2-oxazolines involving stereoregular glycosylation

This paper describes the acid-catalyzed polymerization of two saccharide monomers, 2-methyl(3,6-di-O-benzyl-1,2-dideoxy-alpha-D-glucopyrano)-[2,1-d]-2-oxazoline (1) and 2-methyl(3,4-di-O-benzyl-1,2-dideoxy-alpha-D-glucopyrano)-[2,1-d]-2-oxazoline (3). The polymerization of 1 and 3 proceeded by stereoregular glycosylation to give natural- and non-natural-type aminopolysaccharides 2 and 4, respectively. The polymer structures were determined by means of H-1 NMR, C-13 NMR, and IR spectra as well as elemental analyses. The molecular weight of 2 was at most 4900, whereas the highest molecular weight of 4 was 13 100. Debenzylation of 2 and 4 was carried out by the catalytic hydrogenation in the presence of 10% Pd-C to give free aminopolysaccharides.