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-α- d -glucopyrano)-[2,1- d ]-2-oxazoline ( 1 ) and 2-methyl(3,4-di- O -benzyl-1,2-dideoxy-α- 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 1 H NMR, 13 C 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.