Globular carbohydrate macromolecule ''sugar balls'' .3. ''Radial-growth polymerization'' of sugar-substituted alpha-amino acid N-carboxyanhydrides (GlycoNCAs) with a dendritic initiator

''Radial-Growth Polymerization (RGP)'', polymerization initiated with multivalent dendrimer to afford dendrimer-based star polymer, was proposed as a new class of polymerization systems. Oligoglycopeptide-type sugar balls, i.e., oligo[O-(beta-D-glucopyranosyl)-L-serine]-persubstituted poly(amido amine) dendrimer (4a) and oligo[O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-serine]-persubstituted poly(amido amine) dendrimer (4b), were obtained by ring-opening oligomerization of sugar-substituted alpha-amino acid N-carboxyanhydrides (glycoNCAs), i.e., O-(tetra-O-acetyl-beta-D-glucopyranosyl)-L-serine N-carboxyanhydride (1a) and O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-L-serine N-carboxyanhydride (1b), respectively, with poly(amido amine) dendrimer (2, generation, 3.0-5.0) as a macroinitiator, followed by quantitative deacetylation with hydrazine monohydrate. Yields and M-w/M-n values of the products of the oligomerization were 97-99% and 1.0(3)-1.1(1), respectively. Sugar balls 4a and 4b wee soluble in water and dimethyl sulfoxide. Molecular recognition ability of 4a and 4b was examined by erythrocyte agglutination inhibition assays using wheat germ agglutinin (WGA). (C) 1997 Elsevier Science Ltd.