Synthesis of a new polylysine-dendritic oligosaccharide with alkyl spacer having peptide linkage

A new polylysine-dendritic cellobiose (8) as a model compound of glycodendrimers with biological activities was synthesized by a core lysine dendrimer generation 3 and cellobiose derivative. The oligosaccharide was connected to the lysine dendrimer G3 through the C12 spacer having a peptide bond. That is, acetylcellobiose was reacted with the benzoyloxycarbonyl (Z)-protected 6-amino-1-hexanol, followed by the deprotection of the Z-group to reproduce amino group. The amino group at the end of the C6 spacer was reacted with adipic acid to form acetylcellobiose with the C12 spacer having a carboxyl group at the end of the spacer. The carboxylic acid was condensed with the amino group of the polylysine dendrimer G3, which was obtained by the stepwise condensation of di-boc-lysine from tris(2-ethylamino)amine, to give the polylysine-dendritic cellobiose (8) after deacetylation. The structure was characterized by NMR, IR, GPC, and MALDI-TOF-MS measurements.The polylysine-dendritic cellobiose synthesized here has the following characteristics: (1) all linkages were connected by peptide bond without an ether bond between cellobiose and the C12 spacer, (2) cellobiose moiety was kept the disaccharide structure and increased the flexibility by the long spacer, and (3) based on the peptide linkage, vital affinities and the stabilization under both alkaline and weak acidic conditions are expected.