Synthesis of new spherical and hemispherical oligosaccharides with polylysine core scaffold

Abstract

A new spherical polylysine dendrimer generation 3 with acetyl cellobiose unit through a C6 spacer (TLACD3) was synthesized for the investigation of the structural effects on the specific biological activities such as anti-HIV and blood anticoagulant activities, which are our continuous research works. Tris(2-ethylamino)amine was used as an initiator of the core compound and was reacted with di- t-butoxycarbonyl lysine (di-boc-lysine) by the stepwise condensation according to the literature to give the polylysine dendrimer generation 3. Adipic acid monocellobiose ester as a model compound of oligosaccharide units was synthesized by the mono-esterification of adipic acid and 1-hydroxyl acetyl cellobiose. The adipic cellobiose was reacted with the deprotected polylysine dendrimer generation 3 to afford the spherical dendrimer with cellobiose unit (TLACD3) in the terminal. The hemispherical polylysine dendrimer generation 3 with acetylated cellobiose in the terminal through the C6 spacer (ALACD3) was also prepared from β-alanine methyl ester and di-boc-lysine by the same procedures as above. The spherical and hemispherical dendrimers have 24 and 8 terminal cellobiose units in each molecule, respectively, and the structure was characterized by NMR, IR, and MALDI TOF mass measurements. Although the hemispherical dendrimer ALACD3 had eight cellobiose units in a molecule, for the spherical dendrimer TLACD3, one cellobiose unit was eliminated partially from the molecule by the results of the MALDI TOF mass measurements.