"Click" Glycodendrimers Containing 27, 81, and 243 Modified Xylopyranoside Termini

A series of large glycodendrimers containing 27, 81, and 243 terminal modified xylose branches from the first (G(1)-27) to the third generation (G(3)-243) were synthesized from 2'-azidoethyl 2,3,4-tri-O-acetyl-beta-D-xylopyranoside and alkynyl-terminated dendrimers by "click" chemistry that is confirmed to be an excellent method to obtain large glyco-dendtimers exemplified by the use of modified xylose. The dendrimers were first characterized by H-1 NMR, C-13{H-1} NMR, elemental analysis, and IR spectroscopy. The size progression in the series was also demonstrated using both DOSY NMR and size exclusion chromatography (SEC), the latter technique showing the good polydispersity of all the dendrimers. The size measured by dynamic light scattering (DLS) for the dendrimer G(3)-243 is close to that obtained by the DOSY NMR method.