First Synthesis of “Majoral-Type” Glycodendrimers Bearing Covalently Bound α- d -Mannopyranoside Residues onto a Hexachlocyclotriphosphazene Core

A short and efficient strategy for the first synthesis of "Majoral-Type" multivalent glycodendrimers bearing covalently bound alpha-D-mannopyranosides onto a cyclotriphosphazene scaffold assembled using single-step Sonogashira and click chemistry is reported. New glycoclusters with valencies ranging from 6 to 18 and different epitope spatial arrangements were obtained. Cross-linking abilities of this series of glycodendrimers were evaluated with the model lectin from Canavalia ensiformis (Concanavalin A). The decameric mannoside 23, built around 19, was shown to be much faster in cross-linking the tetravalent lectin Concanavalin A than the positive control, which is the polysaccharide mannan from yeast. The new glycoconjugates reported may be promising tools as probes or effectors of biological processes involving multivalent carbohydrate-binding proteins.