Controlled synthesis of glycopolymers with pendant D-glucosamine residues by living cationic polymerization

Abstract

D-glucosamine-containing glycopolymers with well-controlled structure were synthesized by living cationic polymerization. To this end, D-glucosamine-containing vinyl ether (VE) of the type [CH2()CH(OCH2CH2OR)] was prepared, where R denotes a 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimide-β-D-glucopyranoside, i.e., the hydroxyl and amino groups in D-glucosamine residues are protected by acetyl and phthaloyl groups, respectively. It was found that (1) the efficient living cationic polymerization of VE monomer is achieved by a combination of ethylaluminum dichloride (EtAlCl2) with an adduct of trifluoroacetic acid (TFA) and isobutyl VE (IBVE) [CH3CH(OiBu)OCOCF3] (i.e., TFA/EtAlCl2 initiating system); and (2) the polymerization in toluene at the elevated temperature (0°C) is most suitable to proceed the homogeneous polymerization over the whole conversion range. The molecular weight distribution of the resulting polymers was very narrow (\documentclass{article}\pagestyle{empty}\begin{document}$ {\bar M}_w/{\bar M}_n \sim 1.1 $\end{document}). Quantitative deprotection of the resulting precursor polymers was successfully achieved with hydrazine monohydrate to afford the corresponding water-soluble polymers with pendant D-glucosamine residues. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 751–757, 1997