Preparation of highly regioselective chitosan derivatives via “click chemistry”

Highly regioselective chitosan derivatives were achieved by copper-catalyzed Huisgen cycloaddition, known as an ideal reaction for click chemistry, using 6-azido-6-deoxy-chitosan derivative. The azide moiety introduced through regioselective bromination and azidation of chitosan was successfully converted with ethynyl compounds having functional groups (hydroxymethyl and phenyl groups) in the presence of copper(II) sulfate, sodium ascorbate and triethylamine. FTIR, elemental analysis, 1H NMR, and 13C NMR spectra showed that C-6 positions of the chitosan derivative were regioselectively transferred by these functional groups with 1,4-triazole linker, and the DS values were approximately 1.