Regioselective grafting of poly(ethylene glycol) onto chitosan through C-6 position of glucosamine units

Synthesis of an O-alkynyl-chitosan and its chemoselective conjugation with a PEG-like amino-azide through click chemistry

“…Again, given prior reports on significant breakdown of the chitosan's backbone in the course of N-dephthaloylation (Makuška & Gorochovceva, 2006), we have run the deprotection for 18 h at only 40 • C. Structural analyses described below allowed confirming full removal of the N-phthaloyl protecting group to give polymer 5. Finally, it should be noted that, in all cases, product polymers kept the fine powder structure of the starting materials, and no grinding was required in any step.…”

Defined Chitosan-based networks by C-6-Azide–alkyne “click” reaction

“…Moreover, N-Phthaloyl-Chitosan is regarded as one of the most useful precursors for subsequent modification due to its solubility in common aprotic polar solvents (DMSO, DMF, NMP) and it also allows the simple deprotection of the amino groups by hydrazine monohydrate [15]. It has therefore been extensively used for the regioselective functionalization and graft copolymerization onto chitosan [16,17].…”

Synthesis and property of chitosan graft copolymer by RAFT polymerization with tosylic acid–chitosan complex

“…In the previous work, we reported controlled graft modification of chitosan via RAFT polymerization using chitosan-RAFT agent to get chitosan graft copolymer with controlled molecular weight and "well-defined" structure [18], and prepared the temperatureresponsive chitosan by this method [19]. However, the amino groups of chitosan need to be protected with phthalic anhydride in this procedure, and N-phthaloylation protection and the subsequent deprotection processes are very tedious, and the chitosan backbone may be subject to significant breakdown during the process [20].…”