Synthesis of N,N,N-trimethyl chitosan homopolymer and highly substituted N-alkyl-N,N-dimethyl chitosan derivatives with the aid of di-tert-butyldimethylsilyl chitosan

► Di-tert-butyldimethylsilyl-3,6-O-protected chitosan used as a precursor for selective N-modification. ► 100% N,N,N-trimethyl chitosan achieved with methyl iodide as methylating agent. ► N-Alkyl chitosan (propyl, butyl, hexyl) synthesized through stepwise reductive alkylation. ► 65-72% N,N-dimethylation of N-alkyl chitosan derivatives with dimethyl sulfate used as the methylating agent. ► Detailed structure characterization with NMR with no O-methylation detected.