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

TY - JOUR

T1 - 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

AU - Benediktsdóttir, Berglind E.

AU - Gaware, Vivek S.

AU - Rúnarsson, Ögmundur V.

AU - Jónsdóttir, Sigríður

AU - Jensen, Knud Jørgen

AU - Másson, Már

PY - 2011/10/15

Y1 - 2011/10/15

N2 - A highly chemoselective strategy for the synthesis of N,N,N-trimethyl chitosan (TMC) homopolymer and highly substituted N-alkyl-N,N-dimethyl chitosan derivatives was achieved using di-tert-butyldimethylsilyl-3,6-O-chitosan (di-TBDMS chitosan) as a precursor. The influence of different solvents, reagents and other reaction conditions on the reduction, trimethylation and quaternization of these di-TBDMS chitosan derivatives was studied. Products were characterized by NMR after each step. Di-TBDMS chitosan was reacted with methyl iodide in NMP, giving a 100% substituted TMC with the trimethyl group appearing at 3.35 ppm in 1H NMR spectrum. N-Propyl-, N-butyl- and N-hexyl-N,N-dimethyl chitosan derivatives were synthesized by stepwise reductive alkylation of di-TBDMS chitosan, followed by quaternization with dimethyl sulfate in dichloromethane, giving 65-72% substituted N-alkyl-N,N-dimethyl chitosan derivatives under optimized conditions. Analysis of these water-soluble chitosan derivatives by FT-IR, 1H NMR, 13C NMR, 1H-1H COSY and 1H-13C HSQC NMR enabled detailed structural characterization. All peaks could be assigned to N-modification, showing the selectivity of the di-TBDMS protection.

AB - A highly chemoselective strategy for the synthesis of N,N,N-trimethyl chitosan (TMC) homopolymer and highly substituted N-alkyl-N,N-dimethyl chitosan derivatives was achieved using di-tert-butyldimethylsilyl-3,6-O-chitosan (di-TBDMS chitosan) as a precursor. The influence of different solvents, reagents and other reaction conditions on the reduction, trimethylation and quaternization of these di-TBDMS chitosan derivatives was studied. Products were characterized by NMR after each step. Di-TBDMS chitosan was reacted with methyl iodide in NMP, giving a 100% substituted TMC with the trimethyl group appearing at 3.35 ppm in 1H NMR spectrum. N-Propyl-, N-butyl- and N-hexyl-N,N-dimethyl chitosan derivatives were synthesized by stepwise reductive alkylation of di-TBDMS chitosan, followed by quaternization with dimethyl sulfate in dichloromethane, giving 65-72% substituted N-alkyl-N,N-dimethyl chitosan derivatives under optimized conditions. Analysis of these water-soluble chitosan derivatives by FT-IR, 1H NMR, 13C NMR, 1H-1H COSY and 1H-13C HSQC NMR enabled detailed structural characterization. All peaks could be assigned to N-modification, showing the selectivity of the di-TBDMS protection.

U2 - 10.1016/j.carbpol.2011.06.007

DO - 10.1016/j.carbpol.2011.06.007

M3 - Journal article

SN - 0144-8617

VL - 86

SP - 1451

EP - 1460

JO - Carbohydrate Polymers

JF - Carbohydrate Polymers

IS - 4

ER -