Highly Norbornylated Cellulose and Its Click Modification by an Inverse-Electron Demand Diels-Alder (iEDDA) Reaction

A facile, catalyst-free synthesis of a norbornylated cellulosic material (NC) with a high degree of substitution (2.9) is presented by direct reaction of trimethylsilyl cellulose with norbornene acid chloride. The resulting NC is highly soluble in organic solvents and its reactive double bonds were exploited for the copper-free inverse-electron demand Diels-Alder (iEDDA) click reaction with 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine. Reaction kinetics are comparable to the well-known Huisgen type 1,3-dipolar cycloaddition of azide with alkynes, while avoiding toxic catalysts.

Automated summary

A facile method for the synthesis of a norbornylated cellulosic material (NC) with a high degree of substitution (2.9) is presented, utilizing direct reaction of trimethylsilyl cellulose with norbornene acid chloride. The resulting NC is highly soluble in organic solvents and its reactive double bonds can be utilized for the copper-free inverse-electron demand Diels-Alder (iEDDA) click reaction with 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine. This reaction kinetics are similar to the Huisgen type 1,3-dipolar cycloaddition of azide with alkynes, but without the use of toxic catalysts.