Stereochemistry-Tunable Isocyanide-Based Polymerization

Regulation of stereochemistry is one of the most important research focuses in synthetic polymer chemistry; however, this area should be further developed. In this work, a new polymerization of diisocyanoacetates and disulfonimines with tunable stereochemistry was developed. Diisocyanoacetates and disulfonimines could easily undergo polycycloaddition in the presence of CuCl/PPh₃, and polyimidazolines with high weight-average molecular weights (M_w, up to 43 900) were produced in excellent yields (up to 99%). Moreover, the stereochemistry of the polymerization and the stereoregularity of the resultant polymers can be fine-tuned by triethylamine (TEA). In addition, TEA could also significantly promote the polymerization, from which polymers with much higher molecular weights (M_w up to 155 400) could be obtained in higher yields. This work not only promotes the development of the isocyanide chemistry and enriches the family of polymerizations based on triple-bond building blocks but also provides an opportunity to study the structure–property relationship of the polyimidazolines.