CO2 conversion to cyclic carbamates through alternative coupling routes catalyzed by hypercrosslinked polymer-supported NHC-Cu complexes

[EN] The catalytic conversion of CO2 into value-added chemicals is an important strategy for CO2 utilization. Herein, hypercrosslinked polymer-supported N-heterocyclic carbene-copper complexes (HCP-NHC-Cu) are synthesized in a single step from imidazolium-based hypercrosslinked polymers and evaluated as heterogeneous catalysts for the conversion of CO2 to cyclic carbamates. Owing to their robustness and insolubility, these materials operate as efficient heterogeneous catalysts in complementary coupling pathways, in three-component coupling reactions involving CO2, propargylic alcohols, and primary amines, as well as the coupling reaction of CO2 with propargylic amines, affording cyclic carbamates in quantitative yields and high selectivity. Cyclic carbamates are obtained in quantitative yields and high selectivity under moderate conditions (CO2 pressure of 5 bar, temperatures of 60-120 degrees C, and reaction times of 4-16 h). The excellent performance of the novel catalysts is attributed to a cooperative effect arising from CO2-philic NHC ligands working in concert with catalytically active Cu(I) sites.