Robust Zinc Complexes that Contain Pyrrolidine-Based Ligands as Recyclable Catalysts for the Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides

New zinc catalysts bearing ligands that contain a pyrrolidine scaffold were synthesized and tested successfully in the coupling of CO2 with terminal and internal epoxides. These catalysts provide excellent activity and total selectivity to the corresponding cyclic carbonates, even for challenging substrates such as cyclohexene oxide, trans-1,2-epoxybutane, and methyl epoxioleate. The robustness of the most active catalytic system was demonstrated by turnover numbers of up to 1840 for propylene oxide. The recycling of this catalytic system was performed up to five times without relevant loss of activity using this substrate.