Cycloaddition of CO2 to Epoxides Catalyzed by N-Heterocyclic Carbene (NHC)-ZnBr2 System under Mild Conditions.

A very simple and convenient method toward coupling of CO2 with epoxides catalyzed by NHC/ZnBr2 has been developed. This catalytic system exhibits excellent activity and selectivity in the cycloaddition reactions of CO2 to terminal epoxides. The reactions can even be carried out under CO2 pressure as low as 0.05 MPa and give carbonates in high yields. [ABSTRACT FROM AUTHOR]