Transformation of CO2 into α-Alkylidene Cyclic Carbonates at Room Temperature Cocatalyzed by CuI and Ionic Liquid with Biomass-Derived Levulinate Anion

Abstract

Utilization of carbon dioxide (CO2) as a renewable C1 building block is of great importance. Herein, a series of ionic liquids (ILs) with biomass-derived anions or/and cations were synthesized, and using these prepared ILs as catalytic solvents, CuI could catalyze carboxylative cyclization of propargylic alcohols with CO2 at room temperature (25 °C). Especially, the IL [Bu4P][Levulinate] with cellulose-derived levulinate anion combined with CuI showed the best performance, affording various corresponding α-alkylidene cyclic carbonates in good yields (>90%). In the reaction, CuI and [Bu4P][Levulinate] played synergistic role to activate the C≡C and hydroxyl groups in propargylic alcohols, respectively, leading to the excellent performance of CuI/[Bu4P][Levuliniate]. Additionally, the CuI/[Bu4P][Levuliniate] catalytic system could be reused for five times without noticeable decrease in activity and selectivity.