Intramolecularly two-centered cooperation catalysis for the synthesis of cyclic carbonates from CO2 and epoxides

A catalyst system containing an electrophilic center and a sterically hindered nUcleophilic center in one molecule was applied to the cycloaddition reaction of CO2 and epoxides. This intramolecularly two-centered cooperation catalyst showed activity even at a high [epoxide]/[catalyst] ratio up to 50000 under mild conditions such as solvent-free, ambient temperature, and low CO2 pressure. The reaction of CO2 with (S)-propylene oxide at 80 degrees C in the presence of the bifunctional catalyst gives (S)-propylene carbonate in 96% ee with retention of stereochemistry. (C) 2008 Elsevier Ltd. All rights reserved,