Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide by Using Bifunctional One-Component Phosphorus-Based Organocatalysts

Numerous bifunctional organocatalysts were synthesized and tested for the atom-efficient addition of carbon dioxide and epoxides to produce cyclic carbonates. These catalysts are based on phosphonium salts containing an alcohol moiety in the side chain for substrate activation through hydrogen bonding. In the model reaction, converting 1,2-butylene oxide with CO2, 19 catalysts were tested to determine structure-activity relationships. In total, 28 epoxides were converted with CO2 to give the respective cyclic carbonates in yields of up to 99 %. Even at 45 degrees C, the most active catalyst was able to produce cyclic carbonates selectively in high yields. The carbonates were generally obtained as analytically pure products after simple filtration over silica gel. This single-component catalyst system works under neat and mild reaction conditions and tolerates several useful moieties.