Selective Conversions of CO2into Value-Added Chemicals via Cooperative Catalysis Using Multifunctional Catalysts

Carbon dioxide (CO2) is not only a greenhouse gas but also a renewable carbon source for organic synthesis. Here we have summarized our studies on the conversions of CO2into value-added chemicals via cooperative catalysis using multifunctional catalysts. For example, bifunctional metalloporphyrin catalysts with quaternary ammonium halides were developed for the selective synthesis of cyclic carbonates or polycarbonates from epoxides and CO2. Bifunctional MgIIand ZnIIporphyrins showed high catalytic activity for the synthesis of cyclic carbonates, while bifunctional AlIIIporphyrins catalyzed the copolymerization of cyclohexene oxide and CO2to give poly(cyclohexene carbonate). The high catalytic activities resulted from the cooperative action of the central metal ion and the quaternary ammonium salts. Chiral catalysts for the kinetic resolution of terminal or internal epoxides with CO2were also developed. In addition, macrocyclic multinuclear metal complex Zn5L3, which was synthesized by the self-assembly of Zn(OAc)2and a BINOL derivative (L), catalyzed the reduction of CO2with phenylsilane to produce various useful synthetic intermediates and organic compounds.Carbon dioxide (CO2) was converted into value-added chemicals via cooperative catalysis with multifunctional catalysts. For example, bifunctional metalloporphyrins catalyzed the selective synthesis of cyclic carbonates or polycarbonates from epoxides and CO2. Macrocyclic multinuclear zinc complexes catalyzed the deoxygenative reduction of CO2with hydrosilanes to produce various useful intermediates and compounds.