Study On The Asymmetric Cycloaddition Reaction Of Carbon Dioxide And Epoxides Catalyzed By Chiral Cobalt Complexes

As an environmental benign chemical process, the carbon dioxide fixation have attracted more and more attention from people because that can be used as a safe and cheap C1 building block in organic synthesis. The kinetic resolution of racemic epoxides, especially of propylene oxide (PO), with carbon dioxide provides enantiopure epoxide and chiral cyclic carbonate. The first are important intermediates in the pharmaceutical and chemical industries. The latter are valuable building blocks for optically active diols and polycarbonates. This thesis aims at the synthesis of optically active cyclic carbonates including three sections:(1) The research progress of the cyclic carbonates, and different catalytic systems for addition reactions of carbon dioxide with epoxides have been classified and summarized.(2) A series of chiral Binol-SalenCo(Ⅲ)X complexes were synthesized with chiral Binol as raw materials.(3) The asymmetric coupling reaction of carbon dioxide with propylene oxide catalyzed by chiral Binol-SalenCo(Ⅲ)X complexes was studied. The effects of different spatial structure of catalysts, counterions, co-catalysts, reaction temperature, the loading amount of catalyst and co-catalyst in chiral cyclic carbonate formation were investigated. Catalytic systems of complex 7d/TBAF can give the best results for various terminal epoxides. The chiral propylene carbonate obtained 69.2% e.e. at 0℃, and the corresponding conversion was 48.4%.