Study On The Synthesis Of New Chiral Schiff-base Cobalt Complexes And Their Catalytic Properties In The Coupling Reaction Of CO₂ With Epoxides

Recently, carbon dioxide as abundant and cheaper feedstocks is of great significant interms of greenhouse gas, have received more and more attention by chemist. Carbon dioxide fixation has the great significance:not only in utilization of cheap carbon source, but also in environmental issue. The cyclic carbonate is one of reaction product of carbon dioxide fixation. Catalytic asymmetric synthesis is hot field in modern organic synthesis, which creates bringht future and great challenge to enantiomerically pure chiral drug and materials. Optically pure cyclic carbonates are precursors of chiral alcohols. Herein, we discuss the synthesis of carbonate, which catalyzed by new chiral catalysts of salen-Co(III)X complexes.A series of chiral salen-Co(III)OAc complex were design and synthesized from optically pure Binol. They were used to catalyze the asymmetric cyeloaddition of propylene with carbon dioxide. We found that under mild condition to afford chiral cyclic carbonate with high eevalue. And he catalyst system of (S;S;S,S)-SalenCo(?)X/TBAF is the best catalyst system that can provide the best eevalue at-10?.