Study On The Synthesis Of Metalloporphyrin And Multi-chiral Schiff-base Complexes And Their Catalytic Properties In The Coupling Reaction Of Carbon Dioxide With Epoxides

Recently,the chemistry of carbon dioxide and the carbon dioxide fixation have received much attention from both an economical and an environmental point of view: utilization of the least-expensive carbon source and reduction of global-warming gas. The cyclic carbonate is one of products of carbon dioxide fixation and widely used as organic synthetic intermediates,aprotic polar solvents,precursors for biomedical applications,and as raw materials for engineering plastics.Catalytic asymmetric synthesis is a hot field in modern organic synthesis,which creates good fortunes to enantiomerically pure chiral drugs and other materials.Optically pure cyclic carbonates are precursors of chiral alcohols.Herein we mainly discuss the reacrion of carbon dioxide with epoxides catalyzed by metal porphyrin and the asymmetric cycloaddition reaction catalyzed by novel mutil-chiral catalysts of BINADCo(â…¢)X complex.(1) Synthesis of cyclic carbonates catalyzed by metal porphyrin/ phenyltrimethylammonium tribromide(PTAT).The experiment investigated the effect of different catalyst,co-catalyst,counterions,Lewis acid center and found that Co(TPP)(OAc)/PTAT was active to various terminal epoxides,producing the responding cyclic carbonate with high yield.(2) The coupling of epoxides with carbon dioxide catalyzed by ruthenium porphyrin was studied.The effect of different complexes,and reaction condition were investigated.It was found that the new catalyst system of Ru(â…¡)(TPP)(PPh₃)₂/PTAT activated by EDA is very effective to catalyze the coupling reaction of various epoxides and CO₂ at 333K,and substrate:catalyst:additives(EDA):co-catalyst= 200:1:1:2.(3) A series of chiral porphyrin complexes were synthesized in several steps from natural amino acids and(R) or(S)-BINOL,and applied in the asymmetric cyclicaddition reaction of carbon dioxide with propylene oxide to yield chiral cyclic propylene carbonate.But the results of enantioselectivity were moderate.(4) Several mutil-chiral BINADCo(â…¢)X(BINAD = Bis(1,1'-2-hydroxy-2'- alkyloxy-3-naphthylidene)-1,2-cyclohexanediamine,X =OAc,CF₃CO₂,CCl₃CO₂, OTs,p-NO₂PhCO₂) complexes were synthesized,and used to catalyze the asymmetric cycloaddition of carbon dioxide with propylene oxide under mild condition to afford chiral cyclic carbonate with very high ee value.Among them,the catalyst of (S,S,S,S)-BINADCo(â…¢)(OAc)(9b) and phenyltrimethylammonium tribromide(PTAT) is the best catalyst system that provide the highest 95%ee value at -20℃.