Three complexes of tetrachlorophenylporphyrinatomanganese acetates have been synthesized and characterized by IR and UV spectra. The asymmetric epoxdation of styrene has been investigated by using these three complexe...Three complexes of tetrachlorophenylporphyrinatomanganese acetates have been synthesized and characterized by IR and UV spectra. The asymmetric epoxdation of styrene has been investigated by using these three complexes as catalysts, chiral quaternary ammonium salts as phase transfer catalysts, and quinine as chiral auxiliary, sodium hypochlorite as oxidant. The results showed that the structure of manganese porphyrins, the chiral auxiliaries and temperature of reaction affected the asymmetric induction. The best enantiomer excess reached 12 8%.展开更多
Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl d...Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl diazoacetate. It was found that the substituents at 3 and 5 positions of salicylaldehyde in the ligands had great effects on catalytic activity and enantioselectivity of the catalyst. The complex with strong electron withdrawing group (NO 2) at 5 position and the smallest stereo hinder (H) at 3 position of salicylaldehyde showed highly catalytic activity and enantioselectivity, up to ee =87 4% for trans and ee =82 8% for cis isomers respectively, and the ratio 39/61 of cis to trans isomers was obtained at 40 ℃ with 1,2 dichloroethane as solvent.展开更多
文摘Three complexes of tetrachlorophenylporphyrinatomanganese acetates have been synthesized and characterized by IR and UV spectra. The asymmetric epoxdation of styrene has been investigated by using these three complexes as catalysts, chiral quaternary ammonium salts as phase transfer catalysts, and quinine as chiral auxiliary, sodium hypochlorite as oxidant. The results showed that the structure of manganese porphyrins, the chiral auxiliaries and temperature of reaction affected the asymmetric induction. The best enantiomer excess reached 12 8%.
文摘Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl diazoacetate. It was found that the substituents at 3 and 5 positions of salicylaldehyde in the ligands had great effects on catalytic activity and enantioselectivity of the catalyst. The complex with strong electron withdrawing group (NO 2) at 5 position and the smallest stereo hinder (H) at 3 position of salicylaldehyde showed highly catalytic activity and enantioselectivity, up to ee =87 4% for trans and ee =82 8% for cis isomers respectively, and the ratio 39/61 of cis to trans isomers was obtained at 40 ℃ with 1,2 dichloroethane as solvent.
