Improvement Of The Salen Mn(Ⅲ)-NaOCl Asymmetric Epxoidation System

Chiral Schiff-base complexes,especially being used as the efficient catalysts for the asymmetric epoxidation of alkenes,have important applied value in various asymmetric syntheses.The Salen-Mn(â…¢)/NaOCl system has a good prospects in the catalytic application.In order to further researth the relationship between structure of the catalyst and the catalytic effects,improve catalysts' reactivity and enantioselectivity and attempt to recovery the catalysts for reuse,four new chiral Salen-Mn(â…¢) complexes containing multihydroxyl amino groups and multiester amino groups at C-5(5') positions of the salen ligand were synthesized and characterized by EA,MS,MC,IR,¹H NMR,UV.The catalytic properties of some complexes on selective unfunctionalized alkene have been tested and employed in the asymmetric epoxidation in the presence of ionic liquid[BMIM]BF₄,[BMIM]PF₆ or chiral ionic liquid.The catalytic results indicate that these Salen Mn(â…¢) complexes improved the rate of asymmetric epoxidation of alkenes and reduced the time of reactions.These catalysts could be recycled in the ionic liquid and overcomed the disadvantage that single-phase catalyst should not been recycled.But asymmetric induction is not obvious by using optically active chiral ionic liquid as solvents,so it needs more research.This thesis consists of three parts:1.The recent advances about the studies in the catalytic asymmetric epoxidation and asymmetric synthesis and catalysis in ILs were reviewed.2.Four of new chiral Salen ligands(R,R)-N,N'-[2,2'-bis(nitrilomethylidyne)] bis[4-(methylene-N,N'-diethanolamino)-6-(1,1-dinethylethyl)phenoloto]-1,2-cyclohex anediamine(H₂L₁),(R,R)-N,N'-[2,2'-bis(nitrilomethylidyne)]bis[4-(methylene-N,N'-diethanolamino) -6-(1,1-dinethylethyl)phenoloto]-1,2-diphenyldiamine(H₂L₂),(R,R)-N,N'-[2,2'-bis(nitrilomethylidyne)]bis[4-(methylene-N,N'-diethylacetateamino)-6-(1,1 -dinethylethyl)phenoloto]-1,2-cyclohexanediamine(H₂L₃),(R,R)-N,N'-[2,2'-bis(nitrilomethylidyne)] bis[4-(methylene-N,N'-diethylacetateamino)-6-(1,1-dinethylethyl)phen oloto]-1,2-diphenyldiamine(H₂L₄) were designed,synthesized and characterized.The composition of the complexes are MnLCl.·n H₂O[n=1,2].The Mn(â…¢) complexes of four ligands were applied to catalyze enantioselective epoxidation of unfunctionalized olefinthe.The result indicate that these Salen Mn(â…¢) complexes improved the rate of asymmetric epoxidation of alkenes and reduced the time of reactions.3.N,N'-dialkyl imidazolium salts([BMIM]PF₆,[BMIM]BF₄) and chiral imidazolium ionic liquids containing one chiral carbon(L-1-Ethyl-3-(1'-hydroxy-2'-propanyl)imida zolium Bromide) were synthesized.These Salen-Mn(â…¢) catalysts could be recycled. in the ionic liquid to catalyze enantioselective epoxidation of unfunctionalized olefinthe.