Synthesis,Application And Self-Assembly Recovery Performance Of Asymmetrical Organocatalysts Based On Proline And Quinine

In this paper,12 organocatalysts basing on proline and cinchona as framework were synthesized.The reaction mechanism、recyclability and applicability of catalysts in the asymmetric reduction of imine and asymmetric Friedel-Crafts reaction of phenylglyoxal hydrate were investigated deeply.At present,the deep theoretical mechanism research for the asymmetric reduction of imine was deficient and imperative.Therefore,we have made a comprehensive study through theoretical calculation method and put forward a new mechanism model which is different from the previous work.Furthermore,the supramolecular host-guest assembly and disassembly techniques were further developed which was introduced into our research.Our proposed catalyst recovery method mixing the homogeneous catalysis and heterogeneous recovery provides a new way to solve the intractable problems that the recovery for homogeneous catalysts was difficult,while the heterogeneous catalysts loading on the materials will cause the decrease of catalyst activity.This thesis contains three chapters as following:1.A new proline-derivative organocatalyst bearing adamantane group was synthesized and applied to the asymmetric reduction of imines.The new reaction mechanism model of catalyst was proposed and deeply investigated by theoretical calculation and control experiments.Furthermore,according to the self-assembly method of beta cyclodextrin(host)and adamantane(guest),the catalyst bearing adamantane group was successfully separated after the reaction using magnetic Fe3O4@SiO2 microspheres modified with beta-CD with the self-assembly method.The result showed that the ee value of product remained over 80%after six runs.Therefore,the method mixing homogeneous catalysis and heterogeneous recovery for chiral catalysts has been established for the first time basing on the supramolecular host-guest self-assembly.2.On the basis of the previous work,an organocatalyst with rich conjugated electrons and recovery ability was prepared using L-proline,which subsequently was investigated its application in the asymmetric reduction of imines.By using more numerous theoretical calculations,the mechanism of transition state and hydrogen bond formation for trichlorosilane was further explored.Moreover the factors affecting the catalytic efficiency in the mechanism model were further investigated.In addition,a more convincing mechanism model was proposed.Then,the supramolecular assembly technology was reemployed to recover the catalyst.After nine runs of catalysis,the ee value of the product was still more than 80%.After that,the lost catalyst was supplemented and the catalytic activity of the reaction was retrieved as that performed in the first run.3.Azophenyl bifunctional cinchona alkaloid derivatives and adamantyl bifunctional cinchona alkaloid derivatives were synthesized using cinchona as chiral framework for the asymmetric Friedel-Crafts reaction of phenyl glyoxal hydrate with naphthol.Both of them show very high catalytic performance,especially the adamantyl catalyst which performs better than the previous reported catalysts.On the basis of our previous work on proline catalysts,we extend the types of catalysts from proline to cinchona derivatives in order to verify the extensive applicability of our catalytic recovery method,which can be applied to a variety of organocatalysts.The recovery performance of adamantyl bifunctional cinchona catalyst was then investigated.It was found that the stereoselectivity of the product decreased from 99%to 87%after six runs,which maintained a high catalytic activity.It indicated that our catalyst recovery method is applicable to the cinchona derivative.