Study On The Asymmetric Michael Addition Reaction Catalyzed By Resin-supported Catalyst Based On(1R,2R)-(+)-(1,2)-DPEN

Chiral is a widespread phenomenon in nature,which is closely related to human relations,especially in the field of biological medicine.In recent years,the small organic molecule catalyst has been a part of the rapid development in the synthesis of chiral molecules,which has the advantages of simplicity and high atomic economy.Michael addition reaction is an important carbon-carbon bond in the synthesis of asymmetric synthesis,and is also a hot research topic in this field.As for asymmetric Michael addition reaction,at present,many small organic molecule catalysts have been reported,such as L-proline or diamine derivatives.But most of them existed a variety of problems and still needed to be improved.In addition,these kind of organic small molecule catalysts were mostly homogeneous catalysts.So there were many kinds of problems such as the complexity of reaction treatment,the difficulty of recycling the catalyst,or the poor universality of the catalyst in the reaction of aldehyde and ketone,especially the asymmetric Michael addition reaction of acetone and nitrostyrene.Aimed at these,this paper carried out a series of studies to improve and solve the above problems.This study is based on(1R,2R)-(+)-(1,2)-diphenylethylenediamine((1R,2R)-(+)-(1,2)-DPEN)as the core of chiral organic small molecular catalysis.Through a series of resin type vector selection(Wang resin,D380,D382),and the choice of a series of connected groups(triazine ring,etc.),the chiral organic small molecule catalyst was immobilized onto the corresponding vector by means of chemical bonding,making the heterogeneous catalyst prepared.The asymmetric Michael reaction of acetone and ?-nitrostyrene was chosen as the template for the evaluation of the catalyst.The solid supported heterogeneous catalysts showed satisfactory catalytic activity and the enantioselectivity.So we improved the supported catalyst,and selected trimesoyl chloride as the linkage between Wang resin and(1R,2R)-(+)-(1,2)-DPEN,and a new type of supported catalyst with better catalytic effect was obtained.Then these supported catalysts were characterized by thermogravimetric analysis(TG),Fourier Transform Infrared Spectoscopy(FT-IR),element analysis,and XPS.Results showed the presence of amide groups,ester,amino group and a considerable amount of(1R,2R)-(+)-(1,2)-DPEN was successfully immobilized onto the surface of the resin.In addition,this paper also carried out the optimization of the reaction parameters of the asymmetric Michael reaction of acetone and ?-nitrostyrene on the supported catalyst: acetone and ?-nitrostyrene molar ratio of 10:1,catalyst dosage 0.05 g,toluene,substrate concentration of 0.1 mol/L(in terms of ?-nitrostyrene),25?,90 h.The conversion of ?-nitrostyrene was 76.1%,with ee of 93.8%.Combined with a series of characterization analysis and reaction results,the catalytic mechanism was supposed.Besides,we also study the universality of the catalysts for the asymmetric Michael reaction of acetone and different derivatives of ?-nitrostyrene.The satisfactory results showed that the heterogeneous catalysts had a good universality.In this paper,the supported catalysts were tested for the continuous catalytic reaction,and the ideal catalytic effect was obtained.As for the heterogeneous catalysts,the treatment of the reaction and the recycling of the catalyst only need to make the reactionmixture filtered,which provides a new idea for the future industrialization.