| Magnetic nanoparticles(MNPs)have recently appeared as a new type of catalyst support because of their easy preparation and functionalization,large surface area ratio,facile separation via magnetic force as well as low toxicity and price.Knoevenagel condensation constitutes an important carbon carbon double bond forming transformation resulting in the ?,?-unsaturated products,which have been widely used as intermediates in the synthesis of natural products,pharmaceuticals and organic photovoltaic materials.The Michael addition of nucleophile to ?,?-unsaturated carbonyl compounds represents one of the most important carbon-carbon forming reactions in organic synthesis.Therefore,it is great industrial significance to explore the magnetic heterogeneous cyclic catalyst to have a green recyclable catalyst in the catalytic Knoevenagel condensation reaction and the Michael addition reaction.In this paper,Magnetic solid sulfonic acid(MSA)was prepared under mild conditions.The magnetic sulfonic acid was characterized by IR,XRD and elemental analysis to confirm its structure and proton acid loading(0.5 mmol g-1).And the magnetic sulfonic acid respectively with N,N'-dimethyl-1,2-ethanediamine(A1),N1,N1,N2,N2-tetramethylethane-1,2-diamine(A2),4-dimethyl aminopyridine(A3),triethylamine(A4)preparing four kinds of magnetic amine catalysts by acid-base interaction.Four magnetically recirculated amine catalysts were applied in Knoevenagel condensation reaction and Michael addition reaction of chalcone and malononitrile to explore their catalytic performance.1.We use p-chlorobenzaldehyde and ethyl cyanoacetate as a model reaction to test the catalytic activity of the catalyst,and found that the catalyst MSA/A1(1 mol%)achieved the complete conversion of p-chlorobenzaldehyde under optimized conditions,the yield of the target product reached about 100%,catalytic cycling experiments showed that the MSA/A1 catalyst can catalyze 5 times,The deactivated catalyst can be found by washing with 0.01 M H2SO4 and reactivating with N,N'-dimethyl-1,2-ethanediamine(A1),followed by catalytic synthesis of the target product after reactivation again restored.In addition,the catalyst MSA/A1 can also be used in the condensation reaction of different aromatic aldehydes and aliphatic ketones with cyanoethyl acetate and malononitrile.2.We also found that the new catalyst MSA/A3 obtained by non-covalent loading of magnetic solid sulfonic acid(MSA)and 4-dimethylaminopyridine(A3),The catalyst has a good catalytic effect on the Michael addition reaction of chalcone with malononitrile.The addition reaction of chalcone with malononitrile as a model reaction to test the catalytic activity of the catalyst.To our satisfaction,the reaction was smoothly carried out in the presence of MSA/A3(5 mol%)in dichloromethane over 24 hours at room temperature and the corresponding product was obtained in good isolated yield(85%).The catalyst could be easily recycled via magnetic force and reused for up to 3 times with essentially no lose of activity.The synthesis of the target product can be found catalytic efficiency and recovery,once again illustrate the acid-base non-covalently loading is a simple and effective viable loading strategy.3.Bicyclol is a novel synthetic antihepatitis drug for the treatment of chronic hepatitis B patients in China.We designed a new method for the synthesis of bicyclol: we use bifendate as a raw material,alkaline hydrolysis and acidification of biphenyl dianhydride,and then by dehydration to give biphenyl anhydride,It is then esterified by alcoholysis to give biphenyl ester acid,and finally the carboxyl group is selectively reduced to alcohol hydroxyl,obtained bicyclol.The method is the advantages of short route,simple and easy operation,without column chromatography and high yields(the total yields is over 90% in four steps). |
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