The Study On The Knoevenagel Condensation Catalyzed By Samarium Triiodide

Knoevenagel reaction is the condensation reaction of activated methylene compounds with aldehydes or ketones,which is one of the important methods to form carbon-carbon double bonds.It is widely used in organic synthesis.This reaction was usually carried out by the base catalysts.Lewis acidsused as catalysts to catalyze the condensation werealso reported,but lessthan base catalysts.The first chapter was the literature review,and the application and properties of samarium,samarium diiodide and samarium triiodide were described in detail,and the research on Knoevenagel condensation reaction was also introduced briefly.In the second chapter,the Knoevenagel condensation reaction of malononitrile and diethyl malonate with aldehydes was studied under the catalysis of samarium triiodide.It was found that the condensation reaction of malononitrile and aromatic aldehydes was easier to carry out.No matter the electron-withdrawing substituents or the electron-donating aromatic aldehydes,the yield of the products was high,and the heterocyclic aldehydes could be also obtained a high yield of the condensation products.However,when a ketone or aliphatic aldehyde was used to react with malononitrile,the corresponding condensation product was hardly obtained.The aromatic aldehydes and diethyl malonate of relatively low reactivity can also be carried out Knoevenagel condensation reaction smoothly.The aromatic aldehydes of the electron-withdrawing substituents had a higher yield product than the electron-donating aromatic aldehydes.In the third chapter,the condensation of active methylene compounds and aromatic aldehydes Knoevenagel catalyzed by samarium triiodide was studied further.It was found that by adjusting the reaction conditions,other products could be obtained based on the Knoevenagel condensation.Catalyzed by SmI₃,Knoevenagel-Michael tandem products were obtained by one pot,when the the dosage of diethyl malonate was 2 times that of aldehyde.Knoevenagel-Michael-Aldol products were obtained by one pot,when the dosage of ethyl acetoacetate was 2 times that of aldehyde.Knoevenagel-Michael-Aldol-dehydrogenation tandem products were obtained by one pot,when the dosage of acetylacetone was 2 times that of aldehyde.The reaction process was discussed and the possible reaction mechanism was put forward in this paperThe compounds were characterized by ¹H NMR and ¹³ C NMR,The characterization data and maps of the products were given in Appendix.