Research On The Synthesis Of Indoles And 1,4-dihydropyridine Compounds Involving Enaminones

Enaminones have been widely applied in the synthesis of various nitrogen-containing heterocyclic compounds due to their functional group structure and their unique chemical properties.In order to improve the efficiency and application value of the conversion from enaminones to nitrogen-containing heterocyclic compounds,combined with the research basis of our group,this thesis presented our effort to utilize enaminone-based compounds as key intermediates,followed by iodine catalysis and zirconocene catalysis to afford indole derivatives and 1,4-dihydropyridine derivatives via one-pot multi-component reaction.The main contents and results are displayed as following:1.A methodology for the synthesis of indole derivatives by one-pot of aza-Michael addition/iodine promoted C-H functionalization was developed.The method can efficiently convert aniline and ?,?-alkynone to N-aryl enaminone intermediate by aza-Michael addition reaction,followed by iodine-promoted C-H functionalized oxidative cyclization,30 kinds of indole derivatives were successfully obtained,with the reaction yields up to 99%,21 of which were reported for the first time.The method does not require the separation of the enaminone intermediate,avoids the usage of transition metal catalyst,which provides a reliable choice for preparation of indole derivatives.In addition,a single crystal of enaminone and indole was separately cultured in the study,and the free radical trapping experiments indicates that the reaction is carried out via free radical mechanism.2.Using a 5-nitrosalicylic acid/Cp2ZrCl2 relay synergistic catalytic system,a one-pot method for the efficient synthesis of 1,4-dihydropyridine derivatives was developed.23 1,4-dihydropyridines were successfully prepared with a maximum yield at 96%.The method has the advantages of mild conditions,simple operation and good applicability of the substrate starting from the fatty amine.In-situ 1H NMR and HR-MS techniques were used to study the reaction process and intermediates.The results shows that(1)Cp2ZrCl(OOC)PhOH(5-NO2)is a possible catalytically active species;(2)5-nitrosalicylic acid is not only used as a Bronsted acid to promote the rapid conversion of amine and 1,3-dicarbonyl compounds,but also as a ligand to regulate the lewis acidity of zirconocene,plays an important role in the synergistic catalytic system.