Study On The Tertiary Amines/Phosphines Catalyzed Dimerization Of Electron-deficient Terminal Olefins

The dimerization of electron-deficient olefins is a typical Morita-Baylis-Hillmanreaction (MBH reaction). The MBH reaction is one of the most important ways toconstruct C-C bond atom-economically, which provides access to multi-functionalproducts from simple molecules. The MBH adducts can be transformed intovarious bioactive structures, such as flustraminol、madindoline which are preparedby a MBH adduct β-hydroxyindolin-2-one. However, its imperfections, such assluggish process、poor yield and selectivity, restrict its application in organicsynthesis. In the thesis, we devote ourself to improving the MBH reaction’s efficiencyby optimizing reaction condition systematically and expanding to otherelectron-deficient terminal olefins.Firstly, we chose the dimerization of acrylonitrile as the model reaction toexplore the effects of catalysts and amount、solvents and amount、additives andamount、reaction temperature and other factors systematically in order to improve theefficiency of MBH reaction. We’ve found out the optimal preparation condition of2-methylenepentanedinitrile from acrylonitrile with85%yield based on SimpleVariable Method. To our delight, the yield didn’t lessen almost when the reaction scalewas enlarged to dozens of grams.Next, many terminal enones were prepared to investigate the effects ofsubstance electronic character on the products. We’ve found that the reactionoccured in polar solvent smoothly and tertiary phosphines were more active thantertiary amines, after screening the catalysts、solvents and temperature. The tertiaryamines were more suitable to catalyze the electron-deficient substances, but the softerphosphines were more effective for electron-sufficient substances. More attention, thephosphines didn’t work with regard to electron-abundant substances.Finally, a bioactive tetrahydropyridine was obtained with68%yield. The MBHadduct2-methylene-1,5-diphenylpentane-1,5-dione underwent well in one pot to givemulti-substituted tetrahydropyridine with methyl amine.