Preparation And Characterization Of A Series Of Tertiary 4-substitued Benzylamine Cyclopalladated Complexes And Its Application In Heck And Suzuki Reactions

In this dissertation, a number of tertiary 4-substitued benzylamine cyclopalladated complexes have been prepared, characterized, and applied to catalyze the Heck reaction and Suzuki coupling reaction. The study is aimed to further widen the application of cyclopalladated complexes and look for high effective catalysts for coupling reaction. The dissertation consists of three parts: 1) The preparation and characterization of series tertiary 4-substitued benzylamine cyclopalladated complexes; 2) Study on the structure-effect relations of the tertiary 4-substitued benzylamine cyclopalladated complexes in Heck reaction and Suzuki coupling reaction; 3) Study of the co-catalytic Suzuki coupling reaction with dihydroimidazole/cyclopalladated complexes as co-catalysts.Part â… . A series of tertiary 4-substitued benzylamine cyclopalladated complexes were designed and prepared by the reaction of 4-substituted N,N-dimethylbenzylamine with Li₂PdCl₄. The 4-substituent groups include NO₂, CH₃, CO₂Et, Cl, F, OMe, NMe₂ etc. All the complexes were characterized by ¹H NMR, ¹³C NMR, IR, MS, and elemental analysis. Furthermore, the structures of the 4-Cl, 4-F, 4-EtOCO substituted complexes have been confirmed by X-ray diffraction. The crystal data showed that the different substituent groups influenced the bond length of Pd-C, which were relatively shorter in the complexes substituted by electron-withdrawing groups such as 4-Cl, 4-F, 4-EtOCO, and longer when substituted by 4-MeO, an electron-donating group. The physical properties investigation of all the complexes showed that the electronic effect also influenced the decomposition temperature, which were relatively lower when substituted by electron-donating group, such as 4-OMe and 4-CH₃, and higher when substituted by electron-withdrawing groups such as 4-Cl, 4-F, 4- EtOCO. All of the above-mentioned results provided some evidence for the catalytic mechanism and the relationship between catalytic activities with stable stability of the complexes.Part â…¡. The prepared six cyclopalladated complexes have been applied to Heck reaction and Suzuki coupling reaction. The results showed that 4-OMe substituted cyclopalladated complex was the most effective catalyst for the Heck reaction when using iodobenzene with butyl acrylic as the model reaction. It was suggested that the relatively lower stable stability of the 4-OMe substituted complex was the main reason which lead to the cleavage of Pd-C and produce Pd (0) easily. In addition, it...