| Pd- and Ni-catalyzed Suzuki-Miyaura cross-coupling reaction is one of the most powerful methods to form carbon-carbon bonds. The reaction proceeds under mild conditions, tolerating a broad range of functionality and yielding few byproducts. Moreover, the organboron reagents are stable in the air and less toxic. In contrast to Pd, Ni complexes show better activity on the catalysis of inactivated chloroarene and their price are much lower, all of which indicate that they are ideal catalysts for Suzuki reaction.Since the Ni catalysts are utilized in Suzuki cross-coupling reaction, various ligands have been developed to achieve the higher efficiency. However, the anion's effect has not been studied in particular. Herein, we used the new catalyst system Ni[N(SO2CF3)2]2/PPh3 to investigate the cross-coupling of phenylboronic acid with inactivated substrate 4-chloroanisole, firstly studying the influence of the anion -N(SO2CF3)2 toward Suzuki coupling reaction.Comparing with NiCl2/PPh3, the anion -N(SO2CF3)2 exhibited much higher activity, especially on case that the amount of the catalyst was reduced. The yield was raised by 12%–30%.Based on the study about the effect of the temperature, it was found that 80℃was optimal. Neither higher nor lower temperature is advantageous to the cross-coupling reaction and the leaving group had little influence on the transmetalation step.The study of the mixing catalysts NiCl2(PPh3)2 and Ni[N(SO2CF3)2]2 revealed that the yield was highly related to the mixing ratio. When NiCl2(PPh3)2 and Ni[N(SO2CF3)2]2 were mixed by 1:1, they can convert the chloroarene completely.In conclusion, the results showed in this thesis suggest that the anion -N(SO2CF3)2 which is often ignored in the past research may play an important role in the catalytic cycle. So it is interesting and worthy to further study how the other special anions, similar to -N(SO2CF3)2, impact the Suzuki reaction and other cross-coupling reactions. |
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