for cross-coupling. In this work, 14 nickel(II) precatalysts of the form (dppf)Ni(aryl)(X) (dppf = 1,1′-bis(diphenylphosphino)ferrocene, X = Cl, Br) were synthesized. In particular, both the electronic and steric properties of the aryl group were modified to understand how this affects precatalyst activation. Using EPR spectroscopy, it was demonstrated that the amount of off-cycle nickel(I) species
目前,人们对开发用于交叉偶联的高效
镍预催化剂有着极大的兴趣。在这项工作中,合成了14种形式为(dppf)Ni(芳基)(X)(dppf = 1,1'-双(
二苯基膦基)
二茂铁,X = Cl,Br)的
镍(II)预催化剂。特别地,对芳基的电子和位阻性质都进行了修饰,以了解其如何影响前催化剂的活化。使用EPR光谱,证明了在预催化剂活化过程中,通过歧化作用形成的循环外
镍(I)种类的数量根据芳基的性质而变化。例如,空间上大体积的芳基减少了歧化。此外,在五种不同的Suzuki-Miyaura偶联反应中评估了预催化剂家族的催化活性。