Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
J Am Chem Soc. 2012 Mar 28;134(12):5480-3. doi: 10.1021/ja300326t. Epub 2012 Mar 13.
Mechanistic studies of the hydrogenolysis of aryl ethers by nickel were undertaken with (diphosphine)aryl methyl ethers. A Ni(0) complex containing Ni-arene interactions adjacent to the aryl-O bond was isolated. Heating led to aryl-O bond activation and generation of a nickel aryl methoxide complex. Formal β-H elimination from this species produced a nickel aryl hydride which can undergo reductive elimination in the presence of formaldehyde to generate a carbon monoxide adduct of Ni(0). The reported complexes map out a plausible mechanism of aryl ether hydrogenolysis catalyzed by nickel. Investigations of a previously reported catalytic system using isotopically labeled substrates are consistent with the mechanism proposed in the stoichiometric system, involving β-H elimination from a nickel alkoxide rather than cleavage of the Ni-O bond by H(2).
采用（二膦基）芳基甲基醚对镍催化芳基醚氢解的机理进行了研究。分离出了含有芳基-O 键相邻镍-芳烃相互作用的 Ni(0)配合物。加热导致芳基-O 键活化，并生成镍芳基甲氧基配合物。该物种的形式β-H 消除生成镍芳基氢化物，该氢化物在甲醛存在下可进行还原消除，生成 Ni(0)的一氧化碳加合物。所报道的配合物描绘了镍催化芳基醚氢解的合理机理。使用同位素标记的底物对先前报道的催化体系的研究与所提出的计量体系的机理一致，涉及镍烷氧基的β-H 消除，而不是 H(2)对 Ni-O 键的断裂。
