Department of Chemistry, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
J Am Chem Soc. 2010 May 12;132(18):6302-3. doi: 10.1021/ja102172m.
We report a series of palladium diarylamido complexes containing a cyclometalated phosphine ligand and a coordinated THF that form enamine products from migratory insertion of ethylene and octene into the metal-nitrogen bond. The reactions of these complexes were sensitive to the electronic properties of the diarylamido group. The complex with the more electron-donating amido ligand reacted nearly 2 orders of magnitude faster than the complex with the least electron-donating amido group. The mechanism of the reactions with alkenes involves exchange of olefin for THF, as revealed by the positive order of the reaction in alkene and inverse order in the concentration of THF. A syn-aminopalladation that would result from migratory insertion was revealed by the stereochemistry of the enamine product resulting from reaction with cis-ethylene-d(2). Finally, a three-coordinate THF-free species was isolated from a synthesis of the amido complex in aromatic solvents, and spectroscopic evidence for an ethylene amido species was gained, in part by the addition of H(2)(13)C=(13)CH(2) to the three-coordinate amido complex at -100 degrees C.
我们报告了一系列钯二芳基酰胺配合物，其中含有一个环金属化膦配体和一个配位的四氢呋喃（THF），它们可以通过乙烯和辛烯的迁移插入到金属-氮键中形成烯胺产物。这些配合物的反应对二芳基酰胺基团的电子性质敏感。具有供电子酰胺配体的配合物的反应速度比具有最少供电子酰胺基团的配合物快近 2 个数量级。与烯烃的反应机制涉及烯烃与 THF 的交换，这可以通过在烯烃中的正反应级数和 THF 浓度的逆反应级数来揭示。由顺式-乙烯-d(2)与反应生成的烯胺产物的立体化学揭示了迁移插入会导致顺式-氨基钯化。最后，在芳香族溶剂中合成酰胺配合物时，从合成中分离出了一个无 THF 的三配位物种，并通过在 -100°C 下将 H(2)(13)C=(13)CH(2)添加到三配位的酰胺配合物中来获得乙烯氨基物种的光谱证据。
