Unitat de Recerca en Síntesi Asimètrica (URSA)-PCB, Institute for Research in Biomedicine (IRB) Barcelona and Departament de Química Orgànica, Universitat de Barcelona, c/Baldiri Reixac 10, 08028 Barcelona, Spain.
Chemistry. 2010 Jul 26;16(28):8340-6. doi: 10.1002/chem.201000357.
An alkyne tetracarbonyl dicobalt complex with a chelated phosphine-alkene ligand, in which the phosphorus atom and the alkene from the ligand are attached to the same cobalt atom has been prepared, isolated, and characterized by X-ray crystallography. The complex serves as a mechanistic model for an intermediate of the Pauson-Khand (PK) reaction. Although the alkene fragment is located in an equatorial coordination site with an appropriate orientation, and, therefore, should undergo insertion, it failed to give the PK product upon either thermal or N-methylmorpholine N-oxide activation. However, a phosphine-alkene complex that contains a terminal alkene readily provided the corresponding PK product. We attribute this change in reactivity to the different ability of each olefin to undergo 1,2-insertion. These results provide further insights into the factors that govern a crucial step in the PK reaction, the olefin insertion.
已经制备、分离并通过 X 射线晶体学进行了表征一种具有螯合膦-烯烃配体的炔基四羰基二钴配合物，其中磷原子和配体的烯烃连接到同一个钴原子上。该配合物可用作 Pauson-Khand (PK) 反应中间体的机理模型。尽管烯烃片段位于具有适当取向的赤道配位位，因此应该进行插入，但无论是在热或 N-甲基吗啉 N-氧化物的激活下，都未能得到 PK 产物。然而，含有末端烯烃的膦-烯烃配合物很容易提供相应的 PK 产物。我们将这种反应性的变化归因于每种烯烃进行 1,2-插入的不同能力。这些结果为控制 PK 反应中关键步骤（烯烃插入）的因素提供了进一步的认识。
