Institute of Chemical Research of Catalonia, The Barcelona Institute of Science and Technology, Avgda. Països Catalans 16, 43007, Tarragona, Spain.
Department de Química, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
Chemistry. 2018 Aug 22;24(47):12383-12388. doi: 10.1002/chem.201800627. Epub 2018 Apr 25.
DFT calculations were applied to study the oxidative coupling between benzoic acid and 1-phenyl-1-propyne catalyzed by [CpRhCl ] (Cp=cyclopentadienyl) by using either Cu(OAc) (H O) or Ag(OAc) as the terminal oxidant, a process that has been experimentally shown to have subtleties related to regioselectivity (placement of the phenyl substituent of the alkyne in the isocoumarin product) and chemoselectivity (isocoumarin or naphthalene derivatives). Calculations reproduced the experimental results and showed the involvement of the oxidant throughout the catalytic cycle. The regioselectivity was found to be decided in the alkyne insertion step, in particular by the relative arrangement of the two phenyl groups. The high chemoselectivity towards isocoumarin associated to Cu(OAc) (H O) could be explained by the fact that the copper moiety blocks the CO extrusion pathway, which would lead to naphthalene derivatives, something that does not happen if Ag(OAc) is used.
我们运用密度泛函理论（DFT）计算，研究了[CpRhCl]（Cp=环戊二烯基）催化下，苯甲酸和 1-苯基-1-丙炔的氧化偶联反应，其中 Cu(OAc)（H2O）或 Ag(OAc)作为末端氧化剂。该过程在实验中表现出与区域选择性（炔烃中苯基取代基在异香豆素产物中的位置）和化学选择性（异香豆素或萘衍生物）有关的细微差别。计算结果重现了实验结果，并表明氧化剂在整个催化循环中都有参与。区域选择性是在炔烃插入步骤中决定的，特别是两个苯基的相对排列。与 Cu(OAc)（H2O）相比，Ag(OAc)对异香豆素具有较高的化学选择性，这可以解释为铜部分阻止了 CO 脱除途径，否则会导致萘衍生物，而如果使用 Ag(OAc)则不会发生这种情况。
