Woolley Matthew, Ariafard Alireza, Khairallah George N, Kwan Kim H, Donnelly Paul S, White Jonathan M, Canty Allan J, Yates Brian F, O'Hair Richard A J
School of Chemistry, ‡Bio21 Institute of Molecular Science and Biotechnology, and §ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, The University of Melbourne , Melbourne, Victoria 3010, Australia.
J Org Chem. 2014 Dec 19;79(24):12056-69. doi: 10.1021/jo501886w. Epub 2014 Oct 20.
Gas-phase carbon-carbon bond forming reactions, catalyzed by group 10 metal acetate cations (phen)M(O2CCH3) (where M = Ni, Pd or Pt) formed via electrospray ionization of metal acetate complexes [(phen)M(O2CCH3)2], were examined using an ion trap mass spectrometer and density functional theory (DFT) calculations. In step 1 of the catalytic cycle, collision induced dissociation (CID) of (phen)M(O2CCH3) yields the organometallic complex, (phen)M(CH3), via decarboxylation. (phen)M(CH3) reacts with allyl acetate via three competing reactions, with reactivity orders (% reaction efficiencies) established via kinetic modeling. In step 2a, allylic alkylation occurs to give 1-butene and reform metal acetate, (phen)M(O2CCH3), with Ni (36%) > Pd (28%) > Pt (2%). Adduct formation, (phen)M(C6H11O2), occurs with Pt (24%) > Pd (21%) > Ni(11%). The major losses upon CID on the adduct, (phen)M(C6H11O2), are 1-butene for M = Ni and Pd and methane for Pt. Loss of methane only occurs for Pt (10%) to give (phen)Pt(C5H7O2). The sequences of steps 1 and 2a close a catalytic cycle for decarboxylative carbon-carbon bond coupling. DFT calculations suggest that carbon-carbon bond formation occurs via alkene insertion as the initial step for all three metals, without involving higher oxidation states for the metal centers.
通过金属乙酸盐配合物[(phen)M(O₂CCH₃)₂]的电喷雾电离形成的第10族金属乙酸根阳离子[(phen)M(O₂CCH₃)]⁺（其中M = Ni、Pd或Pt）催化的气相碳-碳键形成反应，使用离子阱质谱仪和密度泛函理论（DFT）计算进行了研究。在催化循环的第1步中，[(phen)M(O₂CCH₃)]⁺的碰撞诱导解离（CID）通过脱羧产生有机金属配合物[(phen)M(CH₃)]⁺。[(phen)M(CH₃)]⁺通过三个竞争反应与乙酸烯丙酯反应，通过动力学建模确定了反应活性顺序（反应效率%）。在第2a步中，发生烯丙基烷基化生成1-丁烯并重新形成金属乙酸盐[(phen)M(O₂CCH₃)]⁺，其中Ni（36%）> Pd（28%）> Pt（2%）。加合物形成[(phen)M(C₆H₁₁O₂)]⁺，其中Pt（24%）> Pd（21%）> Ni（11%）。加合物[(phen)M(C₆H₁₁O₂)]⁺在CID时的主要损失，对于M = Ni和Pd是1-丁烯，对于Pt是甲烷。仅Pt（10%）会发生甲烷损失，生成[(phen)Pt(C₅H₇O₂)]⁺。第1步和第2a步的顺序完成了脱羧碳-碳键偶联的催化循环。DFT计算表明，碳-碳键形成是通过烯烃插入作为所有三种金属的初始步骤，而不涉及金属中心的更高氧化态。
