Resting state and elementary steps of the coupling of aryl halides with thiols catalyzed by alkylbisphosphine complexes of palladium.
Resting state and elementary steps of the coupling of aryl halides with thiols catalyzed by alkylbisphosphine complexes of palladium.
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DOI：
10.1021/ja901793w
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发表时间：
2009-06-10
影响因子：
15
通讯作者：
Hartwig JF
中科院分区：
文献类型：
--
作者：
Alvaro E;Hartwig JF
报道了烷基双膦配体CyPF-tBu（1-二环己基膦基-2-二叔丁基膦基乙基二茂铁）的钯配合物催化芳基卤与硫醇偶联反应的详细机理研究。构成催化循环的基本步骤，即氧化加成，金属转移和还原消除，已被研究，并报告其相对速率。催化过程的每个步骤都在比由钯前体和CyPF-tBu的组合催化的反应所需的温度低得多的温度下发生。为了解释催化反应和化学计量反应之间的这些速率差异，进行研究以鉴定由Pd（OAc）2和CyPF-tBu的组合、Pd（dba）2和CyPF-tBu的组合或可能的中间体Pd（CyPF-tBu）（Ar）（Br）催化的反应的催化剂的静止状态。这些表明，在每种情况下，主要的钯络合物都不在催化循环中。Pd（OAc）2和CyPF-tBu催化的反应的静止态为双硫醇钯配合物[Pd（CyPF-tBu）（SR）2]（R =烷基或芳基）。Pd 2（dba）3和CyPF-tBu催化的反应中的静止状态是双核配合物[Pd（CyPF-tBu）]2（μ2，η2-dba）（9）。[Pd（CyPF-tBu）（p-tolyl）（Br）]（3a）催化芳香族和脂肪族硫醇反应的静止状态为钯硫醇盐配合物[Pd（CyPF-tBu）（H）（SR）]（R=烷基和芳基）。所有这些钯物种已独立制备，并详细研究了它们进入催化循环的机制。这些特征的反应催化的钯和CyPF-tBu已被比较的烷基双膦DiPPF和Pd（乙酸乙酯）2或Pd（dba）2催化的反应。我们的数据表明，这些反应的静止状态是彼此相似的，我们的机制的结论，钯和CyPF-tBu催化的反应可以外推到其他富电子的双膦络合物催化的反应。
Detailed mechanistic studies on the coupling of aryl halides with thiols catalyzed by palladium complexes of the alkylbisphosphine ligand CyPF-tBu (1-dicyclohexylphosphino-2-di-tert-butylphosphinoethylferrocene) are reported. The elementary steps that constitute the catalytic cycle, i.e. oxidative addition, transmetalation and reductive elimination, have been studied, and their relative rates are reported. Each of the steps of the catalytic process occurs at temperatures that are much lower than those required for the reactions catalyzed by a combination of palladium precursors and CyPF-tBu. To explain these differences in rates between the catalytic and stoichiometric reactions, studies were conducted to identify the resting state of the catalyst of the reactions catalyzed by a combination of Pd(OAc)2 and CyPF-tBu, a combination of Pd(dba)2 and CyPF-tBu, or the likely intermediate Pd(CyPF-tBu)(Ar)(Br). These show that the major palladium complex in each case lies off of the catalytic cycle. The resting state of the reactions catalyzed by Pd(OAc)2 and CyPF-tBu was the palladium bis-thiolate complex [Pd(CyPF-tBu)(SR)2] (R = alkyl or aryl). The resting state in reactions catalyzed by Pd2(dba)3 and CyPF-tBu was the binuclear complex [Pd(CyPF-tBu)]2(μ2, η2-dba) (9). The resting state of reactions of both aromatic and aliphatic thiols catalyzed by [Pd(CyPF-tBu)(p-tolyl)(Br)] (3a) was the hydridopalladium thiolate complex [Pd(CyPF-tBu)(H)(SR)] (R= alkyl and aryl). All these palladium species have been prepared independently, and the mechanisms by which they enter the catalytic cycle have been examined in detail. These features of the reaction catalyzed by palladium and CyPF-tBu have been compared with those of reactions catalyzed by the alkylbisphosphine DiPPF and Pd(OAc)2 or Pd(dba)2. Our data indicate that the resting states of these reactions are similar to each other and that our mechanistic conclusions about reactions catalyzed by palladium and CyPF-tBu can be extrapolated to reactions catalyzed by complexes of other electron-rich bisphosphines.
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影响因子：
1.8
作者：
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通讯作者：
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