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首页> 外文期刊>Organometallics >Bis(dialkylphosphino)ferrocene-Ligated Nickel(II) Precatalysts for Suzuki-Miyaura Reactions of Aryl Carbonates
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Bis(dialkylphosphino)ferrocene-Ligated Nickel(II) Precatalysts for Suzuki-Miyaura Reactions of Aryl Carbonates

机译：双（二烷基膦铝）二茂铁镍（II）含碳酸芳基的铃木 - 霉果反应的预催化剂

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摘要

Aryl carbonates, a common protecting group in synthetic organic chemistry, are potentially valuable electrophiles in cross-coupling reactions. Here, after performing a thorough evaluation of different precatalysts, we demonstrate that (dcypf)Ni(2-ethylphenyl)(Br) (dcypf = 1,1-bis-(dicyclohexylphosphino)ferrocene) is an efficient precatalyst for Suzuki-Miyaura reactions using a variety of aryl carbonates as substrates. Mechanistic studies indicate that (dcypf)Ni(2-ethylphenyl)(Br), which contains a bidentate phosphine that binds in a trans geometry, is an effective precatalyst for these reactions for two reasons: (i) it rapidly forms the Ni(0) active species and (ii) it minimizes comproportionation reactions between the Ni(0) active species and both the unactivated Ni(II) precatalyst and on-cycle Ni(II) complexes to form catalytically inactive Ni(I) species. In contrast, the state of the art precatalyst (dppf)Ni(o-tolyl)(Cl) (dppf = 1,1-bis(diphenylphosphino)ferrocene), which contains a bidentate phosphine that binds in a cis geometry, forms Ni(I) species during activation and is essentially inactive for aryl carbonate couplings. Although the exact reasons on a molecular level why the dcypf system is more active than the dppf system are unclear, our results indicate that in general Ni catalysts supported by the dcypf ligand will give better performance for catalytic reactions involving substrates which undergo relatively slow oxidative addition, such as aryl carbonates.
机译：碳酸芳基，合成有机化学中的共同保护基团是潜在的交叉偶联反应中的有价值的亲电子剂。在此，在进行对不同预催化剂的彻底评估后，我们证明（DCYPF）Ni（2-乙基苯基）（BR）（DCYPF = 1,1-双 - （二环己基膦基）二茂铁是使用的有效预催化剂使用各种碳酸芳基作为基材。机械研究表明（DCYPF）Ni（2-乙基苯基）（BR），其含有在反式几何形状中结合的二齿膦，是这些反应的有效预催化剂，原因有两个：（i）它迅速形成Ni（0 ）活性种和（ii）它最大限度地减少（0）活性种和两个未活化的Ni（II）预催化剂和导通周期的Ni（II）络合物在Ni之间的反应歧化以形成催化活性的Ni（I）的物种。相反，最先版预催化剂（DPPF）Ni（O-甲苯基）（CL）（DPPF = 1,1-双（二苯基膦基）二茂铁），其含有在顺式几何形状中结合的二齿膦（ i）活化期间的物种，对于碳酸芳基偶联基本上是无活性的。虽然分子水平的确切原因是DCYPF系统比DPPF系统更加有效，但我们的结果表明，在DCYPF配体支持的一般NI催化剂中，将为涉及经过相对缓慢的氧化添加的基材的催化反应提供更好的性能，例如碳酸芳基。

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