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首页> 外文期刊>Chemistry: A European journal >Oxidative ortho CC Coupling of 4-Ethylphenol by Dual Substrate Activation at a Bioinspired Dicopper Complex—Trapping of an Unusual Oligophenolic Cu6 Species
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Oxidative ortho CC Coupling of 4-Ethylphenol by Dual Substrate Activation at a Bioinspired Dicopper Complex—Trapping of an Unusual Oligophenolic Cu6 Species

机译：在生物启发的Dicopper配合物上双底物活化的4-乙基苯酚的氧化邻位CC偶联-罕见的低酚Cu6物种的捕获。

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Oxidative phenol coupling is a valuable transformation and is of great importance in the synthesis of natural products or polymeric materials for resin and coating technologies.[1] Inter alia, oligomeric compounds derived from paracresol were shown to have interesting antioxidant effects and antimicrobial properties.[2] These properties are strongly dependent on the presence of hydroxyl groups in the skeleton of the oligomeric or polymeric phenolic products, and catalysts that selectively mediate the ortho–ortho coupling of para-substituted phenols are thus required. Enzymatic phenol dehydropolymerization mostly relies on oxidoreductases that contain iron or copper within their active sites.[3]Even though our mechanistic understanding of the reactivity patterns of biological copper-containing oxidases is increasing rapidly, successful application of this knowledge to the development of bioinspired synthetic oxidase systems is still in its infancy.[4, 5] Chemically the oxidative ortho-coupling leading to the formation of aryl–aryl bonds is usually achieved with strong oxidants such as FeCl3 or hypervalent iodine reagents. Many stoichiometric or catalytic methods have meanwhile been developed that work well for sterically hindered phenols or 2-naphthol derivatives.[6] Simple phenols such as para-cresol, however, are usually poor substrates because of a lack of regioselectivity, giving not only the desired ortho–ortho linkages but also polycyclic by-products that result from ortho–para coupling with subsequent 1,4-addition (Pummerers ketone).[7] Template-directed approaches using tetraphenoxyborates in electrochemical processes have recently been developed to overcome these problems.[8] In a conceptually related approach, major progress towards the enantioselective coupling of 2-naphthol has been achieved with bimetallic systems that use a dual activation mechanism at dicopper or divanadium complexes.[9, 10] Highly preorganized bimetallic systems that can simultaneously bind and activate two phenol substrates in a way that favors the desired ortho–ortho coupling appear to be promising scaffolds in this respect.
机译：氧化苯酚偶联是一种有价值的转化，在合成用于树脂和涂料技术的天然产物或聚合物材料中具有重要意义。[1]除其他外，衍生自对甲酚的低聚化合物显示出有趣的抗氧化作用和抗菌性能。[2]这些性质很大程度上取决于低聚或聚合酚类产品的骨架中羟基的存在，因此需要选择性介导对位取代酚的邻-邻偶联的催化剂。酶促苯酚脱氢聚合反应主要依赖于在其活性位点内含有铁或铜的氧化还原酶。[3]尽管我们对含铜生物氧化酶生物反应模式的机械理解正在迅速提高，但这一知识已成功地应用于生物启发性合成酶的开发氧化酶系统仍处于起步阶段。[4，5]化学上，导致形成芳基-芳基键的氧化邻位偶联通常是通过强氧化剂如FeCl3或高价碘试剂实现的。同时，已经开发出许多化学计量或催化方法，这些方法对于位阻酚或2-萘酚衍生物均适用。[6]然而，由于缺乏区域选择性，简单的酚（例如对甲酚）通常是较差的底物，不仅提供所需的邻-邻键，而且还提供了邻-对偶联以及随后的1,4-加成产生的多环副产物（Pummerers酮）。[7]为克服这些问题，最近开发了在电化学过程中使用四苯氧基硼酸酯进行模板指导的方法。[8]在一种概念上相关的方法中，在双铜或双钒配合物上使用双重激活机制的双金属系统已经取得了2-萘酚对映选择性偶联的重大进展。[9，10]高度预组织的双金属系统可以同时结合并激活两个在这方面，以有利于期望的邻-邻偶联的方式使用苯酚底物似乎是很有前途的支架。

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