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Iridium-catalysed arylation of C–H bonds enabled by oxidatively induced reductive elimination
Nature Chemistry ( IF 21.8 ) Pub Date : 2017-12-11 , DOI: 10.1038/nchem.2900
Kwangmin Shin , Yoonsu Park , Mu-Hyun Baik , Sukbok Chang

Direct arylation of C–H bonds is in principle a powerful way of preparing value-added molecules that contain carbon–aryl fragments. Unfortunately, currently available synthetic methods are not sufficiently effective to be practical alternatives to conventional cross-coupling reactions. We propose that the main problem lies in the late portion of the catalytic cycle where reductive elimination gives the desired carbon–aryl bond. Accordingly, we have developed a strategy where the Ir(III) centre of the key intermediate is first oxidized to Ir(IV). Density functional theory calculations indicate that the barrier to reductive elimination is reduced by nearly 19 kcal mol–1 for this oxidized complex compared with that of its Ir(III) counterpart. Various experiments confirm this prediction, affording a new methodology capable of directly arylating C–H bonds at room temperature with a broad substrate scope and in good yields. This work highlights how the oxidation states of intermediates can be targeted deliberately to catalyse an otherwise impossible reaction.



中文翻译:

铱诱导的C–H键芳基化通过氧化诱导的还原消除实现

原则上,C–H键的直接芳基化是制备包含碳-芳基片段的增值分子的有效方法。不幸的是,当前可用的合成方法不足以有效替代常规的交叉偶联反应。我们认为主要的问题在于催化循环的后期,在该阶段的还原消除会产生所需的碳芳基键。因此,我们制定了一种策略,其中关键中间体的Ir(III)中心首先被氧化为Ir(IV)。密度泛函理论计算表明,与Ir(III)相比,该氧化配合物的还原消除势垒降低了近19 kcal mol –1)对应对象。各种实验证实了这一预测,提供了一种新的方法,该方法能够在室温下直接芳构化CH键,具有广泛的底物范围,并具有良好的收率。这项工作强调了中间体的氧化态如何可以有针对性地定向以催化原本不可能的反应。

更新日期:2017-12-11
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