Nature Chemistry ( IF 19.2 ) Pub Date : 2022-01-31 , DOI: 10.1038/s41557-021-00869-x
Xiang Li 1, 2 , Jianbo Jin 1 , Pinhong Chen 1 , Guosheng Liu 1, 2
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Primary alkyl halides have broad utility as fine chemicals in organic synthesis. The direct halogenation of alkenes is one of the most efficient approaches for the synthesis of these halides. Internal alkenes, in particular mixtures of isomers from refineries, constitute readily available and inexpensive feedstock and are the most attractive starting materials for this synthesis. However, the hydrohalogenation of alkenes generally affords branched alkyl halides; there are no catalytic methods to prepare linear alkyl halides directly from internal alkenes, let alone from a mixture of alkene isomers. Here we report the remote oxidative halogenation of alkenes under palladium catalysis via which both terminal and internal alkenes yield primary alkyl halides efficiently. Engineering pyridine-oxazoline ligands by introducing a hydroxyl group is essential for achieving excellent chemo- and regioselectivity. The catalytic system is also good for the mixture of alkene isomers generated from dehydrogenation of alkanes, providing a window to investigate the high-value utilization of inexpensive alkanes.
中文翻译:
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内烯烃催化远程卤化氢
伯烷基卤化物在有机合成中作为精细化学品具有广泛的用途。烯烃的直接卤化是合成这些卤化物的最有效方法之一。内部烯烃,特别是来自炼油厂的异构体混合物,构成了容易获得且廉价的原料,并且是该合成最有吸引力的起始材料。然而,烯烃的卤化氢通常会产生支链烷基卤化物。没有直接从内部烯烃制备直链烷基卤化物的催化方法,更不用说从烯烃异构体的混合物中制备了。在这里,我们报告了在钯催化下烯烃的远程氧化卤化,末端和内部烯烃都可以有效地产生伯烷基卤化物。通过引入羟基来设计吡啶-恶唑啉配体对于实现出色的化学和区域选择性至关重要。该催化体系也适用于烷烃脱氢生成的烯烃异构体混合物,为研究廉价烷烃的高价值利用提供了窗口。