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Chemoselective Aliphatic C–H Bond Oxidation Enabled by Polarity Reversal
ACS Central Science ( IF 12.7 ) Pub Date : 2017-12-13 00:00:00 , DOI: 10.1021/acscentsci.7b00532
Valeria Dantignana 1 , Michela Milan 1 , Olaf Cussó 1 , Anna Company 1 , Massimo Bietti 2 , Miquel Costas 1
Affiliation  

Methods for selective oxidation of aliphatic C–H bonds are called on to revolutionize organic synthesis by providing novel and more efficient paths. Realization of this goal requires the discovery of mechanisms that can alter in a predictable manner the innate reactivity of these bonds. Ideally, these mechanisms need to make oxidation of aliphatic C–H bonds, which are recognized as relatively inert, compatible with the presence of electron rich functional groups that are highly susceptible to oxidation. Furthermore, predictable modification of the relative reactivity of different C–H bonds within a molecule would enable rapid diversification of the resulting oxidation products. Herein we show that by engaging in hydrogen bonding, fluorinated alcohols exert a polarity reversal on electron rich functional groups, directing iron and manganese catalyzed oxidation toward a priori stronger and unactivated C–H bonds. As a result, selective hydroxylation of methylenic sites in hydrocarbons and remote aliphatic C–H oxidation of otherwise sensitive alcohol, ether, amide, and amine substrates is achieved employing aqueous hydrogen peroxide as oxidant. Oxidations occur in a predictable manner, with outstanding levels of product chemoselectivity, preserving the first-formed hydroxylation product, thus representing an extremely valuable tool for synthetic planning and development.

中文翻译:

通过极性反转实现化学选择性脂肪族CH键的氧化

通过提供新颖,更有效的途径,人们呼吁采用脂肪族CH键选择性氧化的方法来彻底改变有机合成方法。要实现这一目标,就需要发现能够以可预测的方式改变这些键的先天反应性的机制。理想情况下,这些机制需要使脂族C–H键氧化,该键被认为是相对惰性的,与高度易被氧化的富电子官能团的存在相容。此外,对分子中不同CH键的相对反应性进行可预测的修饰,将使所得氧化产物快速多样化。在这里,我们表明,通过参与氢键作用,氟化醇对富含电子的官能团产生了极性反转,指导铁和锰催化的氧化朝着先验的更强和未激活的CH键结合。结果,使用过氧化氢水溶液作为氧化剂,可以实现碳氢化合物中亚甲基位点的选择性羟基化,以及对否则敏感的醇,醚,酰胺和胺类底物的脂肪族CH远程氧化。氧化以可预测的方式发生,具有优异的产物化学选择性水平,保留了第一个形成的羟基化产物,因此代表了用于合成规划和开发的极有价值的工具。用过氧化氢水溶液作氧化剂可得到胺底物。氧化以可预测的方式发生,具有优异的产物化学选择性水平,保留了第一个形成的羟基化产物,因此代表了用于合成规划和开发的极有价值的工具。用过氧化氢水溶液作氧化剂可得到胺底物。氧化以可预测的方式发生,具有优异的产物化学选择性水平,保留了第一个形成的羟基化产物,因此代表了用于合成规划和开发的极有价值的工具。
更新日期:2017-12-13
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