Institut de Recherches sur la Catalyse et l'Environnement de Lyon, IRCELYON, UMR 5256, CNRS Université Lyon 1, 2 Av. Albert Einstein, 69626, Villeurbanne Cedex, France.
The Manchester Institute of Biotechnology and Department of, Chemical Engineering and Analytical Science, The University of, Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
Chemistry. 2019 Nov 13;25(63):14320-14331. doi: 10.1002/chem.201902934. Epub 2019 Sep 10.
The biodegradation of compounds with C-F bonds is challenging due to the fact that these bonds are stronger than the C-H bond in methane. In this work, results on the unprecedented reactivity of a biomimetic model complex that contains an N-bridged diiron-phthalocyanine are presented; this model complex is shown to react with perfluorinated arenes under addition of H O effectively. To get mechanistic insight into this unusual reactivity, detailed density functional theory calculations on the mechanism of C F activation by an iron(IV)-oxo active species of the N-bridged diiron phthalocyanine system were performed. Our studies show that the reaction proceeds through a rate-determining electrophilic C-O addition reaction followed by a 1,2-fluoride shift to give the ketone product, which can further rearrange to the phenol. A thermochemical analysis shows that the weakest C-F bond is the aliphatic C-F bond in the ketone intermediate. The oxidative defluorination of perfluoroaromatics is demonstrated to proceed through a completely different mechanism compared to that of aromatic C-H hydroxylation by iron(IV)-oxo intermediates such as cytochrome P450 Compound I.
由于 C-F 键比甲烷中的 C-H 键更强，因此含 C-F 键的化合物的生物降解具有挑战性。在这项工作中，介绍了一种仿生模型配合物的前所未有的反应性，该模型配合物在添加 H O 的情况下可有效地与全氟芳族化合物反应；为了深入了解这种不寻常的反应性，对 N-桥联二铁酞菁体系中铁(IV)-氧活性物种的 C-F 活化机理进行了详细的密度泛函理论计算。我们的研究表明，反应通过速率决定的亲电 C-O 添加反应进行，然后进行 1,2-氟化物迁移得到酮产物，该产物可以进一步重排为苯酚。热化学分析表明，最弱的 C-F 键是酮中间体中的脂肪族 C-F 键。与铁(IV)-氧中间体（如细胞色素 P450 化合物 I）催化的芳香族 C-H 羟化相比，全氟芳烃的氧化脱氟反应通过完全不同的机制进行。
