A mild, metal-free bromination method of arenes has been developed using the combination of bis(trifluoroacetoxy)iodobencene and trimethylsilyl bromide. In situ-formed dibromo(phenyl)-λ3-iodane (PhIBr2) is proposed as the reactive intermediate. This methodology using PIFA/TMSBr has been applied with success to a great number of substrates (25 examples). The treatment of mono-substituted activated arenes led to para-brominated products (2u-z) in excellent 83-96% yields. Density functional theory calculations indicate a stepwise mechanism involving a double bromine addition followed by a type II dyotropic reaction with concomitant re-aromatization of the six-membered ring.

中文翻译：

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高价碘试剂溴化芳烃的逐步机理。

使用双（三氟乙酰氧基）碘苯苄酯和三甲基甲硅烷基溴化物的组合，开发了一种温和，无金属的芳烃溴化方法。提出了原位形成的二溴（苯基）-λ3-碘（PhIBr2）作为反应中间体。使用PIFA / TMSBr的这种方法已成功应用于大量基材（25个实例）。单取代的活化芳烃的处理产生对溴化产物（2u-z），产率高达83-96％。密度泛函理论计算表明了一种逐步机理，该机理涉及添加双溴，然后进行II型正离子反应，并伴随六元环的重新芳构化。