College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, Hubei, China.
State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.
Nat Commun. 2017 Oct 3;8(1):775. doi: 10.1038/s41467-017-00873-1.
Intermolecular [3 + 2] annulation is one of the most straightforward approaches to construct five membered heterocycles. However, it generally requires the use of functionalized substrates. An ideal reaction approach is to achieve dehydrogenative [3 + 2] annulation under oxidant-free conditions. Here we show an electrooxidative [3 + 2] annulation between phenols and N-acetylindoles under undivided electrolytic conditions. Neither external chemical oxidants nor metal catalysts are required to facilitate the dehydrogenation processes. This reaction protocol provides an environmentally friendly way for the selective synthesis of benzofuroindolines. Various N-acetylindoles bearing different C-3 and C-2 substituents are suitable in this electrochemical transformation, furnishing corresponding benzofuroindolines in up to 99% yield.Electrochemical oxidation provides a green alternative to the use of hazardous chemical oxidants and forcing conditions. Here, the authors show the electrocatalytic cross-coupling of phenols and indoles to generate biologically relevant benzofuroindolines in high yields.
分子间[3+2]环加成是构建五元杂环的最直接方法之一。然而，它通常需要使用功能化的底物。理想的反应方法是在无氧化剂条件下实现脱氢[3+2]环加成。在这里，我们展示了在非分隔电解条件下酚类和 N-乙酰吲哚之间的电氧化[3+2]环加成。不需要外部化学氧化剂或金属催化剂来促进脱氢过程。该反应方案为选择性合成苯并呋喃并吲哚啉提供了一种环保的方法。各种带有不同 C-3 和 C-2 取代基的 N-乙酰吲哚都适合这种电化学转化，以高达 99%的收率得到相应的苯并呋喃并吲哚啉。电化学氧化为使用危险化学氧化剂和强制条件提供了一种绿色替代方案。在这里，作者展示了电催化酚类和吲哚的交叉偶联，以高产率生成生物相关的苯并呋喃并吲哚啉。
