Herein, we describe a high yielding approach towards the synthesis of 3‐amino‐indoles and ‐benzofurans through 6π‐electrocyclization. This was made possible by taking advantage of the high reactivity of keteniminium salts, formed in‐situ by treating with triflic anhydride and 2‐fluoropyridine amides bearing at the α‐position either an aniline or a phenoxy moiety. These mild conditions, on top of furnishing rapidly the 3‐aminobenzoheteroles, allow the tolerance of various functional groups. Control experiments were carried out to highlight that the keteniminium is, indeed, in most cases, the reactive intermediate and conformational preferences of such species were investigated through a DFT study.

中文翻译：

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酮丁胺盐作为有效合成3-氨基吲哚和苯并呋喃的关键中间体

在此，我们描述了一种高产朝向的3-氨基-吲哚和-benzofurans至6中合成的方法π -electrocyclization。这是通过采取keteniminium盐，形成的高反应性的优点成为可能在原位通过与三氟甲磺酸酐和2-氟吡啶酰胺在轴承治疗α位上或者苯胺或苯氧基部分。这些温和的条件，除了快速提供3-氨基苯并杂环之外，还可以耐受各种官能团。进行了对照实验，以突出显示，在大多数情况下，烯酮胺确实是此类物种的反应性中间体和构象偏好，这是通过DFT研究进行了调查。