A reductive cyclization to prepare a variety of N-heterocycles, through the use of ortho-vinylanilides, is reported. The reaction is catalyzed by an inexpensive and bench-stable iron complex and generally occurs at ambient temperature. The transformation likely proceeds through hydromagnesiation of the vinyl group, and trapping of the in situ generated benzylic anion by an intramolecular electrophile to form the heterocycle. This iron-catalyzed strategy was shown to be broadly applicable and was utilized in the synthesis of substituted indoles, oxindoles and tetrahydrobenzoazepinoindolone derivatives. Mechanistic studies indicated that the reversibility of the hydride transfer step depends on the reactivity of the tethered electrophile. The synthetic utility of our approach was further demonstrated by the formal synthesis of a reported bioactive compound and a family of natural products.

中文翻译：

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水镁化作用下的铁催化还原环化：一种针对 N-杂环的模块化策略

通过使用邻位还原环化制备各种N-杂环-乙烯基苯胺，据报道。该反应由廉价且稳定的铁络合物催化，通常在环境温度下发生。转化可能是通过乙烯基的水镁化作用进行的，并通过分子内亲电试剂捕获原位生成的苄基阴离子以形成杂环。这种铁催化的策略被证明具有广泛的适用性，并被用于合成取代的吲哚、羟吲哚和四氢苯并氮杂吲哚酮衍生物。机理研究表明，氢化物转移步骤的可逆性取决于束缚的亲电试剂的反应性。通过正式合成已报道的生物活性化合物和一系列天然产物，进一步证明了我们方法的合成效用。