N-Oxyl radicals (compounds with an N–O^• fragment) represent one of the richest families of stable and persistent organic radicals with applications ranging from catalysis of selective oxidation processes and mechanistic studies to production of polymers, energy storage, magnetic materials design and spectroscopic studies of biological objects. Compared to other N-oxyl radicals, oxime radicals (or iminoxyl radicals) have been underestimated for a long time as useful intermediates for organic synthesis, despite the fact that their precursors, oximes, are extremely widespread and easily available organic compounds. Furthermore, oxime radicals are structurally exceptional. In these radicals, the N–O^• fragment is connected to an organic moiety by a double bond, whereas all other classes of N-oxyl radicals contain an R₂N–O^• fragment with two single C–N bonds. Although oxime radicals have been known since 1964, their broad synthetic potential was not recognized until the last decade, when numerous selective reactions of oxidative cyclization, functionalization, and coupling mediated by iminoxyl radicals were discovered. This review is focused on the synthetic methods based on iminoxyl radicals developed in the last ten years and also contains some selected data on previous works regarding generation, structure, stability, and spectral properties of these N-oxyl radicals. The reactions of oxime radicals are classified into intermolecular (oxidation by oxime radicals, oxidative C–O coupling) and intramolecular. The majority of works are devoted to intramolecular reactions of oxime radicals. These reactions are classified into cyclizations involving C–H bond cleavage and cyclizations involving a double C=C bond cleavage.

中文翻译：

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肟自由基：产生、性质及其在有机合成中的应用。


N-氧基自由基（具有 N–O ^•片段的化合物）代表最丰富的稳定和持久有机自由基家族之一，其应用范围从选择性氧化过程的催化和机理研究到聚合物的生产、能量存储、磁性材料设计和生物物体的光谱研究。与其他N-氧基自由基相比，肟自由基（或亚氨氧基自由基）作为有机合成的有用中间体长期以来一直被低估，尽管它们的前体肟是极其广泛且容易获得的有机化合物。此外，肟基在结构上也很特殊。在这些自由基中，N–O ^•片段通过双键连接到有机部分，而所有其他类别的N -氧基自由基均包含带有两个单 C–N 键的 R ₂ N–O ^•片段。尽管肟自由基自 1964 年以来就已为人所知，但直到最近十年，人们才认识到其广泛的合成潜力，当时发现了亚氨基氧基自由基介导的许多氧化环化、官能化和偶联的选择性反应。本综述重点介绍了过去十年中开发的基于亚氨氧基自由基的合成方法，并且还包含了有关这些N-氧基自由基的产生、结构、稳定性和光谱性质的先前工作的一些精选数据。肟自由基的反应分为分子间反应（肟自由基氧化、氧化C-O偶联）和分子内反应。大多数作品致力于肟自由基的分子内反应。 这些反应分为涉及C-H键断裂的环化和涉及双C=C键断裂的环化。