Institut für Chemie, Universität Rostock, Albert-Einstein-Straße 3a, 18059, Rostock, Germany.
Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Straße 29a, 18059, Rostock, Germany.
Chemistry. 2023 Jun 13;29(33):e202300764. doi: 10.1002/chem.202300764. Epub 2023 Apr 27.
Differently substituted phenyl isonitriles (with C-H bonds in ortho-position) and naphthyl isonitriles were reacted with the cyclic biradical [⋅P(μ-N-Ter) P⋅] (1). Insertion of the isonitrile formed a cyclic five-membered biradical [⋅P(NTer) C(R)P⋅] (2R, R=phenyl, naphthyl) in the first step, followed by C-H activation at the aryl substituent, resulting in novel azaphospholes (5R), which could be isolated and fully characterized. The formation of the azaphospholes can be prevented by the addition of a second equivalent of isonitrile, which causes the blocking of the radical centers in 2R by adduct formation (3R). Quantum mechanical calculations showed that a significant increase in the aromaticity of the benzo- and naphtho-azaphospholes is one of the driving forces for the activation process leading to the formation of thermodynamically favored azaphospholes. Targeted activation of C-H bonds using biradical systems represents a new synthetic approach to generate benzo- and naphtho-azaphospholes.
不同取代的苯基异腈（邻位有 C-H 键）和萘基异腈与环状双自由基 [⋅P(μ-N-Ter) P⋅]（1）反应。异腈的插入在第一步中形成了环状的五元双自由基 [⋅P(NTer)C(R)P⋅]（2R，R=苯基，萘基），随后在芳基取代基上发生 C-H 活化，生成新型的氮杂膦（5R），可以将其分离并进行充分的表征。通过添加第二个当量的异腈，可以防止氮杂膦的形成，这会导致 2R 中的自由基中心通过加合物形成而被阻断（3R）。量子力学计算表明，苯并和萘并氮杂膦芳香性的显著增加是导致形成热力学有利的氮杂膦的活化过程的驱动力之一。使用双自由基体系靶向活化 C-H 键代表了一种新的合成方法，可用于生成苯并和萘并氮杂膦。
