Phenyl(triazolyl)carbene revisited: Unique role of triazolyl group on carbene chemistry
Phenyl(triazolyl)carbene revisited: Unique role of triazolyl group on carbene chemistry
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重温苯基（三唑基）卡宾：三唑基在卡宾化学中的独特作用
DOI：
10.1002/poc.4187
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发表时间：
2021
影响因子：
1.8
通讯作者：
Tomioka Hideo
中科院分区：
文献类型：
--
作者：
Hirai Katsuyuki;Yamaguchi Masao;Okazaki Takao;Kitagawa Toshikazu;Tomioka Hideo
Smith等人最初报道的(1,4-二苯基-1H-1,2,3-三唑-5-基)(苯基)卡宾(1T)的化学性质，通过使用现代光谱方法和密度泛函理论(DFT)计算进行了重新研究，并将结果与类似的二苯基卡宾(1H)的观察结果进行了比较，以阐明三唑基团在二芳基卡宾化学中的作用。产物分析表明，卡宾对三唑环1位和4位苯环进行形式攻击，形成两个分子内环化产物（2和3）。结果与 1H 观察到的结果非常相似。不仅通过低温下刚性基质中的电子自旋共振（ESR）和紫外-可见光谱方法直接监测三线态卡宾31T的行为，还通过室温溶液中的激光闪光光解直接监测三线态卡宾31T的行为，并与31H观察到的行为进行比较。虽然 31T 的寿命比 31H 长约 2 个数量级，但 31T 对典型三重态捕获试剂的反应性比 31H 更高。为了阐明这些相当矛盾的观察结果，通过 DFT 方法计算了卡宾 1T 和 1Has 的几何形状和相对能量以及参与最终产物反应的物质。结果表明 31H 比 31T 更容易通过参与上层 11H 的反应而发生衰变。通过考虑两者之间卡宾中心周围空间拥挤度的差异，可以解释对外部捕获剂的反应性差异。
The chemistry of (1,4‐diphenyl‐1H‐1,2,3‐triazol‐5‐yl)(phenyl)carbenes (1T), originally reported by Smith et al., was reinvestigated by using modern spectroscopic methods as well as density functional theory (DFT) calculations, and the results were compared with that observed for analogous diphenylcarbene (1H) to clarify the role of triazole group in diarylcarbene chemistry. Product analysis indicated that1Tgave two intramolecular cyclization products (2and3) formed as a result of a formal attack of carbene on the phenyl rings at 1‐ and 4‐positions of the triazole ring. The results were closely similar to that observed for1H. The behaviors of triplet carbene31Twere directly monitored not only by electron spin resonance (ESR) and UV‐Vis spectroscopic methods in rigid matrix at low temperature but also by laser flash photolysis in solution at room temperature and compared with those observed for31H. Whereas the lifetime of31Twas some 2 orders of magnitude longer than that of31H, the reactivity of31Ttoward typical triplet trapping reagents was greater than that of31H. In order to elucidate these rather conflicting observations, geometries and relative energies of carbenes1Tand1Has well as species involved in the reactions leading to the final products were calculated by the DFT method. The results are interpreted as indicating that31Hdecays by participating in the reaction of upper‐lying11Hmuch more easily than31T. The difference in the reactivity toward external trapping reagents is explicable by taking into account the difference in steric crowdedness around carbene center between the two.