Photochemical & Photobiological Sciences ( IF 2.7 ) Pub Date : 2022-07-22 , DOI: 10.1007/s43630-022-00267-3 Edward S Chinn 1 , Daniel E Falvey 1
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A photochemical precursor to the 5-endo-10,11-dihydroazepine nitrenium ion (1) was synthesized and used to characterize the intermediate by laser flash photolysis and stable product analysis. In addition, DFT calculations were carried out on the nitrenium ion. These results were compared with earlier studies on the diphenylnitrenium ion in order to ascertain the effect of the 2 carbon bridge on the reactions and properties of 1. It is shown that the geometric constraints provided by the bridging group (a) destabilize the triplet state of 1 relative to the singlet state (b) substantially increase the lifetime of 1 relative to Ph2N+ by inhibiting the unimolecular cyclization pathway possible in the latter and (c) modestly increases the barrier for nucleophilic addition to the ring carbons.
Graphical abstract
中文翻译：
5-endo-10,11-dihydrodibenzoazepine nitronium 离子的光化学生成和表征
合成了 5-endo-10,11-dihydroazepine nitronium 离子 ( 1)的光化学前体，并通过激光闪光光解和稳定产物分析对中间体进行表征。此外，对硝鎓离子进行了 DFT 计算。将这些结果与早期对二苯基氮鎓离子的研究进行比较，以确定 2 碳桥对1 的反应和性质的影响。结果表明，桥接基团 (a) 提供的几何约束使1相对于单重态 (b) 显着增加了1相对于Ph 2 N +的寿命通过抑制后者中可能的单分子环化途径和（c）适度增加亲核加成环碳的障碍。
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