Generation of radical ions of pyrazolines and construction of an electron transfer system.

最近研究了由环状偶氮烷通过光诱导电子转移(PET)产生的自由基阳离子，并通过重排和溶剂加成生成了一些特征化合物。当生成的自由基阳离子由于其几何约束和稳定性而有可能重排时，反应机理变得复杂，因为这些物种似乎参与了脱氮。在我们以前使用1-吡唑啉和9，10-二氰基菲(DCA)作为电子接受增敏剂的研究中，发现PET反应会引起涉及自由基阳离子中间体的芳基迁移。尽管人们对含氮自由基阳离子的行为很感兴趣，但通过PET反应还没有得到固氮产物，并且产物是除氮化合物。在这个项目中，我们报道了第一个使用环偶氮烷进行PET反应的例子，在这个反应中，固氮产物来自具有外环双键的3-亚烷基-1-吡唑啉的自由基阳离子物种，并且通过激光闪光光解(LFP)技术成功地检测到了固氮自由基阳离子。

Radical cations generated from cyclic azoalkanes by photoinduced electron transfer (PET) have recently been investigated and produced a few characteristic compounds by rearrangements and solvent additions. The reaction mechanisms become complex when the generated radical cations have the possibility of rearranging due to their geometric constraints and stabilities, as these species appear to be involved in denitrogenation. In our previous studies using the 1-pyrazolines and 9,10-dicyanoanthracene (DCA) as an electron accepting sensitizer, the PET reaction was found to cause aryl migration involving the radical cation intermediates. In spite of the fact that the behavior of the nitrogen-retained radical cations are of considerable interest, nitrogen-retained products by the PET reaction have not been obtained, and the products are nitrogen-eliminated compounds. In this project, we report the first example of the use of cyclic azoalkanes for the PET reaction in which nitrogen-retained products are obtained from the radical cation species of 3-alkylidene-1-pyrazolines having an exocyclic double bond, and that the successful detection of the nitrogen-retained radical cations was accomplished by a laser flash photolysis (LFP) technique.