Novel Cycloaddition Reactions of Nonvertical Radical Cations

为了深入了解上述新型自由基阳离子的结构和反应性，我们选择了硝基(1)-恶氮嘧啶(2)、稳定的磷(3)和硫酰(4)以及羟基苯乙酮(5)作为底物，研究了光和热单电子转移（SET）反应。研究结果总结如下：1。在光敏电子转移（PET）条件下，化合物1和2根据芳基上取代基的不同可以相互转换。在PET条件下以立体选择的方式开环2。也适用于方便制备立体受阻1.3。虽然在非常有限的范围内使用了稳定的3，但这类化合物的SET性质主要是为了提高反应性。芴取代3与丙氧基苯重氮盐反应得到二氢苯并呋喃衍生物。反应通过set -自由基偶联-离子终止序列进行。此外，还研究了3与缺电子烯烃和炔烃的（环）加成反应，目的是通过电荷转移性质来提高反应活性。对取代3的氟酰基乙基二烯与取代4.4的核磁共振异常温度依赖性进行了研究。通常在光照射下不反应的5的光反应性在卤化铝的存在下得到增强。在一种情况下，邻烷基溴化以反马可夫尼科夫方式发生。在另一种情况下，在PET条件下发生了显著的结构转化为oxabiccycloheptenone。反应似乎是通过SET和随后的加氧进行的。

In order to gain insight into the structure and reactivity of the above novel radical cations, nitrones (1)-oxaziridines (2), stable phosphorus (3) and sulfur ylides (4), and hydroxyacetophenones (5) were chosen as the substrates and photo and thermal single electron-transfer (SET) reactions were studied. The results are summarized as follows :1. Compound 1 and 2 were interconvertable each other depending on the substituent on the aryl group under photosensitized electron-transfer (PET) conditions.2. Ring-opening of 2 were proceeded in a stereoselective manner under PET conditions. It is also applicable to the convenient preparation of sterically hindered 1.3. Although stable 3 are employed for the synthesis in a very limited scope, SET nature of such ylides are focused to enhance the reactivity. The reaction of fluorene substituted 3 with prenyloxybenzene diazonium salt gave dihydrobenzofuran derivative. The reaction proceeded via the SET-radical couplingionic termination sequence. Additionally, (cyclo)addition reactions of 3 with electron-deficient alkenes and alkynes were studied to aim at enhancing the reactivity by charge-transfer nature. Unusual temperature-dependence of NMR of fluorenylideneethylidene substituted 3 was also studied in comparison with the analogously substituted 4.4. Photoreactivity of 5 which usually is unreactive upon photoirradiation were enhanced in the presence of aluminum halides. In one case, bromination of the neighboring alkyl group occurred in anti-Markownikoff manner. In another, remarkable structural conversion into oxabicycloheptenone occurred under PET conditions. The reaction seemed to be proceeded by the SET and the following addition of oxygen.