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，选择硝酮（1）-氧氮杂环丙烷（2），稳定的磷（3）和硫叶立德（4），和羟基苯乙酮（5）作为底物，并研究了光和热单电子转移（SET）反应。主要研究结果如下：1.在光敏电子转移（PET）条件下，化合物1和2可根据芳基上的取代基相互转化.在PET条件下以立体选择性方式进行2的开环。它也适用于空间位阻1.3的方便制备。虽然稳定的3在非常有限的范围内用于合成，但这些叶立德的SET性质集中于提高反应活性。芴取代3与异戊烯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，研究了3与缺电子烯烃和炔的（环）加成反应，旨在通过电荷转移性质提高反应活性。与类似取代的4.4相比，还研究了芴亚乙基取代的3的NMR的不寻常的温度依赖性。在卤化铝存在下，通常在光照射下不反应的5的光反应性增强。在一种情况下，相邻烷基的溴化反应以反马尔可夫方式发生。在另一种情况下，在PET条件下发生了向氧杂双环庚烯酮的显著结构转化。该反应似乎是通过SET和随后的氧添加进行的。

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.