Researches on the Effect of Spiro-Activation of Small Ring Compounds in Their Ring Cleavage Reactions.

在环丙烷螺环活化法的继续研究中，考察了螺环烷、螺螺烯、螺庚烯和螺庚二烯与TCNE的反应。虽然基本的反应历程是[Pi2+Pi2]和[Pi2+sigma2]环加成反应，但根据底物上取代基的不同，可以观察到不同的反应发生。最有趣的观察之一是1，1-二环丙基螺环[2.4]七-4，6-二烯与TCNE的反应，除了预期的Diels-Alder加合物外，还生成了亚胺衍生物，应该经过广泛的重排得到。在螺环烯的反应中也观察到类似的转变。显然，这应该是允许Tone与乙烯基环丙烷反应时要考虑的基本反应之一。另一个有趣的结果是，螺庚烯和螺庚烯的氧化电位和电离电位受到环丙烷环上取代基的影响，而螺庚二烯的氧化电位和电离电位不受取代基影响。这些结果对五元不饱和阳离子自由基的结构很有意义。此外，还研究了TCNE环加成反应的立体化学和二苯基取代螺荧衍生物的反应。所有结果都为环丙烷的螺环活化反应提供了重要的基础知识。最后发现，在一定的反应条件下，1，2-二环丙基乙烯也能以[Pi2+sigma2]的方式与TCNE反应。根据这一结果，还考察了1，2-二环丙基乙烯与氯苯胺光化学反应。这些结果为环丙烷裂解反应可能具有阳离子自由基中间体的特征提供了证据。

In continuation of the study on spiro-activation of cyclopropanes, reactions of spiroindans, spiroindenes, spiroheptenes, and spiroheptadienes with TCNE were examined. Although the basic reaction courses were [pi2+pi2] and [pi2+sigma2] cycloaddition as those observed in the reactions of spirofluorene derivatives, varied reactions were observed to occur depending upon substituents on the substrates. One of the most interesting observation was that the reaction of 1, 1-dicyclopropylspiro [2.4] hepta-4, 6-diene with TCNE gave, in addition to the expected Diels-Alder adduct, an imine derivative, which should be produced after extensive rearrangement. Similar transformation was observed to occur also in the reactions of spiroindenes. Evidently, this should be one of the basic reactions to be considered when TONE was allowed to react with vinylcyclopropanes. The other interesting result was that oxidation potential as well as ionization potential of spiroheptanes and spiroheptenes were influenced by the substituents on the cyclopropane ring as expected, but those of spiroheptadienes were not subjected to the substituent effect. The results are of great interest with regard to the structure of five-membered unsaturated cation radicals. In addition to these studies, the stereochemistry of TCNE cycloaddition and the reaction of diphenyl-substituted spirofluorene derivatives were investigated. All results gave important basic knowledge with regard to the spiro-activation of cyclopropanes. Finally, it was found that even 1, 2-dicyclopropylethylene reacted with TCNE in the [pi2+sigma2] manner under certain reaction conditions. In relation to this result, the photochemical reaction of 1, 2-dicyclopropylethylene with chloranil was also examined. The results provided supporting evidences that the reaction involving cyclopropane cleavage might be characteristic to that of cation radical intermediates.