CREATION AND CHARACTERIZATION OF CARBENES HAVING UNUSUAL STRUCTURE

虽然已有报道，在溶液中辐照二苯基亚甲基环丙烷会产生其异构体2,2-二苯基-1-亚甲基环丙烷，但对其机理知之甚少。本研究为2,2-二苯基环丁烯的中间体作用提供了实验支持。详细的产物分析表明，除了生成2,2-二苯基-1-亚甲基环丙烷外，还生成2,2-二苯基环丁烯。类似的光反应在氧下也产生2,2-二苯基环丁酮。与母体苯卡宾相反，苯并环丁烯二烯从未被直接观察到。我们对这种特殊的碳感兴趣，并试图从前体生成苯并环丁烯，以研究其反应性。苯并环丁烯酮的N-（2-苯基苄基）亚胺光解生成苯并环丁烯二聚体和三聚体。在烯烃或甲醇存在下进行类似的光解反应可生成环丙烷或甲氧基苯并环丁烯。很可能是苯并环丁烯二烯参与了光反应。虽然N-（2-苯基苄基）亚胺的稳态光解产生了苯并环丁烯，但即使在我们的激光闪光光解条件下，它也是难以捉摸的。然而，研究表明，吡啶似乎能捕获苯环丁二烯，得到一个吡啶。

Although it has been reported that irradiation of diphenylmethylenecyclopropane in solution results in its isomer, 2,2-diphenyl-1-methylenecyclopropane, little has been known on the mechanism. The present study provides experimental support for the intermediacy of 2,2-diphenylcyclobutylidene. The detailed product analysis showed that 2,2-diphenylcyclobutene is formed in addition to 2,2-diphenyl-1-methylenecyclopropane. Similar photoreaction under oxygen afforded 2,2-diphenylcyclobutanoneas well.In contrast to parent phenylcarbene, benzocyclobutenylidene has never been observed directly. We are interested in this particular carbene and have attempted to generate benzocyclobutenylidene from precursors in order to investigate its reactivity.Photolysis of N-(2-phenylazyridyl)imine of benzocyclobutenone results in dimers and trimers of benzocyclobutenylidene. Similar photolysis in the presence of alkenes or methanol leads to formation of cyclopropanes or methoxybenzocyclobutene. It is most likely that benzocyclobutenylidene is involved in the photoreactions.Although the steady-state photolyses of the N-(2-phenylazyridyl)imine afford products suggestive of benzocyclobutenylidene, it is elusive even under our laser flash photolytic conditions. However, it is shown that pyridine seems to trap bensocyclobutelideneto give a ylide.