CAREER: Towards Space- and Time- resolved Generation of p-Benzyne Diradical: Development of Photoswitchable Analogs of Natural Enediyne Antibiotics

在化学系有机动力学项目的支持下，鲍灵绿色州立大学的弗拉基米尔·波皮克教授将开发有效光化学生成反应性十元和九元环环状烯二炔化合物的方法。已经设计了几种类型的前体，其在黑暗中是稳定的，但在用光照射时产生高产率的反应性烯二炔。所得烯二炔然后经历快速热环芳构化，产生对苯炔双自由基。高应变的环烯二炔化合物，环化非常迅速，光化学生成将被用来研究对苯炔双自由基使用闪光光解技术。探讨了烯二炔类前体的双光子活化。将制备几种结构不同的环状烯二炔前体，其包含三种光反应基团之一：a-重氮二羰基、环丙烯酮或a-二酮。这些化合物将进行研究，以确定热和水解稳定性，以及量子和化学产率的烯二炔代。本论文将利用传统的时间分辨技术研究烯二炔光产物的Bergman环化反应的动力学和机理。已经合成了三种可光转换的烯二炔，目前正在研究它们的光化学。有机和高分子化学计划支持保龄球州立大学州立大学绿色教授弗拉基米尔Popik，他的研究将提供反应性烯二炔的时间和空间分辨生成方法。这些方法将为探索Bergman环化反应机理和直接观察对苯炔双自由基提供新的工具。光开关烯二炔也可以作为开发新的光活化烯二炔抗生素和3-D选择性光核酸酶的基础。烯二炔环芳构化反应的空间控制可能会导致光刻和信息记录的新方法的发展。该项目为本科生和研究生提供合成和物理有机化学界面的跨学科培训，以及光化学和生物化学的培训。该项目的跨学科性质将需要并导致与当地和国际其他研究团体的广泛合作。

With the support of the Organic Dynamics Program in the Chemistry Division, Professor Vladimir Popik of Bowling Green State University will develop methods for the efficient photochemical generation of reactive ten- and nine-membered ring cyclic enediyne compounds. Several types of precursors that are stable in the dark but produce a high yield of reactive enediynes upon irradiation with light have been designed. The resulting enediyne then undergoes a rapid thermal cycloaromatization producing p-benzyne diradical. The photochemical generation of highly strained cyclic enediyne compounds, which cyclize very rapidly, will be employed to study the p-benzyne diradical using flash photolytic techniques. The two-photon activation of enediyne photoprecursors will be explored. Several structurally different cyclic enediyne precursors, which incorporate one of three photoreactive groups: a-diazodicarbonyl, cyclopropenone, or a-diketone, will be prepared. These compounds will be studied to determine thermal and hydrolytic stability, as well as quantum and chemical yield of the enediyne generation. The kinetics and mechanism of the Bergman cyclization of enediyne photoproducts will be investigated using conventional and time-resolved techniques. Three of the photoswitchable enediynes have been already synthesized and their photochemistry is currently under investigation. The Organic and Macromolecular Chemistry Program supports Professor Vladimir Popik of Bowling Green State University whose research will provide methods for the time- and spatially-resolved generation of reactive enediynes. These methods will supply new tools for exploring the mechanism of Bergman cyclization and for the direct observation of p-benzyne diradicals. Photoswitchable enediynes could also serve as a basis for the development of new photoactivatable enediyne antibiotics and 3-D selective photonucleases. Spatial control of the enediyne cycloaromatization reaction might lead to the development of new approaches to photolithography and information recording. This project provides undergraduate and graduate students with an interdisciplinary training at the interface of synthetic and physical organic chemistry, as well as training in photochemistry and biochemistry. The interdisciplinary nature of the project will require and result in extensive collaboration with other research groups both locally and internationally.