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，鲍林格林州立大学的Vladimir Popik教授将开发有效地光化学产生反应性的十元环和九元环二炔化合物的方法。已经设计了几种在黑暗中稳定但在光照射下产生高产率反应烯二炔类化合物的前体。然后，生成的烯二炔经历快速的热环芳构化反应，生成对苯炔二基。高应变环烯二炔化合物的光化学生成反应非常迅速，将被用来利用闪光光解技术来研究对苯并二自由基。我们将探索烯二炔类光前体的双光子激活。将制备几种结构不同的环烯二炔前驱体，它们包含三个光反应基团之一：A-重氮二羰基、环丙烯或a-二酮。将对这些化合物进行研究，以确定热稳定性和水解性，以及烯二炔生成的量子和化学产率。将使用常规和时间分辨技术来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开关的乙烯二炔类化合物，它们的光化学目前正在研究中。有机和高分子化学项目支持鲍林格林州立大学的弗拉基米尔·波皮克教授的研究，他的研究将为活性烯二炔的时间和空间分辨生成提供方法。这些方法将为探索Bergman环化反应机理和直接观察对苯基自由基提供新的工具。可光开关的烯二炔类化合物也可以作为开发新的可光激活的烯二炔类抗生素和三维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有机化学和物理有机化学的跨学科培训，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上的其他研究小组进行广泛合作。

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.