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

在化学学部有机动力学项目的支持下，鲍灵格林州立大学的Vladimir Popik教授将开发有效的光化学生成活性十元和九元环烯二炔化合物的方法。设计了几种前体，它们在黑暗中稳定，但在光照射下产生高收率的活性烯二炔。所得到的烯二炔然后经历快速的热环芳构化，产生对苯二基。光化学生成的高应变环内二炔类化合物，其环化速度非常快，将用于研究对苯二基的闪光光解技术。将探讨内二炔光递质的双光子活化。将制备几种结构不同的环内二炔前体，它们包含三种光反应基团之一：a-二氮二羰基、环丙烯酮或a-二酮。将对这些化合物进行研究，以确定其热稳定性和水解稳定性，以及烯二炔生成的量子和化学产率。动力学和机制的伯格曼环的烯二炔光产物将研究使用常规和时间分辨技术。三种可光开关烯二炔已经合成，其光化学性质目前正在研究中。有机和大分子化学项目支持鲍灵格林州立大学的Vladimir Popik教授，他的研究将为反应性烯二炔的时间和空间分辨生成提供方法。这些方法将为探索伯格曼环化机理和对苯二自由基的直接观察提供新的工具。光可切换内酯也可作为开发新的光活化内酯抗生素和3-D选择性光核酸酶的基础。对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新方法的发展。本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交叉学科的培训，以及光化学和生物化学的培训。该项目的跨学科性质将要求并导致与本地和国际其他研究小组的广泛合作。

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.