NONCOVALENT INTERACTIONS AND HYPERCONJUGATION IN CONTROL OF RADICAL REACTIVITY: APPLICATION TO 5-ENDO-DIG CYCLIZATIONS

控制自由基反应性的非共价相互作用和超共轭：在 5-ENDO-DIG 环化中的应用

• 批准号: 0848686
• 负责人: Igor Alabugin
• 金额: $ 36万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0848686&HistoricalAwards=false
• 关键词: NONCOVALENT; INTERACTIONS; HYPERCONJUGATION; CONTROL; RADICAL

This proposal extends studies of unusual aspects of alkyne reactivity into a new direction. It will concentrate on fundamental factors controlling radical cyclizations of alkynes and utilize this knowledge for the design of synthetically useful transformations. Because stereoelectronic patterns are significantly different for radical cyclizations of alkenes and alkynes, understanding these fundamental differences is essential for the development of alkyne chemistry.In this project, the Alabugin group will utilize stereoelectronic and thermodynamic factors in search of the apparently favorable but virtually unexplored radical process: 5-endo-dig radical cyclization and apply this and related reactions to the synthesis of new carbo- and heterocyclic systems. Proposed experiments will test earlier computational predictions regarding the relative efficiency of different cyclization patterns, discover new cyclization topologies and test the efficiency of cooperative hyperconjugative interactions in control of radical reactivity. In parallel, the group will combine efficient radical cyclizations with radical translocations for the rapid construction of functionalized polycyclic systems. These reactions take advantage of synthetic potential which is present in alkynes but not in alkenes by utilizing both pi-bonds of the alkyne moiety in the C-C bond forming steps. The intellectual merit of this research is in unraveling the contribution of electronic and structural factors controlling the efficiency and selectivity of radical processes through a combination of experimental and theoretical studies. The underlying focus on electronic effects will increase the general importance of these findings, broaden understanding of these fundamental factors and lead to the development of new paradigms of radical reactivity. The broader impact will be the laying of mechanistic, structural, and kinetic foundations for successful applications of radical reactions of alkynes in synthesis and materials science. The proposed research will enhance understanding of the reactivity of the alkyne moiety as well as radical species. The combination of computations and kinetic studies will be used to validate theoretical approaches for studies of organic reactions. The theoretical and experimental components of this work will allow training of specialists in each area and will provide researchers at the undergraduate, graduate and postdoctoral levels with an opportunity to integrate learning and discovery. The results will be disseminated in the PI's publications and outreach activities, including participation in symposia and lecturing at undergraduate and graduate institutions. The PI and his students will also record their research presentations for the Global Educational Outreach for Science Engineering and Technology (GEOSET), a new initiative to provide outstanding Science, Engineering and Technology (SET) teaching material through the new technology. The recorded research presentations will be posted on the GEOSET website and linked to the the PI's and Departmental websites. This exposure will also help in the development of further career opportunities for participating students since these recordings may even take the place of job interviews, thus reducing carbon footprints and travel costs to prospective employers.

这一建议将对炔烃反应性的不寻常方面的研究扩展到一个新的方向。它将集中在控制炔烃自由基环化的基本因素上，并利用这些知识设计出综合有用的转化。在这个项目中，Alabugin小组将利用立体电子和热力学因素来寻找表面上有利但几乎未被探索的自由基过程：5-内-DIG自由基环化反应，并将该反应和相关反应应用于合成新的碳环和杂环体系。拟议的实验将测试早期关于不同环化模式的相对效率的计算预测，发现新的环化拓扑结构，并测试合作超共轭相互作用在控制自由基反应活性方面的效率。同时，该小组将结合有效的自由基环化和自由基易位来快速构建功能化的多环系统。这些反应通过在C-C键形成步骤中利用了炔基的两个pi键，从而利用了在炔烃中存在但在烯烃中不存在的合成潜力。这项研究的智力价值在于，通过实验和理论研究相结合，揭示了电子和结构因素对控制自由基过程的效率和选择性的贡献。对电子效应的潜在关注将增加这些发现的总体重要性，扩大对这些基本因素的理解，并导致激进反应新范式的发展。更广泛的影响将是为炔烃自由基反应在合成和材料科学中的成功应用奠定机械、结构和动力学基础。拟议的研究将加强对炔烃部分以及自由基物种的反应性的了解。计算和动力学研究的结合将被用来验证有机反应研究的理论方法。这项工作的理论和实验部分将允许培训每个领域的专家，并将为本科生、研究生和博士后一级的研究人员提供一个将学习和发现结合起来的机会。结果将在国际和平协会的出版物和外联活动中传播，包括参加本科生和研究生机构的座谈会和讲座。他和他的学生还将为全球科学、工程和技术教育外展(GEOSET)录制他们的研究报告，这是一项新的倡议，旨在通过新技术提供优秀的科学、工程和技术(SET)教材。录制的研究报告将张贴在GEOSET网站上，并链接到国际和平研究所和部门网站。这种接触还将有助于为参与其中的学生开发更多的职业机会，因为这些录音甚至可能取代求职面试，从而减少未来雇主的碳足迹和旅行成本。