A study of vinyl cations as intermediates in bond forming reactions

佛蒙特大学化学系的Matthias Brewer教授正在研究乙烯基阳离子的反应性，该项目由化学系化学结构、动态和机理B项目资助。这项研究的目的是为了更好地了解这些高能中间体的反应性，并开发新的碳-碳键形成反应。这项工作利用了乙烯基阳离子可以通过独特的和知之甚少的机制途径反应的事实，这些途径尚未在合成中得到充分利用。除了提供对乙烯基阳离子固有反应性的更好理解外，这项工作还提供了一些有用的复杂构建环形成反应，这些反应可以合成结构复杂的双环和多环产物以及作为有用合成中间体的更基本的分子支架。参与该项目的研究生、本科生和经济困难的高中生（通过ACS项目SEED项目）接受了有机化学方面的优秀培训，学会了进行机理研究、反应优化和发展研究，并熟练地进行化合物表征和结构解析。此外，PI正在寻找创新的方法来促进化学和生物化学专业本科生的研究机会和出国留学机会。虽然三取代阳离子（即碳离子）是有机化学中研究得最好和最重要的中间体之一，但二取代阳离子（即乙烯基阳离子）尚未得到合成界的同等重视。本提案旨在更好地了解乙烯基阳离子的内在反应性以及乙烯基阳离子反应的机制。具体来说，这项工作：1)探索乙烯基阳离子在内部氧化还原反应中的反应性，通过远程碳氢官能化形成C-C键；2)通过机理研究，更好地理解插入过程；3)定义了乙烯基阳离子在烯烃上的1,2-shift基团的迁移倾向；4)研究了乙烯基阳离子与远端pi体系反应形成C-C键。这些研究可以提供新的和独特的方法来制备简单的结构，这些结构将是有价值的合成中间体，以及传统方法难以制备的重要碳环支架。

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Matthias Brewer of the Department of Chemistry at the University of Vermont is studying the reactivity of vinyl cations. The goal of this research is to better understand the reactivity of these high-energy intermediates and to develop new carbon-carbon bond forming reactions. This work takes advantage of the fact that vinyl cations can react through unique and poorly understood mechanistic pathways that have not been fully exploited in synthesis. In addition to providing a better understanding of the inherent reactivity of vinyl cations, this work provides several useful complexity-building ring-forming reactions that could enable the synthesis of structurally complex bicyclic and polycyclic products and more basic molecular scaffolds that serve as useful synthetic intermediates. The graduate and undergraduate students and economically disadvantaged high school students (via the ACS Project SEED program) who work on this project receive excellent training in organic chemistry and learn to conduct mechanistic studies, reaction optimization and development studies, and become adept at compound characterization and structure elucidation. In addition, the PI is looking for innovative ways to promote undergraduate research opportunities and study abroad opportunities for undergraduate Chemistry and Biochemistry majors. While trisubstituted cations (i.e. carbenium ions) are one of the best studied and most important classes of intermediates in organic chemistry, disubstituted cations (i.e. vinyl cations) have not received the same level of attention from the synthetic community. This proposal seeks to better understand the intrinsic reactivity of vinyl cations and the mechanisms through which vinyl cations react. Specifically, this work: 1) Explores the reactivity of vinyl cations in internal redox reactions that result in C-C bond formation by remote C-H functionalization; 2) Provides a better understanding of the insertion process through mechanistic studies; 3) Defines the migratory aptitude of groups in 1,2-shifts across the alkene of vinyl cations; 4) Studies C-C bond formation by reaction of vinyl cations with remote pi-systems. These studies could provide new and unique ways to prepare simple structures that will be valuable synthetic intermediates, as well as important carbocyclic scaffolds that would be difficult to prepare by traditional means.