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.
