Interrogating Properties and Reaction Pathways of Aryl "onium" Reagents to Reveal New Chemical Functions

About This Grant

With the support of the Chemical Mechanism, Function, and Properties Program of the Division of Chemistry, Professors David Stuart and Theresa McCormick of the Department of Chemistry at Portland State University are studying the properties and reactivity of a class of chemical compounds called aryl “onium” species. Synthetic molecules enhance daily life by advancing human health and food security through medicine and crop protection agents – aromatic rings are a component of many of the molecules used in these areas. Aryl “onium” compounds are an emerging class of versatile building blocks for attaching aromatic rings in synthetic pursuits of candidates for drugs and agrochemicals. This project will uncover the properties of aryl “onium” compounds that dictate reaction pathways and enable their use in synthesis. This project is at the intersection of reagent development and mechanistic analysis and therefore provides a fertile training ground for the next generation of scientists and will include graduate and undergraduate students. Aryl “onium” compounds have emerged as novel reagents for a wide range of arylation reactions. The linchpin nature of aryl thianthrenium and diaryliodonium building blocks has captured the attention and creativity of synthetic chemists and those in allied industries that use organic synthesis. Yet, a full understanding the atomic and molecular properties that control the function and reactivity of these reagents remains to be known. This project will establish the mechanism for reactions that form aryl “onium” compounds and that use them as arylation reagents. The former will emphasize the use of commercial aromatic compounds such as simple arenes and arylboron compounds and the latter will focus on arylation reactions that involve aryne and iodonium reactive intermediates. Physical organic chemistry techniques (kinetics, Arrhenius analysis, Hammett plots) and computational tools (DFT/NBO analysis) will be used to determine the molecularity and energy profile of these reactions and the nature of the frontier orbitals on the main group elements at the core of these reagents. The new knowledge from this project will advance synthetic methods used to synthesize a wide range of aromatic compounds. The broader impacts of this project include the development of a globally competitive STEM workforce and increased partnership between academia and industry. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.