Real and Formal Pericyclic Processes of Reactive Intermediates

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

This project will continue studies involving pericyclic reactions or their equivalents using reactive intermediates. Allylic cations offer a wide range of reactive motives, including cycloadditions and ene reactions. The latter have not been studied extensively and formally offer a process by which C-H activation occurs. Studies to explore the scope of this process, both in an inter- and intramolecular context, will be undertaken. The basic scheme lends itself naturally to an investigation of the homo-Cope rearrangement, which will also be pursued. Ketenes undergo a cycloaddition reaction with alkenes to form cyclobutanones. Details of the control of regiochemistry in such cycloadditions are incomplete. A study of this process, linked to specifically controlling the outcome of the reaction with vinylcyclopropanes will lead to the synthesis of cyclobutanones substituted regioselectively with cyclopropanes. Such substrates are envisioned to undergo a ring expansion to form seven-membered rings, under the influence of catalytic amounts of certain transition metals. Finally, the influence of substituents on the rates of certain electrocyclic reactions is a topic of current interest. The electrocyclization of hexatrienes is generally a slow process with a relatively high activation energy. Recent evidence suggests that electronic effects can have a profound influence on the rate of such processes. Carbanions offer the opportunity to develop extremely rapid electrocyclizations in this class that are also diastereoselective and enantioselective, depending on the exact means by which the carbanion is generated, resulting in the preparation of highly substituted six-membered rings. The development of such reactions will be undertaken. With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Professor Michael Harmata of the Department of Chemistry at University of Missouri-Columbia. Professor Michael Harmata's research efforts revolve around the development of new carbon-carbon bond forming reactions based on pericyclic reactions of reactive intermediates, especially those of allylic cations and cyclopentadienones, among others. The studies to be undertaken will expand the scope of knowledge of reactive species, resulting in the discovery/invention of new, powerful synthetic processes of use for the synthesis of complex organic chemicals of potential impact to the synthesis of new pharmaceuticals, new materials, and new agrochemicals, as well as new entities of fundamental interest to a broad scientific community.