Professor Michael Harmata's studies of the cycloaddition chemistry of cyclic oxyallylic cations are supported by the Organic Synthesis Program. Dr. Harmata, of the Department of Chemistry at the University of Missouri - Columbia, is studying (4+3) cycloaddition reactions, focusing on several novel aspects of this class of reactions. Cycloaddition reactions of substrates containing halogen substituents provide products which may be elaborated into more complex structures, particularly through quasi-Favorskii rearrangements. Use of chiral bases to mediate the (4+3) cycloadditions, particularly in substrates designed to permit intramolecular delivery of the chiral base, will impart chirality to the cycloadducts. Representative members of the cyclooctanoid class of natural products, dactylol and 11-hydroxyjasionone, will be prepared through synthetic routes highlighting the efficacy of the (4+3) cycloaddition reactions of oxyallylic cations. Synthesis of the often-complex molecules forming the basis of modern chemical and pharmaceutical science requires the formation of carbon-carbon bonds in a highly selective manner. `Cycloaddition` reactions, in which two (or more) reacting molecules add to one another to form a cyclic product, represent a particularly powerful way in which to achieve such selective bond formation. Dr. Harmata studies cycloaddition reactions which result in the formation of compounds containing seven carbon atoms in a ring, exploring ways to introduce additional selectivity and versatility into these reactions. He will exploit an unusual ring transformation reaction which allows the conversion of these seven-membered ring compounds into products containing eight-membered rings. These studies will culminate in the synthesis of several specific compounds, including 11-hydroxyjasionone, which displays antibacterial and antifungal activity, and will serve as a general platform for the synthesis of other eight-membered ring compounds of known or potential biological or medicinal activity.
