published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 115-116). Also available in print.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 25, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Silvia Jurisson and Dr. Mike Lewis. Vita. Includes bibliographical references.

Thesis (Ph. D.), Memorial University of Newfoundland, 1998. / Bibliography: leaves 142-156.

Thesis (M.S.)--Florida State University, 2005. / Advisor: Dr. Marie E. Krafft, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Sept. 19, 2005). Document formatted into pages; contains 147 pages. Includes bibliographical references.

Title from first page of PDF document. Includes bibliographical references (p. 55-57).

Thesis (Ph.D.)--Baylor University, 2009. / Includes bibliographical references (p. 233-237).

Diels-Alder cycloaddition of methylcyclopentadienes to 2,5-dibromo-p-benzoquinone was performed. A single, isomerically pure cycloadduct was isolated, whose structure was assigned via analysis of its 1-D and 2-D NMR spectra. Diels-Alder cycloaddition of methylcyclopentadienes to 2 -methoxy-p-benzoquinone was performed. A single, isomerically pure cycloadduct was isolated, whose structure was assigned via analysis of the 1-D and 2-D NMR spectra of this cycloadduct and its reduction product obtained via stereo-specific reduction with sodium borohydride in the presence of cerous chloride. The structure of Thiele's ester was assigned via analysis of its 1-D and 2-D NMR spectra.

A new synthetic route to natural and novel pyrethroid acids was developed utilizing ketene cycloaddition which is a significant improvement over existing syntheses. The newly synthesized pyrethroid acids were converted to pyrethroid esters and used to study structure-activity relationships. The cycloaddition of dichloroketene with 2,5-dimethyl-2,4-hexadiene yields (2+2) cycloaddition products, 2,2-dichlorocyclobutanones. The reductive removal of one chlorine atom from these cycloaddition products gave monochlorocyclobutanones which underwent a Favorskii-type ring contraction to yield cis- and trans-chrysanthemic acids. 4-Methyl-1,3-pentadiene was also used as a precursor in this synthetic scheme to yield an analogue of the chrysanthemic acid. These results are consistent with a concerted cycloaddition process involving a dipolar transition state. The zinc reduction is not a regiospecific reaction which accounts for the two regioisomers of the monochlorocyclobutanones. The Favorskii-type ring contraction is a regiospecific reaction. A variety of different bicyclo(3.1.0)alkenecarboxylates and bicyclo(4.1.0)heptenecarboxylates were synthesized from alkylcyclopentadiene and fulvene derivatives. These new bicyclo pyrethroid acids are structurally similar to the natural chrysanthemic acid but are rigid and locked in a single conformation which is likely the least stable conformer of the natural acid. The acids were converted to pyrethroid esters and tested against the housefly and cockroach. The test results indicate that the bicyclo pyrethroids synthesized are not as active as the natural pyrethroid. Apparently, these bicyclo pyrethroids with structures similar to the less stable conformer of the natural pyrethroids are of little consequence as it binds to the target site in the insect. In an effort to learn more about the conformational requirements of the pyrethroid acid, a new bicyclo-spiro pyrethroid system with a structure similar to the most stable conformation of the natural pyrethroid was designed and synthesized. These bicyclo-spiro pyrethroids were derived from a new isopropylidenecyclobutane derivatives as a starting compound instead of a conjugated diene. The test results of these bicyclo-spiro pyrethroid esters revealed a much greater activity against the housefly and cockroach. This study establishes that the more stable conformer of the natural pyrethroid acid provides a much higher toxicity against the insects tested.