Thesis (Ph. D.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 334-361). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Thesis (Ph. D.)--University of Oregon, 1999. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 281-294). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9955921.

Thesis (Ph. D.)--University of Oregon, 2005. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 433-470). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Oregon, 2001. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 237-258). Also available for download via the World Wide Web; free to University of Oregon users.

Graduate / 0485

Graduate / 0485

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 243-262). Also available for download via the World Wide Web; free to University of Oregon users.

Graduate

Neste trabalho foram desenvolvidos alguns estudos que tiveram como objetivo principal a utilização de reações de cicloadição como a Reação de Diels–Alder e a Cicloadição do tipo [6+4] na síntese de anulenos e baquenolidas. Na primeira parte (Parte A) são apresentadas algumas abordagens com o objetivo de produzir sistemas do tipo biciclo[6.2.1]undecano (42), similares a sistemas existentes em produtos naturais e que são precursores diretos do 1,4–metano[10]anuleno (41), uma estrutura hipotética, cuja síntese ainda não foi descrita. Os melhores resultados foram obtidos através de uma cicloadição [6+4] entre o ciclopentadieno 43 e a tropona 139 o que forneceu 140. Este produto guarda grande semelhança estrutural com o anuleno 41. Para efetuar o rompimento da ponte carbonílica, o melhor método que encontramos consistiu em transformar a cetona 140 em oxima, depois em lactama através de um rearranjo de Beckmann, transformação na forma tosilada e redução com LiAlH4. O álcool primário de 171 pôde ser eliminado com relativa facilidade, mas o grupo NHTs mostrou–se extremamente resistente à alquilação exaustiva/eliminação; apenas quando utilizamos sal de oxônio tivemos evidências de formação de carbocátion. No entanto, os resultados experimentais indicaram fortemente que o anuleno 41 não deve possuir estabilização aromática, pois não encontramos nada deste material no produto da eliminação que, além de Me2NTs, continha apenas polímeros. Alguns cálculos teóricos levaram também à conclusão de que 41 não deve ser aromático. Na segunda parte deste trabalho (Parte B) foram realizados alguns estudos sobre a síntese do produto natural (±)–baquenolida A (184). A etapa principal da síntese realizada foi uma reação de Diels–Alder entre o dieno 298 e o dienófilo 299 sob catálise de NbCl5. O aduto obtido (300) encontra–se devidamente funcionalizado e com a estereoquímica relativa apropriada para a síntese de vários produtos naturais da classe dos eremofilanos e dos bacanos, incluindo as baquenolidas. A síntese do produto natural 184 foi concluída em 8 etapas e com rendimento global de 13,3%. Finalmente foram realizados alguns estudos teóricos dos estados de transição envolvidos nas ciclizações dos enolatos dos compostos 286 e 305 obtendo–se proporções teóricas entre os epímeros 287/288 e 306/307 razoavelmente de acordo com os resultados experimentais. / In this work are described some studies of cycloaddition reactions, such as [4+2] (Diels–Alder reaction) and [6+4] cycloadditions, for the purpose of synthesizing annulenes and bakkenolides. In the first part (Part A) are presented some approaches for the synthesis of the bicyclo[6.2.1]undecane system (42), which is not only similar to systems that occur in some natural products, but also can be considered as a direct precursor of 1,4–metano[10]annulene (41) (a hypothetical structure, which has not yet been synthesized). The best results were obtained through the [6+4] cycloaddition between cyclopentadiene (43) and tropone (139), which furnished 140. This product is already very similar to the annulene 41. To perform the rupture of the carbonyl bridge, the best method that we found consists in transforming the ketone 140 in to the oxime, which was converted to the lactam 142 through a Beckmann rearrangement. This compound was tosilated and subsequently reduced with LiAlH4. The primary alcohol of 171 was easily eliminated but the NHTs group did not react under exhaustive alkylation/elimination conditions; we have obtained evidence of carbocation formation only when the alkylation was performed with oxonium salt. However, the experimental results could indicated that the hypothetical annulene 41 is not aromatic, because we not find this material in the elimination product, which contained only Me2NTs and polymers. Some theoretical calculations also confirmed that 41 should not be aromatic. In the second part of this work (Part B) are described some studies about the synthesis of the natural product (±)–bakkenolide A (184). The main step of the synthesis was a Diels–Alder reaction between diene 298 and dienophyle 299 under catalysis by NbCl5. The obtained adduct (300) is suitably functionalized and exhibit the appropriate relative stereochemistry for the synthesis of some natural products belonging to the class of eremophilanes and bakkanes, including the bakkenolides. The synthesis of 184 was realized in 8 steps, with a global yield of 13.3%. Finally, some theoretical studies, involving the transition states in cyclizations of the enolates of compounds 286 and 305, were carried out. These studies furnished the theoretical ratios between the epimers 287/288 and 306/307 in good agreement with the experimental results.

Lee Ho-Lam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 71-72). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Tables --- p.vi / List of Figures --- p.vii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The Gaussian´ؤ3 Method --- p.1 / Chapter 1.2 --- "The G2++, a Modified Gaussian-2 Method" --- p.2 / Chapter 1.3 --- Density Functional Theory (DFT) --- p.2 / Chapter 1.4 --- Calculation of Thermodynamical Data --- p.3 / Chapter 1.5 --- Remark on the Location of Equilibrium and Transition Structures --- p.3 / Chapter 1.6 --- Natural Bond Orbital (NBO) Analysis --- p.3 / Chapter 1.7 --- Scope of the Thesis --- p.4 / Chapter 1.8 --- References --- p.4 / Chapter Chapter 2 --- Structures and Energetics of C3H6S+´Ø Isomers: A Gaussian-3 ab initio Study --- p.6 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Methods of Calculation --- p.8 / Chapter 2.3 --- Results and Discussion --- p.8 / Chapter 2.4 --- Conclusion --- p.21 / Chapter 2.5 --- Publication Note --- p.21 / Chapter 2.6 --- References --- p.22 / Chapter Chapter 3 --- A Gaussian-3 Study of the C3H6S Isomers and the Dissociation Channels of Diradical ´ØCH2CH2SCH2´Ø and Its Radical Cation ´ØCH2CH2SCH2+ --- p.24 / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- Methods of Calculation --- p.25 / Chapter 3.3 --- Results and Discussion --- p.26 / Chapter 3.3.1 --- Structures and Energetics of C3H6S Isomers --- p.26 / Chapter 3.3.2 --- Dissociation Channels of ´ØCH2CH2SCH2´Ø and ´ØCH2CH2SCH2+ --- p.34 / Chapter 3.4 --- Conclusion --- p.40 / Chapter 3.5 --- Publication Note --- p.41 / Chapter 3.6 --- References --- p.41 / Chapter Chapter 4 --- Computational Study on the Electrocyclic Reactions of [16]Annulene --- p.43 / Chapter 4.1 --- Introduction --- p.43 / Chapter 4.2 --- Methods of Calculation --- p.45 / Chapter 4.3 --- Results and Discussion --- p.45 / Chapter 4.3.1 --- Reaction (1) --- p.49 / Chapter 4.3.2 --- Reaction (2) --- p.50 / Chapter 4.3.3 --- Reaction (3) --- p.52 / Chapter 4.3.4 --- Overall Reaction --- p.53 / Chapter 4.4 --- Conclusion --- p.54 / Chapter 4.5 --- Publication Note --- p.55 / Chapter 4.6 --- References --- p.55 / Chapter Chapter 5 --- Computational Study on the Structures and Stabilities of Some Hypothetical Silicon Nanotubes --- p.57 / Chapter 5.1 --- Introduction --- p.57 / Chapter 5.2 --- Model Design and Methods of Calculation --- p.59 / Chapter 5.3 --- Results and Discussion --- p.59 / Chapter 5.3.1 --- "Armchair (n,n) SiNTs" --- p.60 / Chapter 5.3.2 --- "Zigzag (n,0) SiNTs" --- p.61 / Chapter 5.3.3 --- "Chiral (n,m) SiNTs" --- p.65 / Chapter 5.3.4 --- Stabilities of SiNTs at Elevated Temperature --- p.69 / Chapter 5.4 --- Conclusion --- p.70 / Chapter 5.5 --- References --- p.71 / Chapter Chapter 6 --- Conclusion --- p.73 / Appendix A --- p.74 / Appendix B --- p.76 / Appendix C --- p.77