Type of Document Dissertation Author Wang, Dong Author's Email Address email@example.com URN etd-04112011-173742 Title Understanding the Selective Detection of Homocysteine and Studies toward the Synthesis of Vinigrol Degree Doctor of Philosophy (Ph.D.) Department Chemistry Advisory Committee
Advisor Name Title Crowe, William E. Committee Chair Nesterov, Evgueni E. Committee Member Taylor, Carol M. Committee Member Vicente, Graca M. Committee Member Cheng, Henrique Dean's Representative Keywords
Date of Defense 2011-03-23 Availability unrestricted AbstractThe first part of the work is dedicated to the selective detection of Homocysteine (Hcy). In order to better understand this colorimetric detection method, a thermodynamic model for the pH
dependence of the effective reduction potential of Hcy derived á-carbon radicals has been
proposed. And using viologen indicators of varying reduction potentials, we demonstrate that
colorimetric changes occur at experimental pH values consistent with the model.
The one-carbon bridge stereochemistry of bicyclo[3.3.1]nonane framework is critical to
make the third ring of the tricyclic precursor of vinigrol. We studied this stereochemistry
carefully and found that the major diastereomer formed from Robinson annulations places the
one-carbon bridge substituent anti to the â-keto ester/amide unit introduced in the reaction and
stereoselectivity appears to be kinetically controlled. The origin of this diastereoselection has been identified by density functional theory calculations.
Efforts toward the total synthesis of vinigrol have been described. The tricyclic precursor of
vinigrol has been efficiently synthesized in gram scale utilizing the Robinson annulation, base catalyzed epimerization and intramolecular alkylation as the pivotal steps. The thermal [2+2]
reaction with dichloroketene remains in vain although several different approaches have been
explored. Finally, an alternative route using the tricyclic enone as the electrocyclic reaction
precursor has been investigated. This enone can be obtained from the tricyclic precursor via
either a selenation- or a bromination-elimination sequence. Further transformation involving
olefination, electrocyclic reaction and oxidative cleavage to generate the bridging eightmembered
ring, would complete the synthesis of the vinigrol core.
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