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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Harnessing single amino acid catalysis : development of the enantioselective intramolecular Morita-Baylis-Hillman and Rauhut-Currier reactions and studies toward the synthesis of (+)-SCH 642305

Aroyan, Carrie Elizabeth January 2008 (has links)
Thesis advisor: J. Scott Miller / The development of two catalytic asymmetric synthetic methods is presented and culminates with studies of their application to the synthesis of a natural product. The intramolecular variant of the Morita-Baylis-Hillman (MBH) reaction has remained almost untouched by asymmetric catalysis. A significant advance in the field is demonstrated with the development of a highly enantioselective intramolecular MBH reaction employing a co-catalytic system of N-methylimidazole (NMI) and pipecolinic acid (Pip). The optimization of various reaction parameters and the use of protic conditions (THF-H2O, 3:1) afforded the desired products in up to 82% yield and 80% ee. The extension of this methodology to include the use of vinylogous reaction partners in the Rauhut-Currier (RC) reaction has been achieved, establishing the first highly enantioselective RC reaction. A single amino acid derivative of cysteine, in the presence of potassium tert-butoxide and a critical concentration of water in acetonitrile, was demonstrated to function as a highly selective catalyst providing products in up to 95% ee. Finally, the application of the MBH and RC reactions to the synthesis of complex molecules presents highly useful methodology for the formation of a new C–C bond in the generation of densely functionalized enantiopure products. Preliminary studies toward the application of this methodology to the stereoselective synthesis of (+)-Sch 642305 are described. Examination of the catalyst’s ability to dictate the stereoselectivity of the key step (catalyst control) and allow the synthesis of both the natural product, and difficult-to-obtain unnatural stereoisomeric analogs, will be the subject of on-going studies. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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