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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

Total synthesis of plakortide E and biomimetic synthesis of plakortone B. / CUHK electronic theses & dissertations collection

January 2011 (has links)
Plakortide E (85), which is isolated from the Jamaican marine sponge Plakortis halichondrioides, contains a five-membered peroxide ring, with the oxygen atoms are linked to tertiary C4 and C6 centers.34,57 In this thesis, the total synthesis of plakortide E (85) is described. A novel palladium-catalyzed approach towards 1,2-dioxolanes has been developed. A lipase-catalyzed kinetic resolution was employed to provide optically pure 1,2-dioxolane central cores. Coupling of the central cores and side chains was achieved by a Negishi reaction. All four isomeric structures of plakortide E methyl ester, namely, 86a-d were synthesized, and one of these molecules, 86d proved to be natural plakortide E methyl ester on the basis of 1H, 13C NMR spectra and specific rotation. With plakortide E methyl ester (4S,6R, 10R)-(-)- cis-(86d) and its other three isomers in hand, we successfully converted them into plakortone B (3S,4S,6 R,10R)-(87a), and its isomers ent-87a, 87b and ent-87b via an intramolecular oxa-Michael addition/lactonization cascade reaction. Saponification converted 1,2-dioxolane 86d into plakortide E (85a) whose absolute configuration (4S,6 R,10R) was confirmed by comparison of spectral and physical data with those previously reported.35b / Sun, Xiaoyu. / Adviser: Henry N. C. Wong. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 183-195). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

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