In this thesis, a review concerning pentacyclic quassinoid total syntheses from 1990 to 2005 and structure activity relationship is presented. / Synthetic studies towards pentacyclic quassinoids, namely (-)-samaderine E and (-)-samaderine Y from (S)-(+)-carvone are described. Total synthesis of (-)samaderine Y was accomplished in 21 steps with 1.1% overall yield in which the synthesis was based on a C→CE→ABCE→ABCDE ring annulation sequence. The crucial points included: (1) a regioselective allylic oxidation to functionalize C ring; (2) a stereoselective epoxymethano bridge formation; (3) an intramolecular Diels-Alder reaction resulting in the construction of AB ring; (4) an intramolecular aldol reaction for the construction of D ring; (5) a regioselective allylic oxidation and an alpha-keto acetoxylation to functionalize the A ring. / Yeung Ying-yeung. / "June 2005." / Adviser: Tony K. M. Shing. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3811. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 172-178). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

by Xue You Zhu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (p. 138-143). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

No / The naturally occurring bitter principle quassin (1) was converted chemically into the gamma-lactone quassilactone (13) in an attempt to enhance its antiplasmodial activity. The in vitro antiplasmodial activity of 13 against Plasmodium falciparum (K1) (IC(50) = 23 microM) was 40-fold greater than that of 1. However, one of the intermediates, compound 8, the 15beta-hydroxy,16-O-m-chlorobenzoyl analogue of 1, was 506-fold more active than 1 against P. falciparum (IC(50) = 1.8 microM) and only 3-fold less potent than chloroquine. In addition, 8 displayed the best cytotoxic/antiplasmodial ratio (112) of all of the compounds tested. In the course of this work a dimer, neoquassin ether (6), linked at C-16 was also prepared; 6 was found to have weak antiplasmodial activity (IC(50) = 9.7 microM).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxiii, 454 p.; also includes graphics (some col.). Includes bibliographical references (p. 246-259). Available online via OhioLINK's ETD Center

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