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Title: Convergent and bidirectional strategies towards the total synthesis of hemibrevetoxin B
Author: Elwood, Jessica
ISNI:       0000 0005 0286 781X
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 2020
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Harmful algal blooms adversely impact the environment, fish populations and humans. They are also responsible for the discolouration of sea water in certain areas of the world. Red tides that occur in the Gulf of Mexico and along the coast of Florida are the result of an excessive growth of Karenia brevis, a marine dinoflagellate. From this dinoflagellate, a family of natural products called the brevetoxins have been isolated. The brevetoxins are fused polycyclic ethers with the characteristic semi-rigid ladder like structure and possess potent biological activities. This thesis describes the development of strategies for the total synthesis of hemibrevetoxin B, the smallest member of the brevetoxin family. In particular, work has focussed on the preparation of key fragments of the natural product by investigation of several synthetic routes; both convergent and bidirectional approaches have been studied. The first chapter of this thesis provides an introduction to marine polycyclic ethers, exploring their origins, mechanism of action and biosynthesis. Previous total and formal syntheses are reviewed along with various ring construction strategies. Following this, there are literature reviews of bidirectional methods developed on centrosymmetric molecules. The initial bidirectional strategy employed by the Clark group for construction of the tetracyclic core of hemibrevetoxin B is also described. The second chapter of the thesis documents the results obtained during studies concerning the implementation of a convergent route in which an O-H insertion was used to construct the A-ring system and oxirane ring expansion was employed to afford the D-ring. The later part of this chapter describes the use of bidirectional strategies to construct the CD-ring system from a centrosymmetric intermediate. This work is followed by an exploration of desymmetrisation reactions to provide advance chiral intermediates from achiral starting materials.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: QD Chemistry