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Approaches towards the synthesis of naturally occurring toxic alkaloids
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Bond, Timothy J. (1995) Approaches towards the synthesis of naturally occurring toxic alkaloids. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3228233~S15
Abstract
This thesis describes the attempted syntheses of polyamine based peptide toxins (enzymatically) and of 5-mono and 5,8-disubstituted indolizidines (by conventional chemical methods).
Chapter 2 describes the construction of the 5,6 bicyclic skeleton of the indolizidine alkaloids. This was achieved by utilizing L-glutamic acid dimethyl ester to form the N-pyrrolo derivative [224], cyclization to the bicyclic compound [214], achieved using acid equivalents, as well as the hydrogenation of [214] to either the alcohol [215] or the fully reduced compound [263] depending on choice of catalyst and pH. Investigations were carried out into the mechanism of hydrogenation of [214] by the attempted synthesis of postulated intermediates [281] and [282]. The results of these syntheses and the submission of the products to our hydrogenation conditions are discussed.
Chapter 3 describes the attempted syntheses of 5-monosubstituted indolizidines from [263] and 5,8-disubstituted indolizidines from [215]. This was undertaken by the activation of the 8-hydroxyl group in [215] and of the alcohol group derived from the ester of [263], followed by attempted substitution. Problems were encountered in both the activation and substitution reactions and these are rationalized in terms of the position of both the alcohol groups β to the nitrogen of the indolizidine skeleton.
Chapter 4 describes attempts towards the differentiation of the two termini of spermidine by various enzymes. The methodology was tested by the chemical protection of the amine functions and attempted enzymatic hydrolysis. The protecting groups chosen were acetyl (Ac) and benzyloxycarbonyl (Cbz) yielding the 1,4-diaminobutane derivatives [378] and [379] and the spermidine derivatives [380] and [381]. The failure of the enzymatic hydrolyses of these compounds is discussed.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Library of Congress Subject Headings (LCSH): | Toxins -- Synthesis, Alkaloids -- Synthesis, Semiochemicals, Natural products -- Synthesis, Chiral drugs -- Synthesis | ||||
Official Date: | December 1995 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Taylor, Paul C. (Professor) | ||||
Format of File: | |||||
Extent: | xiii, 185 leaves : illustrations, charts | ||||
Language: | eng |
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