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An Asymmetric Horner-Wittig reaction: Synthesis of Phytosterols and unravelling their role in disease

Phytosterols are major components of food and are structurally related to
cholesterol, but differ from it by virtue of a carbon substituent at the C-24
position and in some cases, a double bond between C-22 and C-23 (Figure i).
Furthermore, phytosterols are shown to have protective actions against colon,
breast, and prostate cancer1; further investigation is required as their mode of
action is unknown. Thus, reported herein is the design and synthetic
implementation required to construct these naturally occurring compounds.
Figure i : Cholesterol
Construction towards a double bond flanked by two asymmetric carbon atoms,
observed in the phytosterol side chain, will be synthesised using an asymmetric
Horner-Wittig (H-W) reaction, involving a chiral α-substituted aldehyde and a
chiral β-substituted phosphine oxide. In addition to the synthesis, the
stereochemical outcomes of these H-W reactions were probed. The results
demonstrated, that by varying the steric bulk, electronic nature, and aromatic properties of the groups β to the phosphorus and α to the aldehyde can control the cis/trans selectivity in alkene formation.
Finally, to display the utility of this methodology, the phytosterol compounds will be synthesised and tested in MD-MBA-231 cancer cell lines, allowing further investigation into the phytosterol mechanism of action.

Identiferoai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/7565
Date January 2014
CreatorsParry, Laura J.
ContributorsAfarinkia, Kamyar, Vinader, Victoria
PublisherUniversity of Bradford, Faculty of Life Sciences
Source SetsBradford Scholars
LanguageEnglish
Detected LanguageEnglish
TypeThesis, doctoral, PhD
Rights<a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>.

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