The total synthesis of a novel diarylheptanoid isolated from a South African
medicinal plant, Siphonochilus aethiopicus, was investigated. S. aethiopicus
(Indungulu in Zulu) is the only South African species of the Zingiberaceae
plant family and is widely used in traditional medicine. One of the compounds
isolated from this plant is a novel diarylheptanoid. Diarylheptanoids constitute
a distinct group of natural plant metabolites characterized by two aromatic
rings linked by a linear seven-carbon aliphatic chain, with varying functional
groups on the aryl and the aliphatic chain. The target molecule for our
synthesis contains two highly oxygenated aryl rings linked by an aliphatic
chain with two stereogenic centres and a trans-alkene.
In this study we present our investigation of different strategies to a viable
synthetic method that could provide material to supplement the relatively
small quantity of product that can be isolated from the plant extract. The
major challenges of this synthesis were to develop procedures for the
preparation of the homobenzylic trans-alkene, the stereogenic centres and to
attach the electron-rich aromatic rings to the aliphatic chain.
In this thesis the following aspects are described:
• Various types of olefination reactions (including Wittig, Julia and
organometalic-mediated type of olefination reactions)
• Various types of alkylation reactions (including Grignard, Friedel-Crafts
and organometalic-mediated type of alkylation reactions)
• Incorporation of the stereogenic centres (including asymmetric
hydroxylation and use of chiral starting materials)
The synthesis will not only give a viable synthetic route to the target
compound but is also versatile enough to allow the preparation of analogues. / Thesis (Ph.D. (School of Chemistry)) - University of KwaZulu-Natal, Pietermaritzburg, 2008.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/216 |
| Date | January 2008 |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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