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Title: Taxadiene : synthesis, extraction and oxidations
Author: Barton, Naomi A.
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2013
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This thesis describes the synthesis, extraction and oxidation studies of taxadiene, a member of the taxane family of natural products. The introduction outlines the biosynthesis and biological activity of taxanes, and then details the challenge of the project- to synthesise a variety of taxanes by oxidation of taxadiene. Potential sources of taxadiene are then discussed, including extraction from genetically modified organisms and total synthesis. Both routes were selected for investigation. A selection of previous syntheses of taxanes is then outlined, including the two previous syntheses of taxadiene and a review of Diels-Alder approaches to taxanes. The retrosynthetic analysis is presented, using a key Diels-Alder cyclisation to install the A and B ring and form taxadienone, alongside a summary of the project mms. The results and discussion begins by detailing the formal synthesis of taxadiene, which began with the formation of the C ring via an acid catalysed cyclisation of a polyene derived from the natural product famesol. The synthesis of the diene moiety is then outlined, which proceeded via a Refonnatsky reaction to fonn a beta-lactone and subsequent decarboxylation. This was followed by installation of the dieneophile. The results of the Diels-Alder studies, which fonned the taxane taxadienone, are then presented. The formal synthesis was then completed via the previously published deoxygenation of taxadienone to taxadiene. As the Diels-Alder reaction was low yielding, the synthesis of an alternative Diels-Alder precursor follows. This precursor had a modified C ring and cyclised in greater yield. A review of genetically modified vectors expressing taxadiene is then discussed, followed by the development of a new procedure for the extraction of taxadiene from genetically modified tomatoes. This yielded 13 mg of taxadiene per I kg of fresh fruit.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available