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Title: Some chemistry relating to turmerones
Author: Pombo-Villar, Esteban
ISNI:       0000 0001 3494 1325
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1985
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The current ideas relating to the biosynthesis of turmerones are discussed, and a biosynthetic pathway leading to α- and β-turmerones is proposed. The conformation of β-turmerone assigned by Japanese workers is shown to be based on erroneous assumptions; their data are insufficient for assignment of the absolute stereochemistry of β-turmerone. A chemical correlation to juvabione is proposed, and all current methodology is inadequate for the selective transformation of a 1, 3-diene to an α β-unsaturated methyl ester. It is shown that this transformation can be performed via the addition of a sulphenyl halide to the 1, 3-diene. Addition of phenylsulphenyl chloride to 2, 3-dimethyl-l, 3-butadiene gives the 1, 2-adduct: 2-chloro-2, 3-dimethyl-l-(phenylthio) but-3-ene. This adduct rearranges thermally to the 1, 4-adduct. The 1, 2-adduct is converted into a variety of β-substituted sulphides by replacing the chloride with a suitable nucleophile: MeOˉ , AcOˉ , ˉCN, ˉOH. Hydride transfer to the tertiary centre is slow, and rearrangement to the 1, 4-adduct is a competing process. Conversion of β-hydroxy- sulphides from 1, 3-dienes to alkenylepoxides is achieved, and the epoxides rearrange to aldehydes by acid treatment. This constitutes an oxidative monofunctionalisation of 1, 3-dienes, and similar transformations are obtained with 4,4-dimethyl-l-methylenecyclohex-2-ene, and with trans-penta-1,3-diene. The thermolysis of (2-hydroxy-l-phenyl- ethyl)pyridinecobaloxime is studied by 1 HNMR, and employed to synthesise l-(carboxymethyl)ethylpyridinecobaloxime. No alkylcobalt species is obtained in the reaction with dienes or unactivated olefins. Finally, the determination of the structure of a new lignan from Virola elongata is described.
Supervisor: Not available Sponsor: Icetex ; Quest International ; Overseas Research Scholarship ; COBE S.A. ; Imperial Chemical Industries Ltd. ; Procter & Gamble Company
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QK Botany ; SB Plant culture