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The Total Synthesis of Analogues of Withanolide F

Manicassamy, Laura (2014) The Total Synthesis of Analogues of Withanolide F. PhD thesis, University of York.

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Abstract

The total synthesis of analogues of withanolide F I, a highly oxygenated C-28 steroidal lactone natural product isolated from the leaves of the plant Withania adpressa is discussed herein. Chapter 1 describes the classification of the withanolides, their biological activity and previous studies towards the synthesis of the withanolides. Based on well-established chemistry, commercially available pregnenolone II was transformed into the key aldehyde III in nine steps, two steps fewer than previously published routes, with an optimised 14% yield as summarised in Chapter 2 Chapter 3 outlines the synthetic efforts towards the construction of the δ-lactone side chain in compound IV. The synthesis of 14,17-dideoxy-17-epi-withanolide F V was then completed via a straightforward acetylation-oxidation-elimination sequence from triol IV. Isomerisation of the 2,3-double bond delivered a novel analogue of withanolide F I, 3,4-dihydro-Δ3,4-14,17-dideoxy-17-epi- withanolide F VI, as reported in Chapter 4. The development of new methodology to form δ-lactone side chain IX, a key structural feature of natural products I, V and VI, from cyclic sulfone VII via the heterocyclic lactone VIII based on the Dreiding-Schmidt reaction was investigated. Chapter 5 discusses the studies towards the synthesis of strategic sulfone VII.

Item Type: Thesis (PhD)
Academic Units: The University of York > Chemistry (York)
Identification Number/EthosID: uk.bl.ethos.605522
Depositing User: Ms Laura Manicassamy
Date Deposited: 27 Jun 2014 11:56
Last Modified: 08 Sep 2016 13:31
URI: http://etheses.whiterose.ac.uk/id/eprint/6373

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