In a series of synthetic studies towards the taxane group of natural products, we have developed a synthesis of 2-lithio-1, 3-butadiene from 3-buten-2-one-2',4',6'-tri-iso-propylbenzenesulphonyl hydrazone using the Shapiro reaction. The reaction of 2-lithio-1,3-butadiene with a series of aldehydes and other electrophiles was then studied. In contrast to the corresponding Grignard, the major isolated products from the reaction of 2-lithio-1,3-butadiene with aliphatic aldehydes were 2-substituted dienyl alcohols, whilst with aromatic and some a,b-unsaturated aldehydes varying amounts of the regioisomeric allenic alcohols were also formed. Two of the dienyl alcohols were shown to undergo the amide acetal Claisen rearrangement. 2-Lithio-1,3- butadiene was then used in an attempt to synthesise a taxane model compound. In an alternative approach to a different taxane model compound, we developed a stereocontrolled route to a trisubstituted cyclohexane derivative. The cyclohexane was then converted into a Diels-Alder substrate using a stepwise diene synthesis which employed silicon as a control element. Lewis acid catalysed cyclisation of the Diels-Alder substrate gave stereospecifically a tricyclo [9. 3.1.03,8] pentadecane taxane model compound, which had the same relative configuration about its chiral centres as the taxane natural products. Attempts were then made to extend the synthesis to incorporate the C-14-gem-dimethyl groups.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:352187 |
| Date | January 1984 |
| Creators | Brown, Paul A. |
| Publisher | University of Leicester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/2381/34035 |
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