Work was undertaken towards the synthesis of the promising antibiotic lactonamycin (iii). Following the work of Parsons et al. it was proposed that cyclisation of the ene-diyne (i) would give access to advanced pentacyclic intermediate (ii) and that from this a total synthesis of lactonamycin would be achieved (scheme I). Scheme I : Proposed Parsons, Board, Waters cyclisation to form the pentacycle (iii)(For image refer to pdf). A synthesis towards the cyclisation precursor (i) was carried out and a route to the key tetrasubstituted phthalide (v) established. Further chemistry was proposed to complete the synthesis of lactonamycin (scheme II). Scheme II : Formation of a fully substituted benzolactone.(For image refer to pdf). During attempts to introduce the β-bromoallyl group of key intermediate (v) using a high temperature Claisen rearrangement it was established that the benzodioxin (vii) underwent thermolysis to generate the reactive quinone methide intermediate (viii) and that in the presence of a nucleophilic solvent the adduct (ix) was formed (scheme III). Model studies showed the reaction to be both general and high-yielding. Scheme III : Novel quinone methide methodology. (For image refer to pdf).
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:554834 |
| Date | January 2012 |
| Creators | Preece, Lewis |
| Publisher | University of Sussex |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://sro.sussex.ac.uk/id/eprint/39607/ |
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