Chapter 1 describes the attempts to synthesize piperidin-2-ones via an aza-Michael-Michael annulation, which were unsuccessful. A general route for the synthesis of piperidin-2,4-diones from β-keto esters via a Dieckmann cyclisation was proposed and five piperidin-2,4-diones with different substituents at positions-5 and -6 were prepared. An asymmetric route to 1-unsubstituted piperidin-2,4-diones was also developed which involved the use of Davies' chiral auxiliary to induce an asymmetric Michael addition. Chapter 2 describes a new approach to the synthesis of codeine. The piperidin-4-one ring was prepared by a Dieckmann cyclisation; a Robinson annulation was performed to construct the cyclohexenone ring and the key bicyclic intermediate was made. However, attempts to prepare the corresponding benzomorphan via a Grewe cyclisation of the α,β-unsaturated ketone were not successful. Synthesis of various 2,3-disubstituted piperidin-4-ones using the same strategy as the codeine synthesis was attempted; six different piperidin-4-ones with alkyl and aryl substituents at the 2-position were prepared. Chapter 3 describes the attempts to synthesize 1,2-dihydropyrrol-3-ones employing the same strategy used to make piperidin-4-ones in Chapter 2. Seven different diester intermediates were successfully prepared but attempts for Dieckman cyclisation failed. The focus was changed to prepare 5-substituted pyrrolidin-3-ones by the protocol used to make piperidin-2,4-diones in chapter 1 and four pyrrolidin-3-ones were made. Enantioselective syntheses using the Davies' chiral auxiliary were attempted and enantiopure 5-methylpyrrolidin-3-one was prepared.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:631985 |
| Date | January 2014 |
| Creators | Yau, K. C. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1451240/ |
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