The development of new methods for the reduction of carboxylic acid derivatives is described. The ability to reduce these carbonyl derivatives through radical intermediates provides an orthogonal approach as compared with hydride based reductions. Initial experiments focused on the development of the SmI2–H2O system, where we have shown that chelation effects can be utilised to facilitate reduction of cyclic esters. Furthermore, a revised mechanism for the SmI2–H2O mediated reduction of lactones is discussed, and the effective reduction potential of the system determined. Also described is the optimisation of barbituric acids using SmI2–H2O to give the corresponding hemiaminal product. Next, experiments towards the development of a more reactive SmI2-based system are presented; where we have demonstrated that the SmI2–amine–H2O system is capable of the reduction unactivated carboxylic acid derivatives. The reductions of carboxylic esters and acids are described with mechanistic discussions. In addition, the design of a new divalent lanthanide system based on thulium diiodide is described. The addition of proton sources to TmI2 increases the effective reduction potential and facilitates unprecedented reactivity with amides. An investigation into the preparation of the reagent is also described, which has been one of the key factors developing all of the chemistry presented.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:626912 |
| Date | January 2014 |
| Creators | Spain, Malcolm Peter |
| Contributors | Procter, David |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/the-first-general-electron-transfer-reductions-of-carboxylic-acid-derivatives-using-samarium-diiodide(0229bb38-0c8d-41c5-a953-e5de81acd6a2).html |
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