Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486455
Title: Super electron donors powerful reductions performed by neutral organic molecules
Author: Schonebeck, Franziska
ISNI:       0000 0001 3556 6598
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2007
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Abstract:
This project aims to explore the ability of organic molecules to transfer electrons and is based on the recent development within the Murphy group of a novel organic molecule, called Super-S.E.T. reagent 1, that allows the reduction of unactivated aryl and alkyl iodides. My study investigates the scope of donor 1 as a reducing agent and extends the study to a more powerful donor 2. Chapter One provides an introduction to the world of electron transfer. After giving a theoretical background, synthetic applications of electron transfer are highlighted, in particular using metal chemistry, electrochemical and photochemical methods. This chapter also discusses the use of sulfones and sulfonamides as challenging substrates for electron transfer. Finally the field of neutral organic electron-donors, which form the basis of my studies, is introduced. Chapters Two to Seven then summarise my work. Chapter Two and the second part of Chapter Six highlight my adventures in investigating the chemistry of donor 1. Until now, donor 1 is known to reduce efficiently only specific aryl and alkyl iodides. This report (i) highlights the scope and limitations of donor 1 in the reduction of different aryl iodide substrates and of aryl halides other than iodides and (ii) discusses the application of donor 1 in the selective reduction of an ortho- over an analogous para-aryl iodide in substrate 3 and (iii) recounts the successful isolation of the first adduct of the donor, i.e. 4. Chapter Three to Six deal with the exploration of the power of Super-S.E.T. reagent 2. This donor was successfully applied as a powerful reducing agent in the reductive cleavages of a number of activated sulfones and sulfonamides, giving the reduced counterparts in excellent yields. Further, strong evidence for the first example of a Julia olefination using a neutral organic electron donor has been given. It was also shown that the reagent has remarkable reducing power, being the first neutral organic reagent to generate highly reactive aryl anion intermediates in the reduction of aryl 3 bromides and iodides. Ester substrates 5,6 and 7 were synthesised and investigated as mechanistic probes in that context. The chemistry of donor 2 with aliphatic halides was investigated, leading to the formation of aldehydes in DMF or DMA. It was found that the proportion of aldehyde can be increased with more equivalents of donor 2, ultimately leading to the aldehyde being the exclusive product. Using non-polar solvents, such as diethyl ether, donor 2 was transformed into a powerful reducing agent for alkyl bromides, reacting at room temperature and showing radical chemistry. Selective reduction of an alkyl over aryl bromide was achieved also. Intriguing reactivity was observed with anthracene esters, giving the dihydroester as one of the major products, if a carbene is added, and dihydroanthracene if not. After a summary of results in Chapter Seven, Chapter Eight presents the experimental procedures and analytical data for the compounds discussed in Chapters Two to Six.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.486455  DOI: Not available
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