Studies on enolate directed carbometallation reactions.
Doctoral thesis, UCL (University College London).
The present thesis is concerned with the concept of an enolate directed carbometallation reaction. The first chapter provides a review of the area of heteroatom directed carbometallation of isolated alkynes and allenes as a powerful method for the formation of double bonds and attempts to rationalise the regio and stereochemistry of such additions. The second chapter begins with the results of a small study on the copper(I) mediated carbometallation reactions of homoallenols. The research into the aforementioned enolate directed carbometallation reaction is then presented and discussed, and especially the efforts made towards efficient formation of a novel “bis-carbanionic” intermediate, possessing both an enolate and a vinyl organometallic reagent. Following on from a preliminary result within the group research was carried out into the carbometallation reactions of enolates derived from carboxylic acids, amides, esters. Whilst amide enolates proved to be problematic, carboxylic acid dianions were found to be suitable substrates for carbometallation and dialkylation of the “bis-carbanion” was successful. After considerable experimentation involving a variety of organometallic reagents and protocols for enolate anion generation, ester enolates were found to be most successful, giving rise to high yields of products and allowing selective reactions of both the vinyl organometallic reagent and the enolate. Finally, very encouraging preliminary results were obtained with an adventurous strategy involving the enolate intermediate obtained from a conjugate addition to an enone. Experiments to probe the reactivity of these novel intermediates, with the aim of selective reaction of only one of the carbanions, are discussed throughout. These results are then summarised and logical conclusions as well as perspectives for future research are drawn. The thesis concludes with a detailed description of the experimental procedures used and characterisation of the compounds prepared.
|Title:||Studies on enolate directed carbometallation reactions|
|Open access status:||An open access version is available from UCL Discovery|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry|
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