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The application of mechanochemical techniques towards organic synthesis and catalysis

Jones, Andrew 2022. The application of mechanochemical techniques towards organic synthesis and catalysis. PhD Thesis, Cardiff University.
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Abstract

This thesis describes a series of studies of organic synthesis and catalysis under mechanochemical conditions. Initial investigations outline the development of the first known C-S coupling under mechanochemical conditions, which builds upon previous work in the group describing a mechanochemical C-N coupling. In this study, oxidation of thiols to disulfides proved a detrimental side reaction, which was overcome with the use of a reductant and subsequent studies revealed a possibility for careful control of this interconversion which led to a 2-step, 1-pot coupling of disulfides. Also discussed in this study is the concept of phase transition induced reactivity, which was demonstrated by alteration of the reactor design to promote a melt-phase phenomenon that enabled reactivity in some cases. Transition metal catalysed cross-electrophile coupling has recently emerged as a powerful strategy for the construction of C-C bonds. Firstly, a mechanochemical cross-electrophile coupling reaction of aryl halides and alkyl halides was developed, demonstrating the excellent capability of ball-milling for the activation of zero-valent metals. A broad scope was shown, including tolerance to a range of metal forms. Further work in this area led to the development of a reductive coupling reaction of twisted amides with alkyl halides for the construction of a range of ketone products. The degree of bond angle distortion for the amide component was examined for its effect in the reaction. Finally, the reactivity of a fluoroiodane reagent was investigated for use under mechanochemical conditions. Initial work showed excellent reactivity for a known fluorocyclisation of unsaturated carboxylic acids to give fluorinated lactones. These promising results then led to development of mechanochemical protocols for the fluorocyclisation of  unsaturated hydrazones and oximes to access novel fluorinated tetrahydropyridazines and dihydrooxazines respectively.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Chemistry
Date of First Compliant Deposit: 18 August 2022
Last Modified: 18 Aug 2022 14:35
URI: https://orca.cardiff.ac.uk/id/eprint/152026

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