Novel transformations of gold carbene and vinyl gold carbenoid intermediates from the addition of oxygen nucleophiles to alkynes

The work described in this thesis focuses on novel transformations of gold carbene and vinyl gold carbenoid intermediates, generated via the addition of oxygen nucleophiles to alkynes. Gold-catalysed oxyarylation of alkynes with benzothiophene S-oxides has been demonstrated for C-3 selective alkylation of benzothiophenes. Current methods for the direct C-3 functionalisation of benzothiophenes are limited. This thesis describes a mild and efficient method, incorporating a novel substitution pattern that allows for further elaboration of the functionalised benzothiophene products. Alongside reaction scope exploration, several studies have been performed to investigate the mechanistic pathway, catalyst degradation, and substrate inhibition. These studies provide further understanding into the reactivity of sulfoxides in gold-catalysed transformations and the stability of phosphite-based cationic gold catalysts, that may aid future research. The second part of this thesis explores the novel transformations of sulfenylated propargyl carboxylates to investigate the influence of sulfur substitution on the gold- catalysed transformations of alkynes. This work demonstrates the first examples of sulfenylated propargyl carboxylates reacting under gold catalysis; a range of compounds have been synthesised from nucleophilic addition reactions and gold- catalysed rearrangements of these novel substrates. In addition, a stereoselective gold-catalysed oxidative rearrangement is demonstrated, to afford a range of captodative olefin products