Applications of density functional theory (DFT) in metal-catalysed and metal-free organic transformations

In this thesis, Density Functional Theory (DFT) was employed to study a range of synthetic reactions involving hypervalent iodine reactants, in addition to gold- and bismuth-catalysed processes.
Chapter One provides an introduction to fundamental computational chemistry with an overview of density functional theory (DFT).
Chapter Two investigates the mechanisms that underpin reactions involving hypervalent iodine species which were carried out in collaboration with experimental research groups. This chapter is structured in three parts. The first section, “An overview of hypervalent iodine compounds and their reactions,” provides a background of the relevant literature and context for the two sections which follow: “Oxidation of Electron-Deficient Phenols Mediated by Hypervalent Iodine(V) Reagents: Fundamental Mechanistic Features Revealed by a Density Functional Theory-Based Investigation”; and “Photochemical Activation of a Hydroxyquinone-Derived Phenyliodonium Ylide by Visible Light: Synthetic and Mechanistic Investigations”. In the first study, DFT was utilised to understand the mechanistic basis of the oxidation of electron-deficient phenols using hypervalent iodine(V) reagents. The second study applies DFT to explore the thermal and photochemical activation of hydroxyquinone-derived phenyliodonium ylides in order to obtain an enhanced understanding of their associated reactivity.
Chapter Three comprises three sections, the first of which provides “An overview of gold-catalysed C–H functionalisation with a focus on DFT studies”. This is followed by two research sections titled: “Hydroalkylation of Alkenes with 1,3-Diketones via Gold (III) or Silver(I) Catalysis: Divergent Mechanistic Pathways Revealed by a DFT-based Investigation”; and “Mechanistic Insights into Gold(I)-Mediated C–H Activation”. In each study, DFT was employed to develop an improved understanding of the fundamental reaction mechanisms that operate in these transformations, while providing key insights that can aid in the development of new C–H activation processes.
Chapter Four contains one study, “Bismuth (III)-Catalysed Hydroalkylation of Styrene with Acetylacetone: A DFT-Based Mechanistic Study”. Computational methods are employed to investigate the mechanism of this transformation and compare and contrast this with analogous reactivity facilitated by gold (III) catalysts which were explored in Chapter three.