Exploring regiocontrolled gold-catalysed alkyne activation for efficient synthesis of nitogen heterocycles

In this thesis the development of regiocontrolled gold-catalysed reactions for the synthesis of complex heterocycles are described. A new methodology for the formation of all-carbon fully substituted oxazoles was designed and developed, through a novel gold-catalysed intermolecular formal [3+2]-cycloaddition across the π-system of electron-rich internal alkynes by employing conjugated \(N\)-ylides as \(N\)-nucleophilic 1,3-\(N\),\(O\)-dipole equivalents. This intermolecular addition to unsymmetrical internal alkynes represents a considerable regioselectivity and reactivity challenge, as there are no examples of intermolecular atom-transfer nitrene addition. A new design of substrates incorporating an electron-rich π-system and a tethered oxidant or a nitrene delivery system was investigated. Several strategies towards the formation of these systems were proposed and the exhibiting limitations were identified. A novel gold-catalysed reaction has been developed for the formation of complex polycyclic systems, which involves a [1,5]-hydride transfer/cyclisation cascade of functionalised aromatic and aliphatic ynamides. Under mild conditions, the process rapidly generates three fused ring systems by the formation of three new C(sp\(^3\))-C(sp\(^3\)) bonds and up to four contiguous stereogenic centres, in a single manipulation