This thesis comprises an introduction chapter, followed by four chapters outlining the research undertaken by the author throughout the duration of study. Chapter one gives an introduction to homogeneous gold catalysis, outlining the explosion of interest into this area of research over the past 15 years. In particular, the introduction focuses on the efforts reported in the literature involving gold(I)-catalysed reactions with cyclopropenes. Chapter two describes the gold(I)-catalysed addition of indoles to 3,3-disubstituted cyclopropenes. The scope of the reaction is discussed, along with an investigation into the mechanism of the reaction. Chapter three outlines the gold(I)-catalysed addition of thiols and thioacids to 3,3-disubstituted cyclopropenes. The selectivity of the reaction is discussed, as well as studies into the mechanism of the reaction. Chapter four presents the findings into how gold(I) catalysts are deactivated in the presence of sulfur and nitrogen nucleophiles. The deactivated species formed in gold(I)-catalysed reactions are isolated and characterised, and their catalytic abilities are probed. Chapter five describes the research undertaken into gold(I)-catalysed etherifications, utilising allylic alcohol substrates with alcohol nucleophiles. Further expansion in this area is also outlined by using novel 1,2,3-triazol-5-ylidene gold(I) catalysts, as well as the gold(I)-catalysed chroman formation from allylic alcohols and phenols.