Search

This thesis describes the development of a metal-free dihydroxylation procedure based on the reactivity of malonoyl peroxide derivatives. Chapter 1 provides an overview of the current methods available for the preparation of 5yw-l,2-diols. Emphasis has been placed on describing the advantages and limitations of each system in order to highlight areas which require further improvement. Chapter 2 describes previous work on the reaction of phthaloyl peroxide (PPO) with alkenes and details a series of exploratory investigations, performed in an effort to develop a new catalytic dihydroxylation procedure. Chapter 3 describes the development of a novel dihydroxylation procedure based on the reactivity of cyclobutane malonoyl peroxide. A simple procedure for the formation of malonoyl peroxides is described. Conditions were optimised for the reaction of 4-methylstyrene and cyclobutane malonoyl peroxide with regards to solvent, temperature, peroxide equivalents and time. An optimised set of conditions provided a two-step procedure which allowed 1-p-tolylethane-l,2-diol to be dihydroxylated in 84% isolated yield. The reaction mechanism was probed in a series of isotopic labelling studies and was proposed to proceed via a dioxolane intermediate. Chapter 4 examines the substrate scope of the cyclobutane malonoyl peroxide mediated reaction. Cyclobutane malonoyl peroxide emerged as an effective reagent for the dihydroxylation of a range of substituted styrene and stilbene derivatives. The diastereoselectivity of the reaction was examined with a range of 1,2-disubstituted alkenes. The effect of altering the peroxide structure was briefly studied and revealed cyclopropane malonoyl peroxide was a more effective dihydroxylating reagent when compared to cyclobutane malonoyl peroxide. These results also indicated a number of intricacies of the reaction mechanism are still to be discovered. A qualitative examination of the factors which affect the reactivity of cyclic diacyl peroxides is also discussed.