Development of novel olefin oxidations

The oxidation of olefins is of central importance in organic synthesis. This thesis is divided into the development of novel approaches to two classes of this transformation: (i) dihydroxylation and (ii) aminohydroxylation. (i) Dihydroxylation 1. Introduction- 1,2-Benzoquinones The chemistry of 1,2-benzoquinones is reviewed, including synthesis and reactivity; particular attention is paid to their cycloaddition chemistry and their reaction as hetero-dienes with alkenes. 2. Results and discussion - Utilising 1,2-benzoquinones as reagents for dihydroxylation The [4+2] reaction of 3,4,5,6-tetrachloro-I,2-benzoquinone as a hetero-diene with a range of alkenes to form the corresponding 2,3-dihydrobenzo[b][1,4]dioxines is studied. The reactivity of a sterically and electronically diverse range of 1,2-benzoquinones with representative alkenes is also studied. The cleavage of a 2,3-dihydrobenzo[b][1,4]dioxine to constitute overall syn-dihydroxylation of the alkene is investigated. (ii) Aminohydroxylation 3. Introduction - Osmium-mediated aminohydroxylation Development of the osmium-mediated aminohydroxylation is discussed, with particular emphasis on its mechanism and the development of an asymmetric variant. The tethered aminohydroxylation (TA) reaction is introduced, including discussion of its scope and limitations. 4. Results and discussion - Development of the osmium-mediated aminohydro~'Ylation reaction Tethered aminohydroxylation Optimisation of the standard TA protocol is investigated. An efficient synthesis of sulfonyloxycarbamate substrates for employment in a novel TA protocol is developed. The scope of the modified reaction is investigated in both allylic and homoallylic systems. Asymmetric aminohydroxylation (AA) The application of sulfonyloxycarbamates and benzoyloxycarbamates in AA reactions is studied, including extensive investigation of reaction conditions. 5. Introduction - MicroscIerodermins Synthetic approaches to the microsclerodermin family of natural products are reviewed. 6. Results and discussion - Towards the synthesis of the microscIerodermins A novel approach to the synthesis of the microsclerodermins utilising the TA reaction is disclosed, including the development of a protecting group strategy based on model studies. 7. Experimental Full experimental procedures and characterisation of compounds are reported.EThOS - Electronic Theses Online ServiceGBUnited Kingdo