Olefins are widely available starting materials which represent a valuable means for introducing novel functionality into a molecule. Oxidative cleavage and dihydroxylation represent two widely applied olefin functionalisations which access the corresponding cleaved carbonyls and vicinal diols, respectively. Traditional methods for these transformations, such as ozonolysis and OsO4 dihydroxylation, rely on toxic reagents and unstable intermediates which raise significant safety concerns. Alternative strategies implementing milder conditions typically have limited substrate scopes, as unactivated olefins are rarely engaged and functional group compatibility is often restricted. The research presented in this thesis displays application of photoexcited nitroarenes towards efficient one-pot olefin oxidative cleavage and dihydroxylation methodologies. Nitroarenes are safe, easy to handle, and easy to dose reagents whose reactivity can be modulated by control of aromatic substituent electronics. Accumulation of 1,3,2-dioxazolidine intermediates, formed in the [3+2]-cycloaddition between olefins and photoexcited nitroarenes, is critical to the success of both strategies. Mild hydrolytic conditions to selectively direct these intermediates towards cleaved carbonyl products were identified, as was a mild reduction to the corresponding diols using readily available reagents as H2 surrogates. Both strategies are indeed effective amongst a range of olefin substitution patterns, both activated and unactivated, and display broad functional group compatibility.
|Date of Award
|1 Aug 2023
- The University of Manchester
|Guillaume De Bo (Supervisor) & Daniele Leonori (Supervisor)