α-functionalisation of various 1,3-dicarbonyl compounds via hypoiodite-mediated oxidative phase transfer catalysis: Alpha-functionalisation of various 1,3-dicarbonyl compounds via hypoiodite-mediated oxidative phase transfer catalysis

α-Functionalization of β-keto esters has been studied by our group using various different approaches. These substance classes are very useful model substrates due to their reactivity and the obtained motifs are widely spread among natural (biologically active or agriculturally relevant) products.
Our colleagues developed two very elegant methods for asymmetric α-hydroxylation of β-keto esters, using our very effective bifunctional phase transfer catalyst and a sufficient oxidant. In this thesis, the limits of these protocols were tested by applying them to a variety of other 1,3-dicarbonyl compounds, such as β-keto amides, β carbonyl lactones, oxindole derivatives, diketones, and 3-substituted β-keto esters. Although in these investigations, the stereo induction to the desired products turned out to be very tricky, some interesting products were obtained in racemic manner at least.
Furthermore, the same substrates were also tested in a recently developed method, which uses the synergism between in situ formed catalytically competent hypoiodite species and simple ammonium salt phase transfer catalysts (PTC). With this protocol, racemic α-nitration and α azidation of the various different substrates can be facilitated under very mild conditions, using benzoyl peroxide as oxidant and the alkali salts of the nucleophiles without the need of external acids or bases.