New reactivity and selectivity in rhodium-catalysed hydroacylation

This thesis documents the development of two new rhodium(I)-catalysed methodologies. The first shows the use of 1,4-dicarbonyl systems in hydroacylation for the preparation of synthetically valuable alpha-N-amido ketones. The second method is a dynamic kinetic resolution process for the synthesis of enantiomerically enriched 1,3-dicarbonyl compounds. Chapter 1 introduces the concept of rhodium-catalysed hydroacylation and presents a literature review covering key developments in the field of intra- and intermolecular hydroacylation, with a focus on chelating aldehydes that can be used to overcome decarbonylation. The advancement of enantioselective hydroacylation reactions has also been briefly summarised in this chapter. Chapter 2 describes that readily available alpha-N-amidoaldehydes are effective substrates for intermolecular Rh-catalysed alkyne hydroacylation reactions. The catalyst [Rh(dppe)(C6H5F)][BArF4], allows a broad range of aldehydes and alkynes to be used as substrates, delivering alpha-N-amido ketone products in high yields and high levels of regiocontrol. The use of alpha-N-amido aldehydes as substrates establishes that 6-membered rhodacyclic intermediates provide suitable chelating stability to enable productive hydroacylation. Chapter 3 presents the development of enantioselective Rh-catalysed alkyne hydroacylation of beta-amido aldehydes via dynamic kinetic resolution. The method delivers enantiomerically enriched 1,3-dicarbonyl products in a highly enantioselective fashion with good yields and high regiocontrol, using a combination of cationtic Rh, commercially available (R)- DMMGarphos ligand and Cs2CO3. To the best our knowledge, this is the first example of dynamic kinetic resolution in intermolecular hydroacylation. Chapter 4 summarises the research work done and the potential future work. Chapter 5 documents the experimental data and procedures.