Rhodium-catalysed intermolecular hydroacylation

My project will concentrate on the catalyst and catalytic cycle in the rhodium-catalysed hydroacylation reaction. This project sits on the boundary between organic and inorganic chemistry and is suitably funded equally by both. During the process of hydroacylation, the carbonyl C-H bond on an aldehyde compound is broken via oxidative addition onto a catalytic metal centre and a new C-C bond with alkene or alkyne substrate is formed. This is particularly interesting to synthetic chemists as the reaction is inherently atom efficient and a useful pathway to C-C bond formation. There are many examples of transition metal catalysed hydroacylation but rhodium catalysis is currently the most prolific. Rhodium-catalysed intermolecular hydroacylation has only been achieved with tethered aldehydes. Currently, there is only limited control of branched to linear selectivity with alkyne substrates. Hydroacylation would be exceptionally useful in synthetic chemistry if the reaction conditions (i.e. catalyst) could be adapted so that the reaction was highly selective, could be used on an industrial scale (mild conditions, low catalyst loading and minimal waste) and has the flexibility to use many different substrates and aldehydes to form a wide range of organic products. In attempts to achieve these goals, or at least contribute towards them, I will modify the catalyst itself by changing the ligands on the catalyst as well as investigating the mechanism by which the selectivity is introduced. This will involve synthesising new ligands altogether, most likely to be diphosphine ligands, or applying known ligands but in previously unexplored catalytic systems. The logic behind this is to encourage C-H oxidative addition (which has been shown to be the rate limiting step) whilst also influencing the selectivity by applying steric and potentially electronic effects to the rhodium metal centre so to manipulate the binding site in a specific fashion. These new catalysts will also be designed in consideration of decarbonylation pathways that have been shown to kill the catalyst in intermolecular hydroacylation through the formation of stable rhodium-carbonyl complexes. This project falls within the EPSRC Physical Sciences research area. The fundamental synthetic chemistry research within this project will contribute towards the extensive research already conducted via investment from EPSRC research grants. This project is a combination of synthetic organic chemistry (the current EPSRC investment is £27.1 million), catalysis (£38.3 million) and synthetic coordination chemistry (£14.1 million) and is why I am co-supervised by some of the most prestigious and dynamic researchers in these disciplines of chemistry at the University of Oxford. The progress within this project will be both innovative and contribute towards the forefront of synthetic chemistry. Other than collaborating between the Weller Group and Willis Group there are currently no companies or collaborators in this project. However, if there is suitable interest from industrial backers then that will be encouraged.