Dr Julian Knight
Dr Knight's research interests are principally in the area of catalysis and synthesis. In particular, the discovery of new catalytic processes, new catalysts, and their application to the synthesis of organic target molecules. One such process is the palladium catalysed carbonylation of vinyloxazolidinones, which can easily be prepared in enantiomerically pure form from amino acids, leading to decarboxylative ring-expansion to give the corresponding enantiopure d-lactam. This key reaction has been used for the synthesis of polyhydroxylated piperidines alkaloids such as deoxymannojirimycin, a naturally occurring mannosidase inhibitor and is currently being applied to more complex targets.
Zirconium-mediated reductive coupling of alkynes has been developed as a one-pot route to conformationally flexible tropos ligands NUPHOS. Platinum group metal complexes of these ligands form highly active and selective catalysts for Grignard cross-coupling, and may be resolved to provide chiral catalysts for enantioselective processes such as Diels-Alder, hetero Diels-Alder, carbonyl ene, and hydrogenation reactions.
The synthesis of enantiopure versions of these ligands are from chiral diynes is being explored, thus removing the need for on-metal resolution. A new approach to tropos and atropos phosphine ligands using rhodium catalysed [2+2+2] cycloaddition is also being developed for applications in catalysis.
The synthesis of immobilised catalysts, to aid in catalyst recovery and recycling, is under investigation. Metal complexes of imidazolium-tagged bisoxazoline ligands can be used for highly enantioselective Lewis acid catalysed reactions in ionic liquids. The ionic tag serves to lock the catalyst into the ionic liquid phase, enabling products to be removed by simple extraction. The catalyst could be recycled ten times without detectable drop in activity, selectivity or catalyst leaching. This methodology is being extended to new reactions and other methods of immobilisation are also under study.
