Simplified access to low oxidation-state earth-abundant metals for catalytic application
Item statusRestricted Access
Embargo end date01/07/2020
Docherty, Jamie H.
A sustainable future lies in the use of first row, low cost, low toxicity, Earth-abundant metals. Despite this, the metals that are most abundant have yet to be widely adopted by the global community. The overarching aim at the outset of the project was to ask the question: Why is this? Why do expensive metals such as; platinum, palladium and rhodium dominate? Why does the synthetic chemist not instinctively use iron, manganese or cobalt? The simple answer: The non-expert chemist is simply not equipped to try. Many modern synthetic methods for the reductive functionalisation of alkenes and alkynes rely on the use of air- and moisture-sensitive pre-catalysts or reagents, which are challenging to handle, store and transport. In the ideal scenario, all reagents and pre-catalysts would be air- and moisture-stable solids that are easily handled, and applicable in large-scale processes with minimal associated hazards. This project entailed the development of a simple pre-catalyst activation protocol using a safe and easily handled reagent (NaOtBu) with wide commercial availability. This has allowed generic access to sustainable first-row transition metal (Fe, Co, Mn, Ni) low oxidation-state catalysis across a wide range of reductive alkene and alkyne functionlisation reactions (hydroboration, hydrosilylation, hydrogenation, hydrovinylation and [2π+2π] cyclisation reactions). Using this straightforward catalyst activation strategy a new regiodivergent cobalt-catalyst alkene hydrosilylation manifold was discovered and mechanistically explored. Taken together, all results are suggestive of a new and unique catalyst activation mechanism that is primed for future reaction, catalyst and mechanistic development.