Lighting up sulfur salts: a general platform for metal-free cross-coupling (S-EDA COUPLING)

The selective and sustainable formation of important bonds is crucial for the assembly of society's pharmaceuticals, agrochemicals

and materials. Metal-catalysed cross-coupling is now routine in every chemistry laboratory and plant worldwide and the positive

impact on science and society has been remarkable. Unfortunately, the majority of these cross-coupling reactions are mediated by

platinum group metals (e.g. Ru, Rh, Pd, Ir and Pt). The environmental and socio-economical cost of extracting such metals from the

earth's crust presents grave consequences, a fact only reinforced by their dwindling supply; this makes their use unsustainable and

our reliance on them simply cannot continue. Inspired by work by the Procter group and others, I believe that the widely-abundant

element, sulfur, can replace metals in cross-coupling by; (i) activating chemical feedstocks, and subsequently, (ii) generating reactive

intermediates for carbon-carbon and carbon-heteroatom bond formation. More specifically, I will use sulfonium salts - generated in

situ from simple, otherwise inert, feedstocks - as coupling partners and reagents for new metal-free catalytic cross-couplings driven

by visible light, that also offer new and improved selectivity profiles when compared to traditional metal-catalysed processes. My

overarching aim is to discover new visible light-mediated, metal-free coupling platforms through the innovative merger of; 1) in situ

sulfonium salt formation, and; 2) EDA complexation chemistry employing simple, catalytic organic molecules for photoactivation. The

three proposed 'concepts' in the action, involve the photochemical functionalisation of important benzothiophenes, amides, and

alkyl halides. My high-risk and ambitious studies will deliver prototypical processes that will pave the way for future coupling processes that can't currently be achieved in a sustainable fashion or are simply not yet possible.