’Photoredox catalysis goes asymmetric’: counterion strategy a breakthrough in reaction control

Photoredox catalysis, which harnesses the power of light to drive chemical reactions, has now gone asymmetric, allowing chemists to prepare valuable single-enantiomer products.

‘Photocatalysis exploits the energy of visible light to generate reactive radical species under remarkably mild conditions,’ explains Mattia Silvi, a photochemistry expert at the University of Nottingham, UK. ‘But the high reactivity of such species makes them particularly difficult to tame in the context of enantioselective processes.’ Many compounds exist in two mirror image forms known as enantiomers, which possess identical physical properties but interact differently with other ‘handed molecules’ such as amino acids and sugars. Access to the separate forms of these compounds is vital for the pharmaceutical industry, which must produce and test single enantiomers to guarantee the safety and efficacy of all new medicines.