A debate over whether photoredox-catalysed reactions proceed via chain processes may now be settled, thanks to new mechanistic insight brought to light by scientists in the US. The research, led by Tehshik Yoon at the University of Wisconsin–Madison, shows that commonly used light/dark experiments can result in mechanistic misdiagnosis.
Whilst interest in photoredox catalysis has recently burgeoned – the reactions are used in natural product and pharmaceutical synthesis – our understanding of their mechanisms hasn’t kept pace. In particular, the extent to which the reactions involve chain processes is not fully understood, leading to conflicting explanations. Several groups have reported that the final product-generating step proceeds only by reduction of the radical cation product by the reduced photocatalyst in a closed catalytic cycle, whilst others have reported that the product is formed by an additional chain propagation step involving another equivalent of substrate. Read the full article in Chemistry World»
Read the original journal article in Chemical Science – it’s open access:
Characterizing chain processes in visible light photoredox catalysis
Megan A. Cismesia and Tehshik P. Yoon
Chem. Sci., 2015, Advance Article, DOI: 10.1039/C5SC02185E, Edge Article