Photoredox Activation for the Direct β-Arylation of Ketones and Aldehydes

Beta Bonding Carbonyl compounds, which incorporate carbon-oxygen double bonds, are among the most productively reactive molecules in synthetic as well as biochemical contexts. The carbon directly bonded to oxygen is rendered highly electrophilic, while the adjacent (α) carbons are easily deprotonated to undergo further transformations. In contrast, the β carbons that are one step further along the chain tend to be relatively inert. Pirnot et al. (p. 1593 ) now show that a dual catalyst system—consisting of an amine and a photoactive metal complex—can activate the β carbons of carbonyl compounds to couple with aryl substrates.