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

The direct beta-activation of saturated aldehydes and ketones has long been an elusive transformation. We found that photoredox catalysis in combination with organocatalysis can lead to the transient generation of 5 pi-electron beta-enaminyl radicals from ketones and aldehydes that rapidly couple with cyano-substituted aryl rings at the carbonyl beta-position. This mode of activation is suitable for a broad range of carbonyl beta-functionalization reactions and is amenable to enantioselective catalysis.