Photoredox Organocatalysis: Asymmetric α-Perfluoroalkylation of Aldehydes

Significance

MacMillan and co-workers report an efficient and highly enantioselective α-perfluoroalkylation of aldehydes employing photoredox organocatalysis. The proposed mechanism involves an organocatalytic and a photoredox catalytic cycle. The organocatalyst 1 reacts with the ­aldehyde to form an enamine intermediate which reacts with the trifluoromethyl radical, formed in the photoredox catalytic cycle. The resulting α-amino radical is oxidized by an excited state species of the photocatalyst 2, generated by irradiation. The reduced photocatalyst is reoxidized by trifluoromethyliodide to give 2 and a new trifluoromethyl radical.