Photocatalytic Three-Component Reductive Coupling Synthesis of gem-Difluorohomoallyl Secondary Amines

gem-Difluorohomoallyl amines, an important class of gem-difluoroalkenes, are prevalent moieties in many bioactive compounds. However, limited methods are suitable for the synthesis of this type of compound containing secondary amines. Here, we display a photocatalytic multicomponent protocol for the synthesis of gem-difluoroalkenes containing secondary amines, which makes use of readily available materials: arylamines, alkyl aldehydes, and alpha-trifluoromethyl alkenes. Moreover, ketones and secondary amines are also suitable substrates. Preliminary mechanistic experiments indicate that a key alpha-amino radical was involved, generated from the reduction of in situ-formed imines (or iminium ions) by a reduced photocatalyst. Subsequent addition of the alpha-amino radical to alpha-trifluoromethyl alkenes and beta-F elimination deliver the desired products.