Gold‐Catalyzed Highly Selective Photoredox C(sp 2 )−H Difluoroalkylation and Perfluoroalkylation of Hydrazones

The first gold‐catalyzed photoredox C(sp 2 )−H difluoroalkylation and perfluoroalkylation of hydrazones with readily available R F −Br reagents is reported. The resulting gem ‐difluoromethylated and perfluoroalkylated hydrazones are highly functionalized, versatile molecules. A mild reduction of the coupling products can efficiently produce gem ‐difluoromethylated β‐amino phosphonic acids and β‐amino acid derivatives. In mechanistic studies, a difluoroalkyl radical intermediate was detected by an EPR spin‐trapping experiment, indicating that a gold‐catalyzed radical pathway is operating.