Visible‐Light Photoredox‐Catalyzed Tandem One‐Pot Construction of C4‐Difluoroalkylated Phthalazin‐1(2H)‐Ones

Abstract Tandem one‐pot regioselective synthesis of C4‐difluoroalkylated phthalazin‐1(2 H )‐ones from readily available hydrazines, 2‐formylbenzoic acids and bromodifluoroacetate derivatives under visible‐light photocatalysis is reported. This mild protocol provides straightforward access to various C4‐difluoroalkylated phthalazin‐1(2 H )‐ones, and displays broad substrate scope and wide functional group tolerance. Moreover, this process is also suitable for the synthesis of C4‐trifluoromethylated and perfluorobutylated phthalazin‐1(2 H )‐ones. The use of fac ‐[Ir(ppy) 3 ] photocatalyst and the introduction of an organic base additive are pivotal to catalysis. magnified image