Novel α,α-Difluorohomophthalimides via Copper-Catalyzed Tandom Cross-Coupling−Cyclization of 2-Halobenzamides with α,α-Difluoro Reformatskii Reagent

Novel α,α-difluorohomophthalimides 2 were prepared by reacting N-substituted 2-halobenzamides with the α,α-difluoro Reformatskii reagent BrZnCF₂CO₂Et (3) in the presence of CuBr at room temperature. The synthesis involves a CuBr-mediated cross-coupling of 3 with aryl iodides or activated aryl bromides, followed by a spontaneous cyclization of the ethyl 2-benzamido-α,α-difluoroacetate intermediates at room temperature. N-unsubstituted α,α-difluorohomophthalimides 2 (R‘ = H), bearing an acidic imide proton capable of acting as a carboxylic acid bioisostere, were also prepared by reacting 3 equiv of 3 with the parent 2-iodobenzamides. Other aryl iodides such as 3-iodo-imidazo[1,2-α]pyridine were also used for the tandem coupling−cyclization reaction.