Thioesterification of Polyfluoroarenes via Copper-Catalyzed Radical Cross-Coupling with K2S and Aldehydes in Water

A novel copper-catalyzed radical cross-coupling reaction for the thioesterification of polyfluoroarenes is developed using K₂S and aldehydes in water. This protocol employs a readily available K₂S as a sulfur source, eliminating the need for hazardous thiols and organic solvents. The mild reaction conditions are compatible with a wide range of functional groups, providing access to diverse polyfluoroaryl thioesters. The mechanistic study not only demonstrates the significant role of K₂S in activating polyfluoroarenes but also proposes that the reaction involves nitrogen radicals abstracting α-hydrogens from aldehydes to yield acyl radicals, which participate in a cross-coupling process with thiyl radicals. The applicability of this thioester in synthetic transformations demonstrates its enhanced reactivity as an acylating agent.