Pd(OAc)2-catalyzed cross-coupling of polyfluoroarenes with simple aromatics in imidazolium ionic liquids (ILs) without oxidant and additive and with recycling/reuse of the IL

Polyfluoroarenes can be cross-coupled with simple aromatics (benzene, toluene, and anisole), in good isolated yields, by using Pd(OAc)2 dissolved in imidazolium ILs [(bmim)PF6 and (bmim)BF4] as solvent, without the need for an oxidant and an additive. The reaction is catalyzed by HOAc and it is subject to a primary isotope effect (KH/KD = 4.87). Competitive cross-coupling reactions of 1,2,4,5-tetrafluorobenzene with benzene/toluene, benzene/anisole, and anisole/toluene gave KB/KT = 5.1, KB/KA = 5.7, and KA/KT = 5.0, respectively, indicative of a remote substituent effect on Pd insertion into the phenyl C-H bond. Mild reaction conditions, simple product isolation and recycling/reuse of the IL are additional advantages of this method.

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