A functionalized ionic liquid containing phosphine-ligated palladium complex for the Sonogashira reactions under aerobic and CuI-free conditions

A Pd-complex functionalized ionic liquid (IL), di-(1-butyl-2-diphenylphosphino-3-methylimidazolium)-dichloropalladium(II) hexafluorophosphate (2), was synthesized and used as the highly efficient and recyclable catalyst for the Sonogashira reactions of aryl iodides and aryl bromides with several terminal acetylenes, under aerobic and CuI-free conditions. The activity loss, Pd black precipitation, and Pd leaching were not observed even after 7 runs in 2-catalyzed Sonogashira reactions using the room temperature IL of [Bmim]PF6 as the reaction medium.

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► A functionalized ionic liquid containing phosphine-ligated palladium complex.
► An efficient and recyclable Pd catalyst for the Sonogashira reactions.
► The Sonogashira reactions under aerobic and CuI-free conditions.
► The catalytic activity maintained well even after 7 recycles.