Ionophilic phosphonium-appended carbopalladacycle catalyst for Suzuki-Miyaura and Heck cross-coupling catalysis

An ionic liquid, covalently tethered to an efficient transition-metal catalyst in the presence of an ionic liquid reaction medium, can utilize ionophilic interactions to improve catalyst activity, recyclability, and product isolation while decreasing catalyst leaching. Given the greater stability of phosphonium salts in comparison to imidazolium ionic liquids under basic conditions, phosphonium-tagged oxime carbopalladacycle salts were prepared and employed in both Heck and Suzuki-Miyaura reactions. The desired product was obtained in good yields for up to four catalyst cycles in the case of the Suzuki-Miyaura reaction. While taking advantage of the non-volatile nature of ionic liquids, the product was isolated through simple sublimation from the reaction mixture, eliminating issues associated with catalyst leaching, and the remaining ionic liquid solvent-catalyst mixture was ready for further catalysis.