Abstract
AbstractNeat reactions of 1‐(pyrazolylmethyl)imidazole with an excess of alkyl or polyfluoroalkyl halides at 100 °C followed by subsequent metathetical reactions with LiN(SO2CF3)2 or KPF6 at 25 °C gave rise to a series of monoquaternary salts 3a–3k. These salts can be also prepared through treatment of 1‐alkylimidazole with 1‐(chloromethyl)pyrazole hydrochloride in the presence of base, followed by anion exchange with LiN(SO2CF3)2 or KPF6. Their phase‐transition temperature, thermal stability, density and solubility in common solvents have been investigated. Most of the bis(trifluoromethanesulfon)amide salts are room‐temperature ionic liquids. The effect of anions and of alkyl substituents bonded to the imidazolium cation on the physicochemical properties was examined. Using 3‐butyl‐1‐(pyrazolylmethyl)imidazolium chloride (2d), the precursor of 3‐butyl‐1‐(pyrazolylmethyl)imidazolium bis(trifluoromethanesulfon)amide (3d), as a reactant, a hemilabile (N‐heterocyclic carbene)palladium(II) complex 4 was synthesized through a (carbene)silver(I) transfer reagent. It was characterized by single‐crystal X‐ray diffraction analysis. The catalytic activity and recyclability of 4 in 3d were preliminarily evaluated by consecutive Heck reactions using different substrates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
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