Aqueous-Phase, Palladium-Catalyzed Heck Reaction: The Significant Role of CN-containing Counter Anion

Water-soluble diol-functionalized imidazolium ionic liquid 1, prepared from 2,2-bis(1-methyl-methyl-imidazolium)propane-1,3-diol bromide, potassium hydroxide, and malononitrile, was used as an efficient phosphine-free ligand for palladium-catalyzed arylation of aryl halides with acrylates in aqueous phase under mild conditions. It was found that the synergistic coordinating action of diol-functionalized imidazolium cation with CN-containing anion played the key role in improving the activity and stability of the catalyst.