Anion-Dependent Imidazolium-Based Catalysts for Allylation of Aniline with Tunable Regioselectivity

Metal-free catalysts based on 1,3-bis(carboxymethyl)imidazolium halides mediate the reaction between allylic alcohols and anilines, providing the correspondingN-, 2- and 4-allylaniline isomers selectively. The imidazolium counterion plays a crucial role in the outcome of the reaction. Thus, while the imidazolium chloride selectively provides theN-substituted aniline, the bromide and iodide imidazolium salts produce the 2- and 4-allylaniline isomers, respectively, with excellent selectivities. A set of complementary catalysts, which are available by simple modulation, is here presented to conduct a highly regioselective allylation reaction of anilines. Not only the catalysts are synthesized in a straightforward and easily scalable manner, but they can be recycled and used under solvent-free reaction condition, due to the favorable interactions with the reactants.