Ethylacetoacetate tagged basic imidazolium salt: multi-task in CuI nanoparticle catalyzed amination of aryl halides

Abstract

Copper catalyzed reactions suffer from harsh conditions of high temperature, high pressure, over-stoichiometric amount of copper reagents and use of expensive ligands. In an attempt to develop a mild, efficient and reusable system for copper catalyzed reactions, ethylacetoacetate was doped into ionic liquid (IL) by tagging it with imidazolium cation stabilized by a counter hydroxide or acetate anion (4a and 4b). The novel ligand-anchored ILs demonstrated high efficiency in generation and stabilization of uniformly dispersed Cu(I)I nanoparticles with particle size in range 9–12 nm. Further, the catalytic system provided an efficient route to amination of aryl iodides, bromides and the less reactive chlorides under mild conditions with very low catalyst loading of only 2 mol % to yield primary aryl amines selectively. Furthermore, the reaction allowed easy isolation of products with recovery of ionic liquid containing an intact built-in ligand and base combination for further reuse.