Role of copper in catalyzing aryl and heteroaryl-nitrogen (or -oxygen) bond formation under ligand-free and solvent-free conditions

Formation of aryl- or heteroaryl-nitrogen (or -oxygen) bonds under ligand and solvent-free conditions are highly selective to the presence of copper. While bromoarenes undergo C-N (or -O) coupling in stoichiometric presence of copper, heteroaryl bromides require only catalytic amounts of copper(I) salts depending on the position of bromo substituents. Such selectivity coupled with ligand and solvent-free protocols appear promising from the viewpoint of ecology and economy and arc more attractive as compared to the existing protocols.