Magnetic Supported Copper Nanoparticles: An Efficient Heterogeneous Catalyst for the Synthesis of 1,2-Diketones by Cross-Coupling Reaction of Imidazo[1,2-a]pyridines with Methyl Ketones

A convenient and new copper nanoparticles-catalyzed cross-coupling reaction of imidazo[1,2-a]pyridines with methyl ketones has been developed to synthesize 1,2-diketones that have an imidazo[1,2-a] pyridine core. Highly active magnetic copper nanoparticles [i.e., Cu4O3@Fe3O4_C(II)] were prepared and characterized by standard materials characterization techniques, which included transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. These methods were also used to acquire information about the size, oxidation state, and crystallinity of the nanoparticle catalyst. With this method, a variety of pharmaceutically important 1,2-dicarbonyl imidazo[1,2-a]pyridines were readily synthesized in moderate to good yields. The catalyst was easily separated from the reaction mixture by using an external magnetic field and could be recycled 6 times with only a negligible change in the catalytic performance.