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

Abstract

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.

Dual Role of Glyoxal in Metal-Free Dicarbonylation Reaction: Synthesis of Symmetrical and Unsymmetrical Dicarbonyl Imidazoheterocycles

“…13 In the last decade, substantial efforts have been devoted for the synthesis and functionalization of the imidazoheterocycles. 14 A few successful and elegant methods have been developed for the synthesis of unsymmetrical dicarbonylated imidazo[1,2- a ]pyridines in the recent past using aryl acetaldehydes, 15 aryl ketones, 16 N,N-disubstituted acetamide, or acetone, 17 tertiary α-amino phenylethanone, 18 and arylglyoxals 19 as the dicarbonyl source (Scheme 1). All these methods require the use of metal catalysts (Cu and Fe), ligands, and an equimolar amount of external halogenated oxidants and bases.…”