Solvent free synthesis of 2, 4, 5-triarylimidazole derivatives catalyzed by CoCl2.6H2O as a cheap, and effective catalyst under microwave irradiation

Imidazole derivatives are very interesting class of Nitrogen containing 5-membered heterocyclic compounds. Because of their wide range of pharmacological importance and significant role in biochemical processes, the Biological importance of the poly substituted imidazole ring system has made it a common structure in numerous synthetic compounds, such as fungicides, herbicides, therapeutic agents and plant-growth regulators. This core also has been utilized in diverse pharmaceutical applications such as anti-inflammatory, anti-thrombotic and antitumor agents. Due to their great biological importance of poly substituted imidazole framework, the synthesis of Poly substituted imidazoles has attracted much attention in organic synthesis [1-3]. Cobalt salts and complexes are well known to have catalytic abilities in coordinating with the carbon-carbon multi bond for - complex and to produce many valuable products through enynecoupling (Pauson-Khand reaction), Alder-Ene and many other reactions [4,5]. In the present work, an efficient, inexpensive, environmentally friendly one-pot route to 2,4,5-triarylimidazole derivatives has been developed, involving three-component reaction of benzyl, aldehydes, and ammonium acetate catalyzed by CoCl2.6H2O in solvent free condition under microwave irradiation (scheme 1). The present methodology offers several advantages such as high yields, relatively short reaction times, mild reaction condition, easy work up, and cleaner reaction.