Synthesis of 2, 4, 5-trisubstituted imidazole derivatives in the presence of Lewis acid as catalyst in different conditions

Abstract

Imidazole derivatives are an essential group of ring compounds with many biological effects and pharmacological activities [1]. The structure of imidazole derivatives is a five-membered ring with two neutrons[2]. They are widely used in pharmaceutical compounds such as analgesics, anti-tumor, anti-inflammatory, pesticides, and fungicides. Various derivatives of triaryl imidazole are also used in photography[3]. Due to the toxic nature of many organic solvents, such as chloroform and carbon tetrachloride, it is suggested to design processes rooted in green chemistry[4]. The synthesis of 2, 4, 5-trisubstituted imidazole derivatives from the past until now has been done under different conditions and using various catalytic systems. As a new reusable and green heterogeneous catalyst, a lewis acid was used to synthesize 2, 4, 5-trisubstituted imidazole derivatives. As a new catalyst, we have performed several tests under different conditions to evaluate the catalyst's performance. Using benzyl derivatives, 1, 2-dicetone, aromatic aldehydes, and ammonium acetate salt, a multicomponent reaction in the presence of Lewis acid as catalyst leads to the one-pot synthesis of 2, 4, 5-trisubstituted imidazole[5], and after the work up derivatives of imidazole characterized by 1H-NMR, 13C-NMR and FT-IR. Short reaction time, simple workup, high yields, and environmentally friendly catalysts are advantages of this protocol. Lewis acid catalyst is prepared and characterized by FT-IR, XRD, SEM, TEM, XRF, EDS, and TGA. Using a microwave, thermal, and ultrasonic methods to synthesize 2, 4, 5-trisubstituted imidazole derivatives shows the high efficiency of catalyst in different conditions.