An Efficient Synthesis of 2,4,5-Triaryl-1H-Imidazole Derivatives Catalyzed by Boric Acid in Aqueous Media Under Ultrasound-Irradiation

Abstract

Boric acid (BO3H3) is an inexpensive, efficient and mild catalyst for the synthesis of 2,4,5-triaryl-1H-imidazoles in excellent yields from the one-pot three-component condensation of benzil/benzoin, an aldehydes and ammonium acetate in aqueous media under ultrasound at room temperature. The remarkable advantages offered by this method are green catalyst, mild reaction conditions, simple procedures, much faster reactions and excellent yield of products.

Environmentally Benign Synthesis of Tetra-Substituted Imidazoles through 4-Components Strategy Mediated by (<I>S</I>)-3-Methyl-1, 1-Diphenylbutane-1, 2-Diamine

“…A lot of synthetic routes are available in the literatures to synthesize imidazoles [11] analogues including annulations of amidines and β-keto esters [12], SBA-Pr-SO 3 H [13], nanocrystalline MgAl 2 O 4 [14], Cellulose/ɤ-Fe 2 O 3 /Ag [15], urea/hydrogen peroxide (UHP) [16], N-acetyl glycine (NAG) [17] [27], 2-cyanopyridine [28], p-TsOH [29], cellulose sulfuric acid [30], ceric (iv) ammonium nitrate (CAN) [31], boric acid [32], PEG-400 [33] [43], eutectic solvents [44], iodine [45], Yb(OTf) 3 [46], ZrCl 4 [47], AcOH [48], disubstituted alkynes [49] are noteworthy. However, almost all of these methods suffer from one or more constraints such as lower yield, harsh reaction conditions, tiresome isolation technique, uses of expensive toxic metal catalysts, limited examples etc.…”