BF3·SiO2: an efficient reagent system for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles

Silica-supported boron trifluoride (BF3·SiO2) is an efficient, readily available and reusable catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles using benzil, an aromatic aldehyde and an amine in the presence of ammonium acetate. This one-pot procedure is very simple, affording good to excellent yields.