A facile and efficient synthesis of tri- and tetrasubstituted imidazoles with potassium hydrogen sulfate and DB18C6 in an aqueous medium

摘要

Potassium hydrogen sulfate in the presence of dibenzo-18-crown-6 (DB18C6) turns out to be a very efficient and effective catalyst for the facile synthesis of a wide variety of tri- and tetrasubstituted imidazoles in an aqueous medium at moderate temperature. The idea behind this is that the potassium ion, being trapped in the crown core, frees the hydrogen sulfate anion, which, because of its acidic nature, succeeds in the ready synthesis of the imidazoles.