Iron-Based Imidazolium Salt as Dual Lewis Acid and Redox Catalyst for the Aerobic Synthesis of Quinazolines

Abstract

A low transition temperature mixture formed with 1-butyl-3-(methoxycarbonylmethyl)imidazolium chloride and iron(III) chloride has proven to be an efficient catalyst for the synthesis of quinazolines following a sequence of condensation-cyclization-oxidation reactions. The protocol is simple and effective for coupling 2-acylanilines and benzylamines to form nitrogen containing heterocycles with moderate to excellent yields (up to 93 %), being possible to perform the reaction in preparative scale. The functionalized imidazolium salt is crucial for the activation of the reagents under solvent-free conditions, and the presence of iron in the catalyst mediates the oxidation step with atmospheric oxygen. These features make the presented procedure better, from an environmental point of view, than other processes previously described. For this comparison, different “green” metrics have been used, such as atom economy, stoichiometric factor, reaction mass efficiency, E-factor, and EcoScale.