Highly efficient one-pot four-component synthesis of polyhydroquinoline derivatives catalyzed by stannous chloride under solvent-free conditions

A rapid and efficient one-pot, four-component protocol towards the synthesis of polyhydroquinoline derivatives has been developed. The condensation of aldehyde, dimedone, ethyl acetoacetate and ammonium acetate in presence of stannous chloride was carried out under solvent free condition to synthesize a variety of polyhydroquinoline derivatives in good to excellent yields. Stannous chloride was proved to be an efficient heterogeneous Lewis acid catalyst, which could be relatively non-toxic, inexpensive, possess good thermal stability and easy to handle. The present method provides several advantages such as mild reaction conditions, green methodology, inexpensive catalyst, simple work-up procedure, short reaction time and high yields.