p-Toluene Sulfonic Acid Catalyzed One-Pot Synthesis of Unsymmetrical 1,4-Dihydropyridines Derivatives via Hantzsch Reaction

Abstract

A simple, inexpensive and efficient one-pot synthesis of a series of unsymmetrical 1,4- dihydropyridines derivatives using p-toluene sulfonic acid as catalyst at room temperature was achieved in excellent yields from the four-component Hantzsch condensation reactions of various aromatic aldehydes, 1,3-cyclohexanedione, methyl acetoacetate (or ethyl acetoacetate) and ammonium acetate in a little methanol (or ethanol). The procedure possesses the advantages of short reaction time, high yields, an environmental friendly procedure as well as easy isolation of products.