Aqua-mediated one-pot synthesis of Biginelli dihydropyrimidinone/thiones (DHPMs), Hantzsch dihydropyridines (DHPs), and polysubstituted pyridines sonocatalyzed by metal-supported nanocatalysts

In this work, catalyst composition-activity relationship of supported catalysts in Biginelli and Hantzsch reactions was investigated under mild conditions. Biginelli dihydropyrimidinone/thiones were prepared over Fe-Cu/ZSM-5 as an efficient, convenient, and environmentally benign catalyst under ultrasonic irradiation in aqueous media in very good yields. The Fe-Cu/ZSM-5-catalyzed synthesis of 1,4-dihydropyridines and their aromatization to polysubstituted pyridines and also a new one-pot, two-step, and sequential protocol for the synthesis of pyridine derivatives, employing an aldehyde, ethyl acetoacetate, and ammonium acetate under the same green experimental conditions were illustrated. Three-component condensation in the presence of supported reagent with operational simplicity, inexpensive reagents, short reaction time, high yield of products, and use of non-toxic reagents makes this synthetic protocol an attractive one.