Iron(III) trifluoroacetate and trifluoromethanesulfonate: Recyclable Lewis acid catalysts for one-pot synthesis of 3,4-dihydropyrimidinones or their sulfur analogues and 1,4-dihydropyridines via solvent-free Biginelli and Hantzsch condensation protocols

Iron(III) trifluoroacetate [Fe(CF3CO2)3] or trifluoromethanesulfonate [Fe(CF3SO3)3] catalyzes three component coupling of β-dicarbonyl compounds, aldehydes and urea or thiourea to afford the corresponding 3,4-dihydropyrimidinones or their sulfur analogues under solvent-free conditions. Also, these catalysts were used for one-pot synthesis of 1,4-dihydropyridines via solvent-free Hantzsch reaction. This new protocol allows the recycling of catalysts with no loss in their potency.