Synthesis of Polyhydroquinoline Derivatives Via Hantzsch Condensation using Sulfuric Acid Supported on Modified Magnetic Fe3O4 Nanoparticles (MNPs-OSO3H) as Catalyst under Solvent-Free Conditions

One- pot reaction in which three or more starting materials react sequentially and lead to product(s) that retain all or most of the atoms of the starting materials are called multicomponent reactions (MCRs) .These reactions are characterized by their convergence, ease of execution, high yields, efficiency and atom economy [1]. Polyhydroquinolines (PHQs) are one of the most important classes of heterocyclic scaffolds providing major ligands for biological receptors. PHQs are the source of some valuable drugs which are very important in pharmacy. For instance, they demonstrate activity for the treatment of angina pectoris and hypertension [2]. Therefore, developing more efficient methods working under mild conditions using more environmentally acceptable catalysts is in high demand [3]. In this work, we present a facile and highly efficient protocol for the synthesis of polyhydroquinolines via Hantzsch multicomponent condensation of dimedone, aldehydes, ethylacetoacetate and ammonium acetate by using sulfuric acid supported on magnetic nanoparticles (MNPs-OSO3H) as a nano-magnetic heterogeneous catalysts. This method has several advantages such as high yield, short reactiontime, simple workup, easy separation of the catalyst and its reusability.