Molecular Iodine: A Versatile Catalyst for the Synthesis of 4-Aryl-3-methyl-1-phenyl-1H-benzo[h]pyrazolo[3,4-b]quinoline-5,10-diones in Water

An efficient methodology for the synthesis of 4-aryl-3-methyl-1-phenyl-1H-benzo[h]pyrazolo[3,4-b]quinoline-5,10-diones has been developed. To our best knowledge, this is the first report for the synthesis of these compounds by multicomponent condensation of 3-methyl-1-phenyl-1H-pyrazol-5-amine, aldehydes and 2-hydroxynaphthalene-1,4-dione in the presence of molecular iodine as a catalyst in water. The simple experimental procedure, utilization of an inexpensive and readily available catalyst, and excellent yields are the advantages of the present method. Multicomponent reactions (MCRs) have attracted considerable attention since they are performed without need to isolate any intermediate during their processes; may reduce time and save both energy and raw materials. They have merits over two-component reactions in several aspects including the simplicity of a one-pot procedure, possible structural variations and building up complex molecules