Magnetic Hybrid Iron Oxide-Based Composite Nanocatalyst for the Synthesis of Polyhydroquinolines U Solvent-Free Conditions at Room Temperature

Nowadays, simple separation and recycling of the catalysts are essential steps in catalytic technology and frequently affect the overall process economy. A possible method is immobilizing catalytically active species in the surface of magnetic particles which can be separated and recovered from the reaction system by applying an appropriate magnetic field. In general, in order to prevent direct contact between magnetite nanoparticles and also provide a chemically inert surface for modification of magnetite nanoparticles, coating of the surface with silica shell is necessary. Silica surface can be easily functionalized with various organic groups for desired purposes such as applications as adsorbent, catalysis support and enzyme immobilization. Polyhydroquinoline (PHQ) derivatives contain a large family of medicinally important compounds that have attracted much attention because of their diverse pharmacological and therapeutic properties. In this work, a magnetic dichromate hybrid with triphenylphosphine surface modified iron oxide nanoparticles as a recoverable and efficient composite nanocatalyst is prepared and applied for the synthesis of polyhydroquinolines under solvent-free conditions at room temperature. This research can be classified as a green approach for efficient and rapid synthesis of biologically active substituted polyhydroquinoline derivatives by using a recyclable nanocatalyst under mild reaction conditions. In comparison with other classical reactions, this method consistently has the advantages of short reaction times, little catalyst loading, high yields, easy magnetic separation and reusability of the catalyst.