Fe3o4-nanoparticles As Efficient Green Catalyst For The Synthesis Nitrogen-containing Heterocycles

The field of new catalysts are expanding and will boost the development new synthetic methods under milder conditions, atom economies and with high yields and selectivities in 21 century. With increasing environmental concerns and the need for efficient and green catalysts for useful organic synthesis, the interest in new catalysts have increased. Recently, nano -particles having used in organic synthesis. Fe₃O₄-nanoparticles are one kind of the most important nanoparticles. Because excluding the normal nano behavior, they impact a characteristic----magnetism. Which is helpful for its recycle. The new applications of Fe₃O₄-nanoparticles in organic synthesis have been expanded.A review has done about nanoparticles as catalyst application in organic synthesis, according to the type of nanoparticles. Common nanoparticles have zinc oxide, magnesium oxide, copper, nickel,copper oxide,etc. which as catalysts in organic reaction such as addition reaction, cyclization, redox reaction, and substitution reaction etc.Replacenment organic solvent with environmentally reaction media fits for the requirements of environment-friendly, that is direction of chemical development. Fe₃O₄-nanoparticles was found to be a high efficient and convenient catalyst for the synthesis of three important heterocyclic compounds using water or ethanol solvents. The catalyst can be recovered by the use of an external magnet and reused. The products were characterized by IR and ¹H NMR , ¹³C NMR.Firstly, quinoxaline has been synthesized by the reaction of diamines and diketones in the presence of Fe₃O₄–nanoparticles in high to excellent yields. Quinoxaline is important class of nitrogen-containing heterocycles. Its derivatives have broad biological activities, such as anticancer,antitumor,antiviral,antibacterial agents. In addition to the medicinal applications, quinoxalines derivatives have been found applications as key intermediates in the synthesis of organic semiconductors. Therefore, the synthesis of quinoxaline has attracted much attention. The reaction proceeds smoothly under water conditions. This method is suitable for various substrates, operational simplicity, high yields of products and devoid usage of toxic solvent. Next, Fe₃O₄-nanoparticles were used as catalyst for the synthesis of 1,4-dihydro -pyridines derivatives via three-component reaction of aniline, cinnamaldehyde and acetoacetate under mild conditions. 1,4-Dihydropyridines derivatives have broad biological activities and have been used in the filed of pharmaceutials which include various antihypertensive, bronchodilator, antitumor,antiatherosclerotic, anticance etc. Therefore, the synthesis of the compounds is present research hot spot. The simple experimental procedure, short reaction times, and good yields are the advantage of the present method. Furthermore, the catalyst can be readily recovered with a permanent magnet and reused without significant loss of catalytic activity.Finally, we developed an efficient method for synthesis of 2,3-dihydroquinazolin -4(1H)-ones by the reaction of isatoic anhydride, aromatic aldehyde and aralkylamine in water. 2,3-Dihydroquinazolin-4(1H)-ones are immportant class of nitrogen-containing heterocycles. Its derivatives have broad biological activities and have been used as antibacterial agents, diuretic agents, antihypertensive,antimalarial, sulfonamides etc. Therefore, the synthesis of 2,3-dihydroquinazolin-4(1H)-ones have important practical significance. The use of water as'green'solvent allows easy recycling of the catalyst.In conclusion, superparamagnetic nano-Fe₃O₄ has been shown to be an effective heterogeneous catalyst for the synthesis of three important heterocyclic compounds. The methodologies offer the competitive advantages such as mild reaction conditions, high product yields, the use of benign solvent, easy separation and reuse of catalyst, wide range of substrate applicability, and simple work-up procedure. This will provide a platform for the expanding the appliation of nanoparticles as catalysts in organic chemistry. It will promote the development of synthetic chemistry.