Recent developments in the scientific world have been increasingly interested in nanotechnology for the last two decades. Thus, in today’s world of “all green” and sustainable energy, the interest to develop new functional materials is not only important but also strategic.Nano-sized magnetic materials have been immensely researched because of their different and improved functionality compared to their bulk counterparts. Dispersions of magnetic NPs are known as ferrofluids.The magnetic properties of materials based on magnetite or other magnetic NPs can be controlled by varying the size, shape, composition and structure of NPs using different matrices.Many of types of magnetic nanoparticles (MNPs) have been synthesized over the past decade. Different MNPs have different properties, methods of synthesis and applications. Magnetite nanoparticles, due to their superparamagnetic properties and biocompatibility can find application as a contrast agent materials in magnetic resonance imaging, in drug delivery systems, as catalysts, as antibacterial agents, as heavy metals absorbers and for direct solar thermal energy harvesting 1-6. Additionally, nanocomposites with Fe3O4 nanoparticles can be used as electrochemical biosensors 7 and electromagnetic interference (EMI) shielding materials 8. Fe3O4 is among the most widely studied metal oxide nanoparticle systems. these iron-based nanoparticles exhibit unique chemical properties resulting from different iron oxidation states.The iron oxide nanoparticles (Fe3O4 NPs) present an interesting potential in the fields of biochemical sensors and nanoelectronics in addition to data storage.functionalized magnetic nanoparticles are studied for targeted therapy in medicine 9–12. Iron oxides are the most commonly used MNPs because of the toxicity and rapid oxidization of the other MNPs. 13 Furthermore, a multitude of studies incorporating magnetic iron oxide within a wide variety of organic materials were intensively reported in the literature 14–20. There exist several methods for the synthesis of ferrite nanomaterials, such as sonochemical, non-hydrolytic, solvothermal, coprecipitation, sol-gel, and microwave assisted 21,22. therefore, Fe3O4 MNPs have brought out some new kinds of biomedical applications such as dynamic sealing23, biosensors24, contrasting agent in magnetic resonance (MR) imaging25, localizer in therapeutic hyperthermia26 and magnetic targeted-drug delivery system27, etc.
Multicomponent condensation reactions (MCRs) are powerful synthetic tools in organic and medicinal chemistry because of the fact that different products can be synthesized by varying the substrate in a one-pot procedure 28.The Biginelli reaction is one of the most important MCRs that A simple and straightforward procedure for synthesis of 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) by three-component condensation of aromatic aldehydes, ?-dicarbonyl compounds, and urea/thiourea was first reported by an Italian chemist Biginelli in 189329. The Biginelli reaction is remarkable for its simplicity and also for the fact that it represents one of the early examples of a multicomponent reaction (MCR) 30–32. 3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) and related compounds have attracted a great deal of attention in organic and medicinal chemistry33. The great interest in DHPs stems from the fact that this class of compounds and their derivatives has, in principle, pronounced biological activity34. As a consequence, many catalytic methodologies have been developed to improve the synthesis of this attractive family of compounds, as very recently reviewed35. Their biological properties include antitubercular36, antifungal37, antimicrobial38, antimitotic 39 and anticancer40 , amongst others 41. This great biological importance of these heterocyclic compounds has prompted the development of new improved methodologies for Biginelli reaction, including transition metal Lewis acid catalysis42 , solid phase synthesis 43 , ionic liquids 44 , activation with certain additives 45, microwave-assisted synthesis technique 46 , ultrasound irradiation 47 , solvent-free techniques48 , grinding techniques 49 and many new catalysts 50.
In order to better the performance of Biginelli reaction, a variety of catalysts have been reported which of them MgBr2 51, NaHSO4/SiO2 52, FeCl3 53, ZrCl4 54, Bi(OTf)3 55, NH2SO3H 56, natural HEU type zeolite 57, Sr(OTf)2 58, ZrOCl2.8H2O 59, silica triflate 60, Fe(HSO4)3 61, TCICA 62, PPh3 63, CaF2 64, SiO2.H2SO4 65, Fe3O4-MWCNT 66, TMSCl, 67, NbCl5 68, Ce(C12H25SO3)3 69, ErCl3 70 , IBX 71 , SBA-15-PrSO3H 72 , Mo/?-Al2O3 73 , bentonite/PS-SO3H 74 , mesoporous SiO2.H2PO3 75, PSPEG-SO3H 76, Carbon-SO3H 77, Fe3O4/PAA-SO3H 78, nano-?-Fe2O3.SO3H 79, [email protected] 80, DBSA81, La2O3 82, Triphenylphosphine 83, BSA or DCC 84, NH4H2PO4/ MCM-41 85 , Et3N–SO3HHSO4 86 , Al(H2O)6(BF4)3 87 , B-CD-PSA 88, LaCl3.7H2O:HCl in EtOH 89, Mn(OAC)3.2H2O 90, silica sulfuric acid in ethanol 91, Cu(OTf)2 92, TPP 93, VB1 94, Fe(OTs)3.6H2O 95, MTSA96, Dendrimer-PWAn97 and so on are examples.
Most of the reported methods suffer from drawbacks such as harsh reaction conditions, use of harmful organic solvents, long reaction times, tedious work-up procedure, expensive and moisture-sensitive reagents, strongly acidic conditions, unsatisfactory yields, non-recoverability of the catalyst and environmental pollution. Thus, it is important to find more effcient catalysts and methods for the synthesis of these types of compounds.
Therefore, development of more selective and greener methods employing recyclable catalysts in Biginelli 3,4-DHPM synthesis is still demanded.In this paper, we describe an one-pot method for the Biginelli reaction using catalyst Fe3O4/ SiO2/ CPTS / C7H7N3O based on iron oxide nanoparticles.(Scheme 1).