An efficient methodology dealing with the Fe3O4@TiO2 nanocomposite-catalyzed direct condensation reaction of 4-hydroxycoumarin, aromatic aldehydes, and 6-amino-1,3-dimethyluracil in aqueous media at room temperature is reported. This new process has been successfully applied to the synthesis of 6-amino-5-[(4-hydroxy-2-oxo-2H-chromen-3-yl)(aryl)methyl]-1,3-dimethyl-2,4,6(1H,3H)-pyrimidinediones in high to excellent yields within 2–3 h.

A PANI-Fe3O4@ZnO nanocomposite is used to prepare a series of novel chromeno-pyrido[d]pyrimidine derivatives in an aqueous medium at room temperature.

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In this research, we synthesized the Fe 3 O 4 /CuO/ZnO@MWCNT magnetic nanocomposites using water extract of Petasites hybridus rhizome, and the high performance of synthesized catalyst was confirmed by using in the solvent-free multicomponent reactions of isatoic anhydride, N-methylimidazole, alkyl bromides, activated acetylenic compounds and 2-aminoacetonitrile at ambient temperature for the production of new cyanopyrroloazepine derivatives in high yields. This catalyst could be used several times in these reactions and have main role in the yield of product. The synthesized cyanopyrroloazepines have NH groups in their structure and for this reason have good antioxidant activity. Also, employing Gram-positive and Gram-negative bacteria in the disk diffusion procedure confirmed some cyanopyrroloazepines antimicrobial effect. The results showed that synthesized cyanopyrroloazepine prevented the bacterial growth. This used process for preparation of new cyanopyrroloazepine has some improvements such as low reaction time, product with high yields, simple separation of catalyst and products.

An efficient and green protocol for the synthesis of 4-aryl-3,4-dihydro-2H,5Hpyrano[3,2-c]chromene-2,5-diones and 8-aryl-7,8-dihydro-6H-[1,3]dioxolo [4,5-g]chromene-6-ones through the Ag 2 Cr 2 O 7 nanoparticles catalyzed cyclocondensation reaction of active methylene compounds including 4-hydroxycoumarin or 3,4-methylenedioxyphenol, aromatic aldehydes, and meldrum's acid in water at ambient temperature was described. This method demonstrates several advantages compared with methods that are currently employed such as a mild reaction conditions, simple work-up, good to excellent yields, avoiding toxic catalyst and hazardous solvent, and recovery and reuse of the catalyst. K E Y W O R D S [1,3]dioxolo[g]chromeneones, aqueous media, environmentally benign procedure, pyrano[c] chromenediones, recyclability of catalyst, silver(I) dichromate (Ag 2 Cr 2 O 7 NPs)

Background: One of the principal factors in the field of research in green chemistry is to drive chemical reactions under ultrasonication as a versatile synthetic tool. Moreover, nanostructured metal salts occupy an important position as low cost, efficient, heterogeneous, and green catalysts in chemical reactions. Pyrimidine has also acquired significance because it is a core structure in a variety of natural and non-natural agents, many of which display versatile biological activities and medical applications. Objective: The aim of this study was to explore the role of nickel(II) chromite nanoparticles (NiCr2O4 NPs) as a green and recyclable catalyst for the synthesis of 2,4-diamino-6-aryl-pyrimidine-5-yl cyanides under ultrasonic radiation. Methods: A direct cyclocondensation reaction of guanidine nitrate, aromatic aldehydes, and malononitrile were performed using NiCr2O4 NPs as an effective heterogeneous catalyst under ultrasonic radiation at room temperature conditions to prepare 2,4-diamino-6-aryl-pyrimidine-5-yl cyanides in high yields. The described catalyst was prepared successfully according to a simple hydrothermal route and fully characterized by the X-Ray diffraction (XRD) technique, energy dispersive X-Ray (EDS) analysis, scanning electron microscopy (SEM), and dynamic light scattering (DLS). Results: A number of 2,4-diamino-6-aryl-pyrimidine-5-yl cyanides were effectively synthesized in high yields (94-98%) within short reaction times (15 min). All synthesized compounds were well characterized by IR, 1H and 13C NMR spectroscopy, and also by elemental analyses. Conclusion: In conclusion, a simple, efficient, and green synthesis of 2,4-diamino-6-aryl-pyrimidine-5-yl cyanides was developed using NiCr2O4 NPs as green nanocatalyst, and under ultrasound radiation as green tool. The mild reaction conditions, avoiding the use of toxic solvents or reagents, high atom economy, high yields, and simple work-up are the attractive features of this new protocol.

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A variety of alcohols were oxidized to the corresponding carbonyl compounds by reaction of ammonium chlorochromate adsorbed on montmorillonite K-10 in dichloromethane at room temperature in excellent yields.