Design and characterization of Fe₃O₄/GO/Au‐Ag nanocomposite as an efficient catalyst for the green synthesis of spirooxindole‐dihydropyridines

Abstract

A novel magnetic nanocomposite of Au‐Ag nanoparticles anchored on Fe3O4/graphene oxide spheres (Fe3O4/GO/Au‐Ag) was successfully fabricated by the layer‐by‐layer assembly technique. The prepared Fe3O4/GO/Au‐Ag was fully characterized by Fourier‐transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), field‐emission scanning electron microscopy (FE‐SEM), energy‐dispersive x‐ray spectroscopy (EDS), transmission electron microscopy (TEM), and Raman spectroscopy. This nanocomposite showed unique catalytic performance for the synthesis of Spiro[indoline‐3,5′‐pyrido[2,3‐d:6,5‐d’]dipyrimidine]‐pentaone derivatives by the three‐component condensation reaction of isatins, barbituric acids and 6‐amino uracil at room temperature and in aqueous media. The significant advantages of this protocol include highly stable, easily separable and reusable catalyst, simple operation, environmental friendliness and excellent yields.

Mg‐catalyzed one‐pot preparation of benzimidazoles and spirooxindoles by an immobilized chlorophyll b on magnetic nanoparticles

“…Due to the catalytic effect of Mg on the reactions (Table 3) and in accordance with the mechanisms reported in the literature, [ 11,21,22,36 ] the catalyst facilitates the nucleophilic attack of malononitrile through the Mg active centers by coordinating the carbonyl groups of isatin (Intermediate II). Subsequently, by removing a water molecule, the intermediate III is formed, which is attacked by the catalyst‐activated ketone, and finally, intermediate IV is formed.…”

“…[ 20 ] Different homogeneous and heterogeneous catalytic systems have been developed to produce spirooxindole derivatives. Some of the catalytic systems reported in recent years include C‐SO 3 H/water/reflux, [ 21 ] Fe 3 O 4 /GO/Au‐Ag/water/ R.T., [ 22 ] porcine pancreas/ H 2 O/EtOH/30°C, [ 11 ] DABCO/EtOH, [ 2 ] DABCO/H 2 O/80°C, [ 10 ] HPA@HNTs‐IMI‐SO 3 H/H 2 O:EtOH/R.T./80 W, [ 1 ] and p ‐TSA, H 2 O:ETOH. [ 3 ]…”

Transition metal-catalyzed synthesis of spirooxindoles

“…Kavyani and Baharfar developed a concept for the generation of spirooxindole-dihydropyridines 90 catalyzed by Fe 3 O 4 /GO/Au-Ag. 68 It was a novel catalyst made by the assembly of Au-Ag alloy NPs on the surface of A novel procedure for the synthesis of spirooxindolo-2iminothiazolines 96 catalyzed by FeCl 3 was established. 70 It involves a [3 + 2] cycloaddition reaction between aryl/alkyl isothiocyanates 94 and 1,3-dipoles produced from spirooxindole aziridines 95.…”

Recent advancements in organic synthesis catalyzed by graphene oxide metal composites as heterogeneous nanocatalysts

“…Kavyani and Baharf designed an efficient and novel Fe 3 O 4 /GO/Au‐Ag catalyst for the synthesis of spirooxindole‐dihydropyridine derivatives via condensation reaction of isatin, barbituric acid, and 6‐amino uracil in the presence of magnetic Fe 3 O 4 /GO/Au‐Ag (20 mg) as a catalyst and H 2 O as a solvent at room temperature [ 198 ] (Scheme 33). Various amount of catalyst was used, namely, 5, 10, 15, 20, and 25 mg.…”