Magnetic nanoparticles-supported tungstic acid (MNP-TA): an efficient magnetic recyclable catalyst for the one-pot synthesis of spirooxindoles in water

Abstract

This paper reports the preparation, characterization and catalytic application of a novel magnetically separable catalyst consisting of tungstic acid supported on silica coated magnetic nanoparticles. To obtain this new catalyst system, first, (3-chloropropyl)triethoxysilane was reacted with silica coted magnetic nanoparticles to generate a 3-chloropropyl magnetic nanoparticle (3-CPMNP) substrate. 10 Subsequently, the addition of sodium tungstate to 3-CPMNP resulted in the stabilization of tungstic acid species on the surface of magnetic nanoparticles (MNP-TA). The synthesized catalyst was characterized using some different microscopic and spectroscopic techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and FT-IR spectroscopy. The catalyst nanoparticles were obtained with near spherical morphology and average size 15 of ~45 nm. The W content of the catalyst was determined by ICP analysis to be 82.5 ppm (82.5 mg/L), which was equal to 8.25% w/w (0.45 mmol/g). The catalyst was successfully used for the one-pot synthesis of spirooxindoles via multicomponent reaction of isatins and dicarbonyl compounds in water as a green solvent. The results revealed that, this new catalyst showed high catalytic activity in this protocol and it can be reused at least 6 times without any treatment in its catalytic activity.

Synthesis of Imidazole and Theophylline Derivatives Incorporating Pyrimidine‐Fused Heterocycles Using Magnetic Nanoparticles‐Supported Tungstic Acid (MNP‐TA) Catalyst

“…In this way this problem associated to synthesis of this class of compounds can be resolved to some extent. To aim this purpose we used from our previously reported magnetic nanoparticles catalyst system MNP‐TA which is consisting of tungstic acid supported on silica coated magnetic nanoparticles .…”

“…In continuation of our previous studies on the synthesis of benzimidazole‐ and theophylline‐based analogues and multicomponent reactions herein we report an efficient protocol for the synthesis of some novel pyrimidine‐fused heterocycles (PFH) incorporating imidazole, benzimidazole, and theophylline backbones using a multicomponent reaction as final step.…”

l-Cysteine-functionalized magnetic nanoparticles (LCMNP): as a magnetic reusable organocatalyst for one-pot synthesis of 9-(1H-indol-3-yl) xanthen-4-(9H)-ones

“…In the structure of this catalyst, system l-cysteine moieties were chemically grafted to the surface of magnetic nanoparticles, creating efficient amino acid-based catalytic sites to be used in organic reactions. In this study and in continuation of over previous works on magnetic nanoparticle-based catalyst systems [47][48][49][50][51][52][53][54], we would like to show the catalytic applicability of this LCMNP in another MCR for efficient synthesis of a class of xanthene derivatives.…”

Sodium Formate‐Catalyzed One‐Pot Synthesis of Functionalized Spiro[indoline‐3,5′‐pyrido[2,3‐d]pyrimidine]/Spiro[acenaphthylene‐1,5′‐pyrido[2,3‐d]‐pyrimidine] Derivatives

“…Hence, it is highly anticipated that the combined Full Papers molecular framework might show some sorts of extended biological profiles. There are just two earlier reports from same group of investigators in developing methods for spirooxindole-fused pyrido[2,3-d]pyrimidine scaffold using two different nano-catalysts such as 3-chloropropyl magnetic nanoparticle-supported tungstic acid (3-CPMNP-TA) [8] and Fe 3 O 4 @SiO 2 -Imid-nanoPMA [9] on refluxing or microwave heating. Under this purview, development of a simple, efficient, and environmentally benign protocol for the one-pot synthesis of such biologically interesting molecular scaffold is of great interest.…”