Thiourea dioxide‐grafted γ‐Fe₂O₃/HAp magnetic nanoparticles: Efficient, green and reusable nanocatalyst for synthesis of pyranopyridine derivatives

Abstract

A novel thiourea dioxide-functionalized hydroxyapatite-encapsulated hybrid coreshell γ-Fe 2 O 3 @HAp-TUD nanoparticles (MNPs) were prepared and characterized by FT-IR, EDX, SEM, XRD, TGA and VSM analytical methods. The catalytic activity of these MNPs was evaluated through one-pot three-component reactions between various substituted aldehydes, malononitrile and 3-cyano-6-hydroxy-4methyl-pyridin-2(1H)-one to afford the corresponding pyrano[2,3-b]pyridines in high yields under mild and solvent-free conditions. The catalyst can be easily recycled in a magnetic field and reused in five consecutive runs without significant decrease of its catalytic activity.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

“…Thiourea dioxide-decorated hydroxyapatite-supported g-Fe 2 O 3 NP (g-Fe 2 O 3 @HAp-TUD)-catalyzed Knoevenagel-Michaelcyclization for the synthesis of pyranopyridines (181) was achieved successfully via the one-pot three-component reaction of malononitrile (29a), substituted benzaldehydes (21e) and 3-cyano-6-hydroxy-4-methyl-pyridin-2(1H)-ones (180) under solvent-free conditions (Scheme 93). 188 The typical process for the preparation of NPs involved the coating of hydroxyapatite on Fe 2 O 3 NPs followed by functionalization with hexamethylene-1,6-diisocyanate and thiourea dioxide. The present catalyst offered the advantages of high yields in shorter reaction times, avoiding the use of solvent compared other thiourea-catalyzed protocols.…”

Fe3O4‐supported Schiff‐base copper (II) complex: A valuable heterogeneous nanocatalyst for one‐pot synthesis of new pyrano[2,3‐b]pyridine‐3‐carboxamide derivatives

“…Among the eco-friendly processes, multicomponent reactions (MCRs) have attracted much interests as high atom-economy and convergent reactions. [52][53][54][55][56][57][58] Recently, few methods have been developed for the synthesis of pyrano [2,3-c] pyridines utilizing Et 3 N in refluxing ethanol and [BMIm]BF 4 ionic liquid. [42][43][44][45] Therefore, these reactions provide the scientists an efficient, time saving and atom economical approach to a wide variety of organic and bioorganic molecules including heterocyclic compounds.…”

“…These well-known heterocyclic compounds have shown a broad range of biological properties such as antiallergic, antitumor, anti-inflammatory, antidyslipidemic, antimicrobial, antihyperglycemic, antiviral and estrogenic agents. [52][53][54][55][56][57][58] Recently, few methods have been developed for the synthesis of pyrano[2,3-c] pyridines utilizing Et 3 N in refluxing ethanol and [BMIm]BF 4 ionic liquid. [59] Also, Pyrano[3,2-c]pyridones have been synthesized by two stepwise procedures in refluxing methanol in the presence of piperidine.…”

Crown ether functionalized magnetic hydroxyapatite as eco‐friendly microvessel inorganic‐organic hybrid nanocatalyst in nucleophilic substitution reactions: an approach to benzyl thiocyanate, cyanide, azide and acetate derivatives

“…Nowadays, magnetic nanoparticles have attracted considerable interest due to their easy separation and also their remarkable physical and chemical properties . To avoid the aggregation of nanoparticles and to improve their chemical stability, the surface of the nanoparticles has been coated with different materials, such as silica, MCM‐41, polymer and hydroxyapatite . Among them hydroxyapatite, a mineral form of calcium apatite, which is shown by Ca 10 (PO 4 ) 6 (OH) 2 has several unique properties such as lower cost of production, availability and environment friendly nature which can make hydroxyapatite‐encapsulated magnetic nanocrystallites an excellent support for the preparation of heterogeneous catalysts in organic chemistry …”

“…[12][13][14][15] To avoid the aggregation of nanoparticles and to improve their chemical stability, the surface of the nanoparticles has been coated with different materials, such as silica, MCM-41, polymer and hydroxyapatite. [16][17][18][19][20][21][22][23] Among them hydroxyapatite, a mineral form of calcium apatite, which is shown by Ca 10 (PO 4 ) 6 (OH) 2 has several unique properties such as lower cost of production, availability and environment friendly nature which can make hydroxyapatite-encapsulated magnetic nanocrystallites an excellent support for the preparation of heterogeneous catalysts in organic chemistry. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Crown ethers performing as excellent phase-transfer catalyst in asymmetric reactions have been reported in several papers, with high enantioselectivities and yields observed applying these compounds; in this work, hydroxyapatite coated uniform γ-Fe 2 O 3 core-shell particles were synthesized and crown ether immobilized on an insoluble support presents can lead to the formation of novel nanocomposites, which combines and enhances the characteristics of the components, such as the electronic, thermal, and catalytic properties and molecular recognition of the macrocyclic hosts.…”