Synthesis of pyranopyrazoles using magnetic Fe3O4 nanoparticles as efficient and reusable catalyst

Preparation and characterization of hexamethylenetetramine‐functionalized magnetic nanoparticles and their application as novel catalyst for the synthesis of pyranopyrazole derivatives

“…Comparing the results, the optimum ones (high yield of product within shortest reaction time) were under solvent-free condition at 60°C (entry 2). Subsequently, the optimum amount of catalyst was found as 0.03 g. Also, the results for the reaction in the presence of Fe 3 O 4 , SiO 2 @Fe 3 O 4 and Fe 3 O 4 @SiO 2 -HMTA (entries [13][14][15] and also in the absence of the catalyst (entry 16) were not as good as the results obtained in the presence of Fe 3 O 4 @SiO 2 -HMTA-SO 3 H. Hence, to study the generality of the effect of Fe 3 O 4 @SiO 2 -HMTA-SO 3 H on this reaction, different pyranopyrazole derivatives (8a-m) were synthesized (Scheme 3), and the results are summarized in Table 2. It is observed that electron-donating substituents on phenyl ring make the reaction slower and lead to a lower yield of the corresponding products compared to electron-withdrawing substituents.…”

“…[7] Thus, they can act as UV absorbers. Until now, various catalysts have been applied in the synthesis of pyranopyrazole derivatives, such as SBA-15-based catalysts, [8,9] L-proline, [10,11] ionic liquids, [12] magnetic nanoparticles (MNPs) [13] and ZrO 2 nanoparticles. [14] Due to the increasing consideration for the use of nanomagnetic catalysts in organic syntheses, [15][16][17][18] efforts have been made to modify the surface of MNPs for increasing their catalytic efficiency.…”

Sodium gluconate: An efficient organocatalyst for the synthesis of dihydropyrano[2,3-c] pyrazole derivatives

“…Recently, several amendments have been done for the synthesis of dihydropyrano[2,3-c] pyrazole which involve the use of morpholine triflate [23], β-cyclodextrin [24], meglumine [25], L-proline [26], Fe 3 O 4 nanoparticles [27], green cellulose-based nanocomposite catalyst [28], lactic acid [29], isonicotinic acid [30], sodium dodecyl sulfate [31], molecular sieve [32], DABCO [33], lipase [34], bovine serum albumin [35], deep eutectic solvent [36], Ag/TiO 2 nano-thin films [37], Ba(OH) 2 [38], polyphosphoric acid supported nanoparticles [39], [Yb(OTf) 3 ] ytterbium triflate [40], and micellar medium [41].…”

Synthesis of water-dispersed magnetic nanoparticles (H2O-DMNPs) of β-cyclodextrin modified Fe3O4 and its catalytic application in Kabachnik–Fields multicomponent reaction

“…Also, various methods are applied for the synthesis, and stabilization of such magnetic nanoparticles (NPs) [5][6][7][8][9][10]. Encapsulation with silica is a one of the important method for stabilization and changing surface reactivity [11][12][13].…”