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

Abstract

A new magnetic catalyst was prepared through the reaction of silanol groups, on the surface of silica‐coated Fe3O4 magnetic nanoparticles, with (3‐chloropropyl)triethoxysilane followed by hexamethylenetetramine and chlorosulfonic acid. The obtained magnetic catalyst was characterized using thermogravimetric analysis, vibrating sample magnetometry, scanning electron microscopy and energy‐dispersive X‐ray analysis. Its catalytic activity was investigated in the synthesis of pyranopyrazole compounds, and the results were excellent regarding high yield of the products and short reaction time.

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

“…Using this catalyst with a low loading, pyranopyrazole derivatives were synthesized by fusing four components, acetylene dicarboxylate (201a), malononitrile (29), 2, and 64a, without the use of solvent in a shorter reaction time (10-18 min, Scheme 107). 218 The authors claimed the superiority of the Fe 3 O 4 @SiO 2 -HMTA-SO 3 H-catalyzed synthesis considering its faster and greener reaction with good yields and feasible recovery of the catalyst assisted by an external magnet compared to other reported protocols. [219][220][221] However, the recyclability of the catalytic system was found to decrease signicantly aer the fourth catalytic cycle.…”

“…Further, in the same year, they also reported the synthesis of pyrans using Fe 3 O 4 NPs supported on polyhedral oligomeric silsesquioxane NCs in ethanol. 240 Ali Maleki reported the silica-supported magnetic MNP (Fe 3 O 4 /SiO 2 )-catalyzed synthesis of benzodiazepines or diazepines (220) from 1,2-diamine (202b), linear/cyclic ketone (218) and isocyanide (219a) in ethanol at rt in 85-98% yield (Scheme 117). 241 The MNPs were prepared using Fe 3 O 4 NPs and TEOS, and characterized via TEM.…”

Butane‐1‐sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles: A novel and heterogeneous catalyst for the one‐pot synthesis of barbituric acid and pyrano[2,3‐d] pyrimidine derivatives in aqueous media

“…In recent years the use of magnetic nanoparticles (MNPs) for the preparation of supported heterogeneous catalysts has attracted significant attention. [1][2][3][4][5][6][7][8][9][10][11][12] This attention can be attributed to the unique properties of these types of compounds including high thermal and mechanical stability, large surface area to volume ratio, low toxicity, ease of recovery by use of an external magnetic field and well-defined pore size distribution. [13] In this regard magnetic metal oxide nanoparticles and especially Fe 3 O 4 nanoparticles have been the focus of much research recently.…”

One‐pot synthesis of magnetic palladium–NiFe2O4–graphene oxide composite: an efficient and recyclable catalyst for Heck reaction

“…Unfortunately, aggregation of naked NPs is often inevitable. For this reason, many attempts have been made to immobilize or stabilize Pd NPs using a wide variety of supports including metal oxides, [8,9] inorganic materials [10][11][12] and carbon materials. [13][14][15][16] Recently, graphene and graphene oxide (GO) materials have been applied as efficient catalysts or catalyst supports owing to their unique physiochemical properties, including high mechanical strength, excellent conductivity and large specific surface area.…”