α-Fe2O3 nanoparticles: An efficient, inexpensive catalyst for the one-pot preparation of 3,4-dihydropyrano[c]chromenes

Abstract

This paper describes the combustion synthesis of a-Fe 2 O 3 nanopowder at much lower temperature and its catalytic activity for the one-pot preparation of 3,4-dihydropyrano[c]chromenes. The combustion derived a-Fe 2 O 3 nanopowder was characterized by powder X-ray diffraction (PXRD), Braunauer, Emmett and Teller (BET) surface area, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Highly efficient, three-component condensation of aromatic aldehyde, malanonitrile and 4-hydroxycoumarin catalyzed by a-Fe 2 O 3 nanoparticles at room temperature is described. The method offers an excellent alternative to the synthesis of 3,4-dihydropyrano[c]chromenes. The reactions are rapid, clean, and the products with good yield and high purity. #

Silica-Grafted Ionic Liquids as Recyclable Catalysts for the Synthesis of 3,4-Dihydropyrano[c]chromenes and Pyra-no[2,3-c]pyrazoles

“…Chemicals were purchased from Fluka, Merck and Aldrich Chemical Companies. All the products were char- [24][25][26][27][28][29][30][31][38][39][40][41]. Silica-grafted N-proprepared according to our previous reported procedure [15].…”

“…A number of methods have been reported for the synthesis of 3,4-dihydropyrano[c] chromenes such as piperidine in organic solvent, i.e. ethanol and pyridine [22], K 2 CO 3 under microwave irradiation [23], diammonium hydrogen phosphate [24], tetrabutylammonium bromide [25], sodium dodecyl sulfate [26], DBU [27], morpholine [28], α-Fe 2 O 3 nanopatricles [29], CuO nanopatricles [30], and silica-bonded N-propyl-piperazine sodium propionate [31].…”

New advances in catalytic performance of erbium‐folic acid‐coated CoFe2O4 complexes for green one‐pot three‐component synthesis of pyrano[2,3‐d]pyrimidinone and dihydropyrano[3,2‐c]chromenes compounds in water

“…Although lots of attempts have been made for the synthesis of pyran derivatives including anchored dysprosium and praseodymium complexes on CoFe 2 O 4 , [ 13 ] visible light irradiation promoted catalyst free and solvent free, [ 26 ] nano‐CuO–Ag, [ 27 ] piperazine‐1,4‐diium dihydrogen phosphate, [ 28 ] imidazole‐based bis‐dicationic Brönsted acidic ionic liquids, [ 29 ] carboxy group functionalized imidazolium salts, [ 30 ] Ni 2+ supported on hydroxyapatite‐core‐shell‐γ‐Fe 2 O 3 , [ 6 ] [EMIM][OH] ionic liquid, [ 31 ] and Fe 3 O 4 @APTES@isatin‐SO 3 H, [ 32 ] and the same attempts have been carried out for the synthesis of chromene such as CTMAB‐bentonite, [ 33 ] Ni(II)‐Schiff base/SBA‐15, [ 34 ] Co 3 O 4 /NiO@GQDs@SO 3 H, [ 35 ] BF 3 ·SiO 2, [ 36 ] α‐Fe 2 O 3 , [ 37 ] and CuO nanoparticles. [ 38 ] Previous reported methods introduced in literature have some drawbacks such as long reaction times, drastic conditions, poor recovery of expensive catalysts, complex synthetic pathways, and unsatisfactory yields.…”

Zr@IL-Fe3O4 MNPs as an efficient and green heterogeneous magnetic nanocatalyst for the one-pot three-component synthesis of highly substituted pyran derivatives under solvent-free conditions

“…The most important route for their preparation is the one-pot three-component condensation of 4-hydroxycoumarin with aldehyde and malononitrile in the presence of a catalyst. Several strategies for the construction of these types of coumarins have been reported under various conditions, such as H 6 P 2 W 18 O 62 ·18H 2 O, 31 nanoparticles, 32 MgO, 33 nanosilica, 34 hexadecyltrimethyl ammonium bromide, 35 ionic liquids, 36 Mg/La mixed metal oxides, 37 and (DAHP). 38 Also, 4 H- benzo-[ b ]-pyrans are other derivatives of heterocycles with a common structural motif in a diversity of natural and synthetic products.…”