Subscribe to RSS
DOI: 10.1055/s-0033-1339588
Synthesis of Tetrahydro-4H-chromenes Using Nano γ-Fe2O3 in H2O
Water Dispersed Magnetic Nanoparticles (H2O-DMNPs) of γ-Fe2O3 for Multicomponent Coupling Reactions: a Green, Single-Pot Technique for the Synthesis of Tetrahydro-4H-chromenes and Hexahydroquinoline Carboxylates.
Tetrahedron Lett. 2013;
54: 3344-3347
Publication History
Publication Date:
19 August 2013 (online)
Key words
γ-Fe2O3 - multicomponent reaction - tetrahydro-4H-chromenes - hexahydroquinoline carboxylatesSignificance
γ-Fe2O3 magnetic nanoparticles (nano-γ-Fe2O3), which were dispersed by ultrasonic irradiation in water, catalyzed the three-component condensation reaction of 1,3-cyclohexanediones, arylaldehydes, and malononitrile to give the corresponding tetrahydro-4H-chromenes in up to 95% yield (14 examples, eq. 1). The dispersed nano-γ-Fe2O3 was also effective for the four-component reaction of dimedone, arylaldehydes, β-keto esters, and NH4OAc to afford the corresponding hexahydroquinoline carboxylates in up to 96% yield (8 examples, eq. 2).
#
Comment
The catalytic activity of the dispersed nano-γ-Fe2O3 was superior to that of FeCl3, Fe(NO)3, bulk-Fe3O4, nano-Fe3O4 and non-dispersed nano-γ-Fe2O3. In the formation of tetrahydro-4H-chromenes, the catalyst was recovered magnetically and reused four times.
#
#