Silica sulfuric acid magnetic nanoparticle: an efficient and ecofriendly catalyst for synthesis of spiro[2-amino-4H-pyran-oxindole]s

Abstract

Silica sulfuric acid magnetic nanoparticles efficiently catalyze the one-pot, three-component reaction of isatins and malononitrile with dimedone, 1,3-dimethylbarbituric acid or 4-hydroxycoumarin in EtOH–H2O to afford the corresponding spiro[2-amino-4H-pyran-oxindole] derivatives in high yields under ultrasound irradiation at 60 °C. The heterogeneous nanocatalyst could be recovered easily from the reaction mixture using an external magnet and reused many times without significant loss of its catalytic activity.

A highly efficient magnetic solid acid nanocatalyst for the synthesis of new bulky heterocyclic compounds

“…27 The functional group of NH 2 was reacted with other group and new catalysts such as Pd(II)-phosphine complexes, 28 Fe 3 O 4 -APTES-N-(2-aminoethyl)acrylamide, 29 Fe 3 O 4 -APTES-quinuclidine, 30 magnetic nanoparticles-crown, 31 polyaniline/Fe 3 O 4 , 32 Naproxen-APTES-Fe 3 O 4 , 33 Fe 3 O 4 -APTES-PEG 34 and Fe 3 O 4 -APTES-TCNP 35 were synthesized. Some of these catalysts like Fe 3 O 4 @ APTES$Ac, Fe 3 O 4 @APTES$SAH, 36 Fe 3 O 4 -APTES$SO 3 H 37,38 are acidic and Fe 3 O 4 @APTS-Py, 39 MNP-NMe 2 , MNP-NH 2 (ref. 40) and Fe 3 O 4 @APTES@Ni(OH) 2 (ref.…”