Introduction of Brönsted acidic ionic liquid supported on nanoporous Na+-montmorillonite as an efficient catalyst for the synthesis of 2-amino-tetrahydro-4H-pyrans

Nanoporous sodium montmorillonite clay (Na+MMT) was used as a support for the immobilization of 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sulfate (Na+MMT-[pmim]HSO4). This catalyst showed excellent catalytic activity for the preparation of 2-amino-3-cyano-5-oxo-5,6,7,8-tetrahydro-4H-benzopyrans via three-component reactions between aldehydes, dimedone and malononitrile. The procedure gave the products in high yields within short reaction times. Also, this catalyst can be reused at least for five times without loss of its catalytic activity. All the products were characterized using melting point, IR, 1H NMR and 13C NMR and were identified by comparison of their spectra with those of authentic samples.