Cyclocondensation reaction of isatins with malononitrile and 4-hydroxycoumarin or 3,4-methylenedioxyphenol catalyzed by TiO2 nanoparticles immobilized on carbon nanotubes

During the past decade, the utility of metal oxide nanoparticles (NPs) as efficient heterogeneous catalysts in organic synthesis has been preferably expanded.1-3 Due to the wide range of biological and medicinal activities the synthesis of spiro compounds has become a significant target over the past decade. in the present work, we report the efficient synthesis of spiro[3,4']1,3-dihydro-2H-indol-2-one-2'-amino-5'-oxo-4'H,5'H-pyrano[3',2'-c]chromen-3'-yl cyanides and spiro[3,8']1,3-dihydro-2H-indol-2-one-6'-amino-8'H-[1',3']dioxolo[4',5'-g]chromen-7'-yl cyanides catalyzed by TiO2-CNTs as a useful recyclable heterogeneous catalyst in aqueous media at room temperature (Scheme 1).

Keywords:

Aqueous media , Environment-friendly procedure , 4-Hydroxycoumarin , Isatin , 3 , 4-Methylenedioxyphenol , TiO2-CNTs.