Ni(II)-Schiff base/SBA-15: a nanostructure and reusable catalyst for one-pot three-component green synthesis of 3,4-dihydropyrano[3,2-c]chromene derivatives

An efficient, rapid, and environmentally benign Ni(II)-Schiff base/SBA-15-catalyzed one-pot three-component cyclocondensation process was described via the reaction between malononitrile, 4-hydroxycoumarin, and various aldehydes in aqueous media for the synthesis of 3,4-dihydropyrano[3,2- c ]chromene derivatives. This nanocatalyst was characterized using FT-IR, SEM, TGA, TEM, BET, AFM, and XRD techniques. It is possible to reuse the heterogeneous catalyst without any marked change in its catalytic activity at least five times. Other remarkable features of this method include excellent yields in pure form, convenient operation, a much milder procedure, short reaction time, simple workup and avoidance of hazardous reagents/solvents.