An expeditious, experimentally simple and rapid 1-methylimidazolium tricyanomethanide {[HMIM]C(CN)3} nano molten salt (NMS) catalyzed tandem Knoevenagel-Michael cyclocondensation procedure for the synthesis of tetrahydrobenzo[b]pyrans was described via reaction between dimedone, aromatic aldehyde and malononitrile under solvent-free conditions at room temperature. Furthermore, 3,4-dihydropyrano[c]chromene derivatives through the condensation of 4-hydroxycoumarin, aromatic aldehyde and malononitrilewere synthesized by a catalytic amount of {[HMIM]C(CN)3} NMS under the same condition
