1-Methylimidazolium tricyanomethanide {[HMIM]C(CN)(3)} as a nano structure and reusable molten salt catalyst for the synthesis of tetrahydrobenzo[b]pyrans via tandem Knoevenagel-Michael cyclocondensation and 3,4-dihydropyrano[c]chromene derivatives

摘要

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 malononitrile were synthesized by a catalytic amount of {[HMIM]C(CN)(3)} NMS under the same condition. (C) 2016 Elsevier B.V. All rights reserved.