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Abstract

In this study, acidic ionic liquid N, N-diethyl-N-sulfoethanaminium hydrogen sulfate {[Et3N-SO3H]HSO4} was utilized to promote two classes of useful organic transformations under solvent-free conditions including, i) the condensation of arylaldehydes with malononitrile and 1-naphthol, leading to 2-amino-4H-chromenes, and ii) the condensation reaction of arylaldehydes with 2-naphthol to give 14-aryl-14H-dibenzo[a, j]xanthenes. The ionic liquid efficiently catalyzed the reactions, and the products were obtained in excellent yields (94-98%) within short reaction times (8-30 min).

Design of a Schiff Base Complex of Copper Coated on Epoxy-Modified Core–Shell MNPs as an Environmentally Friendly and Novel Catalyst for the One-Pot Synthesis of Various Chromene-Annulated Heterocycles

“…It seems that the reaction was carried out to proceed through a Knoevenagel–Carba–Michael–Thorpe–Ziegler-type cascade method . Recently, various heterogeneous or homogeneous catalysts such as ionic liquids, diammonium hydrogen phosphate (DAHP), α-Fe 2 O 3 nanoparticles, H 6 P 2 W 18 O 62 ·18H 2 O, cetrimonium bromide, Mg–La mixed metal oxides, silica-grafted ionic liquid, TiCl 4 , InCl 3 , triethylbenzylammonium chloride, Preyssler heteropoly acid, and γ-alumina . However, each of these approaches may have its own merits and some typical shortcomings like high cost, long reaction times, high temperature, usage of toxic solvent, low product yields, and difficulty of removal and recovery.…”