Synthesis of 2-amino-4H-chromenes catalyzed by N,N-diethyl-Nsulfoethanaminium hydrogen sulfate

In this research condensation reaction between arylaldehydes, malononitrile and 1-naphthol, in the presence of acidic or basic catalysts, has been used as the best synthetic way toward 2-amino-4H-chromenes as biologically and industrially significant compounds. Some biological activities of this class of chromene derivatives include antimicrobial, antitumor, antiviral, and sex pheromone properties[1]. They have also been employed as potent biodegradable agrochemicals, and as cosmetics as well as pigments .Ionic liquids are of importance because they have been extensively used as solvent, catalyst and reagent in organic synthesis. These attractive compounds have various unique properties including non-flammability, non-volatility, wide liquid-state temperature range, high thermal and chemical stability, large electrochemical window, favorable solvation behavior and enhanced reactivity[2] In this work, we have introduced Brønsted acidic ionic N,N-diethyl-Nsulfoethanaminium hydrogen sulfateas a highly efficient, general and homogeneous catalyst for the reaction between arylaldehydes, malononitrile and 1- naphthol to afford 2-amino-4H-chromenes in high yields and short reaction times[3]. (Scheme 1).