A Green and Convenient Approach for the Synthesis of Indole–acrylonitrile and Indole-coumarin Hybrids in Aqueous Media

Abstract

: Indole–acrylonitrile hybrids were synthesized via a catalyst-free reaction of aromatic aldehydes and 3-(cyanoacetyl)indole in aqueous media. Also, indole-coumarin hybrids were synthesized via a domino reaction of salicylaldehyde derivatives and 3-(cyanoacetyl)indole in the presence of ammonium acetate in aqueous media. The advantages of the present protocol are high yields, short reaction times, mild reaction conditions, operational simplicity, and environmentally benign, and also there is no need to purification of products. objective: The development of hybrid molecules through the combination of indole and other heterocycles may lead to compounds with interesting biological activity. method: The Knoevenagel condensation reaction of 3-(cyanoacetyl)indole with benzaldehyde derivatives was carried out in EtOH/H2O 1:1 in reflux condition and 3-aryl-2-(1H-indol-3-ylcarbonyl)acrylonitrile 3a-h were obtained in excellent yields. The indole-coumarin hybrids 5a-g were obtained from the reaction of salicylaldehyde derivatives and 3-(cyanoacetyl)indole in EtOH/H2O (2:1) in the presence of 1 equivalent ammonium acetate as a catalyst at reflux condition.