Calcium lactate catalyzed tandem Michael addition-cyclization reaction: A green protocol to synthesize 2-amino-4H-chromene-3-carbonitriles

Abstract

An eco-friendly, green protocol catalyzed by non-toxic calcium lactate to synthesize 2-amino-4H-chromene-3-carbonitriles via a tandem Michael addition-cyclization reaction in green solvents is described here. The 2-amino-4H-chromene-3-carbonitriles are formed by the Michael addition reaction of malononitrile to 2-hydroxychalcones/2-(E)-2-nitrovinylphenols, followed by an intramolecular ring closure in aqueous ethanol (1:1 v/v). The present method can tolerate functional groups with different electronic properties and produce good to excellent yields of the desired chromenes.