Potassium phthalimide-N-oxyl: a novel, efficient, and simple organocatalyst for the one-pot three-component synthesis of various 2-amino-4H-chromene derivatives in water

A wide variety of 2-amino-4H-chromene derivatives with diverse substituents on the 4H-chromene ring were efficiently prepared via one-pot, three-component reaction of an aromatic aldehyde, malononitrile (or ethyl cyanoacetate), and diverse enolizable C-H activated acidic compounds in the presence of low loading of potassium phthalimide-N-oxyl (POPINO), as a new organocatalyst, in aqueous media. This procedure is a clean, transition metal-free, and environmentally friendly approach to prepare different 2-amino-4H-chromen derivatives that offers many advantages including short reaction time, high to quantitative yields, low cost, and straightforward work-up.