Highly efficient organocatalytic synthesis of diverse and densely functionalized 2-amino-3-cyano-4H-pyrans under mechanochemical ball milling

An improved one-pot three-component and environmentally benign approach for the synthesis of a wide range of densely functionalized 2-amino-3-cyano-4H-pyran annulated derivatives has been described by the reaction of aryl aldehydes, malononitrile and diverse electron-rich phenolic or enolizable carbonyl compounds under mechanochemical ball milling conditions in the presence of potassium phthalimide (POPI), as a mild basic organocatalyst, at ambient temperature. In comparison to the conventional methods, the remarkable advantages of this green protocol are high to quantitative yields, avoiding the use of any hazardous transition metal-free catalyst or solvent, shorter reaction time at ambient temperature, low cost, and straightforward work-up procedure.