NaN₃ Catalyzed Highly Convenient Access to Functionalized 4H-chromenes: A Green One-pot Approach for Diversity Amplification

An energy efficient, one-pot synthetic method has been described for the access of biologically privileged tetrahydro-4H-chromene derivatives via Knoevenagel condensation and Michael additions of various aldehydes with malononitrile and dimedone in aqueous ethanol solvent system. Good chemical yields were obtained in relatively shorter reaction times under mild conditions using sodium azide as a commercially accessible, inexpensive and less-toxic catalyst. Easy isolation of products, high atom-economy, environmental benignity and applicability to gram scale synthesis are the prominent features of this protocol.