Sodium Formate-Catalyzed One-Pot Synthesis of Benzopyranopyrimidines and 4-Thio-substituted 4H-Chromenes via Multicomponent Reaction at Room Temperature

A simple, straightforward and highly efficient multicomponent one-pot synthesis of a series of pharmaceutically interesting benzopyranopyrimidine and 4H-chromene derivatives has been developed on the basis of low-cost and environment-friendly sodium formate catalyst via tandem reactions of salicylic aldehydes, malononitrile, and cyclic secondary amines in ethanol at room temperature. Nature of nucleophile used in this reaction directs the course of the reaction; cyclic secondary amines result in the formation of benzopyrano[2,3-d]pyrimidines, whereas thiophenol furnish corresponding 4-thio-subtituted 4H-chromenes under the same reaction conditions. High atom-economy, good yields, eco-friendly, and mild reaction conditions are some of the important features of this protocol.