Facial and Efficient Access to Dihydropyrano[3,2-c]Chromenes via Three-Component Reaction Using N,N-Dimethylbenzylamine As a New Organocatalyst

The N,N-dimethylbenzylamine (DMBA), as an efficient and commercially available organocatalyst was employed for the one-pot synthesis of dihydropyrano[3,2-c]chromene derivatives in ethanol medium. In this work, the one-pot Knoevenagel-Michael-Thorpe-Ziegler type cascade heterocyclization has been developed for the synthesis of dihydropyrano[3,2-c]chromene-containing heterocycles from the one-pot multicomponent condensation reaction of 4-hydroxycoumarin, malononitrile/ethyl cyanoacetate, and various aldehydes at 60°C. The salient features of this basecatalyzed reaction are mild reaction conditions, reusability of the reaction medium, shorter reaction times, and easy separation of the reaction mixture.