Three-Component Synthesis of Mono and Bis 4,5-Dihydropyrano[3,2-C]Chromenes and 4,5- Dihydropyran[4,3-B]Pyrans Catalyzed by Sodium Benzenesulfinates as a Green Organocatalyst

Abstract Mono and bis 4,5-dihydropyrano[3,2-c]chromene and 4,5- dihydropyrano[4,3-b]pyran derivatives were synthesized by three-component reaction of aromatic aldehydes, malononitrile and 4-hydroxycoumarin or 4- hydroxy-6-methylpyrone, in the presence of catalytic amounts of sodium benzenesulfinates, as a organocatalyst, in H2O/EtOH, at reflux. High conversions, short reaction times, cleaner reaction profiles and usage of a stable and also inexpensive catalyst are some of the advantages of this method.