A new method for synthesis of tetrahydrobenzo[b]pyrans and dihydropyrano[c]chromenes using p-dodecylbenzenesulfonic acid as catalyst in water

p-Dodecylbenzenesulfonic acid (DBSA) was used as a catalyst for a simple and efficient one-pot synthesis of aryl substititued tetrahydrobenzo[b]pyrans and dihydropyrano[c]chromens via initial Knoevenagel, subsequent Micheal and final heterocyclization reactions of aryl aldehyde, malononitrile and 4-hydroxycoumarin/dimedone in moderate to excellent yields. The present method was operationally simple and use of water as the reaction medium made the process environmentally benign.