A facile and efficient synthesis of tetrahydrobenzo[b]pyrans using lactose as a green catalyst

Lactose has been used as a mild, efficient, green, and inexpensive catalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives via a one-pot, three-component condensation between aryl aldehydes, malononitrile, and dimedone in H2O:EtOH at 60 A degrees C. This method offers a considerable number of advantages including short reaction time, high to quantitative yields, low cost, easy accesses, and simple work-up.