Highly efficient synthesis of tetrahydrobenzo[b]pyrans under visible light promoted by cesium carbonate

Multi-component coupling reaction (MCR) is a powerful synthetic tool for the synthesis of biologically active compounds. Development of such multi-component coupling reaction strategies in visible light has been of considerable interest, as they provide simple and rapid access to a large number of organic molecules through a sustainable path. An efficient and green protocol for the synthesis of tetrahydrobenzo[b]pyrans derivatives by one-pot, three component coupling reaction of aromatic aldehyde, malononitrile, and dimedone has been developed using readily available cesium carbonate as the catalyst under visible light. This efficient procedure has the advantages of giving the target compounds in high yields, short reaction times, simple work-up procedure, use of chief and easily available catalyst, and environmentally benign conditions.