Ce(SO4)2•4H2O as a Recyclable Catalyst for an Efficient, Simple, and Clean Synthesis of 4H-Benzo[b]pyrans

An efficient method for the synthesis of 4H-benzo[b]pyrans has been developed by the use of Ce(SO4)(2)center dot 4H(2)O (2.5 mol%) as a catalyst. Heating the mixture of an appropriate aldehyde, malononitrile, and dimedone in the presence of the catalyst at 45 degrees C in a mixture of water: ethanol (1: 1) as solvent for about 9-55 min resulted excellent yields of the corresponding products. Short experimental time of the reaction, excellent yields, simple workup, not using cumbersome apparatus for purification of the products, and inexpensiveness and commercially availability of the catalyst are the advantages of this method.