A convenient synthesis of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives catalyzed by KF-alumina

A series of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives were prepared by the reaction of arylmethylidenemalononitriles or 2-cyano-3-aryl-1-acrylate with 5,5-dimethyl- 1, 3-cyclohexanedione (dimedone) in DMF at room temperature catalyzed by KF-alumina. The structure of the product was confirmed by X-ray analysis.