Piperazine catalyzed convenient synthesis of 4h-pyran derivatives from a,a0-bis (substituted-benzylidene) cycloalkanones and malononitrile under reflux conditions

A facile, simple and convenient method for the synthesis of 4H-pyran derivatives has been achieved through the condensation reactions of a,a0-bis(substituted-benzylidene) cycloalkanones and malononitrile in the presence of piperazine as an odorless and easy to work catalyst under reflux conditions. With the optimized reaction conditions, the desired products were obtained with 62–82% yields.