Synthesis of α,α′-bis(R-benzylidene)cycloalkanones catalyzed by potassium hydrogen sulfate under solvent-free conditions

Cyclopentanone or cyclohexanone were condensed with aromatic aldehydes to give corresponding α,α′-bis(R-benzylidene)cyclopentanones or α,α′-bis(R-benzylidene)cyclohexanones. The reaction was catalyzed by potassium hydrogen sulfate with a yield of 84–95% under solvent-free conditions.