[BMIm]BF4-LiCl as an effective catalytic system for the synthesis of dicoumarols

A homogeneous ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate doped with LiCl ([BMIm]BF4-LiCl) was found as catalyst solvents for the synthesis of dicoumarols by the condensation of 4-hydroxycoumarin and aldehyde at 80 ?C. In this field, several types of aromatic aldehyde, containing electron-withdrawing groups as well as electron-donating groups, were rapidly changed to the corresponding derivatives in good to excellent yields. Application of this new homogeneous catalyst system offered the advantages of short reaction times, solvent-free conditions, high yields, and easy work-up procedure compared to the conventional methods of the syntheses. The ionic liquid can be recovered for the subsequent reactions and reused without any loss of efficiency.