Tandem catalytic condensation and hydrogenation processes in ionic liquids

A domino reaction composed of a Knoevenagel condensation combined with a simultaneous catalytic hydrogenation is reported in an ionic liquid solvent under mild conditions (298–363 K and 300 kPa). No interference between the catalysts (Pd/C and amine acetate salt) of the two diverse steps was monitored. The product could be neatly extracted by diethyl ether and the solvent containing the catalysts could be recycled and reused five times without any loss in activity or selectivity. The same methodology in a common organic solvent such as DMA resulted in significant competing parallel hydrogenation of the aldehyde to alcohol.