Chiral Room Temperature Ionic Liquids as Enantioselective Promoters for the Asymmetric Aldol Reaction

Abstract

Chiral ionic liquids derived from natural amino acids are shown to be green and efficient media for direct asymmetric aldol reactions at room temperature catalyzed by (S)-proline. The corresponding aldol products were obtained with moderate to good enantioselectivities. A transfer of chirality from the chiral reaction media has been observed as well as the participation of match/mismatch interactions of the chiral medium with both enantiomers of proline. Moreover, these catalytic systems were easily recovered by simple filtration, and studies on their reuse have demonstrated that recycling is possible for at least four runs with only a slight reduction in activity.