Direct catalytic asymmetric cross-aldol reactions in ionic liquid media

Enantioselective proline-catalyzed direct asymmetric cross-aldol reactions with aldehydes were performed in ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate media, which simplified product isolation and catalyst recycling, affording 3-hydroxy aldehydes in high yield with excellent stereoselectivity. In addition, the enhanced reactivity of the asymmetric cross-aldol reactions in ionic liquid allowed the catalyst loading to be lowered significantly.