Organocatalytic Direct Asymmetric Crossed-Aldol Reactions of Acetaldehyde in Aqueous Media

A new type of diarylprolinol-based catalyst, which contains a dioctylamino group in the presence of a newly developed ionic liquid supported (ILS) benzoic acid as cocatalyst, is shown to be an effective catalytic system for the asymmetric direct crossed-aldol reaction of acetaldehyde in aqueous media using brine. For the reactions studied, the catalyst loading could be reduced to 5 mol %; high yields (up to 97%) and high enantioselectivities (up to 92% ee) were also achieved for a wide variety of aromatic aldehyde.