Diarylprolinol-Mediated Asymmetric Direct Cross-Aldol Reaction of α,β-Unsaturated Aldehyde as an Electrophilic Aldehyde.

The diarylprolinol-mediated asymmetric direct cross-aldol reaction of α,β-unsaturated aldehyde as an electrophilic aldehyde was developed. The reaction becomes accelerated by an acid when a carbonyl group is introduced at the γ-position of the α,β-unsaturated aldehyde. Synthetically useful γ,δ-unsaturated β-hydroxy aldehydes were obtained with high anti-selectivity and excellent enantioselectivity.