Dry and wet prolines for asymmetric organic solvent-free aldehyde–aldehyde and aldehyde–ketone aldol reactions

Dry and wet prolines were found to catalyze the direct aldol reactions of aldehyde-aldehyde and aldehyde-ketone, respectively, to afford aldols with excellent diastereo- and enantioselectivities, and an organic solvent-free reaction was realized in some cases.