Highly Efficient Organocatalyzed Direct Asymmetric Aldol Reactions of Hydroxyacetone and Aldehydes

Novel organocatalysts derived from L ‐threonine and L ‐leucine have been synthesized for catalyzing direct aldol reactions of hydroxycetone and unactivated aliphatic aldehydes with as low as 2 mol% loading of the catalyst, good to excellent yields and excellent enantioselectivities have been achieved for aliphatic aldehydes, whereas aromatic aldehydes yield only moderate enantioselectivities.