Wednesday, November 4, 2009
Ballroom A+B (Camino Real Hotel)
Hydroxy acetone, dihydroxy acetone-based aldol reactions are very important because they provide direct access to both natural carbohydrates and unnatural molecules of significance in medicine and materials and food sciences. As a result, great advances have been made in asymmetric direct aldol reactions. In biological system, direct asymmetric reaction is catalyzed by aldolase enzymes with excellent sterocontrol. Based on this idea, seven primary amine organocatalysts were designed and were readily prepared from simple chiral cyclohexanediamine and primary amino acids via three steps and then were used to catalyze the direct asymmetric syn-aldol reactions of various aromatic aldehydes and hydroxy acetone/ dihydroxy acetone with moderate to high yields (up to 98%), high enantioselectivites (up to 96% ee) and good diastereoslectivities (up to 1:5, anti:syn).