The effects of twenty proteinogenic amino acids have been investigated in the aldol reaction of aldehyde and ketone in DMSO and aqueous DMSO (in the presence of three equivalents of water). Not only proline but also other amino acids promote the al-dol reaction enantioselectively. The effect of water varies with amino acid, and water does not affect the enantioselectivity in most cases, the exceptions being Pro, Ser and His. In the case of Pro, large positive effects on diastereo- and enantioselectivities were ob-served in the reaction of a-substituted methyl ketone, while no ef-fect was observed in that of methyl ketone.
- asymmetric synthesis, aldol reactions, organocatalyst, amino acids, water