Proline−β3-Amino-Ester Dipeptides as Efficient Catalysts for Enantioselective Direct Aldol Reaction in Aqueous Medium

Dipeptides obtained from l-proline and β3-l-amino acids are reported to catalyze enantioselective direct aldol reaction in aqueous medium, leading to significant anti:syn diastereomeric ratios and enantiomeric excesses. The simple introduction of a polar substituent at the C-2 position of the β3-l-amino acid was also found to enhance appreciably both diastereo- and enantioselectivity of the catalyst.