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Dipeptides obtained from l-proline and beta(3)-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 beta(3)-l-amino acid was also found to enhance appreciably both diastereo- and enantioselectivity of the catalyst.

4-Deoxy-l-hexoses were synthesized starting from our previously reported reagent 1 and (R)-benzyl glycidyl ether, which led in few steps to a substituted dihydropyran 6. The stereocontrolled hydroxylation of the latter afforded the corresponding 4-deoxy-l-hexoses 7a, 9, and 11. The same procedure, starting from (S)-benzyl glycidyl ether, enabled the preparation of their d-series enantiomers.