Efficient enzymatic routes for the synthesis of new eight-membered cyclic β-amino acid and β-lactam enantiomers

Abstract

Efficient enzymatic resolutions are reported for the preparation of new eight-membered ring-fused enantiomeric β-amino acids [(1R, 2S)-9 and (1S, 2R)-9] and β-lactams [(1S, 8R)-3, (1R, 8S)-3 (1S, 8R)-4 and (1R, 8S)-7], through asymmetric acylation of (±)-4 (E > 100) or enantioselective hydrolysis (E > 200) of the corresponding inactivated (±)-3 or activated (±)-4 β-lactams, catalyzed by PSIM or CAL-B in an organic solvent. CAL-B-catalyzed ring cleavage of (±)-6 (E > 200) resulted in the unreacted (1S, 8R)-6, potential intermediate for the synthesis of enantiomeric anatoxin-a. The best strategies, in view of E, reaction rate and product yields, which underline the importance of substrate engineering, are highlighted.