Advanced procedure for the enzymatic ring opening of unsaturated alicyclic β-lactams

Abstract

Enantiopure β-amino acids 1a– 4a and β-lactams 1b– 4b were prepared simultaneously through the lipolase-catalysed enantioselective ring opening of unsaturated racemic β-lactams (±)- 1-(±)- 4. High enantioselectivities ( E>200) were observed when the reactions were performed with 1 equiv of water in iPr 2O at 70 °C. The resolved (1 R,2 S)-amino acids (yield⩾45%) and (1 S,5 R)-, (1 S,6 R)- and (1 S,8 R)-lactams (yield⩾47%) could be easily separated. The ring opening of lactam enantiomers 1b– 4b with 18% HCl afforded the corresponding β-amino acid hydrochlorides 1c·HCl– 4c·HCl (ee >95%).