Candida antarctica lipase B-catalyzed ring opening of 4-arylalkyl-substituted β-lactams

The Lipolase-catalyzed ring opening of racemic 4-benzyl- 3 and 4-phenylethyl-2-azetidinone 4 was performed with 0.5 equiv of H2O in diisopropyl ether at 45 °C. The resulting (S)-β-amino acid 5 or 6 (ee ⩾ 87%) and (R)-β-lactam 7 or 8 (ee >99%) enantiomers could easily be separated. The ring opening of enantiomeric β-lactams with 18% aqueous HCl afforded the corresponding enantiopure β-amino acid hydrochlorides 9 and 10 (ee >99%).