Enzymatic resolution of alicyclic beta-lactams

Racemates of N-hydroxymethylated beta -lactams (4-6) were resolved through the lipase-catalyzed asymmetric acylation of the primary hydroxy group at t he 6S stereogenic centre. High enantioselectivity (E >200) was observed whe n the enzymatic reactions were performed in acetone with lipase PS as catal yst and vinyl butyrate as acyl donor. The hydrolysis of the enantiomeric az etidinones 4a-6a and 4b-6b resulted in the enantiomerically pure alicyclic beta -amino acids 4c-6c and 4d-6d. When the less reactive enantiomers 4b-6b were treated with NH4OH/MeOH, enantiomerically pure beta -lactams 4e-6e we re formed.