Synthesis of 4-aryl-substituted β-lactam enantiomers by enzyme-catalyzed kinetic resolution

Enantiopure 4-phenyl- and 4-(p-tolyl)-2-azetidinones 3a, 3b, 4a and 4b (with e.e.s of greater than or equal to 96%) were prepared through lipase-catalyzed asymmetric butyrylation of the primary OH group of N-hydroxymethylated beta -lactams (+/-)-5 and (+/-)-6 at the (R)-stereogenic centre or by lipase-catalyzed asymmetric debutyrylation of O-butyryloxymethyl-2-azetidinones (+/-)-7 and (+/-)-8 at the (R)-stereogenic centre. The ring-opening of lactams 5a. 5b, 6b and 8a with HCl/EtOH afforded the corresponding P-amino ester enantiomers 9a, 9b, 10a and 10b with e.e.s or greater than or equal to 92%, (C) 2001 Elsevier Science Ltd. All rights reserved.