The bakers' yeast reduction of ethyl 3-oxo-4-phenylthiobutanoate gave ethyl (R)-3-hydroxy-4-phenylthiobutanoate with >99%ee. The resultant enantiomerically pure alcohol was easily transformed into beta-lactam without loss of its enatiomeric purity via the oxamate derivative. Copyright (C) 1996 Elsevier Science Ltd