((2S,3R)-2-Benzenesulfonyl-4-oxo-azetidin-3-yl)-carbamic acid benzyl ester

lithium dimethylcuprate

O-acetyl N-(benzyloxycarbonyl)-L-threoninehydroxamate

(3R,4S)-3-(benzyloxycarbonylamino)-4-(1'-oxo-ethyl)-azetidin-2-one