(4S,1'Z)-1-tert-Butyldimethylsilyl-4-(2-benzyloxycarbonylethenyl)azetidin-2-one

(Z)-3-[(S)-1-(tert-Butyl-dimethyl-silanyl)-4-oxo-azetidin-2-yl]-acrylic acid benzyl ester

(1'S,2'S,4S)-1-tert-Butyldimethylsilyl-4-(1,2-dihydroxy-2-benzyloxycarbonylethyl)azetidin-2-one

(1'S,2'S,4S)-1-tert-Butyldimethylsilyl-4-<1,2-(dimethylmethylenedioxy)-2-benzyloxycarbonylethyl>azetidin-2-one