(3R,4R)-1-(4-fluorophenyl)-3-[(4-fluorobenzoyl)methylthio]-4-[4-(t-butoxycarbonylmethoxy)phenyl]azetidin-2-one

tert-butyl (4-{[(4-fluorophenyl)imino]methyl}phenoxy)acetate

tert-butyl (2-(4-((2R,3R)-1-(4-fluorophenyl)-3-((2-(4-fluorophenyl)-2-oxoethyl)thio)-4-oxoazetidin-2-yl)phenoxy)acetyl)-D-valinate

(4-{(2R,3R)-1-(4-fluoro-phenyl)-3-[(RS)-2-(4-fluoro-phenyl)-2-oxoethylsulfanyl]-4-oxo-azetidin-2-yl}-phenoxy)-acetic acid

(3R,4R)-1-(4-fluorophenyl)-3-[(3-nitropyridin-2-yl)dithio]-4-[4-(t-butoxycarbonylmethoxy)phenyl]azetidin-2-one