{4-[(2R,3R)-3-{[2-(4-ethoxyphenyl)-2-oxoethyl]thio}-1-(4-fluorophenyl)-4-oxoazetidin-2-yl]phenoxy}acetic acid

tert-butyl {4-[(2R,3R)-3-{[2-(4-tert-butylphenyl)-2-oxoethyl]thio}-1-(4-fluorophenyl)-4-oxoazetidin-2-yl]phenoxy}acetate

[4-((2R,3R)-1-(4-fluorophenyl)-4-oxo-3-{[2-oxo-2-(4-pentylphenyl)ethyl]thio}azetidin-2-yl)phenoxy]acetic acid

N-{[4-((2R,3R)-1-(4-fluorophenyl)-3-{[2-(4-fluorophenyl)-2-hydroxyethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl}-D-alanine

N-{[4-((2R,3R)-1-(4-fluorophenyl)-3-{[2-(4-fluorophenyl)-2-oxoethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl}-L-alanine