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

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

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

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

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