(R)-2-[(2R,3S)-3-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-2-(2-methoxycarbonyl-ethylsulfanyl)-4-oxo-azetidin-1-yl]-3-methyl-butyric acid benzyl ester

(R)-2-[(2R,3S)-3-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-2-(2-methoxycarbonyl-ethylsulfanyl)-4-oxo-azetidin-1-yl]-3-methyl-but-3-enoic acid benzyl ester

(R)-2-[(2R,3S)-3-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-2-(2-methoxycarbonyl-ethanesulfinyl)-4-oxo-azetidin-1-yl]-3-methyl-but-3-enoic acid benzyl ester