p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-(5-p-nitrobenzyloxycarbonylaminopentanoylthio)-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

2-Acetyl-2-{(2S,3S)-1-allyloxyoxalyl-3-[(R)-1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-2-yl}-pent-4-enoic acid ethyl ester

(5S,6S)-6-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-3-(3-hydroxy-propylsulfanyl)-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester