p-nitrobenzyl (5R,6S)-6-<(1R)-hydroxyethyl>-2-ethyl-2-penem-3-carboxylate

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

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

(S)-2-{(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-1-[chloro-(4-nitro-benzyloxycarbonyl)-methyl]-4-oxo-azetidin-2-ylsulfanylcarbonyl}-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

2-Oxo-propionic acid (2R,3R)-1-[benzyloxycarbonyl-(triphenyl-λ5-phosphanylidene)-methyl]-3-((R)-1-hydroxy-ethyl)-4-oxo-azetidin-2-yl ester