p-nitrobenzyl (5R,6S)-6-<(1R)-(tert-butyldimethylsiloxy)ethyl>-2-<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>-2-penem-3-carboxylate

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

2-{(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-2-yl}-3,4,5,6,7,8-hexahydro-2H-acridin-1-one

p-nitrobenzyl (5R,6S)-6-<(1R)-hydroxyethyl>-2-<((RS)-N-p-nitrobenzyloxycarbonylpiperidin-2-yl)methyl>-2-penem-3-carboxylate

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