(5R,6S)-6-<(1R)-hydroxyethyl>-2-<(2R)-pyrrolidin-2-yl>-2-penem-3-carboxylic acid

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-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

(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

(5R,6S)-6-<(1R)-hydroxyethyl>-2-<(2S)-pyrrolidin-2-yl>-2-penem-3-carboxylic acid