(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

<(R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbothioic S-acid

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

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