(3S,4S)-1-(allyloxycarbonylmethyl)-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-4-[(1R)-1-carboxyethyl]-2-azetidinone

(3S,4S)-3-[(R)-1-[[(R)-2-oxopyrrolidin-4-ylthio]carbonyl]ethyl]-3-[(R)-1-(trimethylsilyloxy)ethyl]-2-azetidinone

potassium (1R,5R,6S)-2-(3'-pyridyl)-6-<(1R)-1-hydroxyethyl>-1-methylcarbapen-2-em-3-carboxylate

potassium (1R,5R,6S)-2-<4'-(hydroxymethyl)phenyl>-6-<(1R)-1-hydroxyethyl>-1-methylcarbapen-2-em-3-carboxylate

pivaloyloxymethyl (1R,5S,6S)-6-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-[(3S,5S)-5-(N,N-dimethylcarbamoyl)-1-(isobutyryloxymethyloxycarbonyl)pyrrolidin-3-ylthio]-1-methylcarbapen-2-em-3-carboxylate