p-nitrobenzyl (1R,5S,6S)-2-[1-(4-{(1S)-2-methyl-[1-(p-nitrobenzyloxycarbonylamino)methyl]propylcarbamoyl}-1,3-thiazol-2-yl)azetidin-3-yl]thio-6-[(R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate

p-nitrobenzyl (1R,5S,6S)-2-[1-(4-N-cyclobutylcarbamoyl-1,3-thiazol-2-yl)azetidin-3-yl]thio-6-[(R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate

p-nitrobenzyl (1R,5S,6S)-2-[1-(4-N-cyclopentylcarbamoyl-1,3-thiazol-2-yl)azetidin-3-yl]thio-6-[(R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate

6-(1-hydroxy-ethyl)-4-methyl-3-{1-(4-nitro-benzyloxycarbonyl)-5-[1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanylmethyl]-pyrrolidin-3-ylsulfanyl}-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester