[1(S),3[4R,5S,6S(R)]]-1-[[[[2-(4-nitrophenyl)methoxy]carbonyl]amino-3-methyl-1-oxobutyl]amino]-2,5-anhydro-3-S-[6-(1-hydroxyethyl)-4-methyl-2-[[(4-nitrophenyl)methoxy]carbonyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-en-3-yl]-1,4-dideoxy-3-thio-D-threo-pentitol

(4R,5S,6S)-6-((R)-1-Hydroxy-ethyl)-3-[(3S,5S)-5-(5-hydroxymethyl-isoxazol-3-yl)-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(4R,5S,6S)-6-((R)-1-Hydroxy-ethyl)-4-methyl-3-[(3S,5S)-1-(4-nitro-benzyloxycarbonyl)-5-(2-sulfamoyl-ethylcarbamoyl)-pyrrolidin-3-ylsulfanyl]-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(4R,5S,6S)-6-((R)-1-Hydroxy-ethyl)-4-methyl-3-[(3S,5S)-1-(4-nitro-benzyloxycarbonyl)-5-(2-ureido-ethylsulfanylmethyl)-pyrrolidin-3-ylsulfanyl]-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(4R,5S,6S)-6-((R)-1-Hydroxy-ethyl)-4-methyl-3-{(3S,5R)-1-(4-nitro-benzyloxycarbonyl)-5-[3-(4-nitro-benzyloxycarbonylamino)-propyl]-pyrrolidin-3-ylsulfanyl}-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester