(4R,5S,6S)-3-((2R,3R)-2-{[1-(2,2-dimethyl-propionyloxy)ethoxycarbonylamino]-methyl}-tetrahydrofuran-3-yl-sulfanyl)-6-(1R-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitrophenylmethyl ester

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

(4R,5S,6S)-3-((2R,3R)-2-Azidomethyl-tetrahydro-furan-3-ylsulfanyl)-6-((R)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester