Doripenem Dimer Impurity A1

(4R,5S,6S)-3-(((3S,5S)-1-((2S,3R)-2-((2S,3R)-5-carboxy-3-hydroxy-4-(((3S,5S)-5-((sulfamoylamino)methyl)pyrrolidin-3-yl)thio)-2,3-dihydro-1H-pyrrol-2-yl)-3-hydroxybutanoyl)-5-((sulfamoylamino)methyl)pyrrolidin-3-yl)thio)-6-((R)-1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid