(4R)-3-{[(3S,5S)-5-[(dimethylamino)carbonyl]pyrrolidin-3-yl]sulfanyl}-1-{[(1S,6aS,6R)-5-{[(3S,5S)-5-[(dimethylamino)carbonyl]pyrrolidin-3-yl]sulfanyl}-1-[(1R)-1-hydroxyethyl]-6-methyl-2-oxo-1,2,6,6a-tetrahydroazeto[1,2-a]pyrrol-4-yl]carbonyl}-5-[(2R)-1-carboxy-2-hydroxypropyl]-4-methyl-4,5-dihydro-1H-pyrrole-2-carboxylic acid