(4S)-3-{[(3S,6aR,6R)-6-({[3-(2,6-dichlorophenyl)-5-methylisoxazol-4-yl]carbonyl}amino)-2,2-dimethyl-5-oxo-3,5,6,6a-tetrahydro-2H-azeto[2,1-b][1,3]thiazol-3-yl]methyl}-2-[carboxy({[3-(2,6-dichlorophenyl)-5-methylisoxazol-4-yl]carbonyl}amino)methyl]-5,5-dimethyl-1,3-thiazolidine-4-carboxylic acid