N-[(2S,5β)-2β-Carboxy-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-6α-yl]phenylmalonamidic acid 1-phenyl ester

6-[(1,3-Dioxo-3-phenoxy-2-phenylpropyl)amino]-3,3-dimethyl-7-oxo-[s-(2,5,6)]4-thia-1-azobycyclo[3,2,0]pentane-2-carbonic acid