4-Thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 6-((aminophenylacetyl)amino)-3,3-dimethyl-7-oxo-, (2,2-dimethyl-1-oxopropoxy)methyl ester, (2S-(2alpha,5alpha,6beta(S*)))-, mono(2S-(2alpha,5alpha,6beta))-6-bromo-3,3-dimethyl-7-oxo-4-thia-