<chemical> 6-((aminophenylacetyl)amino)-3,3-dimethyl-7-oxo-4-thia-1- azabicyclo(3.2.0)heptane-2-carboxylic acid (2,2-dimethyl- 1-oxopropoxy)methyl ester. Pivalate ester analog of ampicillin. ... Pharmacological action: penicillins. ... Chemical name: 4-Thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 6-((aminophenylacetyl)amino)-3,3-dimethy...