Synonyms: 4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid, 3,3-dimethyl-7-oxo-6-[(phenylacetyl)amino]- [2S-(2a,5a,6b)]-, 4-oxide; Penicillin G, 4-oxide (8CI); Penicillin G, S-oxide (7CI);1-Oxo-6-(2-phenylacetylamino)-1-penicillanic acid; Benzylpenicillin S-oxide;Benzylpenicillin sulfoxide; Penicillin G sulfoxide; [2S-(2a,5a,6b)]-3,3-Dimethyl-7-oxo-6-(phenylacetamido)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid 4-oxide