Synonyms: 4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid, 3,3-dimethyl-7-oxo-6-(2-phenylacetamido)-, p-methoxybenzyl ester,4-oxide, stereoisomer (8CI);4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid, 3,3-dimethyl-7-oxo-6-[(phenylacetyl)amino]- [2S-(2a,5a,6b)]-,(4-methoxyphenyl)methyl ester, 4-oxide, (4b)-;Penicillin G Sulfoxide P-methoxybenzyl Ester;