4-Carboxy-5,5-diMethyl-α-[(2-phenoxyacetyl)aMino]-2-thiazolidineacetic Acid;NSC 74505;Nsc163496;Penicilloic V Acid;Penicilloic acid V;4-Carboxy-5,5-dimethyl-alpha-[(2-phenoxyacetyl)amino]-2-thiazolidineacetic acid;Phenoxymethylpenicillin Impurity 5(Phenoxymethylpenicillin EP Impurity E);Phenoxymethylpenicillin EP Impurity E