Ampicillin EP Impurity I 

Chemical Name: (2S,5R,6R)-6-[[(2R)-2-[[(2R)-2-amino-2-phenylacetyl]amino]-2-phenylacetyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid (as per EP); (2S,5R,6R)-6-{(R)-2-[(R)-2-Amino-2-phenylacetamido]-2-phenylacetamido}-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid (as per USP)

Smile: O=C([C@@H](C(C)(C)S[C@]1([H])[C@@H]2NC([C@H](NC([C@H](N)C3=CC=CC=C3)=O)C4=CC=CC=C4)=O)N1C2=O)O