phenylacetyl chloride
trimellitic anhydride acid chloride
3-hydroxymethyl-8-oxo-7-phenylacetylamino-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid
(6R,7R)-7-amino-3-hydroxymethyl-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid
(6R,7R)-benzhydryl 3-(hydroxymethyl)-8-oxo-7-(2-phenylacetamido)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate