Ethyl 4-[2-[(4-Ethoxyphenyl)amino]-2-oxoethoxy]-1,6-dihydro-1-(4-methylphenyl)-6-oxo-3-pyridazinecarboxylic Acid Ester is derived from Diethyl 3-Oxopentanedioate (D444595), which is a reactant used in the synthesis of 2-(3-benzoylthioureido)-thiophene-3-carbonitrile derivatives with antimicrobial activity.