Diethyl oxalacetate is widely used in organic synthesis as a key intermediate for the production of various pharmaceuticals, agrochemicals, and fine chemicals. It serves as a building block in the synthesis of heterocyclic compounds, such as pyrimidines and quinolines, which are essential in drug development. Additionally, it is employed in the preparation of dyes, pigments, and flavoring agents due to its reactive carbonyl and ester groups. In the field of biochemistry, it is utilized as a substrate in enzymatic studies and metabolic pathway research. Its versatility in forming complex structures makes it a valuable reagent in both industrial and academic research settings.