Phenylmethyl (2S)-2-[[(2,5-Dioxo-1-pyrrolidinyl)oxy]carbonyl]-5-oxo-1-pyrrolidinecarboxylic Acid Ester is an intermediate used in the synthesis of 5-Oxo-L-prolyl-L-proline (O859055), which is a dipeptide taste-active compound found in hydrolyzed wheat proteins.