L. ethyl-(2S)-2-[(3S,5aS,8aS,9aiS')-9a-hydroxy-3-methyl-1,4-dioxodekahydro-1H-cyklopenta[e]pyrrolo[1,2-a]pyrazin-2-yl]-4-fenylbutanoat (ramiprilhydroxydiketopiperazin),