(3S)-2-[(2S)-2-[[(2S)-1-ethoxy-1-oxo-4-phenylbutan-2-yl]-nitrosoamino]propanoyl]-3,4-dihydro-1H-isoquinoline-3-carboxylic acid; ((S)-2-(N-((S)-1-ethoxy-1-oxo-4-phenylbutan-2-yl)-N-nitroso-L-alanyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid)