(2S,2'S)-diethyl 2,2'-((2R,5S)-2,5-dimethyl-3,6-dioxopiperazine-1,4-diyl)bis(4-phenylbutanoate); (?1S,?4S,2S,5S)-2,5-Dimethyl-3,6-dioxo-?1,?4-bis(2-phenylethyl)-1,4-piperazinediacetic Acid 1,4-Diethyl Ester;[2S-[1(R*),2?,4(R*),5?]]-2,5-Dimethyl-3,6-dioxo-?,?'-bis(2-phenylethyl)-1,4-piperazinediacetic Acid Diethyl Ester
