(S)-2-Benzyloxycarbonylamino-3-hydroxy-propionic acid (S)-2-benzyloxycarbonylamino-2-((S)-2-benzyloxycarbonylamino-2-carboxy-ethoxycarbonyl)-ethyl ester

(R)-2-Benzyloxycarbonylamino-3-hydroxy-propionic acid (R)-2-benzyloxycarbonylamino-2-[(R)-2-benzyloxycarbonylamino-2-(9,10-dioxo-9,10-dihydro-anthracen-2-ylmethoxycarbonyl)-ethoxycarbonyl]-ethyl ester