(2R,3S)-2-[(S)-2-((R)-2-{2-[((R)-4-tert-Butoxycarbonylamino-4-methoxycarbonyl-butyryl)-methyl-amino]-acryloylamino}-propionylamino)-4-methyl-pentanoylamino]-3-[(S)-1-(2,2,2-trichloro-ethoxycarbonyl)-ethylcarbamoyl]-butyric acid methyl ester

methyl(2S,3R)-3-tert-butoxycarbonylamino-4-methoxycarbonyl-3-methylbutanoic acid

(2R,3S)-2-Amino-3-methyl-N-[(S)-1-(2,2,2-trichloro-ethoxycarbonyl)-ethyl]-succinamic acid methyl ester

(2R,3S)-2-tert-Butoxycarbonylamino-3-methyl-N-[(S)-1-(2,2,2-trichloro-ethoxycarbonyl)-ethyl]-succinamic acid methyl ester