(S)-2-((S)-4-Benzyloxycarbonylamino-2,2-difluoro-5-hydroxy-pentanoylamino)-pentanedioic acid 1-tert-butyl ester 5-(2-trimethylsilanyl-ethyl) ester

(S)-2-(2-tert-Butoxycarbonylamino-benzoylamino)-4-{(S)-1-tert-butoxycarbonyl-3-[(S)-1-tert-butoxycarbonyl-2-(4-hydroxy-3-nitro-phenyl)-ethylcarbamoyl]-propylcarbamoyl}-4,4-difluoro-butyric acid tert-butyl ester