(S)-4-Benzyloxycarbonylamino-4-tert-butylcarbamoyl-butyric acid tert-butyl ester

(S)-4-tert-Butylcarbamoyl-4-(4-methylamino-benzoylamino)-butyric acid tert-butyl ester

tert-butyl N1-(tert-butyl)-L-α-glutaminate

p-[N-methyl-N-(trifluoroacetyl)amino]benzoyl chloride

(S)-4-tert-Butylcarbamoyl-4-{4-[methyl-(2,2,2-trifluoro-acetyl)-amino]-benzoylamino}-butyric acid tert-butyl ester