tert-butyl (2S)-2-{bis[(tert-butoxy)carbonyl]amino}-5-oxopentanoate

tert-butyl (S)-2-<(tert-butyloxycarbonyl)amino>-5-hydroxypentanoate

(S)-α-tert-butoxycarbonylamino-γ-(2,6-diphenylpyrimidin-4-yl)butyric acid α-tert-butyl ester

(S)-α-tert-butoxycarbonylamino-γ-(2-methyl-6-phenylpyrimidin-4-yl)butyric acid α-tert-butyl ester

(S)-2-tert-butoxyxarbonylamino-5-oxohept-6-ynoic acid tert-butyl ester