(2S,4R)-4-(tert-Butoxycarbonylamino-methyl)-5-oxo-pyrrolidine-2-carboxylic acid tert-butyl ester

(2S,4R)-2-Amino-4-(tert-butoxycarbonylamino-methyl)-pentanedioic acid 1-tert-butyl ester 5-methyl ester

(S)-2-tert-Butoxycarbonylamino-4-hydroxyphosphinoylmethyl-pentanedioic acid di-tert-butyl ester

(S)-2-tert-Butoxycarbonylamino-4-(hydroxy-phenyl-phosphinoylmethyl)-pentanedioic acid di-tert-butyl ester

(2S,4R)-2-Amino-4-methyl-hept-6-enoic acid tert-butyl ester