(2R,4S)-2,4-Diamino-5-hydroxy-2-methyl-pentanoic acid

(2R,4S)-2,4-Bis-tert-butoxycarbonylamino-5-hydroxy-2-methyl-pentanoic acid methyl ester

(3-tert-butoxycarbonylamino-4-hydroxy-1-methyl-butyl)-carbamic acid tert-butyl ester

(2S,4R)-methyl 2-((benzyloxycarbonyl)(tert-butoxycarbonyl)-amino)-4-(tert-butoxycarbonylamino)-5-hydroxy-4-methylpentanoate

(2S,6S,E)-methyl 2-((benzyloxycarbonyl)(tert-butoxycarbonyl)amino)-6-(carbamoyloxy)-4-methylhept-4-enoate