ethyl (2R,3R,4S)-3-(N-tert-butoxycarbonyl-2'-pyrrolidinyl)-3-hydroxy-2-methylpropanoate

ethyl (3R,4S,5S)-4-(N-tert-butoxycarbonyl-N-methylamino)-3-methoxy-5-methyl-heptanoate

(4S,5S)-4-Benzyloxycarbonylamino-5-methyl-3-oxo-heptanoic acid tert-butyl ester

(3R,4S,5S)-4--3-methoxy-5-methylheptanoic acid

(3R,4S,5S)-4-Benzyloxycarbonylamino-3-hydroxy-5-methyl-heptanoic acid tert-butyl ester