(3R,2'S) N-(Benzyl)-3-(3'-acetoxy-2'-tert-butyldimethylsilylpropyl)-isoxazolidin-5-one

1-benzyl 5-methyl (R)-3-tert-butoxycarbonylaminoglutarate

(R)-3-Amino-pentanedioic acid benzyl ester methyl ester

(R)-N-benzyl-4-cyanomethyl-2-azetidinone

(R)-3-Benzylamino-4-chlorocarbonyl-butyric acid methyl ester; hydrochloride