erythro-(2S,3RS)-ethyl 2-amino-3-hydroxy-pentanoate

ethyl 2-(tert-butoxycarbonylamino)-3-oxo-pentanoate

(2SR)-ethyl 2-(dibenzylamino)-3-oxo-pentanoate

(+/-)-erythro-2-benzoylamino-3-hydroxy-valeric acid methyl ester

反式-2-戊烯酸