Highly pure (2R,3S)-3-tert-butoxycarbonylamino-1-chloro-2-hydroxy-4-phenylbutane or (2S,3R)-3-tert-butoxycarbonylamino-1-chloro-2-hydroxy-4-phenylbutane may be conveniently produced in high yield by: (a) reacting compound (1) with lithiumchloromethane to give compound (2) and at least a byproduct; (b) dissolving compound (2) and the byproduct in a polar solvent and adding water to the solution to precipitate compound (2) as crystals; (c) reducing the crystals of compound (2) to give compound (3) and at least its diastereomer as an impurity; (d) adding sulfuric acid thereto to give compound (4) and at least its diastereomer as an impurity; and (e) precipitating compound (4) as crystals from a solution containing acetic acid ester or acetic acid ester.
(2R,3S)-3-tert-butoxycarbonylamino-1-chloro-2-hydroxy-4-phenylbutane或(2S,3R)-3-tert-butoxycarbonylamino-1-chloro-2-hydroxy-4-phenylbutane可以通过以下步骤方便地高产率地制备:(a)将化合物(1)与
氯甲基锂反应,得到化合物(2)和至少一种副产物;(b)将化合物(2)和副产物溶解在极性溶剂中,并向溶液中加入
水,使化合物(2)以晶体形式沉淀出来;(c)将化合物(2)的晶体还原,得到化合物(3)和至少其对映异构体作为杂质;(d)加入
硫酸至其中,得到化合物(4)和至少其对映异构体作为杂质;(e)从含有
乙酸酯或
乙酸酯的溶液中沉淀化合物(4)为晶体。