The present invention provides a method of producing easily and in a high yield a threo-2-hydroxy-3-nitrobutanoic acid compound or a mixture of a threo- and an erythro-2-hydroxy-3-nitrobutanoic acid compounds, this mixture having an erythro compound:threo compound ratio of about 1:1, which method includes reacting, in a solvent, a 2-hydroxy-3-nitrobutanoic acid compound having the formula (I)
wherein R is optionally substituted alkyl or optionally substituted aryl, with not less than 1 equivalent of a base to isomerize (i) the erythro compound into the threo compound, or (ii) the threo compound into the erythro compound, and a method for separating the erythro and the threo compounds easily and in a high yield. The separation method includes reacting the mixture of threo- and erythro-compounds with not more than 1 equivalent of potassium carbonate per threo compound in a solvent. According to the method of the present invention, useful pharmaceuticals can be produced easily in a high yield.
本发明提供了一种容易和高产率地生产苏
铁-2-羟基-
3-硝基
丁酸化合物或苏
铁-2-羟基-
3-硝基
丁酸化合物和赤式-2-羟基-
3-硝基
丁酸化合物的混合物的方法,这种混合物的赤式化合物∶苏
铁化合物的比例约为1∶1,该方法包括在溶剂中使具有式(I)的2-羟基-
3-硝基
丁酸化合物与不少于1当量的碱反应,使(i)赤式化合物异构化为苏
铁化合物,或(ii)苏
铁化合物异构化为赤式化合物。
其中 R 是任选取代的烷基或任选取代的芳基,与不少于 1 个当量的碱反应,使(i)赤式化合物异构化成苏
氨酸化合物,或(ii)苏
氨酸化合物异构化成赤式化合物,以及一种易于高产率分离赤式化合物和苏
氨酸化合物的方法。分离方法包括将苏
氨酸化合物和
赤藓红化合物混合物在溶剂中与每种苏
氨酸化合物不超过 1 个当量的
碳酸钾反应。根据本发明的方法,可以很容易地以高产率生产出有用的药物。