Abstract: Provided in the present invention is a method for preparing an oseltamivir intermediate. The method comprises the following steps: subjecting compound 1 to a tert-butyl removal reaction under an acidic condition to obtain compound 2, wherein the acidic condition is trichloroacetic acid, chloroacetic acid, dichloroacetic acid, acetic acid, methanesulfonic acid, benzenesulfonic acid, formic acid or a mixture thereof. The post-treatment step comprises: after the reaction is completed, dissolving the compound 2 with an organic solvent to obtain a solution containing a compound of formula 2, then cooling the solution containing the compound of formula 2 obtained above, adjusting the pH value with an aqueous solution of an inorganic base, performing extraction and layering, and concentrating same to obtain the title compound.

Abstract: The present invention relates to a method for purifying pregabalin, comprising the following steps: 1) heating a reaction solution, maintaining the temperature and removing impurities; and 2) adding an acid into the reaction solution in step 1) to adjust the pH value, crystallizing and centrifugally drying the solution to obtain high-purity pregabalin. The pregabalin prepared and obtained by employing the purification method of the present invention has a product purity that reaches 99.8% or above, a product yield of 90% or above, an impurity X and impurity Y content that is ?0.05%, and has no detected impurity peak the relative retention time of which is 1.3.

Abstract: The present invention relates to the field of pharmaceutical chemical engineering, in particular to a method for purifying a levetiracetam intermediate, which comprises the following steps: (1) hydrolyzing and acidifying a crude product of a compound of formula III and performing crystallization to obtain a compound of formula IV; and (2) subjecting the compound of formula IV to an esterification reaction and separation to obtain a purified compound of formula III. The present method has a purification effect obviously superior to that of a physical purification mode, can reach a total yield of 90% or above, and has a great practical value.

Abstract: The present invention belongs to the field of pharmaceutical and chemical engineering, and relates to a high-purity losartan potassium and a preparation method therefor. The present invention also relates to a high-purity losartan or a pharmaceutically acceptable salt thereof and a preparation method therefor. The present invention uses organic phosphorus to reduce an azide compound to an amino compound so that the genotoxicity of losartan or a pharmaceutically acceptable salt thereof can be well controlled. The method of the present invention involves fewer steps, uses a small amount of reagent, does not require activated carbon decolorization, and produces a high-purity product, and therefore is suitable for industrial production and is very practical.

Abstract: A high-quality (RS)-?-ethyl-2-oxo-1-pyrrolidine acetic acid acquired by racemization recovery is provided. A method provided significantly increases the quality and appearance of the product (RS)-?-ethyl-2-oxo-1-pyrrolidine acetic acid recovered using racemization and does not affect the product yield.

Abstract: Disclosed in the present invention is a method for preparing high-purity losartan, which belongs to the fields of medicine and chemical engineering. The losartan is obtained by means of a multi-stage temperature reaction in the presence of a catalyst and sodium azide, wherein the temperature in the first stage of the multi-stage temperature reaction is higher than that in the second stage. According to the method, the generation of dimer impurities can be reduced, and the risk of impurities being introduced into a finished losartan potassium product is reduced.

Abstract: A high-quality (RS)-?-ethyl-2-oxo-1-pyrrolidine acetic acid acquired by racemization recovery is provided. A method provided significantly increases the quality and appearance of the product (RS)-?-ethyl-2-oxo-1-pyrrolidine acetic acid recovered using racemization and does not affect the product yield.