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 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: 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 synthesis method for a candesartan cilexetil intermediate represented by formula (II) is provided. The method includes (1) dissolving a compound represented by formula (IV) to an aprotic solvent to obtain a first mixed solution, and dissolving a phase transfer catalyst and an azidation reagent to water to obtain a second mixed solution; (2) dropping the first mixed solution to the second mixed solution for azidation reaction, and after the reaction is ended, standing and layering same to obtain an organic phase containing a compound represented by formula (V); (3) dropping the obtained organic phase containing the compound represented by formula (V) to tertiary butyl alcohol for rearrangement reaction, and after the reaction is ended, concentrating same to obtain a solid or oily material, then adding a crystallizing solvent to the obtained solid or oily material for recrystallization, and separating same to obtain a crystal.

Abstract: Provided is a method for resolution of formula 4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxy-methyl benzonitrile as an enantiomer thereof, comprising the following steps: a salt of (S)-4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxymethyl benzonitrile with a resolving agent D-(+)di-p-toluoyl tartaric acid was crystallized in a resolving solvent; the method is characterized in that the resolving solvent is an ether solvent. Also provided is a new crystal form of the resolved intermediate.

Abstract: Provided is a method for resolution of formula 4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxy-methyl benzonitrile as an enantiomer thereof, comprising the following steps: a salt of (S)-4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxymethyl benzonitrile with a resolving agent D-(+)di-p-toluoyl tartaric acid was crystallized in a resolving solvent; the method is characterized in that the resolving solvent is an ether solvent. Also provided is a new crystal form of the resolved intermediate.

Abstract: Provided is a method for resolution of formula 4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxy-methyl benzonitrile as an enantiomer thereof, comprising the following steps: a salt of (S)-4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxymethyl benzonitrile with a resolving agent D-(+)di-p-toluoyl tartaric acid was crystallized in a resolving solvent; the method is characterized in that the resolving solvent is an ether solvent. Also provided is a new crystal form of the resolved intermediate.

Abstract: The present invention relates to a method for preparing a citalopram diol represented by formula IV, comprising the following steps: in the existence of an auxiliary reagent of metal salt, allowing 5-cyanophthalide to sequentially subjected to Grignard addition reactions with p-fluorophenyl magnesium halide and N, N-dimethylaminopropyl magnesium halide in an organic solvent; and after the reactions are completed, performing hydrolysis and separation to obtain citalopram diol represented by formula IV. In the present invention, by adding an auxiliary reagent of metal salt, the activity and the selectivity of the Grignard reactions are remarkably improved, and the reaction yield is obviously enhanced.

Abstract: The present invention relates to a method for preparing a citalopram diol represented by formula IV, comprising the following steps: in the existence of an auxiliary reagent of metal salt, allowing 5-cyanophthalide to sequentially subjected to Grignard addition reactions with p-fluorophenyl magnesium halide and N, N-dimethylaminopropyl magnesium halide in an organic solvent; and after the reactions are completed, performing hydrolysis and separation to obtain citalopram diol represented by formula IV. In the present invention, by adding an auxiliary reagent of metal salt, the activity and the selectivity of the Grignard reactions are remarkably improved, and the reaction yield is obviously enhanced.

Abstract: Provided is a method for resolution of formula 4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxy-methyl benzonitrile as an enantiomer thereof, comprising the following steps: a salt of (S)-4-[4-dimethylamino-1-(4-fluorophenyl)-1-hydroxylbutyl]-3-hydroxymethyl benzonitrile with a resolving agent D-(+)di-p-toluoyl tartaric acid was crystallized in a resolving solvent; the method is characterized in that the resolving solvent is an ether solvent. Also provided is a new crystal form of the resolved intermediate.