阅读说明：本技术 一种立他司特杂质及其制备方法和去除方法 (Impurity of sitagliptin, preparation method and removal method thereof ) 是由 周福委 赵成良 张耀春 黄帅 左小勇 周旭东 于 2020-12-16 设计创作，主要内容包括：本发明公开了一种立他司特杂质及其制备方法和去除方法。所述制备方法包括以立他司特为起始原料,经过缩合和水解反应得到立他司特杂质I。所述去除方法,使得立他司特成品中的杂质I残留≤0.10％,从而提高立他司特的用药安全性。(The invention discloses a sitagliptin impurity, a preparation method and a removal method thereof. The preparation method comprises the steps of taking the sitagliptin as a starting material, and carrying out condensation and hydrolysis reaction to obtain the impurity I of the sitagliptin. The removal method ensures that the residue of the impurity I in the finished product of the sitagliptin is less than or equal to 0.10 percent, thereby improving the medication safety of the sitagliptin.)

1. A sitagliptin impurity, the chemical structure of which is shown in formula I:

2. the process for the preparation of the sitagliptin impurity according to claim 1, comprising the steps of:

1) carrying out condensation reaction on the compound 1 and the compound 2 to obtain a compound 3;

2) removing a protecting group from the compound 3 obtained in the step 1) through hydrolysis reaction to obtain an impurity I

In the above preparation method, the substituent R in the compounds 2 and 3 is unsubstituted C1-C4 alkyl, phenyl-substituted C1-C4 alkyl, or alkyl-substituted phenyl-substituted C1-C4 alkyl, preferably, R is methyl, ethyl, tert-butyl, or benzyl.

3. The preparation method according to claim 2, wherein the condensation reaction in step 1) is carried out in the presence of a condensing agent, which is Dicyclohexylcarbodiimide (DCC), Diisopropylcarbodiimide (DIC), 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI), O-benzotriazol-tetramethyluronium Hexafluorophosphate (HBTU), 2- (7-azabenzotriazole) -N, N' -tetramethyluronium Hexafluorophosphate (HATU), 1-Hydroxybenzotriazole (HOBT), 1-hydroxy-7-azabenzotriazole (HOAT), or a mixture thereof; and/or

In the step 1), condensation reaction is carried out in the presence of organic base, wherein the organic base is one or more of triethylamine, DIPEA and DMAP; and/or

The condensation reaction in the step 1) is carried out in a solvent, wherein the solvent is one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane; and/or

The reaction temperature of the condensation reaction is 0 ℃ to 50 ℃, preferably 20 ℃ to 30 ℃.

4. The preparation method according to claim 2, wherein the hydrolysis reaction in step 2) is carried out in a solvent, the solvent being one or more of water, methanol, ethanol, acetone, tetrahydrofuran, N-dimethylformamide, acetonitrile and dioxane; and/or

The hydrolysis reaction in the step 2) is carried out in the presence of alkali, wherein the alkali is one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, lithium hydroxide and cesium carbonate; and/or

And step 2) acid dissociation is further included after the hydrolysis reaction, and the acid used for dissociation is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and acetic acid.

5. A process for removing the impurities of claim 1 from crude sitagliptin, comprising pulping the crude sitagliptin after it is converted to calcium salt, and dissociating under acidic condition to obtain the finished product of sitagliptin.

6. The method of removing of claim 5, comprising the steps of:

i) after salifying the crude product of the sitaxel, dropwise adding the crude product of the sitaxel into a calcium salt solution to obtain a calcium salt of the sitaxel;

ii) pulping the calcium salt of lithotriptolide obtained in step i);

iii) replacing the beaten calcium salt of the sitagliptin obtained in the step ii) with a sodium salt, and dissociating under an acidic condition to obtain a finished product of the sitagliptin.

7. The removal process according to claim 6, wherein the salt formation in step i) is carried out in a solvent, the solvent being one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane; and/or

The salifying reagent used for salifying is one of sodium hydroxide and sodium methoxide;

the calcium salt forming reagent of the calcium salt forming solution is one of calcium hydroxide, calcium oxide, calcium chloride, calcium bromide, calcium fluoride and calcium nitrate.

8. The removal method according to claim 6, wherein the solvent used for the beating in the step ii) is one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane.

9. The removal method according to claim 6, wherein the replacement into the sodium salt in step iii) is performed in a solvent, the solvent being one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane; and/or

Replacing sodium salt with alkali in the step iii), wherein the alkali is one or two of sodium carbonate and sodium bicarbonate; and/or

The acid used for the free reaction in the step iii) is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and acetic acid.

10. The removal method according to claim 6, wherein the temperature of the dissociation in the step iii) is 0-10 ℃.

11. The finished sitagliptin product obtained by the removal method according to claims 5 to 10, wherein the impurity I residue in the finished sitagliptin product is less than or equal to 0.10%.

Technical Field

The invention relates to the field of pharmaceutical chemicals, and particularly relates to a sitagliptin impurity, and a preparation method and a removal method thereof.

Background

The chemical name of the compound is ((S) -2- [2- (benzofuran-6-carbonyl) -5, 7-dichloro-1, 2,3, 4-tetrahydroisoquinoline-6-formamido group)]-3- (3-methylsulfonylphenyl) propionic acid), a novel inhibitor of intercellular adhesion factor, which acts by blocking the binding between intercellular adhesion molecule-1 and integrin protein lymphocyte function-associated antigen-1. The drug was approved by FDA at 11/07/2016 for marketing and use in ocular dryness syndrome, formula: c₂₉H₂₄Cl₂N₂O₇Relative molecular mass of S: 615.4, the structural formula is shown below:

disclosure of Invention

The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the present application.

The inventor of the application finds that an impurity I compound of (S) -2- [ (S) -2- (2- (benzofuran-6-carbonyl) -5, 7-dichloro-1, 2,3, 4-tetrahydroisoquinoline-6-formamido) -3- (3- (methylsulfonyl) phenyl) propionamido ] -3- [3- (methylsulfonyl) phenyl ] propionic acid is inevitably generated in the preparation process of a finished product of the sitaxel in the sitaxel research, and becomes one of main impurities of the sitaxel.

The physical and chemical properties of the impurity are similar to those of the sitagliptin, so that the conventional method is difficult to remove, and the specific removal method is adopted by the inventor, so that the residue of the impurity I in the finished product of the sitagliptin is less than or equal to 0.10 percent, and the medication safety of the sitagliptin is improved.

The invention provides a sitaxel impurity, the chemical name of which is (S) -2- [ (S) -2- (2- (benzofuran-6-carbonyl) -5, 7-dichloro-1, 2,3, 4-tetrahydroisoquinoline-6-formamido) -3- (3- (methylsulfonyl) phenyl) propionamido ] -3- [3- (methylsulfonyl) phenyl ] propionic acid, and the chemical structure of the impurity is as follows:

in another aspect, the present invention provides a method for preparing the above impurities, comprising the steps of:

1) carrying out condensation reaction on the compound 1 and the compound 2 to obtain a compound 3;

2) removing a protecting group from the compound 3 obtained in the step 1) through hydrolysis reaction to obtain an impurity I.

In the above preparation method, the substituent R in the compound 2 and the compound 3 is unsubstituted C1-C4 alkyl, phenyl-substituted C1-C4 alkyl, or alkyl-substituted phenyl-substituted C1-C4 alkyl, preferably, R is methyl, ethyl, tert-butyl, or benzyl.

In the above preparation method, the step 1) is performed in the presence of a condensing agent, which is Dicyclohexylcarbodiimide (DCC), Diisopropylcarbodiimide (DIC), 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI), O-benzotriazol-tetramethyluronium Hexafluorophosphate (HBTU), 2- (7-azabenzotriazole) -N, N, N ', N' -tetramethyluronium Hexafluorophosphate (HATU), 1-Hydroxybenzotriazole (HOBT), 1-hydroxy-7-azabenzotriazole (HOAT) or a mixture thereof, preferably, the condensing agent is O-benzotriazol-tetramethyluronium Hexafluorophosphate (HBTU), 2- (7-azabenzotriazole) -N, n, N' -tetramethyluronium Hexafluorophosphate (HATU).

In the above preparation method, the molar ratio of the compound 1 to the condensing agent in the step 1) is 1 (1.1-1.5), preferably 1: 1.1.

In the above preparation method, the reaction temperature of the condensation reaction of the step 1) is 0 ℃ to 50 ℃, preferably 20 ℃ to 30 ℃.

In the above preparation method, the condensation reaction of step 1) is carried out in the presence of an organic base, wherein the organic base is one or more of Triethylamine (TEA), N-Diisopropylethylamine (DIPEA) and 4-Dimethylaminopyridine (DMAP), and preferably, the organic base is selected from triethylamine or DIPEA; optionally, the molar ratio of compound 1 to the organic base is 1 (1-6.0), preferably 1: 4.0.

In the above preparation method, the condensation reaction in the step 1) is performed in a solvent, and the solvent is one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane.

In the above production method, the reaction temperature of the condensation reaction in the step 1) is 20 ℃ to 30 ℃.

In the preparation method, the hydrolysis reaction in the step 2) is performed in a solvent, and the solvent is one or more of water, methanol, ethanol, acetone, tetrahydrofuran, N-dimethylformamide, acetonitrile and dioxane.

In the above preparation method, the hydrolysis reaction in step 2) is carried out in the presence of a base, and the base used is one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, lithium hydroxide and cesium carbonate.

In the above preparation method, the acid used in step 2) is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and acetic acid.

On the other hand, the invention also provides a method for removing the impurity I of the sitagliptin from the crude product of the sitagliptin, which comprises the steps of pulping the crude product of the sitagliptin after being made into calcium salt and dissociating the calcium salt under an acidic condition to obtain a finished product of the sitagliptin.

In the above method of removing, the method of removing includes the steps of:

i) salifying the crude product of the sitagliptin, and then dropwise adding the salt solution of the sitagliptin to obtain a calcium salt of the sitagliptin;

ii) pulping the calcium salt of lithotriptolide obtained in step i);

iii) replacing the beaten calcium salt of the sitagliptin obtained in the step ii) with a sodium salt, and dissociating under an acidic condition to obtain a finished product of the sitagliptin.

In the above removal method, the salt formation in step i) is performed in a solvent, and the solvent used is one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane.

In the above removing method, in the step i), the salt-forming reagent used for salt formation is one of sodium hydroxide and sodium methoxide.

In the above removing method, in the step i), the calcium salt forming agent of the calcium salt forming solution is one of calcium hydroxide, calcium oxide, calcium chloride, calcium bromide, calcium fluoride and calcium nitrate; optionally, the concentration of the calcium salt-forming solution is 0.2-1.0mol/L, preferably 0.5 mol/L.

In the above removing method, the beating solvent used in the step ii) is one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane.

In the above removing method, the replacing sodium salt in the step iii) is performed in a solvent, and the solvent used is one or more of methanol, ethanol, tetrahydrofuran, N-dimethylformamide, water, dioxane and dichloromethane.

In the above removing method, the sodium salt is replaced by alkali in the step iii), and the alkali used is one or two of sodium carbonate and sodium bicarbonate.

In the above removing method, the acid used in step iii) is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and acetic acid.

In the above method of removing, the free temperature in the step iii) is 0 ℃ to 10 ℃.

In another aspect, the invention provides a finished product of sitagliptin prepared according to the removing method, wherein the impurity I residue in the finished product of the sitagliptin is less than or equal to 0.10%.

In a further aspect, the invention provides the use of impurity I of sitagliptin as a reference substance in the quality study of a raw material drug of sitagliptin or a formulation of sitagliptin.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. Other advantages of the present application may be realized and attained by the instrumentalities and combinations particularly pointed out in the specification and the drawings.

Drawings

The accompanying drawings are included to provide an understanding of the present disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the examples serve to explain the principles of the disclosure and not to limit the disclosure.

FIG. 1 is an HPLC plot of impurity I of example 1;

FIG. 2 is a MS plot of impurity I from example 1;

FIG. 3 is a HNMR picture of impurity I of example 1;

FIG. 4 is a CNMR map of impurity I of example 1;

FIG. 5 is an HPLC plot of a crude sitaxel of example 6;

FIG. 6 is a HPLC chart of a purified product of sitaxel in example 6.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

The main raw materials, reagents and solvents used in the experiment are all chemical pure products or analytically pure products sold in the market, and are directly used without purification.

The main instruments and models used in this experimental example: nuclear magnetic resonance apparatus: model AVANCE III 600 nmr apparatus; mass spectrometry Bruker (impact II) mass spectrometer; agilent 1260II high performance liquid chromatography.

HPLC method

The high performance liquid chromatography is adopted to analyze the sitagliptin and impurities thereof, and the parameters are as follows:

comparative example 1

1) 2g of crude sitaxel (prepared in example 13 of WO2019043724A1, purity 97.67%, impurity I0.64%) was charged into a reaction flask, 20mL of tetrahydrofuran was added, the mixture was stirred to dissolve, 0.8mL of dicyclohexylamine was added, the mixture was stirred at room temperature for 24 hours, 4mL of methyl t-butyl ether was added, the mixture was stirred at room temperature for 16 hours, filtered and dried to obtain sitaxel dicyclohexylamine salt.

2) Adding 22.5g of sitafloxacin dicyclohexylamine salt into a reaction bottle, adding 112mL of dichloromethane and 112mL of 1 mass% phosphoric acid aqueous solution, stirring, standing, layering, collecting a dichloromethane layer, washing with 112mL of 1 mass% phosphoric acid aqueous solution for three times, concentrating under reduced pressure, adding 90mL of acetone, dissolving, dripping into 900mL of methyl tert-butyl ether precooled to 0 ℃, stirring for 1 hour, filtering, and drying to obtain a finished product of sitafloxacin. (purity 98.84%, impurity I0.60%).

Synthesis of impurity I

Example 1

1) 5.0g of Compound 1, 3.4g of HATU, 100.0g of dichloromethane, 4.2g N and N-diisopropylethylamine were sequentially added to a reaction flask, the mixture was stirred at 20-30 ℃ for reaction for 3 hours, 2.6g of Compound 2(R is methyl) was added to the mixture, the reaction was carried out for 2 hours, TLC was used to monitor completion of the reaction, 1N hydrochloric acid was added to the mixture, the mixture was stirred and separated, the lower organic layer was collected, the mixture was washed with 1N hydrochloric acid, water, a saturated sodium bicarbonate solution and water in this order, and the mixture was concentrated to dryness under reduced pressure.

2) Adding the product obtained in the previous step and 50.0mL of tetrahydrofuran into a reaction bottle, adding 32mL of 0.5mol/L lithium hydroxide aqueous solution, reacting for 2 hours at 20-30 ℃, monitoring the reaction by TLC to be complete, concentrating under reduced pressure to remove tetrahydrofuran, back-extracting the aqueous phase twice with ethyl acetate, collecting the aqueous phase, concentrating under reduced pressure to remove residual ethyl acetate, dropwise adding 1N hydrochloric acid to adjust the pH to 4, filtering, and drying to obtain the target product, namely the impurity I of lithostat (purity 94.72%, yield 55.6%). ESI M/z 840.12 (M)⁺¹)；¹H NMR(600MHz,DMSO-d₆)δ：12.96(s,1H),8.84(t,J＝9.1Hz,1H),8.45(d,J＝7.8Hz,1H),8.31(d,J＝7.3Hz,0H),8.11(s,1H),7.89(d,J＝13.5Hz,1H),7.83–7.67(m,5H),7.63(t,J＝7.0Hz,1H),7.54(tq,J＝21.3,7.6Hz,3H),7.32(s,2H),7.04(s,1H),4.92–4.57(m,4H),3.62(s,2H),3.28–3.22(m,2H),3.20–3.11(m,6H),3.04(dq,J＝22.6,8.7,7.1Hz,1H),2.98–2.86(m,1H),2.73(s,2H).；¹³C NMR(151MHz,DMSO)δ172.26,172.19,170.15,169.91,169.37,163.40,153.62,147.65,140.65,140.62,140.54,140.45,139.25,139.15,138.95,138.92,136.92,136.85,134.59,134.51,134.40,131.59,131.52,131.48,130.99,129.22,129.07,128.97,128.62,128.26,127.69,127.66,127.61,127.56,125.54,125.09,125.05,124.90,124.80,121.94,121.38,110.25,106.78,53.44,53.36,53.19,53.05,43.68,43.60,43.53,39.94,39.80,39.66,39.52,39.38,39.24,39.10,37.29,37.19,36.95,36.57.

Example 2

1) Adding 5.0g of compound 1, 3.4g of HATU, 100.0g of tetrahydrofuran and 3.3g of triethylamine into a reaction bottle in sequence, stirring at 20-30 ℃ for reaction for 3 hours, adding 2.6g of compound 2(R is methyl), reacting for 2 hours, monitoring the reaction by TLC (thin layer chromatography), distilling under reduced pressure until the reaction is completed, adding dichloromethane, adding 1N hydrochloric acid, stirring, separating, collecting a lower organic layer, washing with 1N hydrochloric acid, water, a saturated sodium bicarbonate solution and water in sequence, and concentrating under reduced pressure until the reaction is completed.

2) Adding the product obtained in the previous step and 50.0mL of tetrahydrofuran into a reaction bottle, adding 32mL of 0.5mol/L lithium hydroxide aqueous solution, reacting for 2 hours at 20-30 ℃, monitoring the reaction by TLC to be complete, concentrating under reduced pressure to remove tetrahydrofuran, back-extracting the aqueous phase twice by ethyl acetate, collecting the aqueous phase, concentrating under reduced pressure to remove residual ethyl acetate, dropwise adding 1N hydrochloric acid to adjust the pH to 4, filtering, and drying to obtain the target product, namely the sitafloxacin impurity I (purity 93.45%, yield 48.5%).

Example 3

1) 5.0g of Compound 1, 3.4g of HATU, 100.0g of dichloromethane, 4.2g N and N-diisopropylethylamine were sequentially added to a reaction flask, the mixture was stirred at 20-30 ℃ for reaction for 3 hours, 2.6g of Compound 2(R is methyl) was added to the mixture, the reaction was carried out for 2 hours, TLC was used to monitor completion of the reaction, 1N hydrochloric acid was added to the mixture, the mixture was stirred and separated, the lower organic layer was collected, the mixture was washed with 1N hydrochloric acid, water, a saturated sodium bicarbonate solution and water in this order, and the mixture was concentrated to dryness under reduced pressure.

2) Adding the product obtained in the previous step and 50.0mL of dioxane into a reaction bottle, adding 32mL of 0.5mol/L sodium hydroxide aqueous solution, reacting for 2 hours at 20-30 ℃, monitoring the reaction by TLC to be complete, concentrating under reduced pressure to remove tetrahydrofuran, back-extracting the water phase twice by ethyl acetate, collecting the water phase, concentrating under reduced pressure to remove residual ethyl acetate, dropwise adding 1N hydrochloric acid to adjust the pH value to 4, filtering, and drying to obtain the target product, namely the sitaster impurity I (purity 92.89%, yield 40.2%).

Example 4

1) 5.0g of Compound 1, 3.4g of HATU, 100.0g of dichloromethane, 4.2g N and N-diisopropylethylamine were sequentially added to a reaction flask, the mixture was stirred at 20-30 ℃ for reaction for 3 hours, 3.0g of Compound 2(R is benzyl) was added to the mixture, the reaction was carried out for 3 hours, TLC was used to monitor the completion of the reaction, 1N hydrochloric acid was added to the mixture, the mixture was stirred and separated, the lower organic layer was collected, the mixture was washed with 1N hydrochloric acid, water, a saturated sodium bicarbonate solution and water in this order, and the mixture was concentrated to dryness under reduced pressure.

2) Adding the product obtained in the previous step and 50.0mL of tetrahydrofuran into a reaction bottle, adding 32mL of 0.5mol/L lithium hydroxide aqueous solution, reacting for 2 hours at 20-30 ℃, monitoring the reaction by TLC to be complete, concentrating under reduced pressure to remove tetrahydrofuran, back-extracting the aqueous phase twice by ethyl acetate, collecting the aqueous phase, concentrating under reduced pressure to remove residual ethyl acetate, dropwise adding 1N hydrochloric acid to adjust the pH to 4, filtering, and drying to obtain the target product, namely the impurity I of lithostat (the purity is 93.62%, and the yield is 36.0%). .

Example 5

1) Adding 5.0g of compound 1, 3.4g of HATU, 100.0g of dichloromethane and 3.3g of triethylamine into a reaction bottle in sequence, stirring at 20-30 ℃ for reaction for 3 hours, adding 3.0g of compound 2(R is benzyl), reacting for 3 hours, monitoring the reaction by TLC, adding 1N hydrochloric acid, stirring, separating, collecting a lower organic layer, washing with 1N hydrochloric acid, water, a saturated sodium bicarbonate solution and water in sequence, and concentrating under reduced pressure to dryness.

2) Adding the product obtained in the previous step and 50.0mL of dioxane into a reaction bottle, adding 16mL of 1mol/L sodium hydroxide aqueous solution, reacting for 2 hours at 20-30 ℃, monitoring the reaction by TLC to be complete, concentrating under reduced pressure to remove tetrahydrofuran, back-extracting the water phase twice by ethyl acetate, collecting the water phase, concentrating under reduced pressure to remove residual ethyl acetate, dropwise adding 1N hydrochloric acid to adjust the pH to 4, filtering, and drying to obtain the target product, namely the impurity I of lithostat (the purity is 93.33%, and the yield is 35.5%).

Refining of sitagliptin

Example 6

1) 10.0g of crude sitaxel (prepared according to example 13 of patent WO2019043724A1, purity 98.59% and impurity I0.32%) is added into a reaction bottle, 0.5mol/L sodium hydroxide solution is added, pH is adjusted to 8-9, the mixture is stirred until the mixture is clear, the temperature is reduced to 0-10 ℃, 36mL of 0.5mol/L calcium chloride aqueous solution is added dropwise, solid is separated out, the mixture is filtered, and the filter cake is washed by purified water and used for the next step.

2) Adding the filter cake into a reaction bottle, adding 100mL of ethanol, heating to reflux, pulping for 2-3 hours, cooling to 30-40 ℃, and filtering to obtain a filter cake for later use.

3) Adding the filter cake into a reaction bottle, adding 100mL of purified water, stirring, adding 48mL of 0.5mol/L sodium carbonate solution, stirring for 3-4 hours, gradually dissolving the solid, performing suction filtration to obtain a clear solution for later use, cooling to 0-10 ℃, dropwise adding 1N hydrochloric acid solution, adjusting the pH value to 2-3, separating out the solid, filtering, and washing with purified water to obtain a finished product of the sitaxel (the purity is 99.75%, the impurity I is 0.04%, and the yield is 88.6%).

Example 7

1) 5.0g of crude sitaxel (prepared according to example 13 of patent WO2019043724A1, purity 98.59% and impurity I0.32%) is sequentially added into a reaction bottle, 0.5mol/L sodium hydroxide solution is added, pH is adjusted to 8-9, the mixture is stirred until the mixture is clear, the temperature is reduced to 0-10 ℃, 18mL of 0.5mol/L calcium bromide aqueous solution is dropwise added, solid is separated out, the mixture is filtered, and the filter cake is washed by purified water and used for the next step.

2) Adding the filter cake into a reaction bottle, adding 50mL of ethanol, heating to reflux, pulping for 2-3 hours, cooling to 30-40 ℃, and filtering to obtain a filter cake for later use.

3) Adding the filter cake into a reaction bottle, adding 50mL of purified water, stirring, adding 24mL of 0.5mol/L sodium bicarbonate solution, stirring for 3-4 hours, gradually dissolving the solid, performing suction filtration to obtain a clear solution for later use, cooling to 0-10 ℃, dropwise adding 1N hydrochloric acid solution, adjusting the pH value to 2-3, separating out the solid, filtering, and washing with purified water to obtain a finished product of the sitaxel (the purity is 99.64%, the impurity I is 0.06%, and the yield is 80.2%).

Example 8

1) 5.0g of crude sitaxel (prepared according to example 13 of patent WO2019043724A1, purity 98.59% and impurity I0.32%) is sequentially added into a reaction bottle, 0.5mol/L sodium hydroxide solution is added, pH is adjusted to 8-9, the mixture is stirred until the mixture is clear, the temperature is reduced to 0-10 ℃, 18mL of 0.5mol/L calcium chloride aqueous solution is dropwise added, solid is separated out, the mixture is filtered, and the filter cake is washed by purified water and used for the next step.

2) Adding the filter cake into a reaction bottle, adding 50mL of ethanol, heating to reflux, pulping for 2-3 hours, cooling to 30-40 ℃, and filtering to obtain a filter cake for later use.

3) Adding the filter cake into a reaction bottle, adding 20mL of ethanol and 30mL of purified water, stirring, adding 24mL of 0.5mol/L sodium carbonate solution, stirring for 3-4 hours, gradually dissolving the solid, performing suction filtration to obtain a clear solution for later use, cooling to 0-10 ℃, dropwise adding 1N hydrochloric acid solution, adjusting the pH to 2-3, separating out the solid, filtering, and washing with purified water to obtain a finished product of the sitafloxacin (purity 99.72%, impurity I0.04%, yield 70.2%).

The present application describes embodiments, but the description is illustrative rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein.