CN112300222B - Azacitidine refining method with high purity and low solvent residue - Google Patents

Abstract

The invention relates to the fields of medicine and chemistry, and provides a refining method of azacitidine, which comprises the following steps: step 1: adding the crude azacitidine into a good solvent for dissolving; step 2: adding a poor solvent into the solution obtained in the step 1, and filtering to obtain a first refined product of azacitidine; and step 3: and (3) adding the first refined product of azacitidine obtained in the step (2) into a good solvent for dissolving, adding a poor solvent, filtering, pulping, and drying to obtain a refined product of azacitidine. The refining process has mild conditions, simple operation, suitability for industrial amplification and high product purity; the solvent residue in the product is low, especially the high boiling point residual solvent DMSO.

Description

Azacitidine refining method with high purity and low solvent residue

Technical Field

The invention belongs to the field of pharmaceutical chemistry, and particularly relates to a refining method with high purity, low residual solvent content and stable crystal form.

Background

Azacitidine is a cytosine nucleoside analog, also known as 5-azacytidine, and has the chemical name 4-amino-1- β -D-ribofuranosyl-1, 3, 5-triazin-2 (1H) -one. Azacitidine for injection is first marketed in the united states in 2004 for 5 months, then marketed in countries such as european union and japan, and imported from china in 2017 for 4 months, with the trade name of vildagsa (Vidaza), and is mainly used for treatment of diseases such as adult myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML), and Acute Myeloid Leukemia (AML). The mechanism of action is to produce an anti-tumor effect by causing DNA demethylation and direct cytotoxic effects on abnormal hematopoietic cells in the bone marrow. Azacitidine, having a molecular formula of C8H12N4O5, a molecular weight of 244.20, and a structural formula shown below (formula I):

in patents WO2019129260, WO2004082619, WO2004082822, US20040186065, CN201810089336, CN201810133988 and the like, a preparation method of a crystal form I most suitable as a raw material medicament of azacitidine is disclosed, namely a good solvent is adopted, a crude product of azacitidine is heated and dissolved, a poor solvent or a mixed solvent of the poor solvents is added, and a refined azacitidine product is obtained by cooling, crystallizing, filtering and drying. In the patent, polar aprotic solvents such as dimethyl sulfoxide (DMSO), N-Dimethylformamide (DMF), N-Dimethylacetamide (DMA), N-methylpyrrolidone (NMP) and the like are used as good solvents. In the patent WO2019129260, the solubility test is carried out on the 4 good solvents, and the DMSO solubility is the highest; and the patent mentions that the higher alcohol with the carbon number more than 2 is used as an anti-solvent for crystallization, and the DMSO residue in the obtained product is high. In the patent, alcohols, esters, nitriles and the like are used as the poor solvent, and a mixed solvent of methanol, ethanol, isopropanol or alcohols is generally preferred as the poor solvent. Patent WO2004082822 reports that stable crystal form I can be obtained by using isopropanol and acetonitrile as poor solvents under both fast and slow crystallization conditions. Based on the summary of the literature, the inventors refer to the literature method, and select a third solvent DMSO as a good solvent, and select methanol, ethanol, isopropanol or mixed alcohol as a poor solvent, and perform a refining test, and the obtained product mainly has the following problems: 1. DMSO is selected as a good solvent, heated to 80-90 ℃ for dissolution, a poor solvent is added to slowly cool to-20 ℃ for crystallization, the refining yield is between 50% and 60%, and the refining yield is low; 2. the obtained refined product does not meet the quality standard, especially the monoacetyl impurity (formula II) exceeds the limit defined by Chinese pharmacopoeia or ICH; 3. the residual DMSO of the obtained refined product is generally more than 10000ppm, which is far more than 5000ppm of DMSO limit specified by pharmacopoeia. In conclusion, the azacitidine crude product is refined by the method reported in the literature, and the defects of low refining yield and product quality which does not meet the pharmaceutical standard exist. The monoacetyl impurity (formula II) has the following structure:

disclosure of Invention

Aiming at the defects found in the refining test process, the inventor carries out systematic experimental research and provides a refining preparation process with high refining yield, low solvent residue of a refined product, high purity and stable crystal form.

Specifically, the invention provides the following technical scheme:

the invention provides a refining method of azacitidine, which comprises the following steps:

step 1: adding the crude product of azacitidine into a good solvent for dissolving;

step 2: adding a poor solvent into the solution obtained in the step 1, and filtering to obtain a first refined product of azacitidine;

and 3, step 3: and (3) adding the first refined product of azacitidine obtained in the step (2) into a good solvent for dissolving, adding a poor solvent, filtering, pulping, and drying to obtain a refined product of azacitidine.

Preferably, steps 1-3 are repeated 1-3 times, preferably 1 time.

Preferably, wherein the good solvent in step 1 is DMSO,

preferably, the mass-volume ratio of the crude azacitidine to DMSO is 1;

more preferably, the mass-to-volume ratio of the crude azacitidine to DMSO is 1.

Preferably, wherein the dissolving temperature in the step 1 is 20-60 ℃;

preferably, the temperature for dissolution in step 1 is 30-40 ℃.

Preferably, in step 2, the poor solvent is one or more of ester solvents, ether solvents and nitrile solvents;

preferably, the step 2 of obtaining the first refined product further comprises the processes of slow cooling and stirring.

Preferably, wherein the esters include one or more of ethyl acetate, isopropyl acetate, ethyl formate, methyl acetate, propyl acetate, butyl acetate and isobutyl acetate,

preferably, one or more of ethyl acetate, methyl acetate, isopropyl acetate and propyl acetate.

Preferably, the ethers include one or more of methyl tert-butyl ether, ethyl tert-butyl ether, methyl tert-amyl ether and methyl isoamyl ether, and preferably, methyl tert-butyl ether.

Preferably, the nitrile includes one or more of acetonitrile, propionitrile and butyronitrile, preferably acetonitrile.

Preferably, in the step 2, the volume ratio of the good solvent DMSO to the poor solvent is 1; preferably 1.

Preferably, in the step 3, the first refined product of azacitidine is dissolved by adding it into a good solvent, wherein the good solvent is DMSO,

preferably, the dissolving temperature is 20-60 ℃; more preferably, the dissolution temperature is 30-40 ℃.

Preferably, in the step 3, the mass-to-volume ratio of the azacitidine first refined product to the DMSO is 1.

Preferably, in the step 3, the poor solvent is an alcohol having 1 to 4 carbon atoms, the alcohol includes one or more of methanol, ethanol, propanol, isopropanol and n-butanol,

preferably one or more of methanol, ethanol and isopropanol;

more preferably, the volume ratio of the good solvent DMSO to the poor solvent is 1.

Preferably, the step 3 of obtaining the refined azacitidine product further comprises the steps of slowly cooling, filtering and pulping the filter cake, and preferably, the filter cake is pulped for 2-4 times.

Preferably, the solvent used for pulping comprises one or more than two of methanol, ethanol, propanol, isopropanol and n-butanol,

preferably, one or more of methanol, ethanol and isopropanol; more preferably, the volume of the solvent used for pulping is 1 to 3 times of the volume of the good solvent in the step 2; further preferably 1 to 2 times.

Preferably, wherein the beating temperature is 10-30 ℃, and the beating time is 15-30 minutes.

Preferably, the method also comprises a vacuum drying process after pulping, wherein the drying temperature is 50-90 ℃, and preferably 60-80 ℃; the drying time is 12 to 24 hours.

The invention also provides application of the specific good solvent in the method in preparing refined products of azacitidine with high purity.

The invention also provides a azacitidine crystal form which is characterized by being prepared by the method, preferably, the azacitidine crystal form is a crystal form I.

The beneficial effects of the invention include:

1. the refining process has mild conditions and simple operation, and is suitable for industrial amplification; 2. the refining process can effectively remove impurities, particularly monoacetyl impurities (formula II), in the crude product, wherein the content of the monoacetyl impurities (formula II) in the crude product is 0.7-1.1%, and the content of the monoacetyl impurities (formula II) is reduced to be below 0.10% after refining. The purity of the obtained product can reach more than 99.6 percent, and the product has high purity; 3. the solvent residue in the refined product is low, especially the high-boiling point residual solvent DMSO is far lower than the requirement of the limit specified by pharmacopoeia; 4. the crystal form of the product obtained by the refining method is stable, is crystal form I, and is suitable for being used as the crystal form of the raw material medicine; 5. the invention has high refining yield, and the total yield of 2-time purification can reach more than 86%.

Drawings

FIG. 1 is an XRPD pattern for the azacitidine product prepared in example 1 of the present invention;

FIG. 2 is an XRPD pattern for the azacitidine product prepared in example 2 of the present invention;

FIG. 3 is an XRPD pattern for the azacitidine product prepared in example 3 of the present invention;

FIG. 4 is an XRPD pattern of azacitidine form I from reference WO 2004/082619.

Detailed Description

Specifically, the invention provides a refining preparation method with high refining yield, low solvent residue, high purity and stable crystal form, and the technical scheme is as follows:

adding the azacitidine crude product into a good solvent DMSO, heating and stirring for dissolving; adding esters, ethers or nitriles, or a mixed solvent of the above solvents as a poor solvent; slowly cooling, stirring and filtering to obtain a refined product of azacitidine for the first time.

Adding the primary refined azacitidine product into a good solvent DMSO, heating and stirring for dissolving; adding alcohols or mixed solvents of the above solvents as poor solvents, slowly cooling, stirring, and filtering; and (4) pulping the filter cake at room temperature, filtering and drying to obtain the refined azacitidine product.

The method specifically comprises the following steps:

adding the coarse azacitidine into a good solvent DMSO, stirring and dissolving at the dissolving temperature of 20-60 ℃, preferably 30-40 ℃; the mass volume ratio of the crude azacitidine to DMSO is 1;

according to the refining preparation process of the invention, the added poor solvent comprises esters, ethers, nitriles or the mixed solvent of the above solvents as the poor solvent.

The esters specifically include ethyl acetate, isopropyl acetate, ethyl formate, methyl acetate, propyl acetate, butyl acetate, isobutyl acetate, etc., or a mixed solvent of the above solvents, preferably ethyl acetate, methyl acetate, isopropyl acetate, propyl acetate; the ethers specifically include methyl t-butyl ether, ethyl t-butyl ether, methyl t-amyl ether, methyl isoamyl ether, etc., or a mixed solvent of the above ethers, preferably methyl t-butyl ether; the nitrile specifically includes acetonitrile, propionitrile, butyronitrile, etc., or a mixed solvent of the above solvents, preferably acetonitrile; the volume ratio of the good solvent DMSO to the poor solvent is 1;

sampling a refined product of azacitidine for the first time, measuring the loss on drying, and weighing by weight after drying; adding the primary refined product of azacitidine into DMSO, and dissolving at 20-60 ℃, preferably 30-40 ℃; the mass volume ratio of the dried azacitidine primary refined product to DMSO is 1;

according to the refining preparation process, the poor solvent added in the second refining is C1-C4 alcohols. The alcohol specifically includes methanol, ethanol, propanol, isopropanol, and n-butanol, or a mixed solvent thereof, preferably methanol, ethanol, isopropanol, or a mixed solvent thereof. The volume ratio of the good solvent DMSO to the poor solvent is 1;

pulping the filter cake for 2-4 times after the second refining, wherein the solvent used for pulping is poor solvent for the second refining, and specifically comprises methanol, ethanol, propanol, isopropanol, n-butanol, or mixed solvent of the above alcohols, preferably methanol, ethanol, isopropanol or mixed solvent of the above alcohols. The volume of the poor pulping solvent is 1 to 3 times, preferably 1 to 2 times of the volume of the good refining solvent in the second refining. The pulping temperature is 10-30 ℃, and the pulping time is 15-30 minutes.

According to the preparation process, the obtained sample is dried in vacuum, and the drying temperature is generally 50-90 ℃, preferably 60-80 ℃; the drying time is 12 to 24 hours.

The azacitidine crystal form obtained by the preparation process is the crystal form I, and can be used for treating myelodysplastic syndrome, leukemia and other diseases.

The invention and its advantageous effects are explained in detail below with reference to the drawings and the respective embodiments.

The reagents and instrumentation used in the following examples were from the following sources:

TABLE 1 reagents and apparatus used in the examples

Reagent/instrument	Type/purity	Manufacturer/supplier
			DMSO	Analytical stage	BEIJING CHEMICAL PLANT
Crude azacitidine	Purity: 96.45%, monoacyl impurities: 0.96 percent	Self-made
			Ethyl acetate	Industrial grade	BEIJING CHEMICAL PLANT
Methanol	Industrial grade	BEIJING CHEMICAL PLANT
			Acetic acid isopropyl ester	Industrial grade	BEIJING CHEMICAL PLANT
Isopropanol (I-propanol)	Analytical grade	BEIJING CHEMICAL PLANT
			Methyl tert-butyl ether	Industrial grade	BEIJING CHEMICAL PLANT
Ethanol	Industrial grade	BEIJING CHEMICAL PLANT
			Acetonitrile	Industrial grade	BEIJING CHEMICAL PLANT
Decompression drying cabinet	DHG-9070A	Shanghai Jiecheng Lab Instruments Co.,Ltd.
			Vacuum pump	2XZ-1	Zhejiang Taizhou vacuum pump Limited
X-ray powder diffractometer	D2Phaser	Bruk instruments Ltd

The preparation method of the crude azacitidine product comprises the following steps:

the crude product of azacitidine is prepared by taking 5-azacytosine as a starting material, performing silanization reaction to obtain an intermediate 1, performing European Union of the intermediate 1 and tetraacetyl ribose to obtain an intermediate 2, and hydrolyzing the intermediate to obtain the crude product of azacitidine. The purity of the azacitidine crude product is 96.45 percent and the monoacetyl impurity is 0.96 percent.

Example 1

Adding 300ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 40 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 900ml ethyl acetate, slowly cooling to 20 ℃, and stirring for 2h; filtration was carried out to obtain a primary refined product having a wet weight of 52.2 g. The loss on drying was measured and was 47.7g on drying, yield 95.4%.

Adding 280ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (wet weight is 55.2 g), heating to 35 ℃ under the protection of nitrogen, and stirring to dissolve; slowly adding 860ml of methanol, slowly cooling to 15 ℃, stirring for 3 hours, and filtering; the obtained filter cake is respectively pulped for 3 times by 280ml of methanol, filtered, decompressed and dried at 80 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa) for 12 hours to obtain 46.7g, and the refining total yield is 90.4%. The purity of the product is 99.77 percent, the monoacetyl impurity (formula II) is 0.04 percent, the DMSO solvent residue is 1120ppm, and the XRPD pattern is shown in figure 1, so that the obtained crystal form is consistent with the crystal form I reported in the literature.

Example 2

Adding 200ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 45 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 800ml isopropyl acetate, slowly cooling to 15-20 ℃, and stirring for 2h; filtration was carried out to obtain 53.0g of a primary purified product in wet weight. The loss on drying was measured and was 45.1g on drying, yield 90.2%.

Adding 170ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (the wet weight is 53.0 g), heating to 45 ℃ under the protection of nitrogen, and stirring to dissolve; slowly adding 680ml of isopropanol, slowly cooling to 15-20 ℃, stirring for 3 hours, and filtering; the obtained filter cake is respectively pulped for 3 times by 170ml of isopropanol, filtered, decompressed and dried at 75 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa) for 18 hours to obtain 43.6g, and the total refining yield is 87.1 percent. The purity of the product is measured to be 99.61%, the monoacetyl impurity (formula II) is measured to be 0.08%, the DMSO solvent residue is 2700ppm, and the XRPD pattern is shown in figure 2, so that the obtained crystal form is consistent with the crystal form I reported in the literature.

Example 3

Adding 300ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 35 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 900ml of methyl tert-butyl ether, slowly cooling to 20-25 ℃, and stirring for 1h; filtration was carried out to obtain 53.1g of a primary purified product in wet weight. The loss on drying was measured and was 46.5g, yield 93.0%.

Adding 230ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (wet weight 54.1 g), heating to 35 ℃ under the protection of nitrogen, and stirring to dissolve; adding 920ml of ethanol slowly, cooling to 15-20 ℃, stirring for 2 hours, and filtering; the obtained filter cake is respectively pulped for 3 times by 230ml of ethanol, filtered, decompressed and dried at 80 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa), and dried for 16h to obtain 43.3g, and the refining total yield is 86.6%. The purity of the product is measured to be 99.68 percent, the monoacetyl impurity (formula II) is measured to be 0.05 percent, the DMSO solvent residue is 1600ppm, and the XRPD pattern is shown in figure 3, so that the obtained crystal form is consistent with the crystal form I reported in the literature.

Example 4

Adding 300ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 40 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 900ml of ethyl acetate and isopropyl acetate with the volume ratio of 1:1, slowly cooling to 20-25 ℃, and stirring for 2h; filtration was carried out to obtain a primary refined product having a wet weight of 54.2 g. The loss on drying was measured and was 46.4g, yield 92.7%.

Adding 180ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (wet weight 54.2 g), heating to 40 ℃ under the protection of nitrogen, and stirring to dissolve; slowly adding 720ml of methanol and ethanol with the volume ratio of 1; the obtained filter cake is respectively pulped for 3 times by 200ml of methanol and ethanol with the volume ratio of 1, filtered, dried under reduced pressure at 80 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa), and dried for 16h to obtain 44.1g, and the refining total yield is 88.1%. The product purity was found to be 99.8%, monoacetyl impurities (formula II) 0.06%, DMSO solvent residue 1400ppm, and XRPD pattern was substantially identical to that of the figure.

Example 5

Adding 300ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 40 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 800ml of ethyl acetate and acetonitrile with the volume ratio of 1 to 1, slowly cooling to 20-25 ℃, and stirring for 2 hours; filtration was carried out to obtain a primary refined product having a wet weight of 52.0 g. The loss on drying was measured and was 45.4g on drying, yield 90.8%.

Adding 180ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (wet weight is 52.0 g), heating to 40 ℃ under the protection of nitrogen, and stirring to dissolve; slowly adding 800ml of methanol and isopropanol in volume ratio, slowly cooling to 15-20 ℃, stirring for 2 hours, and filtering; the obtained filter cake is respectively pulped for 3 times by 200ml of methanol and isopropanol with the volume ratio of 1, filtered, dried under reduced pressure at 80 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa), and dried for 16h to obtain 43.9g, and the refining total yield is 87.7%. The product purity was found to be 99.86%, monoacetyl impurities (formula II) 0.06%, DMSO solvent residue 1800ppm, and XRPD pattern was substantially in accordance with the figure.

Comparative example

Comparative example 1

Adding 125ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 90 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 450ml of methanol, slowly cooling to 45-55 ℃, and keeping the temperature for 1 hour; then slowly cooling to-10-20 ℃, and stirring for 2h; filtering, washing with 125ml methanol for 3 times, drying under reduced pressure at 80 deg.C (vacuum degree controlled at-0.08 MPa) for 16h to obtain 27.5g, and refining total yield 55.0%. The product purity was found to be 99.48%, the monoacetyl impurity (formula II) was not detected, and the DMSO solvent residue was 4800ppm.

Comparative example 2

Adding 300ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 50 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 900ml of methanol, keeping the temperature at 45-50 ℃ for 1 hour, slowly cooling to 20-25 ℃, and stirring for 2 hours; filtration gave 55.2g of a primary refined product in wet weight. The loss on drying was measured and was 45.0g on drying, yield 90%.

Adding 180ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (wet weight is 55.2 g), heating to 50 ℃ under the protection of nitrogen, and stirring to dissolve; slowly adding 800ml of isopropanol, keeping the temperature at 45-50 ℃ for 1 hour, slowly cooling to 20-25 ℃, stirring for 2 hours, and filtering; the obtained filter cake is pulped for 3 times by 200ml of isopropanol, filtered, decompressed and dried at 80 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa), and dried for 16h to obtain 38.3g, and the total refining yield is 76.5%. The product purity was found to be 99.28%, the monoacetyl impurity (formula II) 0.21%, and the DMSO solvent residue 1700ppm.

Comparative example 3

Adding 300ml of DMSO into a 2L reaction bottle, continuously adding 50g of crude azacitidine, heating the solution to 45 ℃ under the protection of nitrogen, and stirring for dissolving; slowly adding 2000ml of ethyl acetate, slowly cooling to 20 ℃, and stirring for 2 hours; filtration was carried out to obtain a primary refined product having a wet weight of 45.1 g. The loss on drying was measured and was 43.1g on dried, yield 86.2%.

Adding 250ml of DMSO into a 2L reaction bottle, continuously adding a primary refined product (the wet weight is 40.5 g), heating to 40 ℃ under the protection of nitrogen, and stirring to dissolve; adding 2500ml methanol slowly, cooling to 15 deg.C slowly, stirring for 2 hr, and filtering; the obtained filter cake is respectively pulped for 3 times by 500ml of methanol, filtered, decompressed and dried at 80 ℃ (the vacuum degree is controlled to be less than or equal to-0.08 MPa) for 12 hours to obtain 39.8g, and the total refining yield is 79.6 percent. The product purity was found to be 99.81%, monoacetyl impurity (formula II) 0.05%, DMSO solvent residue 970ppm.

The purities of azacitidine products and the monoacetyl impurities obtained by the purification of azacitidine products in examples and comparative examples are summarized in Table 2 below.

TABLE 2 summary of azacitidine product obtained by refining in examples and comparative examples

As can be seen from the above table, the first refining yield of the crude azacitidine in examples 1-5 is in the range of 90.8% -95.4%, the yield of the azacitidine product is in the range of 87.1% -90.4% and the purity of the azacitidine product is above 99.6%, the amount of the monoacetyl-containing impurity (formula II) is below 0.08%, the DMSO solvent residue is low and is below 2700ppm, and the total yield of the products refined in examples 1-5 is high, the product purity is high and the impurity content is low.

Comparative example 1 reference method (WO 2004/082619) was repeated, however, there was a low yield; and the final treatment does not adopt a pulping mode, so that the DMSO residue is high, and the total yield of the obtained product is low. Comparative example 2, recrystallization 2 times with DMSO/alcohol, but there are problems of low mono acetyl impurity clearance and low yield; comparative example 3 the amount of the poor solvent was changed out of the scope of claims, and there was a problem that the yield was remarkably lowered.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (30)

1. A method for refining azacitidine, comprising the following steps:

step 1: adding the crude azacitidine into a good solvent for dissolving;

step 2: adding a poor solvent into the solution obtained in the step 1, and filtering to obtain a first refined product of azacitidine;

and step 3: adding the azacitidine first refined product obtained in the step 2 into a good solvent for dissolving, adding a poor solvent, filtering, pulping, and drying to obtain a refined azacitidine product;

the good solvent in the step 1 is DMSO; in step 2, the poor solvent is an ester, an ether or a mixed solvent of the ester and the nitrile; in the step 2, the volume ratio of the good solvent DMSO to the poor solvent is 1; the esters comprise one or more than two of ethyl acetate, isopropyl acetate, ethyl formate, methyl acetate, propyl acetate, butyl acetate and isobutyl acetate; the ethers comprise one or more than two of methyl tert-butyl ether, ethyl tert-butyl ether, methyl tert-amyl ether and methyl isoamyl ether; the nitrile comprises one or more of acetonitrile, propionitrile and butyronitrile;

in the step 3, adding the first refined product of azacitidine into a good solvent for dissolving, wherein the good solvent is DMSO; the poor solvent is C1-4 alcohol, wherein the alcohol comprises one or more of methanol, ethanol, propanol, isopropanol and n-butanol; the volume ratio of the good solvent DMSO to the poor solvent is 1;

in the step 3, the solvent used for pulping comprises one or more than two of methanol, ethanol, propanol, isopropanol and n-butanol; and the volume of the solvent used for pulping is 1-3 times of the volume of the good solvent in the step 2.

2. The method of claim 1, wherein steps 1-3 can be repeated 1-3 times.

3. The method of claim 1, wherein steps 1-3 can be repeated 1 time.

4. The method of claim 1, wherein the mass-to-volume ratio of crude azacitidine to DMSO is 1.

5. The method of claim 1, wherein the mass-to-volume ratio of crude azacitidine to DMSO is 1.

6. The method of claim 1, wherein the temperature for dissolution in step 1 is 20-60 ℃.

7. The method according to claim 4, wherein the temperature for dissolution in step 1 is 20-60 ℃.

8. The method of claim 1, wherein the temperature of dissolution in step 1 is 30-40 ℃.

9. The method of claim 1, wherein the step 2 of obtaining the first refined product further comprises a slow cooling and stirring process.

10. The method of claim 1, wherein the esters comprise one or more of ethyl acetate, methyl acetate, isopropyl acetate, and propyl acetate.

11. The process according to claim 1, wherein the ethers comprise methyl tert-butyl ether.

12. The method of claim 1, wherein the nitrile comprises acetonitrile.

13. The method according to claim 1, wherein in step 2, the volume ratio of the good solvent DMSO to the poor solvent is 1.

14. The method according to claim 1, wherein the first refined product of azacitidine is dissolved in the good solvent at 20-60 ℃ in step 3.

15. The method according to claim 4, wherein the first refined product of azacitidine is dissolved in the good solvent at 20-60 ℃ in step 3.

16. The method according to claim 6, wherein the first refined product of azacitidine is dissolved in the good solvent at 20-60 ℃ in step 3.

17. The method according to claim 1, wherein the first refined product of azacitidine is dissolved in the good solvent at 30-40 ℃ in step 3.

18. The method of claim 14, wherein in step 3, the mass-to-volume ratio of the azacitidine first refined product to the DMSO is 1.

19. The method according to claim 14, wherein in the step 3, the mass-to-volume ratio of the azacitidine first refined product to the DMSO is 1.

20. The method according to claim 1, wherein the poor solvent in step 3 is one or more selected from methanol, ethanol and isopropanol.

21. The method according to claim 20, wherein in the step 3, the volume ratio of the good solvent DMSO to the poor solvent is 1.

22. The method of claim 1, wherein the step 3 of obtaining refined azacitidine further comprises the steps of slowly cooling, filtering, and pulping the filter cake.

23. The method as claimed in claim 22, wherein the step 3 of obtaining refined azacitidine further comprises the steps of slowly cooling, filtering, and pulping the filter cake for 2-4 times.

24. The method according to claim 22, wherein the solvent used for pulping comprises one or more of methanol, ethanol and isopropanol.

25. The method according to claim 24, wherein the volume of the solvent used for the beating is 1-2 times the volume of the good solvent in step 2.

26. The method according to claim 22, wherein the beating temperature is 10-30 ℃ and the beating time is 15-30 minutes.

27. The method according to claim 23, wherein the beating temperature is 10-30 ℃ and the beating time is 15-30 minutes.

28. The method according to claim 24, wherein the beating temperature is 10-30 ℃ and the beating time is 15-30 minutes.

29. The method according to any of claims 22-28, wherein the beating is followed by a vacuum drying process, wherein the drying temperature is between 50 ℃ and 90 ℃.

30. The method according to claim 29, wherein the pulping is followed by a vacuum drying process, wherein the drying temperature is 60 ℃ to 80 ℃; the drying time is 12 to 24 hours.

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