KR102723759B1 - Processes for preparing apixaban - Google Patents

Abstract

The present invention provides a process for preparing apixaban, comprising treating an apixaban-containing reaction mixture with an aqueous NaCl solution, purifying the mixture using a basic ion exchange resin, and crystallizing the mixture using water.

Description

{Processes for preparing apixaban}

The present invention relates to a process for preparing apixaban. More specifically, the present invention relates to a process for preparing apixaban, which comprises treating an apixaban-containing reaction mixture with an aqueous NaCl solution, purifying the mixture using a basic ion exchange resin, and crystallizing the mixture using water.

Apixaban is an anticoagulant represented by the following chemical formula 1, and its chemical name is 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide.

<Chemical formula 1>

Apixaban, sold as Eliquis ^TM Tablets, is an anticoagulant used to prevent and treat blood clots ⁱⁿ patients with nonvalvular atrial fibrillation and to prevent stroke by directly inhibiting factor Xa. In particular, apixaban is used to prevent blood clots after hip or knee replacement surgery and in people with a history of blood clots. Apixaban is used as an alternative to warfarin and does not require monitoring by blood tests or dietary restrictions.

Methods for preparing apixaban are disclosed in various documents, and a representative example is disclosed in US 7,153,960B, which prepares apixaban by reacting ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate, formamide, and sodium methoxide to convert the carboxylic acid ethyl ester into the carboxamide. However, when apixaban is manufactured according to the manufacturing method disclosed in US 7,153,960B, there is a problem in that impurity A (Impurity A, referred to as 'IMP A' below) and impurity B (Impurity B, referred to as 'IMP B' below) are produced together, and unreacted starting material remains in apixaban as impurity C (Impurity C, referred to as 'IMP C' below).

<IMP A>

<IMP B>

<IMP C>

In particular, impurity A (IMP A) is produced by hydrolysis of apixaban and shows a high content of about 8% by HPLC. In order to improve the problem of such a manufacturing method, CN 109400606 B has disclosed a method for purifying apixaban. The method for purifying apixaban disclosed in CN 109400606 B includes the steps of (1) dissolving crude apixaban in a mixed solvent (a mixed solvent of dichloromethane and methanol) to obtain an apixaban solution, (2) mixing the apixaban solution with a basic anion exchange resin and water, and filtering to obtain a filtrate and an adsorption-anion exchange resin, (3) washing the adsorption-anion exchange resin with the mixed solvent (a mixed solvent of dichloromethane and methanol) to obtain a washed anion exchange resin and a washing solution, (4) mixing the filtrate obtained in step (2) and the washing solution obtained in step (3), separating the layers, concentrating the obtained organic phase under reduced pressure, crystallizing with n-hexane, filtering, and drying to obtain apixaban.

However, the purification method of apixaban disclosed in CN 109400606 B requires that the crude apixaban produced in the final step of apixaban synthesis be isolated and used through a separate reaction work-up process. However, the reaction work-up process requires the performance of multi-step unit processes such as precipitation using an antisolvent, filtration, washing, and drying, and therefore has a disadvantage in that the reaction-work-up process and the multi-step purification process must be performed. In particular, the purification method of apixaban disclosed in CN 109400606 B requires the use of n-hexane, which is a water-immiscible organic solvent, in the crystallization step, and therefore has a disadvantage in that it causes environmental pollution due to the use of an organic solvent.

The present inventors have conducted various studies to develop a method for producing apixaban in high yield and high purity, while minimizing the number of unit processes and also producing apixaban in an environmentally friendly manner. The present inventors have discovered that when the reaction mixture obtained in the final stage of apixaban synthesis is treated with an aqueous NaCl solution and then purified using a basic ion exchange resin, not only is there no need to separate crude apixaban, but also crystallization using water is possible, thereby minimizing the number of unit processes and also producing apixaban in an environmentally friendly manner.

Accordingly, the present invention aims to provide a process for preparing apixaban, which comprises treating an apixaban-containing reaction mixture with an aqueous NaCl solution, purifying the mixture using a basic ion exchange resin, and crystallizing the mixture using water.

According to the present invention, a method for preparing apixaban is provided, comprising the following steps:

(a) reacting ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate, formamide, and a base to obtain an apixaban-containing reaction mixture;

(b) a step of adding a mixed solvent of ethanol and dichloromethane to the reaction mixture obtained in step (a), adding an aqueous NaCl solution, and then separating the organic layer;

(c) (c1) a step of mixing the organic layer obtained in step (b) with a basic ion exchange resin and then filtering to obtain a filtrate, or (c2) a step of passing the organic layer obtained in step (b) through a column filled with a basic ion exchange resin to obtain an eluent; and

(d) A step of concentrating the filtrate or eluent obtained in step (c) and then crystallizing it with water.

The reaction of step (a) can be preferably carried out using dichloromethane as a solvent. Additionally, the base can be a methanol solution of sodium methoxide.

The volume ratio of the mixed solvent of ethanol and dichloromethane in step (b) may be in the range of 1:1.5 to 3.5, and the concentration of the NaCl aqueous solution in step (b) may be in the range of 1 to 27 wt%.

The basic ion exchange resin of step (c) can be used in an amount of 3 to 7 parts by weight per 1 part by weight of ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate.

In step (d), the water can be used in an amount ranging from 7 to 12 parts by weight per 1 part by weight of the filtrate or eluent obtained in step (c).

The manufacturing method of the present invention treats the reaction mixture obtained in the final stage of apixaban synthesis with an aqueous NaCl solution and then performs purification using a basic ion exchange resin, thereby minimizing the number of unit processes since there is no need to separate crude apixaban, and apixaban can be manufactured in an environmentally friendly manner since crystallization using water is possible. In particular, the manufacturing method of the present invention can manufacture apixaban with a minimized content of impurities such as IMP A, IMP B, and IMP C in a high yield.

Figure 1 is an HPLC chromatogram of an apixaban-containing reaction mixture obtained by reacting ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate, formamide, and sodium methoxide.
Figure 2 is an HPLC chromatogram of apixaban obtained by the manufacturing method of the present invention.

The present invention provides a process for preparing apixaban comprising the following steps:

(a) reacting ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate, formamide, and a base to obtain an apixaban-containing reaction mixture;

(b) a step of adding a mixed solvent of ethanol and dichloromethane to the reaction mixture obtained in step (a), adding an aqueous NaCl solution, and then separating the organic layer;

(c) (c1) a step of mixing the organic layer obtained in step (b) with a basic ion exchange resin and then filtering to obtain a filtrate, or (c2) a step of passing the organic layer obtained in step (b) through a column filled with a basic ion exchange resin to obtain an eluent; and

(d) A step of concentrating the filtrate or eluent obtained in step (c) and then crystallizing it with water.

In the manufacturing method of the present invention, ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate is an intermediate of apixaban (P-1 intermediate), which can be prepared, for example, according to the method disclosed in US 7,153,960B. The reaction of step (a) is an ammonia decomposition reaction of the P-1 intermediate, which can be carried out by reacting the P-1 intermediate and formamide in the presence of a base, such as sodium methoxide. The formamide and the base can usually be used in an excess amount compared to the P-1 intermediate. For example, the formamide may be used in an amount of 5 to 15 equivalents, preferably 10 to 12 equivalents, relative to 1 equivalent of the P-1 intermediate, and the base may be used in an amount of 1.5 to 3.5 equivalents, preferably 2 to 3 equivalents, relative to 1 equivalent of the P-1 intermediate. The base may preferably be a solution of sodium methoxide in methanol.

It has been found by the present invention that the reaction of step (a) can be preferably performed using dichloromethane as a solvent. When dichloromethane is used as a solvent, the subsequent layer separation process (i.e., step (b)) and crystallization process (i.e., step (d)) can be performed effectively. This is presumed to be because dichloromethane has a relatively low polarity compared to other organic solvents (e.g., dimethylformamide, etc.).

The manufacturing method of the present invention includes a step [i.e., step (b)] of adding a mixed solvent of ethanol and dichloromethane to the reaction mixture obtained in step (a), adding an aqueous NaCl solution, and then separating an organic layer. That is, the manufacturing method of the present invention does not perform a step of isolating crude apixaban from the reaction mixture obtained in step (a). The volume ratio of the mixed solvent of ethanol and dichloromethane may be in the range of 1:1.5 to 3.5, preferably about 1:3, but is not limited thereto. The amount of the mixed solvent of ethanol and dichloromethane used may be in the range of 1.2 to 2 parts by weight based on 1 part by weight of the reaction mixture obtained in step (a). In addition, the concentration of the aqueous NaCl solution may be in the range of 1 to 27 wt%, preferably about 3 wt%, but is not limited thereto. The amount of the NaCl aqueous solution used may be in the range of 0.2 to 1 part by weight relative to 1 part by weight of the reaction mixture obtained in step (a), but is not limited thereto.

The manufacturing method of the present invention includes a purification step [i.e., step (c)] using a basic ion exchange resin. The basic ion exchange resin may be a commercially available conventional basic ion exchange resin, for example, TRILITE ^TM SAR10MBOH (Samyang Corporation), TRILITE ^TM MA-12OH (Samyang Corporation), and preferably TRILITE ^TM SAR10MBOH (Samyang Corporation). The basic ion exchange resin may be used in an amount of 3 to 7 parts by weight, preferably about 5 parts by weight, relative to 1 part by weight of the P-1 intermediate (i.e., ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate).

In one embodiment, the purification step may be performed by mixing the organic layer obtained in step (b) with a basic ion exchange resin, and then filtering to obtain a filtrate. The mixture of the organic layer obtained in step (b) and the basic ion exchange resin may preferably be stirred at room temperature for 0.5 to 1 hour, and then a subsequent filtration process may be performed.

In another embodiment, the purification step can be performed by passing the organic layer obtained in step (b) through a column filled with a basic ion exchange resin to obtain an eluent. The column filled with the basic ion exchange resin can be prepared in the form of a resin tower by filling a conventional column with a basic ion exchange resin. The organic layer obtained in step (b) can be passed through the resin tower prepared as described above by a conventional method.

The manufacturing method of the present invention includes a step of concentrating the filtrate or eluent obtained in step (c) and then crystallizing it with water [i.e., step (d)]. The concentration can be performed according to a conventional method, and can be performed, for example, by concentrating under reduced pressure at about 50°C. If necessary, a step of washing the filtrate or eluent obtained in step (c) with ethanol can be additionally performed before performing the concentration. Since the manufacturing method of the present invention performs crystallization using water, the use of an organic solvent such as n-hexane can be fundamentally avoided. That is, the manufacturing method of the present invention can perform crystallization in an environmentally friendly manner. The amount of water used for the crystallization can be in the range of 7 to 12 parts by weight, preferably 8 to 10 parts by weight, relative to 1 part by weight of the filtrate or eluent obtained in step (c), but is not limited thereto. The crystallization can be performed, for example, by stirring at 50 to 60°C for 1 to 2 hours. After the crystallization process is performed, apixaban can be isolated by conventional methods, such as cooling to about 15°C or lower, filtering, washing, and drying (e.g., drying at 50 to 70°C).

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to illustrate the present invention, and the present invention is not limited to these examples.

Example 1: Preparation and evaluation of apixaban

(1) Preparation of apixaban-containing reaction mixture

A mixture of ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate (5 g), formamide (4.9 ml, 12 eq.), a methanol solution of sodium methoxide (2.3 eq., 4.4 ml), and dichloromethane (25 ml) was reacted under a nitrogen atmosphere for 5 hours.

(2) Apixaban tablets

Ethanol (25 ml) and dichloromethane (50 ml) were added to the reaction mixture obtained in the above (1), and 3% NaCl aqueous solution (25 ml) was added, followed by layer separation. 25 g of a basic ion exchange resin (TRILITE ^TM SAR10MBOH, Samyang Corporation) was added to the separated organic layer, stirred at room temperature for 1 hour, and then filtered. The obtained filtrate was washed with ethanol and concentrated under reduced pressure at about 50°C. Purified water (50 ml) was added to the obtained residue, stirred at 50°C for 1 hour, cooled to 15°C or lower, and filtered. The obtained filtrate was washed with purified water and dried at 70°C to obtain apixaban (4.15 g). (Yield: 90.2%)

(3) Evaluation of apixaban and impurity content by stage

The reaction mixture obtained in the above (1); the residue obtained by concentrating under reduced pressure after treatment with a basic ion exchange resin in the above (2); and apixaban obtained by crystallization using purified water were each diluted with a mixed solvent of water and acetonitrile (50:50, v/v), and the contents of apixaban and impurities were analyzed by HPLC under the following conditions.

<HPLC analysis conditions>

Column: Xbridge Shield RP18, 150mm x 4.6mm, 3.5μm particle size

Moving:

Mobile phase A: Buffer:acetonitrile (90:10)

Mobile phase B: Buffer:acetonitrile (5:95)

(Buffer: 30 mM ammonium acetate aqueous solution)

Measurement wavelength: 280 nm (276-284) Column temperature: 40 ℃

Injection volume: 10 mL

Temperature: 25℃

Flow rate: 1.5 mL/min

The results of analyzing the content of apixaban and impurities as described above are shown in Table 1 below.

IMP A Apixaban IMP B IMP C Reaction mixture obtained in (1) 7.9 91.5 0.04 0.1 Residue obtained by concentrating under reduced pressure after treatment with basic ion exchange resin 1.5 97.9 0.02 0.05 Apixaban obtained by crystallization using purified water 0.2 99.7 0.02 0.01

In addition, the HPLC chromatograms of the reaction mixture obtained in (1) above and apixaban obtained according to the present invention (i.e., apixaban obtained by crystallization using purified water) are as shown in FIG. 1 and FIG. 2, respectively.

Example 2: Preparation and evaluation of apixaban

Ethanol (25 ml) and dichloromethane (50 ml) were added to the reaction mixture obtained in the same manner as in (1) of Example 1, and a 3% NaCl aqueous solution (25 ml) was added, followed by layer separation. A column (inner diameter 2.9 cm, outer diameter 3.5 cm, height: 7.7 cm) was filled with 25 g of a basic ion exchange resin (TRILITE ^TM SAR10MBOH, Samyang Corporation) to prepare a resin tower. The organic layer separated above was passed through the resin tower. The obtained eluent was washed with ethanol and concentrated under reduced pressure at about 50°C. Purified water (50 ml) was added to the obtained residue, stirred at 50°C for 1 hour, cooled to 15°C or lower, and filtered. The obtained filtrate was washed with purified water and dried at 70°C to obtain apixaban (4.30 g). (Yield: 93.5%)

In addition, the apixaban and impurity contents at each step were measured using the same method as (3) of Example 1, and the results are shown in Table 2 below.

IMP A Apixaban IMP B IMP C Reaction mixture obtained in (1) 8.2 91.4 0.06 0.1 Residue obtained by concentrating under reduced pressure after treatment with basic ion exchange resin 2.4 97.2 0.02 0.08 Apixaban obtained by crystallization using purified water 0.8 99.0 0.02 0.07

Comparative Example 1: Performance and Evaluation of Purification Without NaCl Treatment

In Example 1, purification using a basic ion exchange resin and crystallization using purified water were performed without NaCl treatment. Specifically, 25 g of a basic ion exchange resin (TRILITE ^TM SAR10MBOH, Samyang Corporation) was added to the reaction mixture obtained by the same method as (1) of Example 1, stirred at room temperature for 1 hour, and then filtered. The obtained filtrate was washed with ethanol and concentrated under reduced pressure at about 50°C. Purified water (50 ml) was added to the obtained residue, stirred at 50°C for 1 hour, cooled to 15°C or lower, and filtered. The obtained filtrate was washed with purified water and dried at 70°C to obtain a product (product 1).

In addition, in Example 1, purification using a basic ion exchange resin was performed twice without NaCl treatment, and then crystallization using purified water was performed. Specifically, 25 g of a basic ion exchange resin (TRILITE ^TM SAR10MBOH, Samyang Corporation) was added to the reaction mixture obtained in the same manner as (1) of Example 1, stirred at room temperature for 1 hour, and then filtered. To the obtained filtrate, 25 g of a basic ion exchange resin (TRILITE ^TM SAR10MBOH, Samyang Corporation) was added again, stirred at room temperature for 1 hour, and then filtered. The obtained filtrate was washed with ethanol and concentrated under reduced pressure at about 50°C. Purified water (50 ml) was added to the obtained residue, stirred at 50°C for 1 hour, cooled to 15°C or lower, and filtered. The obtained filtrate was washed with purified water and dried at 70°C to obtain a product (product 2).

For the above products 1 and 2, the contents of apixaban and impurities were measured in the same manner as in (3) of Example 1, and the results are shown in Table 3 below.

Imp A Apixaban Imp B Imp C Product 1 6.6 91.8 0.2 0.8 Product 2 6.1 92.9 0.04 0.5

As can be seen from the results in Table 3 above, when purification using a basic ion exchange resin was performed without NaCl treatment, impurities, especially Imp A (apixaban acid), were present in high amounts even when this was performed twice. This is presumed to be because the selectivity of the ion exchange resin for apixaban acid was reduced due to the excessive amount of formamide and sodium methoxide added.

Comparative Example 2: Crystallization and Evaluation Using a Mixed Solvent of Water and a Water-miscible Organic Solvent

Purification was performed using a mixed solvent of water and a water-miscible organic solvent, i.e., a mixed solvent of water and ethanol (5:1, v/v) instead of water as a crystallization solvent. Specifically, 25 g of a basic ion exchange resin (TRILITE ^TM SAR10MBOH, Samyang Corporation) was added to the reaction mixture obtained in the same manner as (1) of Example 1, stirred at room temperature for 1 hour, and then filtered. The obtained filtrate was washed with ethanol, and concentrated under reduced pressure at about 50°C. A mixed solvent of purified water and ethanol (5:1, v/v) (50 ml) was added to the obtained residue, stirred at 50°C for 1 hour, cooled to 15°C or lower, and filtered. The obtained filtrate was washed with purified water, and dried at 70°C to obtain apixaban (4.26 g). (Yield: 92.6%)

In addition, the apixaban and impurity contents at each stage were measured using the same method as (3) of Example 1, and the results are shown in Table 4 below.

IMP A Apixaban IMP B IMP C Reaction mixture obtained in (1) 8.4 91.1 0.03 0.06 Residue obtained by concentrating under reduced pressure after treatment with basic ion exchange resin 1.0 98.8 0.02 0.01 Apixaban obtained by crystallization using a mixed solvent of purified water and ethanol 1.1 98.6 0.02 0.01

From the results in Table 4 above, it can be seen that when crystallization is performed using a mixed solvent of ethanol and purified water, which are representative water-miscible solvents, the yield can be increased, but the removal effect of impurities, especially Imp A (apixaban acid), is significantly reduced.

Claims (7)

(a) reacting ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate, formamide, and a base to obtain an apixaban-containing reaction mixture;
(b) a step of adding a mixed solvent of ethanol and dichloromethane to the reaction mixture obtained in step (a), adding an aqueous NaCl solution, and then separating the organic layer, wherein the concentration of the aqueous NaCl solution is in the range of 1 to 27 wt%;
(c) (c1) a step of mixing the organic layer obtained in step (b) with a basic ion exchange resin and then filtering to obtain a filtrate, or (c2) a step of passing the organic layer obtained in step (b) through a column filled with a basic ion exchange resin to obtain an eluent; and
(d) A step of concentrating the filtrate or eluent obtained in step (c) and then crystallizing it with water.
A method for manufacturing apixaban, comprising: A manufacturing method characterized in that in claim 1, the reaction of step (a) is performed using dichloromethane as a solvent. A manufacturing method according to claim 1, characterized in that the base is a methanol solution of sodium methoxide. A manufacturing method characterized in that in claim 1, the volume ratio of the mixed solvent of ethanol and dichloromethane in step (b) is in the range of 1:1.5 to 3.5. delete A manufacturing method characterized in that in the first paragraph, the basic ion exchange resin of step (c) is used in a range of 3 to 7 parts by weight per 1 part by weight of ethyl 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate. A manufacturing method characterized in that in the first paragraph, the water of step (d) is used in a range of 7 to 12 parts by weight per 1 part by weight of the filtrate or eluent obtained in step (c).