Technical Field

The invention relates to a new production and purification method of polymorphs and solvates of dasatinib.

Background Art

Dasatinib, N-(2-chloro-6-methylphenyl)-2-[[6-[4-(2-hydroxyethyl)- 1 -piperazinyl]-2- methyl-4-pyrimidmyl]amino]-5-thiazole carboxamide of formula I, also known as BMS- 354825, is a cancer treatment drug developed by Bristol-Myers Squibb and sold under the trade name Sprycel®. Dasatinib is a multi- BCR/ABL and Src family tyrosine kinase inhibitor and it is used for treatment of chronic myelogenous leukaemia (CML) as a secondary drug after primary treatment with imatinib (Gleevec®). It is also used for treatment of acute lymphoblastic leukaemia caused by mutation/translocation of chromosomes and development of the so-called Philadelphia chromosome (Ph+ ALL). However, its potential is so wide that the possibility of using it for treatment of other types of cancer, including advanced stages of prostate cancer, is still being investigated.

(I)

In accordance with the basic patent WO2000062778A1, dasatinib is prepared by reaction of the key intermediate of formula II with l-(2-hydroxyethyl)piperazine in the presence of a base and a suitable solvent (Scheme 1). A similar preparation method was later used in a number of other process patents, only varying the corresponding base or solvent. Through the selection of a suitable solvent or procedure a great number of solvates or polymorphs can be prepared. Polymorphs have been one of the most frequently studied physical characteristics of active pharmaceutical substances (API) recently. Thus, different polymorphs of one API may have entirely different physical-chemical properties such as solubility, melting point, mechanical resistance of crystals but they may also influence the chemical and physical stability. Then, these properties may have an impact on further processes such as handling of the particular API, grinding or formulation method. These various physical-chemical characteristics of polymorphs influence the resulting bioavailability of the solid dosage form. Therefore, looking for new polymorphs and solvates is becoming an important tool for obtaining a polymorph form with the desired physical-chemical characteristics.

The process patent WO2005077945A2 describes preparation of the following solvates of dasatinib: monohydrate, butanol solvate, as well as two anhydrous forms (N-6 and T1H1- 7). A related patent also mentions two ethanol solvates, the hemi-ethanol and diethanol solvates (US 8 242 270 B2). Salts, various combinations of salts and their solvates have been described in detail in the patent application WO2007035874A1.

Another process patent, WO2009053854A2, dealt with the preparation of a number of solvates or mixed solvates out of which especially the isopropanol and mixed isopropanol/dimethyl sulfoxide solvates, as well as a new solid form B, another anhydrous polymorph of dasatinib, are worth mentioning. Other patent applications have also dealt with the preparation of other solvates/mixed solvates (WO2010067374A2), or processes for the preparation and purification of the monohydrate/anhydrous form (WO2010139981A2) and its polymorphs (WO2011095059 Al).

API solvates or salts are used in drug formulations in many cases. In the case of solvates the limits for individual solvents, their contents or maximum daily doses have to be strictly observed. Then, these limits can dramatically restrict their effective use. Thus, the clearly most convenient option is the use of sufficiently stable polymorphs of API that do not contain any solvents bound in the crystalline structure.

Some of the above mentioned patent documents describe preparation of a stable anhydrous form of dasatinib (N-6). In accordance with individual patent documents the main disadvantages of the preparation of N-6 is the necessity of desolvation of the solvated form of the API at high temperatures (WO2009053854A2), or application of an increased temperature (50°C and more) and vacuum for a relatively long time (8-12h; WO2010139981A2 and WO2005077945A2). These procedures are very demanding from the point of view of general technology, energy and time, to say nothing of the necessity to work under an inert atmosphere to prevent possible oxidation-degradation reactions of the API. This is because dasatinib may be oxidized by atmospheric oxygen to the corresponding N-oxide (oxidation occurs in the piperazine ring), which may undergo the Cope elimination at increased temperatures. This secondary reaction may subsequently impair the purity of the prepared API.

With a view to the above mentioned facts it is obvious that completely new methods and processes have to be developed even for polymorphs or solvates that are already well- known. Generally, the development of technologically and economically more efficient procedures is the main decisive parameter in their industrial utilization for the preparation of the API.

Disclosure of Invention

The invention relates to a method for the preparation of dasatinib of formula I in the anhydrous form N-6, characterized by the following reflections in an X-ray powder diffraction pattern, measured using the CuKa radiation: 6.8; 12.3; 13.2; 13.8; 16.7; 21.0; 24.3 and 24.8 ± 0.2° 2-theta

a) preparation and isolation of dasatinib in the form of a solvate or unsolvated form; b) dissolution of dasatinib from step a) in a crystallization solvent from the group of lower alcohols;

c) addition of a co-solvent from the group of acetonitrile and propionitrile, or a mixture thereof, and isolation of crystalline dasatinib in the polymorph form N-6.

The preparation method in accordance with the invention is based on the surprising finding that the anhydrous polymorph of dasatinib N-6 can be obtained by re-crystallization of any form of dasatinib from a mixture of a suitable solvent and a suitable co-solvent. This new preparation method of the anhydrous polymorph N-6 differs from the hitherto known procedures by excellent repeatability and, above all, simple execution. Intensive drying (at a high temperature, for a long time, in vacuo) is no longer required and the product aspirated directly after crystallization corresponds, according to the XRPD pattern, to the polymorph N- 6 as described in literature.

Detailed Description of Invention

Dasatinib of formula I is prepared by a reaction of the intermediate of formula II with l-(2- hydroxyethyl)piperazine in the presence of diisopropylethylamine (DIPEA) in an organic solvent from the group of dipolar aprotic solvents, higher alcohols or diols.

If a dipolar aprotic solvent from the group of N-methyl-2-pyrrolidone (NMP), N^iV-dimethyl formamide (DMF), AyV-dimethyl acetamide (DMA), dimethyl sulfoxide (DMSO), formamide (FA), N,N -dimethyl propylene urea (DMPU) and l,3-dimethyl-2-imidazolidinone (DMI) is used, the reaction is carried out at 50-110°C under an inert atmosphere for 1/2-6 hours. In a preferable embodiment, NMP, DMSO, DMPU or DMI is used and the reaction is carried out at 90°C for 1-3 hours. The result of the reaction is crude dasatinib in the form of a solution in the corresponding solvent.

If an alcohol from the group of isoamyl alcohol or 1,3-propanediol is used as a solvent for preparation of the crude dasatinib, the reaction mixture is heated at 120-160°C for 2-12 hours, in a preferable embodiment at 135°C for 3-6 hours.

If dipolar aprotic solvents (NMP, DMF, DMA, DMSO, FA, DMPU and DMI) are used, in step a) a precipitant is added to the hot solution (90°C) under continuous stirring in an inert atmosphere in a 2- 15 fold, most preferably 4-10fold (by volume) amount with respect to the dipolar aprotic solvent. Suitable precipitants comprise especially acetonitrile, propionitrile, most preferably acetonitrile.

After addition of the precipitant the obtained solution is withdrawn from the heating bath and is slowly left to cool down to 22°C under continuous stirring in an inert atmosphere. Crystallization occurs within 1-120 minutes (depending on the volume, until complete cooling). After having cooled down to 22°C (laboratory temperature), the suspension is stirred for another hour. The corresponding solvate of dasatinib is aspirated by well-known techniques in an inert atmosphere at 10-35 °C, most preferably at 22°C, and washed with the respective co-solvent.

The solvate of dasatinib obtained this way can be directly used in the next step - recrystallization, without the necessity of drying. If necessary, the product may be dried at 10- 35°C, most preferably at 25°C, and at the pressure of 10-200 kPa, most preferably 50 kPa, for 6-24 hours, most preferably 12 hours.

If NMP is used as the solvent in step a), the corresponding NMP solvate is isolated. The obtained dried crystalline NMP solvate (NM) of dasatinib has a characteristic XRPD pattern, which is presented in Figure no. 1. The NMP solvate (NM) has the following characteristic peaks: 5.88; 6.73; 10.73; 11.92; 13.39; 14.97; 16.72; 18.95; 20.17; 21.46; 22.81; 24.65; 25.18; 26.02 and 28.06 ± 0.2° 2-theta.

If isoamyl alcohol or 1,3-propanediol are used as the solvents in step a), the reaction mixture is left to cool down to 22°C after expiration of the reaction time (3-6 h). Crystallization generally begins when the inner temperature of the reaction mixture drops to 100°C. After cooling down to 22°C (laboratory temperature), the suspension is further stirred for another 1 hour. Crystalline dasatinib is aspirated by well-known techniques in an inert atmosphere at 10-35°C, most preferably at 22°C, and washed with the corresponding solvent.

The obtained product is dried at 10-35°C, most preferably at 25°C, and at the pressure of 10-200 kPa, most preferably 50 kPa, for 6-24 hours, most preferably 12 hours.

The obtained crystalline isoamyl alcohol solvate (SI) of dasatinib has a characteristic XRPD pattern, which is shown in Figure no. 2. The solvate (SI) has the following characteristic peaks: 5.72; 10.35; 11.42; 12.61; 13.14; 14.27; 15.33; 17.18; 17.44; 17.97; 19.12; 19.95; 20.38; 22.05; 22.42; 23.01; 23.46; 23.68; 25.26; 26.20; 26.45; 26.62 and 27.78 ± 0.2° 2-theta.

The obtained crystalline 1,3-propanediol solvate (SP) of dasatinib has a characteristic XRPD pattern, which is shown in Figure no. 3. The solvate (SP) has the following characteristic peaks: 6.04; 12.01; 15.10; 17.95; 18.35; 18.77; 21.25; 21.51; 22.96; 24.08; 24.62; 25.80; 26.16; 28.16 and 33.6578 ± 0.2° 2-theta.

These solvates (or polymorph forms) are then easily converted to the desired anhydrous polymorph N-6 or another solvate in steps b) and c). All the forms prepared this way are sufficiently stable and can easily be isolated in the chemical purities of 99% and higher (in accordance with HPLC).

The anhydrous polymorph form N-6 is prepared in the following way: any solvate or another polymorph is dissolved under an inert atmosphere at 90°C (reflux) in a 10-30 times, most preferably 20 times, the (weight) amount of the crystallization solvent. Suitable crystallization solvents include especially methanol, ethanol, isopropanol, most preferably methanol.

A co-solvent is added in 0.1-10 times, most preferably ½-l times, the volume of the crystallization solvent used in an inert atmosphere at 90°C. The co-solvent can be, e.g., acetonitrile, propionitrile and their mixtures, most preferably acetonitrile. After addition of the co-solvent the obtained solution is withdrawn from the heating bath and is slowly left to cool down to 22°C under continuous stirring in an inert atmosphere. Crystallization occurs during 1-120 minutes (depending on the volume, until complete cooling). After having cooled down to 22°C (laboratory temperature), the suspension is stirred for another hour. Crystalline dasatinib is aspirated by well-known techniques in an inert atmosphere at 10-35°C, most preferably at 22°C, and washed with the corresponding co-solvent. The chemical purity of the obtained product is 99% (in accordance with HPLC); it is the polymorph form N-6 and its XRPD pattern is shown in Figure no. 4. The polymorph form N-6 has the following characteristic peaks: 6.77; 12.31; 13.16; 13.75; 16.70; 17.20; 18.54; 19.34; 20.25; 20.95; 21.94; 24.28; 24.82; and 27.80 ± 0.2° 2-theta.

Brief Description of Drawings:

Figure 1: shows an X-ray powder diffraction pattern of the crystalline solvate NM. Individual axes: independently variable: reflection angle 2Θ, dependently variable: intensity of detected radiation.

Figure 2: shows an X-ray powder diffraction pattern of the isoamyl alcohol crystalline solvate SI. Individual axes: independently variable: reflection angle 2Θ, dependently variable: intensity of detected radiation. Figure 3: shows an X-ray powder diffraction pattern of the 1,3 propanediol crystalline solvate SP. Individual axes: independently variable: reflection angle 2Θ, dependently variable: intensity of detected radiation.

Figure 4: shows an X-ray powder diffraction pattern of the crystalline anhydrous form N-6. Individual axes: independently variable: reflection angle 2Θ, dependently variable: intensity of detected radiation.

Examples: The following working examples illustrate methods for the preparation of dasatinib of formula I, its polymorph form N-6 and its solvates NM, SI, SP.

The polymorph forms and solvates of dasatinib were characterized with X-ray powder diffraction using the following methods:

The diffraction patterns were measured using an X'PERT PRO MPD PANalytical diffractometer with a graphite monochromator, radiation used CuKa (λ=1.542 A), excitation voltage: 45 kV, anode current: 40 mA, measured range: 2 - 40 ^° 2Θ, increment: 0.01° 2Θ. The measurement was carried out using a flat powder sample that was placed on a Si plate. For the primary optic setting programmable divergence diaphragms with the irradiated sample area of 10 mm, Soller diaphragms 0.02 rad and an anti-dispersion diaphragm ¼ were used. For the secondary optic setting an X'Celerator detector with the maximum opening of the detection slot, Soller diaphragms 0.02 rad and an anti-dispersion diaphragm 5.0 mm were used. HPLC method:

Stock solution of samples: dissolve 5.0 mg of the sample in 10.0 ml of 50% acetonitrile R with water.

Dimensions of the chromatographic HPLC column: / = 0.10 m, d= 3 mm

- stationary phase: Zorbax Eclipse Plus Phenyl-Hexyl RRHD 1.8 μιη; temperature: 35 °C. Mobile phase: A: phosphate buffer (0.01 M sodium dihydrogen phosphate, pH treated by addition of sodium hydroxide to 7.00 ± 0.05); B: acetonitrile R.

Gradient (A/B; flow 0.6 ml/min): 0 min 80/20; 10 min 50/50; 11 min 50/50; 12 min 80/20. Detection at the wavelength of 220 nm.

Feed: 2 μΐ of the sample stock solution Example 1.

Preparation of the NMP solvate (NM) of dasatinib:

The intermediate of formula II (1.00 g; 2.54 mmol) and l-(2-hydroxyethyl)piperazine (1.66 g; 12.77 mmol) were dissolved in N-methylpyrrolidone (5 ml) under an inert atmosphere and diisopropylethylamine (0.9 ml, 5.18 mmol) was added to the reaction mixture. The reaction mixture was stirred and heated up to 90°C for 70 minutes and then acetonitrile (30 ml) was added to the reaction. The mixture was withdrawn from the heating bath and stirred intensively. Crystallization started after 5 minutes, the suspension was left to cool down under continuous stirring. After achieving the laboratory temperature it was stirred for another 2 hours. The crystalline substance was aspirated on frit S3, washed with acetonitrile (5 ml) and dried by suctioning under an inert nitrogen atmosphere for 15 minutes. The XRPD pattern of the sample obtained this way corresponds to the NMP solvate (NM) and can be used in the subsequent steps without the necessity of drying. Drying after 6 hours in an exsiccator at the laboratory temperature in vacuo (50 kPa) provided 1.2 g of crystalline dasatinib; 80% of the theoretical yield. HPLC purity 99.12%. The 1H NMR and ¹³ C NMR spectra correspond to the data known from the literature. The XRPD pattern of the dried product corresponds to the NMP solvate (NM). The NM solvate is characterized by the reflections presented in Table 1 :

Table 1 - NM form

interplanar

pos. distance

[°2Th.] [nm] rel. int. [%]

5.88 1.5024 81.8

6.73 1.3131 100.0

10.73 0.8236 10.6

11.92 0.7420 59.2

13.39 0.6606 19.6

14.97 0.5915 38.4

16.72 0.5298 45.0

18.95 0.4679 10.9

20.17 0.4399 13.9

21.46 0.4138 13.4

22.81 0.3895 21.0

24.65 0.3608 13.3

25.18 0.3534 14.4

26.02 0.3422 11.9

28.06 0.3177 5.8 Example 2.

Preparation of the DMF solvate of dasatinib:

The intermediate of formula II (0.50 g; 1.27 mmol) and l-(2-hydroxyethyl)piperazine (0.8 g; 6.15 mmol) were dissolved in DMF (2.5 ml) under an inert atmosphere and diisopropylethylamine (0.45 ml, 2.59 mmol) was added to the reaction mixture. The reaction mixture was stirred and heated up to 90°C for 3 hours; then the reaction was terminated by addition of acetonitrile (15 ml). The mixture was withdrawn from the heating bath and stirred intensively. Crystallization started after 1 minute, the suspension was left to cool down under continuous stirring. After achieving the laboratory temperature it was stirred for another 2 hours. The crystalline substance was aspirated on frit S3, washed with acetonitrile (10 ml) and dried in an desiccator at the laboratory temperature in vacuo (50 kPa) for 6 hours. The yield was 0.52 g; 73% of the theoretical yield. HPLC purity 98.12%. The XRPD patterns before and after drying in the exsiccator correspond to the DMF solvate known from literature (WO2009053854A2).

Example 3.

Preparation of the DMSO solvate of dasatinib:

The intermediate (II) (0.50 g; 1.27 mmol) and l-(2-hydroxyethyl)piperazine (0.8 g; 6.15 mmol) were dissolved in DMSO (2.5 ml) under an inert atmosphere and diisopropylethylamine (0.45 ml) was added to the reaction mixture. The reaction mixture was stirred and heated up to 90°C for 3 hours and then the reaction was terminated by addition of acetonitrile (15 ml). The mixture was withdrawn from the heating bath and stirred intensively. Crystallization started after 3 minutes, the suspension was left to cool under continuous stirring. After achieving the laboratory temperature it was stirred for another 2 hours. The crystalline substance was aspirated on frit S3, washed with acetonitrile (15 ml) and dried in an desiccator at the laboratory temperature in vacuo (50 kPa) for 6 hours. The yield was 0.48 g; 67% of the theoretical yield. HPLC purity 99.20%. The XRPD patterns before and after drying in the exsiccator correspond to the DMSO solvate known from literature (WO2009053854A2). Example 4.

Preparation of the isoamyl alcohol solvate (SI) of dasatinib:

The intermediate of formula II (0.42 g; 1.07 mmol), l-(2-hydroxyethyl)piperazine (0.8 g; 6.15 mmol) and diisopropylethylamine (0.38 ml, 2.18 mmol) were suspended in isoamyl alcohol (7 ml) under an inert atmosphere. The reaction mixture was stirred and heated up to 140°C for 6 hours. The reaction mixture was withdrawn from the heating bath and stirred intensively. Crystallization started at the inner temperature of 95°C, the suspension was left to cool under continuous stirring. After achieving the laboratory temperature it was stirred for another 2 hours. The crystalline substance was aspirated on frit S3, washed with isoamyl alcohol (7 ml) and dried at the laboratory temperature in vacuo (2.5 kPa) for 5 hours. The yield was 0.5 g; 81% of the theoretical yield. HPLC purity 99.10%. The XRPD pattern corresponds to the isoamyl alcohol solvate (SI). The SI solvate is characterized by the reflections presented in Table 2:

Table 2 - SI solvate

Example 5.

Preparation of the 1 ,3 -propanediol solvate (SP) of dasatinib:

The intermediate of formula II (0.25 g; 0.63 mmol), l-(2-hydroxyethyl)piperazine (0.42 g; 3.23 mmol) and diisopropylethylamine (0.22 ml, 1.26 mmol) were suspended in 1,3- propanediol (3 ml) under an inert atmosphere. The reaction mixture was stirred and heated up to 140°C for 3 hours. The reaction mixture was withdrawn from the heating bath and stirred intensively. The suspension was left to cool under continuous stirring. After achieving the laboratory temperature it was stirred for another day. The crystalline substance was aspirated on frit S3, washed with 1,3 -propanediol (6 ml), acetone (5 ml) and dried with a stream of nitrogen for 30 minutes. The yield was 0.1 g; 28% of the theoretical yield. HPLC purity 99.43%. The XRPD pattern corresponds to the 1,3 -propanediol solvate (SP). The SP solvate is characterized by the reflections presented in Table 3:

Table 3 - SP solvate

Recrystallization of dasatinib: Example 6.

Preparation of the N-6 anhydrous form of dasatinib:

Any solvate of dasatinib (0.4 g, obtained in accordance with Example 1, or 2, 3, 4 or 5, respectively) was dissolved in MeOH (8 ml) under boiling; the mixture was stirred in an inert atmosphere for 5 minutes. Acetonitrile (4 ml) was added under continuous stirring and under boiling in an inert atmosphere. The clear solution was withdrawn from the heating bath, stirred intensively and left to cool under continuous stirriiig. After achieving the laboratory temperature the resulting suspension was stirred for another hour. The crystalline substance was aspirated on frit S3 and washed with acetonitrile (4 ml). The XRPD pattern of the undried sample obtained this way corresponds to the polymorph anhydrous form N-6. Drying at the laboratory temperature in vacuo (50 kPa) for 3 hours provided 0.3 g of crystalline dasatinib; 90% of the theoretical yield. HPLC purity 99.70%. The XRPD pattern corresponds to the polymorph anhydrous form N-6. The 1H NMR and ¹³ C NMR spectra correspond to data known from literature. The N-6 form is characterized by the reflections presented in Table 4:

Table 4 -N-6 form.

Example 7.

Preparation of the IBMK solvate of dasatinib:

Any solvate of dasatinib (0.85 g, obtained in accordance with Example 1, or 2, 3, 4 or 5, respectively) was suspended in boiling IBMK (20 ml) and boiling was maintained under an inert atmosphere for 15 minutes. The suspension was withdrawn from the heating bath, intensively stirred and left to cool under continuous stirring. After achieving the laboratory temperature (20 minutes) the solvent was aspirated using an adapter for return filtration. The remaining crystalline substance was again overlayered with IBMK (20 ml), the suspension was brought to boil and heated up and stirred intensively for 15 minutes. The suspension was withdrawn from the heating bath, stirred intensively and left to cool under continuous stirring. After achieving the laboratory temperature the crystalline substance was aspirated on frit S3, washed with IBMK (5 ml) and dried at the laboratory temperature in vacuo (50 kPa) for 12 hours. The yield was 0.70 g. HPLC purity 99.54%. The XRPD pattern corresponds to the IBMK solvate known from literature (WO2009053854A2). Example 8.

Preparation of the N-6 anhydrous form of dasatinib:

The IBMK solvate of dasatinib (0.4 g, 0.68 mmol; obtained in accordance with Example 7) was dissolved in a boiling mixture of MeOH (6 ml), acetonitrile (3 ml) in an inert atmosphere. Active carbon was added, the suspension was heated up to boil. After 5 minutes the hot solution was filtered through a Seitz filter, the filtration cake was washed with a hot mixture of MeOH/acetonitrile (3 ml, 2:1). The clear filtrate was stirred and left to cool under continuous stirring for 90 minutes. The crystalline substance was aspirated on frit S3, washed with 3 ml of acetonitrile. The XRPD pattern of the undried sample obtained this way corresponds to the N- 6 polymorph anhydrous form. Drying at the laboratory temperature in vacuo (50 kPa) for 12 hours provided 0.22 g pf crystalline dasatinib; 66% of the theoretical yield. HPLC purity 99.90%. The XRPD pattern corresponds to the N-6 polymorph anhydrous form.