WO2015062560A1

WO2015062560A1 - An industrially applicable process for preparing high purity aclidinium bromide

Info

Publication number: WO2015062560A1
Application number: PCT/CZ2014/000123
Authority: WO
Inventors: Igor CERNA; Josef Hajicek
Original assignee: Zentiva KS
Current assignee: Zentiva KS
Priority date: 2013-10-29
Filing date: 2014-10-29
Publication date: 2015-05-07
Anticipated expiration: 2016-04-29
Also published as: CZ306791B6; CZ2013827A3; WO2015062560A9; HUP1600350A2; CN105683186A

Abstract

An efficient and industrially applicable process for preparing aclidinium bromide of formula I, comprising the following steps a) preparation of the quinuclidinyl ester by transestenfication of methyl di(2-thienly)giycolate with R-(-)-3-quinuclidinol in the presence of a sterically hindered base in an inert solvent; b) isolation of the quinuclidinyl ester; and c) quaternization of the quinuclidinyl ester by 3-phenoxypropyl bromide in a suitable solvent.

Description

An industrially applicable process for preparing high purity aclidinium bromide

Technical Field

The invention relates to an efficient and industrially applicable process for preparing aclidinium bromide of formula I. The new process is focused on applicability of the process in industrial-scale synthesis. In addition, the newly developed process results in elimination of the formation of impurities and thus to preparation of the API with high purity, complying with high requirements for purity in pharmaceutical production.

I

Aclidinium bromide

Background Art

Aclidinium bromide of structure I is the name for (3R)-3-{[hydroxy{di-2- thienyl)acetyl]oxy}-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]acetate bromide. Aclidinium bromide, first described in document WO0104118 by Almirall, is a selective antagonist of cholinergic receptors with a long-term effect on M₃ receptors. It has significant bronchodilatory effects. It is used for treatment of the chronic obstructive pulmonary disease (COPD). The therapeutic dosage of the active substance is low (400 pg), in the form of powder, which is applied by means of an inhalation device. Aclidinium bromide is a promising successor of Tiotropium bromide as with the same bronchodilatory effect is exhibits fewer side effects.¹ Synthesis of aclidinium bromide described in document WO0104118 formally includes two steps: preparation of (3R)-1-azabicyclo[2.2.2]oct-3-yl ester of 2,2-dithienyl-glycolic acid of structure V (hereinafter the quinuclidinyi ester) and subsequent quaternization of the adduct V in the presence of an excess of 3-phenoxypropyl bromide.

The process for preparing the quinuclidinyi ester V in accordance with document WO0104 18 is shown in Scheme 1. It starts with oxothien-2-yl acetic acid, which has been converted to the acyl chloride by reaction with oxalyl chloride and subsequently substituted with R-(-)-3-quinuclidinol {(3R)-1-azabicyclo[2.2.2]octan-3-ol}, producing the adduct IV. This further reacts with 2-thienylmagnesium bromide in THF. The total yield of this medicinal two-step preparation of the quinuclidinyi ester V was only 25%.

Scheme 1

NEt^ PS-DMAP, 7G°C

45%

The alkylation of the quinuclidinyi ester V (Scheme 2) was carried out in a mixture of the solvents acetonitrile and chloroform, in the presence of a high excess of the alkylation agent (5 equivalents of 3-phenoxypropyl bromide). The reaction mixture was agitated at 23°C for 72 hours in an inert atmosphere. After completion of the period the reaction mixture was concentrated at a reduced pressure. The evaporation product was suspended in ether, filtered, washed with ether, which provided the product aclidinium bromide in the yield of 90% and the melting point of 227X. No information about the crystalline form of aclidinium bromide prepared this way has been mentioned. Scheme 2

Aclidinium bromide

The last step was later improved and described in the process patent EP2044067, wherein a ketone or cyclic ether was selected as the solvent instead of the mixture of chloroform and acetonitrile. The reaction was also carried out with a lower excess of the alkylation agent (1.1-1.5 equivalents), but at an increased temperature (boiling point of the solvent). In some cases (acetone, THF, dioxan), these changes have led to a reduction of the potential genotoxic impurity (amount of 3-phenoxypropyl bromide in the final API: 117 ppm when reproducing the process of the basic document WO0104118 as compared 60 ppm when using the conditions of the process patent EP2044067).

Patent application WO2004096800 describes a different procedure for preparing the quinuclidinyl ester V (Scheme 3). It consists in transesterification of the 2,2-dithienyl- glycolic acid methyl ester of formula VI with R-(-)-3-quinuclidinol of formula III in toluene in the presence of sodium in the stoichiometric amount as the base. The reaction mixture was agitated in an inert atmosphere of argon at 85°C for 4 hours, the solvent being systematically removed by distillation. The crude evaporation product was dissolved in DCM (dich!oromethane) and washed with a solution of sodium hydrogen carbonate, the organic phase was concentrated after drying and the resulting brown oil was triturated with acetonitrile. No yield is given for this method; in addition, the use of metallic sodium as the base, of a chlorinated solvent for extraction and triturating as the final purification method are not suitable solutions for synthesis in the industrial scale. Scheme 3

In addition, in J. Med. Chem, 2009, 52, 5076-5092, a method of transesterification of the 2,2-dithienyl-glycolic acid methyl ester of formula VI with R-(-)-3-quinuclidinol of formula III was published, wherein sodium hydride (60% suspension in mineral oil) in a sub-stoichiometric amount was selected as the base (Scheme 4). The reaction was carried out in toluene under boiling and with parallel removal of the solvent by azeotropic distillation and replenishment of fresh toluene for 1.5 hours. Then, acid- base extraction and final crystallization from diisopropyl ether followed. The yield of the described preparation method of the quinuclidinyl ester V was 50%. The subsequent alkylation was carried out in accordance with the process of the document WO0104118. A similar method of preparing the quinuclidinyl ester V was also described in patent application WO2009139710.

Scheme 4

Patent application EP2130830 describes transesterification of the 2,2-dithienyl- glycolic acid ethyl ester with f?-(-)-3-quinuciidinol of formula III in an excess of sodium ethanolate (1.2 equivalents) as the base in a small scale (0.6 mmol). Sodium ethanolate, as specified in the application, must be fresh, prepared just before the reaction itself. The reaction was carried out in dry toluene and under the inert argon atmosphere. The reaction temperature starts at 70°C and is gradually increased to the internal temperature of up to 115°C. Subsequently, the reaction mixture was cooled, diluted with an organic solvent, washed with water and then with a 1N solution of methanesulfonic acid. Then, the aqueous phase was alkalinized at 0°C using a saturated solution of potassium carbonate and extracted with ethyl acetate. The organic layer was washed again with water and brine, dried and concentrated at a reduced pressure, the result of which was the crude product with unknown purity in the yield of 60%.

The above mentioned account of methods of preparation of both the intermediate hygroscopic strong bases (sodium, sodium hydride, sodium ethoxide) are used, mostly in the stoichiometric amount, are used for the transesterification. In turn, except the process patent EP2044067, a high excess of the alkylation agent, long reaction times or chlorinated solvents are inconveniently used for the alkylation of the quinuc!idinyl ester V.

Disclosure of Invention

The invention relates to an efficient and industrially applicable process for preparing of aclidinium bromide of formula I, which comprises the following steps: a) preparation of the highly pure quinuclidinyl ester of formula V

transesterification of methyl di(2-thienyl)glycolate of formula VI with R-(-)-3- quinuclidinol of formula III

VI III in the presence of a sterically hindered base selected from the group of alkali salts of a sterically branched C3 to C5 alkoxide in an inert solvent, b) isolation of the quinuclidinyl ester of formula V c) quaternization (alkylation) of the quinuclidinyl ester of formula V by 3- phenoxypropyl bromide in a suitable solvent, producing aclidinium bromide in high purity. The new synthesis process of aclidinium bromide I is shown in Scheme 5 below. Scheme 5

Aclidinium bromide Widespread experiments have surprisingly shown that the most suitable bases for the transestenfication reaction are sterically hindered bases. Unlike the other bases used in the prior art (Na, NaH, NaOEt), these sterically hindered bases represent an advantage, especially due to elimination of the formation of side products and impurities, the latter being associated with the necessity of using a strong base. One of the side products accompanying the use of a sterically unhindered strong base is di(2-thienyl)glycolic acid VII generated by hydrolysis of methyldi(2-thienyi)glycofate VI.

VII

Di(2-thienyl)giycolic acid VII is subsequently a non-reactive partner in the esterification by the alcohol III under strongly basic conditions. Suitable solvents for the transestenfication reaction comprise toluene, xylene, THF, MeTHF and cyclopentyl methyl ether. In a preferable embodiment, 2-methyl tetrahydrofuran (MeTHF) was used as the solvent for the transestenfication. The optimum reaction temperature was 80°C (temperature of the reaction mixture 70°C), the sterically hindered base being fed as a 2M solution in MeTHF at 35°C. The side product of the reaction (methanol) is removed concurrently from the reaction mixture by azeotropic distillation at the atmospheric or reduced pressure (50 kPa to 30 kPa). For processing of the reaction an acid-base extraction was selected. After completion of the reaction time the reaction mixture was cooled down and mixed with a 2M aqueous solution of HCI. For better separation the reaction mixture was diluted with ethyl acetate. The aqueous phase was alkalinized with a 2M aqueous solution of Na₂C0₃ and the quinuclidinyl ester V was extracted with dichloromethane. After evaporation of the solvent the crude product was re-crystallized from acetonitrile.

As suitable sterically hindered bases, especially sodium and potassium fert-butoxides were investigated, which are relatively well soluble in organic solvents (e.g. THF, MeTHF, cyclopentyl methyl ether), are commercially available (also as a solution: 1M or 2M solutions of tert-butoxide in THF), and are also technologically acceptable due to good physical and chemical properties.

Table 1 summarizes the results of transesterification optimization with the use of sodium and potassium fert-butoxides as the sterically hindered base (Scheme 6). Scheme 6

Table 1 after final crude

reaction crystallization experiment tBuOX/equiv. extraction product crystallization

time

with yield/purity yield/purity

1 tBuOK/0.5 1.5h DCM 53%/97.4% MeCN 39%/99.5%

2 tBuONa/0.5 1.5h DCM 53%/99.1% MeCN 48%/99.5%

3 tBuONa/0.5 2.5h DCM 56%/85.8% MeCN 31 %/96.3% 4 tBuONa/0.5 3.5h DCM 50%/88.0% MeCN 32%/99.6%

5 tBuONa/0.5 1.5h CHCi₃ 62%/99.8% -

6 tBuONa/1 1.5h CHCI₃ 70%/99.8%

7 tBuONa/1.5 1 h CHCI3 67%/99.7% -

8 tBuONa/1 2.5h MeTHF 75%/99.0% MeTHF 60%/99.9%

9 tBuONa/1 2.5h EA 74%/99.3% EA 56%/99.9%

Suitable solvents for the final extraction of the product (quinuclidinyl ester V) comprise especially dichloromethane, chloroform, MeTHF, cyclopentyl methyl ether, ethyl acetate or isopropyl acetate. Experiments 1 and 2 (Table 1 ) describe the use of sodium and potassium ie/f-butoxides in the stoichiometric amounts, the yield of the reaction being 53% in both cases, but in using sodium iert-butoxide the crude product was isolated in higher purity. Then, we focused on the possibility of increasing the conversion of the reaction by extending the reaction time (experiments 3 and 4), wherein extension by one hour only resulted in a slightly better yield. However, lower purities of the crude products were surprising. A GCMS (gas chromatography) analysis and subsequently also independent synthesis identified a characteristic impurity whose formation was observed in the mixture besides the desired product V. The identified impurity was (3/?)-3-{[hydroxy(di-2-thienyi)acetyl]oxy}-1-(chloromethyl)- 1-azoniabicyclo[2.2.2]acetate chloride of formula VIII,

which was the product of /V-alkylation of the quinuclidinyl ester V by dichloromethane (antecedent for /V-alkylation of amines with methylene chloride in literature: J.Org.Chem. 1987, 52, 9, 1857-1859). The only case where the reaction mixture was in contact with dichloromethane was the final extraction. This means that the quinuclidinyl ester V reacts with dichloromethane very readily even when the solution is just left to stand for some time at the room temperature.

Thus, DCM was completely excluded from the preparation process of the quinuclidinyl ester V for the subsequent experiments.

The comparative experiment 5, where dichloromethane as the extraction solvent was replaced by the more internal chloroform (selected for excellent solubility of the product V in chlorinated solvents) illustrates the increase of purity and yield. A comparison of experiments 2 and 5 shows not only the improvement of the reaction yield, but also of the product purity (yield/purity=53%/99.1 %->62%/99.8%).

Further, we also investigated the influence of the base used on the reaction conversion. A reaction in the presence of the stoichiometric amount of sodium tert- butoxide resulted in an 8% increase of the conversion (experiment 6; 70%). Further increasing of the amount of the base (1.5 equivalents) had a rather negative effect on the reaction yield (experiment 7; 67%).

High toxicity of chloroform (the concentration limit in pharmaceutical products is 60ppm) and the risk of /V-alkylation of the quinuclidinyl ester V by chlorinated solvents finally led to a change of the solvent for the final extraction. Based on an investigation of solubility of the quinuclidinyl ester V in various solvents and with regard to the physical-chemical properties of the investigated solvents 2-methyltetrahydrofuran (MeTHF) and the acetic acid ethyl ester were selected as the most suitable candidates for the final extraction of the product V (experiments 8 and 9). In a preferable embodiment, MeTHF was used for the final extraction. The lower solubility of the product V in 2-methyltetrahydrofuran and ethyl acetate as compared to chloroform or dichloromethane was simply compensated by increasing of the temperature of the mixture during the extraction.

Acetonitrile, ethyl acetate, tetrahydrofuran or 2-methyltetrahydrofuran, cyclopentyl methyl ether and their mixtures, in a preferable embodiment acetonitrile, ethyl acetate or 2-methyltetrahydrofuran, were used as suitable solvents for the crystallization. In a most preferable embodiment, MeTHF was subsequently used also for the crystallization. After the extraction the organic phase was dried (removal of the mixture of water and the selected solvent by azeotropic distillation or use of Na2SC>4), concentrated by removal of the excessive solvent by distillation and left to crystallize. In both cases an excellent result was achieved, wherein the crude product was isolated in an excellent yield of 74-75% and excellent purity of 99%. After re- crystallization a nearly 100% pure product was obtained (experiments 8 and 9).

The second step of the synthesis of aclidinium bromide was alkylation of the quinuclidinyl ester V by 3-phenoxypropyl bromide (Scheme 7). As mentioned in the prior art, alkylation of the quinuclidinyl ester V (Scheme 2), described in document WO0104118, was carried out in a mixture of the solvents acetonitrile and chloroform, in the presence of a high excess of the alkylation agent (5 equivalents of 3- phenoxypropyl bromide). The use of a high excess of the alkylation agent as a potential genotoxic impurity in the final step is not a suitable solution. Similarly, one could speculate about the use of chloroform as the solvent in the final step. On the one hand, there is a real risk of formation of the impurity VIII and, moreover, chloroform belongs to the group of solvents whose use in pharmaceutical products is limited and amounts strictly controlled (the concentration limit is 60ppm).

It has been surprisingly found out that a similar reaction can also be carried out solely in acetonitrile. Thus, we eliminated the use of chloroform in our process. The reaction was carried out in acetonitrile only and, in addition, the amount of 3-phenoxypropyl bromide was reduced to 1.25 equivalents with respect to the quinuclidinyl ester V. While this process required the use of more vigorous conditions (the reaction is conducted under boiling of the solvent for 2.5 to 4 hours), which, however, did not have any negative impact on the purity of the final product (Table 2, experiment 13). The polymorphy of the final product was also studied. It has been found out that the above mentioned change of conditions had no impact on the formation of the crystalline form. The crystalline form obtained by the process 13 was identical to that which was produced by the preparation aclidinium bromide mentioned in document WO0104118 (Example 44, page 40). For comparison, three independent experiments of reproducing the process of Example 44 of document WO0104118 have been conducted (Table 2, Experiments 10-12*). In comparison of the powder diffraction patterns it is clear that the same crystalline form of aclidinium bromide, hereinafter Scheme 7

Aclidinium bromide

Table 2

*Reference examples in accordance with the process in document WO0104118

In order to verify this two-step preparation process of aclidinium bromide at a larger scale the process was applied in a synthesis of a 50g batch of aclidinium bromide. By the use of the optimized process developed crystalline aclidinium bromide of Form 1 was prepared in the total yield of 57% after the two steps and the excellent purity of 99.96%.

General description of the invention, definitions of terms and specifications of individual steps that illustrate the process improvement in accordance with the invention: The sterically hindered base means a sterically hindered alkoxide in the form of a salt with an alkali metal such as ferf-butoxide, ferf-pentoxide, amoxide and isopropoxide. In a preferable embodiment the sodium or potassium salt of terf-butoxide was used, most preferably sodium ferf-butoxide.

The transesterifioation was carried out in an inert organic solvent such as aromatic hydrocarbons and cyclic ethers, especially toluene, xylene, tetrahydrofuran, 2- methyltetrahydrofuran (MeTHF), cyclopentyl methyl ether or their mixtures, in a preferable embodiment in 2-methyltetrahydrofuran.

For the reaction 1-1.2 equivalents of R-(-)-3-quinucIidinol III were used per mole of methyl di(2-thienyl)glycolate VI, in a preferable embodiment 1.15 equivalents of HI.

The reaction was carried out by slow addition of the base to an agitated solution of the starting compounds III and IV in a suitable solvent. The base was added dropwise as a solution of the base in a suitable solvent; preferably a 1 M solution of sodium tert- butoxide in 2-methyltetrahydrofuran is used. The base was added at a temperature of 30 to 50°C, in a preferable embodiment at 35°C.

The reaction itself was conducted in the temperature range of 55 to 90°C, preferably at 75°C and at the pressure range of 101 kPa to 40 kPa, methanol being periodically removed from the reaction mixture by distillation, for 1 to 4 hours, preferably for 2.5 hours or less.

The isolation in step b) means admixing of an aqueous solution of an inorganic acid to the reaction mixture cooled to a temperature of 22 to 26°C. In a preferable embodiment hydrochloric acid, or its aqueous solution, was used as the inorganic acid. For better separation the reaction mixture can be diluted with a solvent suitable for washing of the reaction mixture and removal of undesired impurities. A suitable washing solvent was ethyl acetate, heptane or toluene. By separation of the aqueous phase containing the quinuclidinyl ester of formula V in the form of a salt most of the organic impurities were removed (as the unreacted residues of the starting compounds).

The aqueous layer containing the salt of the quinuclidinyl ester of formula V was alkalized with a suitable base to pH in the range of 8 to 11 , preferably 10. Suitable bases comprise especially inorganic bases of the NaOH, KOH, LiOH, K2CO3, of sodium carbonate is used. The product was subsequently finally extracted with an extraction solvent (final/last extraction) from the group of ethyl acetate, tetrahydrofuran, 2-methyltetrahydrofuran, cyclopentyl methyl ether; in a preferable embodiment 2-methy!tetrahydrofuran was used as the solvent. The extraction was conducted in the temperature range of 45 to 70°C, in a preferable embodiment at 60°C.

This way, the product quinuclidinyl ester V was obtained with the high purity of 95.0 to 99.9% (determined by UPLC and GC), in a preferable embodiment with a purity higher than 98.5% (determined by UPLC and GC). The product may be further re-purified by crystallization from a suitable solvent as necessary. Crystallization of the quinuclidinyl ester of formula V was carried out either directly from the concentrated solution of the crude product V after extraction and re- drying, or the crude product V was obtained by evaporation at a reduced pressure, which was re-crystallized from the solution by dissolving the quinuclidinyl ester of formula V at an increased temperature in a suitable solvent. Acetonitrile, ethyl acetate, tetrahydrofuran or 2-methyltetrahydrofuran, cyclopentyl methyl ether or their mixtures, in a preferable embodiment acetonitrile, ethyl acetate or 2- methyltetrahydrofuran, were used as suitable solvents. The crystallization was carried out by cooling of the saturated solution of the quinuclidinyl ester V in a suitable solvent to a temperature of 0 to 30°C.

The crystalline product was isolated by filtration and dried at the atmospheric pressure or in vacuo at temperatures in the range of 23 to 50°C. After crystallization the product V was isolated in the purity of 99.5% to 99.9%, in a preferable embodiment in a purity higher than 99.5%. The second step of the synthesis of aclidinium bromide I was quaternization of the quinuclidinyl ester of formula V with the alkylation agent 3-phenoxypropyl bromide in a suitable solvent.

Acetonitrile was selected as a suitable solvent.

3-Phenoxypropyl bromide was slowly added dropwise to a suspension of the slight excess of the alkylation agent in the range of 1.05 to 3 equivalents with regard to the quinuclidinyl ester of formula V; in a preferable embodiment 1.25 equivalents of the alkylation agent are used.

The reaction was carried out at the boiling temperature of the solvent until the starting compounds have reacted, usually for 2 to 5 hours, preferably for 2.5 hours or less.

After the end of the reaction the reaction mixture was cooled down, filtered and the fine crystalline product was washed with acetonitrile. The drying was done at the atmospheric pressure or in vacuo, at a temperature of 20 to 45°C, for 4 to 12 hours. This way, the final product aclidinium bromide I was obtained in high yield and purity of 99.95% to 99.99%, in a preferable embodiment with a purity higher than 99.95%.

The invention is clarified in a more detailed way in the working examples below. These only have an illustrative character and do not restrict the scope of the invention in any respect.

Brief Description of Drawings Fig. 1. X-ray powder pattern of Form 1 of Example 5 (Experiment 10*, Table 2)

Fig. 2. X-ray powder pattern of Form 1 of Example 5 (Experiment 11*, Table 2)

Fig. 3. X-ray powder pattern of Form 1 of Example 5 (Experiment 12*, Table 2}

Fig. 4. X-ray powder pattern of Form 1 of Example 6 (Experiment 13*, Table 2)

Fig. 5. X-ray powder pattern of Form 1 of Example 7

Examples

The melting points were measured using a Kofler block

Analysis method of the reaction mixture of transesterification VI by the alcohol III after extraction and after crystallization

Liquid chromatography is carried out (Ph.Eur. 2.2.29):

Chromatographic conditions:

Instrument: a UPLC system with a UV/VIS or PDA detector

Chemicals: acetonitrile R1 water for the chromatography R

perchloric acid 70% R

Column:

- dimensions length = 100 mm, inner diameter = 4.6 mm

- stationary phase: XSelect CSH Phenyi-Hexyl 2.5 pm

- temperature: 35°C

Mobile phase: A: 2 ml of 70 % perchloric acid R are dissolved in 1000 ml of water for the chromatography R.

B: acetonitrile R1

elution: gradient

flow rate: 0.7 ml/min

injected amount: 1.0 pi

Sample temperature: 18°C

Detection: UV, 237 nm

time: 5.0 min

Solvent for the sample: dimethylsulfoxide:acetonitrile R1 , 10:90 (v/v)

Typical retention and relative retenUon times (the reference peak RRT 1

quinuclidinyl ester V):

Quinuclidinyl ester V about 4.0 min

Correction factor: d i(2-th ienyl)g lycolic acid VII

methyl di(2-thienyl)glycolate VI other impurities 0.8 - 1.2 (without correction)

DMSO peak (RT 1.6) ignored. Analysis method of R-{-)-3-Quinuciidinol III in the reaction mixture after

transestenfication

Gas chromatography (2.2.28) in carried out with direct injection and Fl detection: Chromatographic conditions:

Capillary column: Rxi-5Sil MS (30 m; 0.32 mm ID; 0.5 μιη df) or equivalent Temperature program: 60°C - 0 min, gradient 10°C /min to 330°C - 5 min,

Carrier gas: helium for the chromatography R; 40 cm/s, constant flow

Injected amount: 1 μΙ

Injector: splitting ratio 10:1 , 250°C

Detector: FID, 340°C

approximate retention times (RT) and relative retention time (RRT)

RT RRT

3-quinuclidinol III 7.5 min 0.33 min quinuclidinyi ester V 22.5 min

Evaluation:

The content of impurities in % is evaluated using the method of internal normalization of peak areas in accordance with the followin formula:

Xi area of the impurity peak on the chromatogram of the tested sample

∑x, sum of all areas on the chromatogram of the tested sample except the peak of the solvent

Analysis method ofaclidinium bromide I

Liquid chromatography (Ph.Eur. 2.2.29):

Chromatographic conditions:

Instrument: a UPLC system with a UV/VIS or PDA detector water for the chromatography R

perchloric acid 70% R

Column:

- dimensions length = 100 mm, inner diameter = 4.6 mm

- stationary phase: XSelect CSH Phenyl-Hexyl 2.5 prn

- temperature: 35°C

Mobile phase: A: 2 ml of 70% perchloric acid R are dissolved in 1000 ml of water for the chromatography R.

B: acetonitrile R1

elution: gradient

flow rate: 0.7 m!/min

injected amount: 1.0 μ I

Sample temperature: 18°C

Detection: UV, 220 nm

time: 15.0 min

Solvent for the sample: dimethylsulfoxide:acetonitrile R1 , 10:90 (v/v)

Typical retention and relative retention times (the reference peak RRT 1 is aclidinium bromide 1):

Aclidinium bromide I about 6.9 min

3-phenoxypropyl-quinuclidinol RRT 0.49

Quinuclidinyl ester V RRT 0.59

chloromethyl-quinuclidinyl ester VIII RRT 0.66

di(2-thienyl)glycolic acid VII RRT 0.92 methyl di(2-thienyl)glycolate VI RRT 1.06

3-phenoxypropyl bromide RRT 1.44

Correction factor: 3-phenoxypropyl-quinuclidinol 1.28

3-phenoxypropyi bromide 0.74

other impurities 0.8 - 1.2 (without correction)

DMSO peak (RT 1.6) ignored.

X-ray powder diffraction: The diffraction patterns were measured using an XPERT PRO PD PANalytical diffractometer, radiation used CuKa (λ=1.542 A = 0.1542 nm), excitation voltage: 45 kV, anode current: 40 mA, measured range: 2 to 40° 2Θ, increment: 0.01° 2Θ. For the measurement a flat powder sample was used that was placed on a Si plate; the sample was not modified before the measurement. For the setting of the primary optical equipment programmable divergence slits with the irradiated area of the sample of 10 mm, 0.02 rad Sol!er slits and a ¼° anti-diffusion slit were used. For the setting of the secondary optical equipment an X^'Ceierator detector with maximum opening of the detection slot, 0.02 rad Soller slits and a 5.0 mm anti-diffusion slit were used.

Preparation of the guinuclidinyl ester V

Example 1 (Reference example: procedure in accordance with the process the patent EP 2 130 830)

Fresh sodium ethoxide (43 mg, 1.2 equivalents) and methyl di(2-thieny!)glycolate VI (200 mg, 1.2 equivalents) were added to a suspension of R-(-)-3-quinuclidinol III (63 mg, 0.5mmol) in dry toluene (5 ml) under an inert argon atmosphere. The reaction mixture was heated up for 2.5 hours (at 70 to 80°C for 1 hour and at 80 to 95°C for 1.5 hours). An azeotropic mixture consisting of toluene and the side product of the reaction, methanol, was simultaneously partly removed by distillation (1.5 ml). When the interna! temperature reached 110 to 115°C, another 2 ml were removed by distillation. 4 ml of dry toluene were added and the distillation continued. The heating was discontinued after the removal of 3 ml of the azeotropic mixture by distillation. The reaction mixture was cooled in an ice bath and 2 mi of ether and 2 ml of water were added. The resulting two layers were separated and the aqueous layer was extracted with ethyl acetate. The combined organic fractions were washed with water and 1N aqueous solution of methanesulfonic acid. The combined aqueous phases were cooled down in an ice bath to 0°C and basified with a concentrated aqueous solution of potassium carbonate. The aqueous phase was extracted with ethyl acetate. The organic phase was washed with water, brine and re-dried with the use of sodium sulphate and concentrated under a reduced pressure, providing 91.4 mg of the crude product (99.7% purity) in the yield of 53% (in EP patent 2 130 830: 104 mg of the crude product in the yield of 60%, purity not mentioned). Example 2 (preparation process for the quinuclidinyl ester V. experiments 1 to 4 of Table 1)

1.5 g of methyl di(2-thienyi)glycolate VI (5.9 mmoi), and 0.86 g of R-(-)-3-quinuclidinol III (1.15 equivalents) were weighed into a flask and 20 ml of MeTHF was added under an inert argon atmosphere. The reaction mixture was heated up to 35°C and a 1 M solution of ferf-butoxide (sodium or potassium in accordance with Table 1) in MeTHF (0.5 equivalents) was added to the reaction mixture dropwise under an inert argon atmosphere during 20 minutes. After addition of the base a distillation apparatus was installed on the flask and the reaction mixture was gradually heated up to 80°C (70°C interna] temperature of the reaction mixture) and further stirred at this temperature for the time mentioned in Table 1. During this time period an azeotropic mixture consisting of MeTHF and the side product of the reaction, methanol, was concurrently removed by distillation at a reduced pressure. The total amount of 5 to 10 ml of the azeotropic mixture was removed by distillation. The reaction mixture was cooled down to 23°C, diluted with 20 mi of ethyl acetate and poured into cooled 2M HCI (50 ml). The separated organic phase was washed with 25ml of 2M HCI twice more. The combined aqueous fractions were basified by gradual and careful addition of a 2M dichloromethane. The combined organic fractions were dried with sodium sulphate and concentrated at a reduced pressure. 10 ml of acetonitrile was added to the crude product and the resulting suspension was agitated at 0°C for 30 minutes. The crystalline product was filtered and dried in vacuum at 23^CC. The yields and purities of the products are summarized in Table 1.

Example 3 (preparation process for the quinuclidinyl ester V, experiments 5 to 7 of Table 1)

1.5 g of methyl di(2-thienyl)glycolate VI (5.9 mmol), and 0.86 g of R-(-)-3-quinuclidinol HI (1.15 equivalents) were weighed into a flask and 20 ml of eTHF was added under an inert argon atmosphere. The reaction mixture was heated up to 35°C and a 1M solution of sodium ferf-butoxide in MeTHF (amount of the base specified in Table 1) was added to the reaction mixture dropwise under an inert argon atmosphere during 20 minutes. After addition of the base a distillation apparatus was installed on the flask and the reaction mixture was gradually heated up to 80°C (70°C internal temperature of the reaction mixture) and further stirred at this temperature for the time mentioned in Table 1. During this time period an azeotropic mixture consisting of MeTHF and the side product of the reaction, methanol, was removed concurrently by distillation at a reduced pressure. The total amount of 5 to 10 ml of the azeotropic mixture was removed by distillation. The reaction mixture was cooled down to 23°C, diluted with 20 ml of ethyl acetate and poured into cooled 2M HCI (50 ml). The separated organic phase was washed with 25 and 15 ml of 2M HCI twice more. The combined aqueous fractions were basified by gradual and careful addition of a 2M solution of sodium carbonate up to pH 10 and subsequently extracted 3 times with chloroform. The combined organic fractions were dried with sodium sulphate and concentrated at a reduced pressure. 40 ml of acetonitrile was added to the crude product and the resulting suspension was dissolved under boiling of the solvent. Then, the solution was left to coo! down to 23°C and subsequently left to crystallize at a temperature of -10°C without agitation. The crystalline product was filtered and dried in vacuum at 23°C. The yields and purities of the products are summarized in Table 1. Example 4 (preparation process for the quinuciidinyl ester V, experiments 8 to 9 of Table 1)

1.5 g of methyl di(2-thienyl)glycolate VI (5.9 mmol), and 0.86 g of R-(-)-3-quinuclidinol III (1.15 equivalents) were weighed into a flask and 20 ml of MeTHF was added under an inert argon atmosphere. The reaction mixture was heated up to 35°C and a 1M solution of sodium ferf-butoxide in MeTHF (1 equivalent of the base, 0.57 g of sodium ferf-butoxide in 6 ml of MeTHF) was added to the reaction mixture dropwise under an inert argon atmosphere during 20 minutes. After addition of the base a distillation apparatus was installed on the flask and tine reaction mixture was gradually heated up to 80°C (70°C internal temperature of the reaction mixture) and further stirred at this temperature for 2.5 hours. During this time period an azeotropic mixture consisting of MeTHF and the side product of the reaction methanol was concurrently removed by distillation at a reduced pressure. The total amount of 5 to 10 ml of the azeotropic mixture was removed by distillation. The reaction mixture was cooled down to 23°C, diluted with 20 ml of ethyl acetate and poured into cooled 2M HCI (50 ml). The separated organic phase was washed with 25 and 15 ml of 2M HCI twice more. The combined aqueous fractions were basified by gradual and careful addition of a 2M solution of sodium carbonate up to pH 10 and subsequently extracted with MeTHF (100 ml), or with ethy! acetate (150 ml) at the temperature of 50 to 60°C. After separation the aqueous phase was extracted with a selected solvent (50 ml) twice more. The combined organic fractions were dried with sodium sulphate and concentrated at a reduced pressure and temperature of 50°C to the volume of 50 ml in the case of using MeTHF or 100 ml in the case of using ethyl acetate (accompanied by product crystallization). Then the solution, or suspension, was cooled down to 23°C and then left to crystallize at -10°C. The crystalline product was filtered and dried in vacuum at 23°C. The yields and purities of the products are summarized in Table 1. Quaternization of the quinuclidinyl ester V with 3-phenoxypropyl bromide

Example 5 (Reference examples of procedure in accordance with the process of Example 44 of document WO0104118, Scheme 7, Table 2, Experiments 10* to 12*1

The quinuclidinyl ester V (0.70 g, 2 mmol, purity 99.6%) was suspended in a mixture of the solvents chloroform (20 ml) and acetonitrile (13 ml). 1.58 ml of 3-phenoxypropyl bromide (5 equivalents) was added dropwise to the agitated suspension and the mixture was stirred at 23°C for 72 hours in an inert nitrogen atmosphere. The reaction mixture was concentrated at a reduced pressure. 20 ml of ether was added to the evaporation product and the mixture was stirred for 30 minutes. Then, the product was filtered, washed with ether and dried under a nitrogen stream. 0.82 g of aciidinium bromide was obtained in the yield of 73% as a white crystalline substance of Form 1 with the melting point of 226 to 229°C and purity of 99.5%. Experiments 11* and 12* were conducted in the same way, the purity of the starting quinuclidinyl ester V as well as of the products, reaction yields and melting point of the products are presented in Table 2.

X-ray powder diffraction - Diffraction peaks of Form 1

21.60 0.4111 39.9

22.30 0.3983 19.6

22.64 0.3925 5.4

23.25 0.3822 17.7

23.59 0.3768 10.4

23.75 0.3743 6.1

24.37 0.3649 24.8

25.42 0.3502 11.4

25.82 0.3448 30.1

26.30 0.3386 19.2

27.01 0.3299 6.5

27.68 0.3220 13.3

28.56 0.3123 5.1

28.80 0.3097 6.0

29.38 0.3037 22.4

31.01 0.2881 12.6

31.56 0.2833 7.2

33.29 0.2689 5.6

33.78 0.2651 7.6

34.50 0.2598 10.1

The X-ray patterns of the crystalline forms are included in the Annex in Figs. 1 to 3.

Example 6 (Example of embodiment of Scheme 7, Table 2. Experiment 3)

The quinuclidinyl ester V (0.5 g, 1.43 mmol, purity 99.99%) was suspended in acetonitrile (10 ml). 0.28 ml of 3-phenoxypropyl bromide (1.25 equivalents) was added to the agitated suspension dropwise at the temperature of 23°C. The reaction mixture was heated up to the boiling point of the solvent and agitated under reflux in an inert nitrogen atmosphere for 4 hours. Then, the reaction mixture was freely cooled down to 23°C and agitated at 23°C for another 48 hours. The resulting suspension was filtered and the white crystalline product was washed with a minimum amount of acetonitrile and dried in a vacuum drier at 23°C for 4 hours. Fine crystalline material was obtained in the yield of 96 %, with the purity of 99.99 % and the melting point of 228 to 229°C. A comparison of the X-ray pattern of the sample to those of the samples coming from the reproduction of Example 44 of document WO0104118 (Examples 1 to 3, Table 2) confirmed the same crystalline structure of Form 1. The X- ray pattern of the obtained crystalline Form 1 is included in the Annex in Figure 4. Preparation of a 50g batch of aclidinium bromide I Example 7

Preparation of the quinuclidinyl ester V

50.0 g of methyl di(2-thienyl)glycolate VI (0.197 mmol), and 27.5 g of f?-(-)-3- quinuclidinol III (1.1 equivalents) were charged into a 2000ml reactor and 500 ml of dry MeTHF was added under an inert nitrogen atmosphere. The reaction mixture was heated up to 35°C and a 1M solution of sodium ferf-butoxide in MeTHF (1 equivalent of the base, 18.9 g of sodium ferf-butoxide in 197 ml of MeTHF) was added to the agitated reaction mixture dropwise under an inert nitrogen atmosphere during 40 minutes. After addition of the base, the reaction mixture was heated up to 75°C (70°C internal temperature of the reaction mixture) during 30 minutes and further stirred at this temperature for 2.5 hours. During this time period an azeotropic mixture consisting of MeTHF and the side product of the reaction, methanol, was concurrently removed by distillation at a reduced pressure (68 kPa). The total amount of 400 ml of the azeotropic mixture was removed by distillation. The reaction mixture was cooled down to 22°C During 25 minutes and 490 ml of a 2M solution of HCI was added dropwise during another 15 minutes so that the temperature of the reaction mixture does not exceed 26°C. For easier separation of the layers 200 ml of ethyl acetate was also poured into the mixture. The separated organic phase was washed with 150ml of a 2M HCI solution twice more. The combined aqueous fractions were basified by gradual dropwise addition of a 2M solution of sodium carbonate up to pH 10 (450 ml) at 23°C. Then, 700 ml of MeTHF was added to the mixture and the mixture was heated up to 58°C and stirred for 15 minutes. The separated aqueous layer was twice more extracted with MeTHF (350 ml) at the temperature of 50°C. The organic fractions were combined and 650 ml of a mixture of MeTHF and water was removed by azeotropic distillation at a reduced pressure (57 kPa) and the temperature of 58 to 61°C. The concentrated solution (1200 ml) was gradually cooled down to -8°C during 1 hour and left to crystallize at -8°C for another hour. The crystalline product was filtered, washed with 2x100 ml of MeTHF and dried in vacuum at 45°C for 48 hours. This way, 39.8 g of quinuclidinyl ester V was obtained in the form of light-brown crystals with the purity of 99.95% in the yield of 58%. Quaternization of the quinuclidinyl ester V with 3-phenoxypropyl bromide

The quinuclidinyl ester V (32 g, 0.0916 moi) was suspended in 500 ml of dry acetonitrile. 18 ml of 3-phenoxypropyl bromide (1.25 equivalents) was added dropwise to the agitated suspension at 23°C under an inert nitrogen atmosphere. The reaction mixture was heated up to the boiling point of the solvent and agitated under reflux in an inert nitrogen atmosphere for 2.5 hours. Then, the reaction mixture was left to freely cool down to 23°C and agitated at 23°C for another 12 hours. The crystalline product was filtered and washed with 200 ml of acetonitrile and dried in a vacuum drier at 45°C for 24 hours. This way 50.53 g of aclidinium bromide was obtained in the form of fine white crystals of Form 1 in the yield of 98% with the purity of 99.96% and the melting point of 227 to 228°C. A comparison of the X-ray pattern of the sample to those of the samples coming from the reproduction of Example 44 of document WO0104118 (Examples 1 to 3_r Table 2) confirmed the same crystalline structure of Form 1. The X-ray pattern of the obtained crystalline form is included in the Annex in Figure 5. An analysis of the concentration of the residual solvents (acetonitrile 81ppm; ethyl acetate <50ppm; eTHF <50ppm) and water (<0.05%) shows that this is an anhydrous form.

Claims

1. A process for preparing high purity aclidinium bromide of formula I,

by transesterification of methyl di(2-thienyl)glycolate of formula VI with R-(-)-3- quinuclidinol of formula III

VI in the presence of a sterically hindered base selected from the group including alkali salts of branched C3 to C5 alkoxides in an inert solvent; c) quaternization of the quinuclidinyl ester of formula V by the alkylation agent 3-phenoxypropyl bromide in an inert solvent, producing aclidinium bromide.

2. The process for preparing aclidinium bromide of formula I according to claim 1, characterized in that in step (a) the sterically hindered base is selected from the group including the sodium and potassium salts of ferf-butoxide, ferf- pentoxide, amoxide and isopropoxide.

3. The process according to claim 2, characterized in that the sterically hindered base is the sodium or potassium salt of ferf-butoxide.

4. The process according to claims 1 to 3, characterized in that in step (a) the sterically hindered base is used in the range of 0.5 to 1 equivalents with regard to the methyl di(2-thienyl)giycolate of formula VI.

5. The process according to claims 1 to 4, characterized in that in step (a) the inert solvent is selected from the group including aromatic hydrocarbons and cyclic ethers, especially toluene, xylene, tetrahydrofuran, 2- methyltetrahydrofuran, cyclopentyl methyl ether, or mixtures thereof.

6. The process according to claims 1 to 5, characterized in that in step (a) the inert solvent is 2-methyltetrahydrofuran.

7. The process according to claims 1 to 6, characterized in that the transesterification is carried out at a temperature in the range of 55 to 90 °C.

8. The process according to claim 7, characterized in that the transesterification is carried out at a pressure in the range of 101 kPa to 40, with simultaneous removing of the produced methanol by distillation.

9. The process of aclidinium bromide of formula I according to claim 1, characterized in that the isolation in step (b) - after optional dilution with an extraction solvent - comprises:

- mixing of the reaction mixture from step (a) with an aqueous solution of an inorganic acid; - alkalization of the aqueous phase with an inorganic base to pH 9 to 11;

- extraction of the product with a final extraction solvent and concentration of the mixture; and

- crystallization of the crude quinuclidinyi ester V from the crystallization solvent.

10. The process according to claim 9, characterized in that the final extraction solvent is selected from the group including ethyl acetate, 2- methyltetrahydrofuran and their mixtures.

11. The process according to claims 9 to 10, characterized in that the final extraction solvent is 2-methyltetrahydrofuran.

12. The process according to claim 9, characterized in that the crystallization solvent is selected from the group including acetonitrile, ethyl acetate, 2- methyltetrahydrofuran and their mixtures.

13. The process according to claims 9 and 12, characterized in that the crystallization solvent is 2-methyltetrahydrofuran.

14. The process according to claim 1 , characterized in that the internal solvent for the quaternization in step (c) is acetonitrile.

15. The process according to claim 14, characterized in that the reaction is conducted at the boiling point of the solvent for 2 to 5 hours, preferably for 2.5 hours.

16. The process according to claims 4-15, characterized in that 3-phenoxypropyl bromide is used for the quaternization in the stoichiometric amount, or a slight excess in the range of 1.05 to 3 equivalents, preferably 1.25 equivalents, with regard to the quinuclidinyi ester of formula V.

17. The process of aclidinium bromide of formula I according to claims 1 to 16, providing aclidinium bromide in a high yield and with the purity of 99.95% to 99.99%, preferably with a purity higher than 99.95%.