WO2023223335A1

WO2023223335A1 - A method for preparing (1s)-2-chloro-1-(3,4-difluorophenyl) ethanol

Info

Publication number: WO2023223335A1
Application number: PCT/IN2023/050078
Authority: WO
Inventors: Parimal Hasmukhlal Desai; Jiteshkumar Bhikhubhai Patel; Dharmrajsinh Narendrasinh Rana
Original assignee: Aarti Pharmalabs Ltd
Current assignee: Aarti Pharmalabs Ltd
Priority date: 2022-05-16
Filing date: 2023-01-24
Publication date: 2023-11-23
Anticipated expiration: 2024-11-16

Abstract

The invention relates to a process for preparation of compound of formula (I) by reacting 2-chloro-1-(3,4-difluorophenyl)ethanone of formula (II) in a buffer and in the presence of an enzyme CDX-023 and co-enzyme NADP.

Description

A METHOD FOR PREPARING (lS)-2-CHLORO-l-(3,4-DIFLUOROPHENYL) ETHANOL

Field of the Invention

The present invention relates to biological pharmaceutical and bio-chemical technology field.

The present invention particularly relates to an improved process for the preparation of (1 S)-2- chloro-l-(3,4-difluorophenyl) ethanol by enzymatic catalysis.

Background and prior art

Ticagrelor, chemically described as (15,25,3A,55)-3-[7-[(lA,25)-2-(3,4-Difluorophenyl)cyclopropy lamino]-5-(propylthio)-377-[l,2,3]triazolo[4,5-r/]pyrimidin-3-yl]-5-(2-hydroxyethoxy)cyclopentane

-1,2-diol, and have anti-bactericidal activity. It is represented as formula [A] below:

Ticagrelor is useful to treat stroke, heart attack and acute coronary syndrome. It is also used to lower the risk of stroke and death in adults with a blockage or decreased blood flow in an artery that supplies blood to the brain. Ticagrelor reversibly binds to the ADP P2Y12 receptor and prevents ADP from binding. This prevents the signal transduction and platelet activation that can lead to pathologic thrombus formation.

(lS)-2-chloro-l-(3,4-difluorophenyl) ethanol of formula (I) is an important chiral synthon useful in the preparation of Ticagrelor and its pharmaceutically acceptable salt.

The chiral purity of the Ticagrelor would affect if the enantiomeric purity of this intermediate is not achieved.

US 7,863,469 B2 discloses preparation of compound of formula (I) by catalytic reduction of 2- chloro-l-(3,4-difluorophenyl)ethanone of formula (II) using transition metal with the chiral ligand. Particularly the reducing agent is oxazaborolidine which is formed by mixing trimethoxy borane and S-diphenylprolinol followed by addition of borane dimethylsulphide. The reaction proceeds in an inert solvent toluene at 35-40°C.

Chemical approach for asymmetric reduction of ketone precursor involves large amount of organic solvents. The process yields large amount of chemical waste and hence the process is not suitable and sustainable at higher scale production. Thus, process becomes costly and hence a need for economical and environment friendly process always exists.

Various Chinese applications such as CN105969757, CN109112166, CN111575334 discloses enzymatic reduction of compound of formula (II) to form compound of formula (I).

Enzymatic conversion in the development of sustainable manufacturing process is very important and essential. Enzyme catalyzes the complex and stereoselective reactions efficiently and selectively to produce enantiomeric excess of the desired isomer. Thus, a search and workability of an enzyme from bicatalytic toolbox to a specific substrate by enzyme screening is always necessary. This provides us a process which can specifically produce the desired isomer with higher yield. Thus, a need for cost effective process for the preparation of optically pure isomer of key intermediate of formula (I) with the green chemistry principles always exists.

The process of the present invention is workable, industrially feasible and economical. Objects of the invention

It is the object of the present invention to provide an enzymatic catalysis process for synthesis of (lS)-2-chloro-l-(3,4-difluorophenyl) ethanol with higher enantiomeric purity.

Detailed description of the invention In one aspect the present invention provides enantiomer-specific synthesis of optically pure(lS)-2- chloro-l-(3,4-difluorophenyl) ethanol (I).

The process can be schematically represented as shown in scheme 1

SCHEME 1 wherein it comprises reduction of 2-chloro-l-(3,4-difluorophenyl)ethanone of formula (II) to (1S)- 2-chloro-l-(3,4-difluorophenyl)ethanol of formula (I) under the influence of an enzyme (CDX- 023).

The enzyme can be extracted from Lactobacillus Kefir. (CDX-023). The enzyme can be a ketoreductase polypeptide having an amino acid sequence that has one or more amino acid differences as compared to a reference amino acid sequence of a wild-type ketoreductase or an engineered ketoreductase reported in US patent US 9,796,964. The ketoreductase enzyme can be preferably recombinant or genetically engineered enzyme and can be obtained from commercially available sources. The ketoreductase enzyme The enzyme stereoselectively reduces compound of formula (II) to compound of formula (I) with higher yields.

The process for preparation of compound of formula (I) comprises reacting 2-chloro-l-(3,4- difluorophenyl)ethanone of formula (II) in a buffer at pH 6-8 with enzyme (CDX-023) and coenzyme NADP at a temperature of 20-40°C.The co-enzyme can be sourced from commercially available resources. The pH of the reaction mixture is preferably maintained at 6.5 to 7.5, particularly the reaction is carried out at pH 7.

The reaction is carried out at 20-40°C, preferably at 25-30°C.

The chiral purity of the compound (I) is 99.90% to 99.99%.

Buffer solution preparation

Triethanol amine and magnesium sulphate is added to de-mineralized or distilled water and stirred well. This solution is used as buffer solution in further reaction.

The pH of the buffer solution is adjusted to 7 using a suitable acid. The acid is preferably concentrated hydrochloric acid.

Enzyme solution preparation

To the buffer solution with the pH adjusted to 7, the enzyme (CDX-023) obtained from commercial available source > and co-enzyme NADP obtained from commercial source was added. The mixture was stirred well to yield the clear catalyst solution of the enzyme.

In a preferred embodiment 2-chloro-l-(3,4-difluorophenyl)ethanone of formula (II) in isopropyl alcohol is charged to the catalyst solution at 25-30°C by maintaining pH to 7. The pH is adjusted by addition of buffer solution. The reaction mass is maintained under nitrogen for 12-36 hours and the pH is adjusted continuously to 7 by adding buffer solution. After completion of the reaction, the reaction mass is extracted with suitable ether and the product is isolated by solvent distillation under vacuum.

The ether solvent is preferably Methyl tertbutyl ether (MTBE).

In an embodiment of the present invention, a process for preparing ticagrelor having Formula (IX) is disclosed. The process comprises preparing ticagrelor from compound of Formula (I).

Compound of Formula (I) prepared by the above disclosed steps. Compound of Formula (III) is formed from compound of Formula (I) in the presence of toluene and sodium hydroxide. Compound of Formula (IV) is formed from compound of Formula (III) in the presence of trimethyl phosphonoacetate (TMPA) and sodium tert-butoxide. Compound of Formula (V) is formed from compound of Formula (IV) in the presence of methanol and sodium hydroxide. Compound of Formula (VI) is formed from compound of Formula (V) in the presence of thionyl chloride, hydroxylamine hydrochloride and toluene. Compound of Formula (VII) is formed from compound of Formula (VI) in the presence of sodium hypochlorite, methanol and R (-) mandelic acid. Compound of Formula (VII) is reacted with compound of Formula (VIII) in the presence of dimethyl formamide and sodium carbonate to form ticagrelor having Formula (A).

The reaction scheme of preparing ticagrelor of Formula A is represented below:

The present invention is further illustrated by following exemplary embodiments, which should not be construed as limiting the scope of the invention.

EXAMPLES

The examples illustrate the invention but are not limiting thereof.

Example 1

Preparation of 2-chloro-l-(3,4-difluorophenyl)ethanone (formula II)

Aluminium trichloride (105.19 gm) was charged to 1 ,2-difluorobenzene and the mixture was stirred at room temperature for 10 minutes. The mixture was heated to 50-55°C and chloroacetyl chloride (118.8 gm) was charged slowly. The mixture was maintained for 1-2 hours at 50° C and the mixture was stirred for 10 minutes. Methylene dichloride (MDC) (400 ml) was charged to the mass and quenched in hydrochloric acid solution chilled to 0-10°C. Temperature of the mass was raised to 20-30°C and stirred for 20-30 minutes. The mass was settled for 20-30 minutes and the layers were separated. Water (100 ml) was charged to organic layer and the mass was stirred for 20-30 minutes and the layers were separated. Sodium sulfate (10 gm) was charged to the organic layer and the mass was stirred for 30 minutes. The organic layer was filtered and distilled under vacuum below 45°C to form thick slurry.

Example 2

Preparation of (lS)-2-chloro-l-(3,4-difluorophenyl)ethanol (formula I)

(i) Buffer solution preparation Magnesium sulphate (0.246 gm) and tri ethanol amine (15 gm) was charged to water (900 ml) at 25 - 30°C. The mixture was stirred for 10 minutes. 100 ml of this buffer solution was kept aside for pH adjustment in the reaction.

The pH of the buffer solution (800 ml) was adjusted to 7 using Concentrated Hydrochloric acid and stirred well. Water (80ml) was charged.

(ii) Catalyst solution preparation

(CDX-023) (0.25 gm) and NADP (0.1 gm) was charged in the above buffer solution (500 ml). The mixture was stirred for 20-30 minutes to obtain a catalyst solution. The catalyst solution (300 ml) was added to the reaction mixture and the mixture was further stirred for 20-30 minutes at 25-30°C.

(iii) Preparation of (lS)-2-chloro-l-(3,4-difluorophenyl)ethanol (formula I) 2-chloro-l-(3,4-difluorophenyl)ethanone (100 gm) was dissolved in isopropyl alcohol (200 ml). This solution was charged to the buffer solution gradually with pH maintaining at 7. The pH was continuously monitored and maintained to 7 by simultaneous addition of buffer solution. After complete addition the reaction mixture was stirred for 12 hours at pH 7. In process analysis shows 80% conversion.

Isopropyl alcohol (IP A) (100 ml) was charged to the reaction mass and stirred for 4 hours. After complete conversion the IPA from the reaction mass distilled under vacuum and recovered.

Methyl tert-butyl ether (MTBE) (500 ml) was charged to the reaction mass and the mixture was stirred well for 20-30 minutes. The mixture was settled, and the layers were separated. MTBE (200 ml) was charged to the aqueous layer and the mixture was stirred for 20-30 minutes. The mixture was settled for 30-45 minutes. The layers were separated. The MTBE layers were combined and filtered on hyflow bed. The hyflow bed was washed with MTBE (100 ml). MTBE was distilled out completely under vacuum below 45°C and further degassed for 1-2 hours under vacuum. The mass was cooled to 25-30°C and (lS)-2-chloro-l-(3,4- difluorophenyl)ethanol oil was isolated. (90 gm, 89% yield).

HPLC purity: 98.8%

Chiral purity: 99.92%.

Example 3

Preparation of (2S)-2-(3,4-difluorophenyl)oxirane (Formula III)

(lS)-2-chloro-l-(3,4-difluorophenyl)ethanol (100 gm) was charged to Toluene (260 ml) at room temperature and stirred for 10 minutes. Sodium hydroxide solution was prepared by dissolving 23 gm in 200 ml water and added to the reaction mixture slowly. The mixture was heated to 40-45°C for 1-2 hours. The mass was cooled to 25-35°C and the organic layer was separated. Water (400 ml) was charged, and mixture was stirred for 20-30 minutes at 20-35°C. The organic layer was separated, and Sodium sulphate (10 gm) was charged. The mass was stirred for 20-30 minutes and filtered. Toluene was distilled out under vacuum and the oily product (2S)-2-(3,4- difluorophenyl)oxirane (Formula III) (70 gm) was isolated.

HPLC purity: 99.4%

Chiral purity: 99.80%

Example 4

Preparation of (lR,2S)-2-(3,4-difluorophenyl)cyclopropanamine (R)-Mandalate salt (Formula VII)

Sodium tert-butoxide (125 gm) was charged to toluene (1600 ml) at room temperature. The mixture and stirred at room temperature for 20 minutes. The mixture was heated to 110-115°C and 10- 12V toluene was distilled. The mass was cooled and Trimethyl phosphonoacetate (209.95) was added. The mass was heated to 60-65°C and (2S)-2-(3,4-difluorophenyl)oxirane (Formula III) (100 gm) and Toluene (250 ml) was charged slowly in 1-1.5 hours. The mass was heated to 90-95°C and maintained for 10-11 hours to form methyl (lR,2R)-2-(3,4-difluorophenyl) cyclopropane carboxylate (Formula IV). The mass was cooled to 25-35°C and water (500 ml ) was charged and stirred for 30 minutes. The mass was settled, and organic layer was separated and used directly in the next step.

Sodium hydroxide solution was prepared by dissolving (51 gm) in 160 ml water. Methanol (60 ml) was charged in Sodium hydroxide solution at room temperature and stirred for 10 minutes. The organic layer in the above step was charged in the reaction mixture and heated to 60-65°C. The mass was maintained for 2-3 hours at 60-65°C to obtain (lR,2R)-2-(3,4- difluorophenyl)cyclopropane carboxylic acid (Formula V). After reaction completion, the mass was cooled, and pH was adjusted to 0.2-1.5 using Cone HC1 and stirred for 30 minutes. The aqueous layer was extracted with Toluene (300 ml) and separated. All the toluene layers were combined, and sodium sulphate (20 gm) was added and stirred. The mixture was filtered, and filtrate was used directly in the next step. Thionyl chloride (123 gm) was charged to the filtrate at 25-35°C. The mixture was heated to 110- 115°C. The mass was maintained for 2-3 hours at 110-115°C. The solvent was distilled out at 110- 115°C after completion of the reaction and the mass was cooled to 25-35°C. Ethyl acetate (250 ml) was charged at 25 -35 °C and the mass was further maintained for quenching.

Liquor ammonia (450 ml) was charged to chilled water (300 ml) and the mixture was further chilled to 0-5°C. Hydroxylamine hydrochloride (4.45 gm) was charged and to this mixture, ethyl acetate mass was quenched. The mass was maintained for 60 minutes at 5-10°C. Ethyl acetate (700 ml) and water (300 ml) was charged at 10-30°C and stirred. The mass was settled, and the aqueous layer was separated. The ethyl acetate layer was extracted with water (300 ml) and mass was settled to obtain (lR,2R)-2-(3,4-difluorophenyl)-N-hydroxycyclopropanecarboxamide (Formula VI). Sodium sulphate (10 gm) was added to ethyl acetate layer and stirred for 15-20 minutes. The mixture was filtered and washed with ethyl acetate. The filtrate was distilled under vacuum at 50- 60°C. n-heptane (500 ml) was charged and the mass was stirred for 30 minutes at 50-60°C. The reaction mixture was cooled to 25 -35 °C and stirred for 1 hour. The mass was filtered and wet cake was obtained.

The wet cake was charged to 1.5M sodium hydroxide (360 ml) at 25-35°C and 10% sodium hypochlorite solution (311 ml) was charged slowly. The mixture was heated to 50-55°C and maintained for 4-5 hours. Ethyl acetate (350 ml) was charged after completion of the reaction and stired for 30 minutes. The layers were separated and aqueous layer was extracted with ethyl acetate (350 ml). Sodium sulphate (10 gm) was charged to the combined ethyl acetate layers and stirred for 10 minutes. The mixture was filtered, and ethyl acetate was distilled under vacuum below 45 °C. Methanol(100 ml) was charged to the mass and stirred for 30-60 minutes. Solution of (R)-Mandelic acid (65 gm) in methanol (200 ml) was prepared separately and charged to above solution. The mixture was heated to 45-50°C and stirred for 30 minutes. The mass was cooled to 25-35°C and stirred for 30 minutes. Further chilling was applied and mass was stirred for 60-90 minutes. The mass was filtered and washed with chilled methanol (50 ml). The material was dried under vacuum at 45-50°C for 7-8 hours to yield (lR,2S)-2-(3,4-difluorophenyl)cyclopropanamine (R)-Mandalate salt (Formula VII) (0.8 gm; 39% yield).

HPLC purity: 99.87%

Chiral purity: 99.7%

Example 5

Preparation of Ticagrelor (Formula A)

Ethyl acetate (600 ml) was charged to (lR,2S)-2-(3,4-difluorophenyl)cyclopropanamine (R)- Mandalate salt (Formula VII) (82.41 gm) at 25-30°C. Aqueous sodium carbonate solution was charged slowly over 30-45 minutes and the mixture was maintained till complete dissolution of solid. Ethyl acetate (200 ml) was charged and aqueous and organic layers were separated. The aqueous layer was extracted with ethyl acetate (400 ml). Both the ethyl acetate layers were combined and dried with sodium sulphate (180 gm). Ethyl acetate was distilled under vacuum at 40-45°C and yellow oily residue of (lR,2S)-2-(3,4-difluorophenyl)cyclopropanamine base was obtained.

Under nitrogen atmosphere (lS,2S,3R,5S)-3-[7-chloro-5-(propylthio)-3H-l,2,3-triazolo[4,5- d]pyrimidin-3-yl]-5-(2-hydroxyethoxy)-l,2-cyclopentanediol (Formula VIII) (100 gm) was charged to dimethyl formamide (DMF) (150 ml) at 25-30°C and stirred for 10-15 minutes. (lR,2S)-2-(3,4- difluorophenyl)cyclopropanamine base (45-50 gm) was charged dropwise. Sodium bicarbonate (64.63 gm) was charged slowly pinch wise at 25-30°C and the mass was stirred for 2-3 hours. Water (1000 ml) was charged dropwise after completion of the reaction over 1-2 hours. The mass was maintained for 8-10 hours. The mass was filtered and washed with water (500 ml).

The wet solid was purified by stirring in water (1000 ml) at 25-30°C for 1 hour. The slurry was filtered and washed with water (500 ml). The wet solid was dried under vacuum at 45-50°C for 8-9 hours to yield Ticagrelor (Formula IX) (Dry weight: 128 gm; 94% yield)

HPLC purity: 99.45%

Example 6

Purification of Ticagrelor

Crude solid (130 gm) obtained in example 4 was charged in ethyl acetate (1200 ml) at 25-30°C. The mixture was heated to 40-45°C for 30 minutes. The solvent was distilled under vacuum at 45- 45°C. n-heptane (300 ml) was charged slowly to the slurry obtained at 25-30°C. The mixture was stirred for 2-3 hours and the mixture was filtered. The solid was washed with Ethyl acetate: heptane 1:1 (300 ml). The solid obtained was dried under vacuum and Ticagrelor Form II is isolated (110 gm; 84% yield). Polymorphic Form II is confirmed by 20 values: 5.40, 13.35, 18.14, 22.53, 24.10+0.02. HPLC Purity: 99.50%

Claims

Claims :

1) A process for preparation of compound of formula (I),

tn comprising reacting 2-chloro-l-(3,4-difluorophenyl)ethanone of formula (II)

(ID in a buffer at pH 6-8 in presence of enzyme CDX-023 and co-enzyme NADP at a temperature of

20°C to 40°C. 2) The process as claimed in claim 1, wherein the compound of formula (II) is dissolved in an isopropyl alcohol solvent.

3) The process as claimed in any of the preceding claim, wherein the buffer solution is prepared by dissolving triethanol amine and magnesium sulphate in distilled water. 4) The process as claimed in claim 3, wherein the enzyme (CDX-023) and co-enzyme NADP is dissolved in the buffer solution.

5) The process as claimed in any of the preceding claim, wherein the reaction is carried out at pH 6.5-7.5.

6) The process as claimed in claim 5, wherein the reaction is carried out at pH 7.

7) The process as claimed in any of the preceding claim, wherein the chiral purity of the compound of formula (I) is 99.90% to 99.99%.

8) A process for preparing ticagrelor having Formula (A), the process comprising: i. preparing compound of Formula (I) as claimed in any one of the preceding claims; ii. forming compound of Formula (III) from compound of Formula (I) in the presence of toluene and sodium hydroxide; iii. forming compound of Formula (IV) from compound of Formula (III) in the presence of trimethyl phosphonoacetate (TMPA) and sodium tert-butoxide; iv. forming compound of Formula (V) from compound of Formula (IV) in the presence of methanol and sodium hydroxide; v. forming compound of Formula (VI) from compound of Formula (V) in the presence of thionyl chloride, hydroxylamine hydrochloride and toluene; vi. forming compound of Formula (VII) from compound of Formula (VI) in the presence of sodium hypochlorite, sodium hydroxide, methanol and R(-) mandelic acid; and vii. reacting compound of Formula (VII) with compound of Formula (VIII) in the presence of dimethyl formamide and sodium carbonate to form ticagrelor of Formula (A).

9) The process as claimed in claim 8 comprising purifying compound of formula (A) in the presence of ethyl acetate and n-heptane.