AU2012201783A1 - Chemical process for preparation of aromatic cyclopropane esters and amides - Google Patents

Abstract

C \NkPonhl)C(\[)AR\'2141 _ I DOC-2001/22 Abstract The present invention relates to compounds useful as pharmaceutical intermediates, to processes for preparing said intermediates, to intermediates used in said processes, and to the use of said intermediates in the preparation of pharmaceuticals. In particular, the present invention concerns enantiomerically pure trans-cyclopropane carboxylic acid derivatives, processes for preparing said carboxylic acid derivatives and their use in preparing pharmaceuticals.

Description

Australian Patents Act 1990 - Regulation 3.2A ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title "Chemical process for preparation of aromatic cyclopropane esters and amides" The following statement is a full description of this invention, including the best method of performing it known to us:- C NR P.0OrIDCCID A R1242U I [WX.2 11'2~12 Chemical process for preparation of aromatic cyclopropane esters and amides This application is a divisional of Australian Patent Application No. 2007282181, the entire content of which is incorporated herein by reference. The present invention relates to compounds useful as pharmaceutical intermediates, to processes for preparing said intermediates, to intermediates used in said processes, and to the use of said intermediates in the preparation of pharmaceuticals. In particular, the present invention concerns enantiomerically pure trans-cyclopropane carboxylic acid derivatives, processes for preparing said carboxylic acid derivatives and their use in preparing pharmaceuticals. The compound [1S-(1a, 2a, 3P (IS*,2R*),5p)]-3-[7-[2-(3,4-difluorophenyl) cyclopropyl]amino]-5-(propylthio)-3H-1,2,3-triazolo[4,5-dlpyrimidin-3-yl)-5-(2 hydroxyethoxy)-cyclopentane-1,2-diol (Compound A), and similar such compounds, are disclosed in WO 00/34283 and WO 99/05143. These compounds are disclosed as P2 (which is now usually referred to as P 2 Y1 2 ) receptor antagonists. Such antagonists can be used as, inter alia, inhibitors of platelet activation, aggregation or degranulation. We have now found an advantageous process for preparing enantiomerically pure trans cyclopropane carboxylic acid derivatives which may be used in the preparation of Compound A. The process offers the following advantages: diastereoselecivity, enantioselectivity, high yield, potential for manufacturing (e.g. reagents and procedures suitable for large scale production, non-hazardous reagents, less waste). According to a first aspect of the present invention there is provided a compound of formula IV F N 1 CO 2 R F IV Wherein R is an alkyl group.

WO 2008/018822 PCT/SE2007/000706 2 Suitable values of R include, for example, (1-6C)alkyl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, and tert-butyl. A particular value for R is ethyl. The compound of formula IV may be prepared from a compound of formula II OH F CI F According to a further aspect of the present invention there is provided a process for 10 preparing a compound of formula H from a compound of formula I. F CI F)D The compound of formula I is reduced to the compound of formula II. The reduction is is carried out using a suitable reducing agent. Suitable reducing agents will include those which are able to reduce the carbonyl group in the compound of formula I to the hydroxyl group of formula H and give an enantiometric excess of the compound of formula II with the stereo chemistry shown in formula II. Examples of suitable conditions include, for example, catalytic reduction or use of a 20 transition metal with chiral ligand. A particular example of a suitable reducing agent is oxazaborolidine which may be formed by mixing trimethoxy borane and S-diphenylprolinol, followed by addition of borane dimethylsulphide. This is generally carried out in an inert solvent such as toluene. The 25 temperature is conveniently maintained at a temperature in the range 25 to 450 C, for example 35 to 400 C.

WO 2008/018822 PCT/SE2007/000706 3 The compound of formula I is treated with the reducing agent so formed. This is generally carried out in an inert solvent such as toluene. The temperature is conveniently maintained at a temperature in the range 25 to 450 C, for example 35 to 400 C. 5 The compound of formula IV may be prepared by treating a compound of formula III 0 F F III with a compound of formula: 0

R

2 0-P C0 2 R

R

2 0 (3) 10 Wherein R' and R 2 are independently selected from alkyl such as (Cl-6C)alkyl. A preferred agent is triethyl phosphonoacetate. The reaction is generally carried out in an inert solvent such as toluene. The reaction is is generally carried out at a temperature in the range 30 to 80 0 C, conveniently 40 to 600 e.g. 400 C. The reaction may conveniently be carried out in the presence of a base. Examples of suitable bases include sodium hydride and alkali metal (for example potassium or sodium) alkoxides (for example t-butoxide). Specific examples are potassium and sodium t-butoxide. 20 The compound of formula III may be prepared by treating the compound of formula II with a base such as an alkali metal hydroxide, for example sodium hydroxide. This is conveniently carried out in a suitable solvent such as water. 25 The compound of formula II may be converted to the compound of formula IV via the compound of formula III, without isolation of the compound of formula III.

WO 2008/018822 PCT/SE2007/000706 4 0 F F IUI In a particular embodiment of the present invention, the compound of formula II is 5 converted to the compound of formula IV by treating the compound of formula II with a base such as sodium hydride. This is generally carried out in an inert solvent such as toluene. This is treated with triethyl phosphonoacetate. This is generally carried out at a temperature in the range 30 to 80 0 C, conveniently 40 to 60 0 C e.g. 40 "C. 10 The present invention also provides a process for preparing a compound of formula VII which comprises treating the compound of formula IV with ammonia in the presence of a suitable base. Suitable bases include alkali metal alkoxides such as potassium methoxide or sodium methoxide. An agent such as methyl formiate may also be present. The reaction is generally carried out in a suitable solvent such as an alcohol in a suitable 15 solvent. In one embodiment, the reaction is carried out in toluene and methanol. F, ./ CONH2 F VII The compound of formula IV may be treated with the base and then treated with ammonia. 20 Preferably, the reaction is under pressure during the treatment with ammonia. An example of a suitable pressure is 2 to 10 bar. The reaction may be carried out at an elevated temperature, such as 40 to 700 C, for example at about 600 C. The present invention is also directed to compounds of formula IV and VII. 25 The present invention also provides novel intermediates of formula II III or VII.

WO 2008/018822 PCT/SE2007/000706 5 The invention will now be further illustrated with reference to the following examples. Example 1 Preparation of 2-chloro-1-(3,4-difluorophenyl)ethanone 5 Aluminium trichloride (210.2 g) was added to 1,2-difluorobenzene (200.0 g) at room temperature. The obtained slurry was heated to 50 *C, then chloroacetyl chloride (198.0 g) was added over 50 minutes. The reaction mixture was stirred for an additional 60 minutes, then added slowly to a mixture of ice (786.0 g), water (196.0 g) and 37 wt% hydrochloric acid (297.0 g), during the addition the temperature was kept below 60 *C. After the 10 addition the reaction mixture was heated to 60 *C and the layers separated. The organic layer was washed twice with a 20 w/v% sodium chloride solution (200.0 mL). 2-Chloro-1 (3,4-difluorophenyl) ethanone (270.2 g) was obtained by vacuum distillation of the organic layer. Spectral data: 15 'H-NMR of 2-chloro-1-(3,4-difluorophenyl)ethanone in CDC 3 , 300 mHz S (ppm) HI Pattern 4.7 CICH 2 S 7.3 Ph H-5 dxdxdxd 7.8 Ph H-6 M Ph H-2 3 C-NM R of 2-chloro-1-(3,4-difluorophenyl)ethanone in CDC 3 , 75 MJ-Iz 8 (ppm) Assignment 45.7 CICH 2 CO 118.4 Ph C-2 and C-5, small JF-C visible 126.2 126.2 Ph C-6, small JF-C visible 131.6 Ph C-1, small JF-C visible 149.1-156.3 Ph C-3 and C-4, large JF-c visible 189.3

CICH

2 COPh WO 2008/018822 PCT/SE2007/000706 6 Example 2 Preparation of 2-chloro-1-S-(3,4-difluorophenyl)ethanol s Trimethoxy borane (2.7 g) was added at room temperature to a stirred solution of S diphenylprolinol (4.7 g) in toluene (128.6 mL). After stirring this mixture for 90 minutes at 40 *C borane dimethylsulfide (22.3 g) was added over 15 minutes maintaining the temperature between 35 and 45 *C. This mixture was stirred for 60 minutes at 40 *C, then a solution of 2-chloro-1-(3,4-difluorophenyl)ethanone (70.0 g) in toluene (184.1 mL) was to dosed over a period of 120 minutes maintaining the temperature between 35 and 45 'C. After the completion of the addition the reaction mixture was stirred for another 60 minutes at 40 *C, then cooled to 10 cC. Methanol (69.7 g) was added over a period of 20 minutes controlling the gas formation and the temperature to a maximum of 35 *C. After the addition the mixture was cooled to 20 *C, then stirred at this temperature for 30 15 minutes. The obtained solution was then distilled, under reduced pressure at maximum 45 CC, till the residual Methanol and trimethoxyborane was less than 2 wt%. The obtained solution in toluene was then washed four times with a 10 wt% aqueous HOAc (280.0 mL) at 45 to 55 *C and the obtained water layer back extracted with toluene (140.0 mL). Both organic layers were combined and washed with water (140.0 mL). The resulting organic 20 layer was azeotroped till less than 0.4 wt% water. After correction with toluene a 33 wt% solution of 2-chloro- 1 -S-(3,4-difluorophenyl)ethanol was obtained (214.4 g theoretical yield). The product in solution was characterized by mass spectroscopy (EI): M/z Identification 175.6 M -H 2 O 143.6 M*-CH 2 C1 25 Example 3 Preparation of ethyl (1R,2R)-trans 2-(3,4-difluorophenyl) cyclopropyl carboxylate Sodium hydride (13.4 g) was suspended in toluene (119.9 mL ) and the resulting slurry WO 2008/018822 PCT/SE2007/000706 7 heated to 40 cC, then a solution of triethyl phosphonoacetate (38.4 g ) in toluene (60.0 mL) was added over a period of 60 minutes keeping the temperature between 40 and 45 *C. When the addition was complete the reaction mixture was stirred for an additional 60 minutes at 40 *C, then 90.9 g of a 33 wt% solution of 2-chloro-1-S-(3,4 s difluorophenyl)ethanol in toluene was added over a period of 35 minutes allowing the temperature to raise to maximum 60 'C. Once the addition was complete the obtained mixture was stirred for an additional 14 hours at 60 *C, then water (155.8 mL) was added and the phases separated at 60 'C. The toluene solution containing ethyl (lR,2R)-trans 2 (3,4-difluorophenyl) cyclopropyl carboxylate was used as such in the next step. 10 The product in solution was characterized by mass spectroscopy (El): m/z Identification 226.3 Ml' 198.3 M--H 2

C=CH

2 180.4 M*-HOCH 2

CH

3 153.7 F 2 PhCH 2

CH

2

CH

2 +' 127.4 F 2 Ph* Example 4 Preparation of (1R,2R)-trans 2-(3,4-difluoropheny) cyclopropyl carboxamide 15 Starting from 2-chloro-1-S-(3,4-difluorophenyl)ethanol (30.9 g), ethyl (IR,2R)-trans 2 (3,4-difluorophenyl) cyclopropyl carboxylate was prepared as in example 3. The solvent was distilled and to the resulting oil methanol (109.0 mL), methyl formiate (7.2 g) and 30 wt% sodium methoxide in methanol (11.5 g) were added at room temperature. The mixture was heated to 60 *C in a closed reactor, then 2 bar NH 3 -pressure was applied. During a 20 period of 4 hours the temperature was maintained at 60 *C and the pressure at 2 bar, then the reactor was cooled to room temperature and vented. The reaction mixture was heated to 60 *C and water (277.2 mL) dosed over 1 hour, the temperature was maintained at 60 *C. The resulting solution was cooled to room temperature, then filtered and washed with 1/1 WO 2008/018822 PCT/SE2007/000706 8 methanol/water (69.3 rmL), then with water (49.5 mL) and finally with DiPE (49.5 mL). The resulting crystals were dried at 50 *C in a vacuum oven. After drying (1R,2R)-trans 2-(3,4-difluorophenyl) cyclopropyl carboxamide (22.8 g) was obtained. 5 Spectral data: HNMR of (R,2R)-trans 2-(3,4-difluorophenyI) cyc oropyl carboxamide 8. H Pattern 1.2 CH (from CH 2 ) dxdxd 1.6 CH (from CH 2 ) dxdxd and CH CONH2 2.5 CH-Ph dxdxd 5.8 NI 2 6.8-7.1 3 x Ph-H M 13 C NM R of (IR,2R)-trans 2-(3,4-difluorophenyl) cyclopropyl carboxamide 8 (ppm) Assignment 16.7 CH 2 25.0

C-CONH

2 or C-Ph 26.1 C-Ph or C-CONH 2 115.3 Ph C-2, 2JF--C: 17.6 Hz 117.6 Ph C-5, 2 JF-c: 17.4 Hz 122.734 Ph C-6, 3 JF-c: 6.0 Hz and 4 JF.c: 3.5 135-155 Ph C-4 and C-3 174.3

CONH

2 10 C \NRPonb\DCCDAR4214 I I _DOC-2M120I12 -9 Example 5 Preparation of (IR, 2S)2-(3,4-difluorophenyl)-cyclopropane amine (I R,2R)-trans 2-(3,4-difluorophenyl) cyclopropyl carboxamide (25.0 g) and 157.4 g of a 30 wt% solution of NaOl-l were mixed and heated to 20-25 'C. A 26 wt% solution of aqueous NaOCl (89.5 g) was dosed over a period of 30 minutes maintaining the temperature below 33 'C. Once the addition was finished the reaction mixture was stirred for an additional 3 hours at 30 to 33 *C. The resulting mixture was then heated to 60 *C and stirred at this temperature for an additional 20 minutes. After cooling to 5 C the pH of the reaction mixture was corrected with HCI 37 wt% (99.1 g) till a p-I of 8.5-9.5. iPrOAc (153.3 mL) and MeOI (85.0 mL) were added followed by water (33.8 mL), after stirring and decantation the phases were separated. The obtained water layer was extracted twice with iPrOAc (75.0 and 55.0 mL respectively). And the combined organic phases were diluted till a concentration of 5 wt%. The obtained solution contains (IR, 2S)2-(3,4-difluorophenyl)-cyclopropane amine (18.0 g in 360.4 g solution). The product in solution was characterized by mass spectroscopy (A PCI) m/z Identification 210.6 MI-l'+ CI- 3 CN 169.9 MI-I 153.2 MI-I 4 - NI- 3 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims (12)

1. A process for preparing a compound of formula IV F , ~KCO 2 R IV wherein R is an alkyl group, which comprises treating a compound of formula III 0 F III with a compound of formula 3 0 Il R 2 0 P-,P CO 2 R' R 2 0 (3) wherein R' and R2 are independently selected from alkyl.

2. A process as claimed in claim I wherein the compound of formula 3 is triethyl phosphonoacetate.

3. A process as claimed in claim I or 2 which includes the step of preparing the compound of formula Ill, which step comprises treating a compound of formula 11 9H F C1 F - 11 with a base.

4. A process for preparing a compound of formula IV F ",<..CO 2 R F:0 F IV which process comprises (a) reducing a compound of formula I F CI F to give a compound of formula II OH F CI F II (b) treating the compound of formula II with a base to give a compound of formula III 0 F F (c) treating a compound of formula III with a compound of formula 3 0 R 2 0-11CO R 1 R0 (3) such as triethyl phosphorioacetate.

5. A process for preparing a compound of formula IV C \NRPonhhDCC\DAR\21 I W I DOC-2611/2112 - 12 F QCO 2 R F IV comprising a) the compound of formula II OH F CI F II is converted to the compound of formula IV by treating the compound of formula 11 with a base such as sodium hydride. b) treating the product of step a) with a compound of formula 3 0 Il R 2 0-P C 2 R 1 R 2 0 (3) such as triethyl phosphonoacetate.

6. A process as claimed in any one of the preceeding claims which also includes a step of converting the compound of formula IV to a compound of formula VII F /$CONH 2 F:0 VII.

7. A process as claimed in claim 6 wherein the compound of formula IV is treated with ammonia in the presence of a suitable base.

8. A process as claimed in any one of claims 1-6 wherein R, R' and R 2 are independently selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, and tert-butyl.

9. A process lor preparing a compound of formula VII C:\NRIOnbl\DCC\DAR\423413_I.IOC-26/"1'/20I12 - 13 F s ..,,' CONH 2 F VIl comprising treating the compound of formula IV F gQ CO 2 R F IV with ammonia in the presence of a suitable base.

10. A process as claimed in claim 9 wherein the base is sodium methoxide.

11. A process as claimed in claim 9 wherein the base is potassium methoxide.

12. A compound of formula 11, 111 or VII.