WO 2015177807, New patent on AVANAFIL by Wanbury

WO 2015177807
Suryakant Shivaji Pol; Nitin Sharadchandra Pradhan; Shashikant Balu Padwal; Vihar Raghunath Telange; Nitn Shankar Bondre
Wanbury ltd

The present invention relates to a novel compound of Formula (II), and its use in preparation of Avanafil, [Formula should be inserted here] wherein R is -OH, -CI or -OR¹ and R¹ is C₁ to C₃ alkyl group
https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2015177807&recNum=1&maxRec=&office=&prevFilter=&sortOption=&queryString=&tab=PCTDescription



It having been developed and launched by VIVUS and JW Pharmaceutical, under license from Mitsubishi Tanabe Pharma, and Auxilium Pharmaceuticals, for treating ED.
A process for preparation of Avanafil was first disclosed in US 6,797,709 (depicted in Scheme I), wherein 4-chloro-5-ethoxycarbonyl-2-methylthio-pyrimidine is coupled with 3-chloro-4-methoxybenzylamine in presence of triethylamine to provide compound of Formula (A), which on oxidization provides a sulfonyl compound of Formula (B). Said compound of Formula (B) is reacted with L-prolinol and exert compound of Formula (C). The resulting compound of Formula (C) undergoes column chromatographic purification and crystallization, while further subjected to hydrolysis to obtain compound of Formula (D). The compound of Formula (D) is coupled with 2-aminomethylpyrimidine to obtain Avanafil of Formula (I). The final product obtained is purified by column chromatography. The need to purify the intermediate compound of Formula (C) and final product, by column chromatography makes this process cumbersome, time consuming and unviable for large scale production thereby contributing to main disadvantages of the process.
Scheme I

Formula (A)
m-CPBA/chloroform

Formula (C) Formula (B)
NaOH/DMSO

Formula (D) Formula (I)
CN 103254179, discloses a process for preparation of Avanafi, wherein 3-chloro-4-methoxybenzylhalide is coupled with cytosine to result compound of Formula (E), later on condensation with L-prolinol yields 4-[(3-chloro-4-methoxy benzyl)amino-2-(2-hydroxymethyl)-l -pyrrolinyl]pyrimidine of Formula (F). The compound of Formula (F) is then condensed with N-(2-pyrimidylmethyl)formamide to obtain Avanafil of Formula (I). Process is depicted in Scheme II
Scheme II

Formula (F) Formula (I)
CN 103254180 describes an alternate process for preparation of Avanafil of Formula (I), wherein a substitution reaction on 6-amino-l ,2-dihydropyrimidine-2-keto-5-carboxylic acid, ethyl ester and 3-chloro-4-methoxybenzylchloride provides 6-(3-chloro-4-methoxybenzylamino)-l ,2-dihydropyrimidine-2-keto-5-carboxylic acid, ethyl ester of Formula (G) which on condensation with L-prolinoI generates 6-(3-chloro-4-methoxybenzylamino)-l ,2-dihydropyrimidine-2-keto-5-carboxylic acid ethyl ester of Formula (H). The compound of Formula (H) is then hydrolysed and coupled with N-(2-pyrimidylmethyI)formamide to obtain Avanafil of Formula (I). Process is depicted in Scheme III
Scheme III

Formula (H) Formula (Γ)
In all the prior art discussed above, chiral compound L-prolinol is coupled in molecule in earlier steps of synthesis. This approach seems to be less feasible for large scale production; the insertion of L-prolinol in early stage may need to exert number of purifications for intermediates. Further the main shortcoming in such process is that the chirality of molecule is disturbed by inserting L-prolinol in early stages because there are number of operations in line in process to obtain the target compound.
CN 103483323, discloses a synthetic method for preparation of avanafil, wherein amidation of pyrimidine-5-carbonyl chlorides with 2-(aminomethyl)pyrimidine at temperature ranging from -10 to 5°C resulted an amide (intermediates A); which underwent condensation with 3-chloro-4-methoxybenzylamine at the temperature ranging from 0 -3°C to give 4-[(3-chloro-4-methoxybenzyl)amino]-5-
pyrimidinecarboxamides (intermediates B), which further on condensation with L-prolinol gave avanafil. The disadvantage of this process is the need to maintain the reaction temperature in range of – 10 to 5°C which adds up to cost of process and makes the process complicated. The process is depicted in Scheme IV.
Scheme IV

Intermediate (A)

wherein, R’ & R² are independently, hydrogen, halogen, alkoxy, alkoxyalkyl, cyno group, amino group
Hence, to overcome shortcomings of prior art the inventors of present invention have skillfully designed a process with novel intermediate which concomitantly result Avanafil compound of Formula (I), substantially free from impurities. Further this invention encompass L-proline in last stage of molecule in order to avoid the number of purifications of intermediate which relent the economic significances by taking into account yield of each stage.


Object of the invention
1. The main object of the invention is to provide a novel compound of Formula
(ID-
2. Another object of present invention is to provide a process for preparation of a novel compound of Formula (II).
3. Yet another object of present invention is to provide a process for preparation of Avanafil of Formula (I), in high yield and purity using a novel compound of Formula (II).
4. Yet another object of the present invention to provide simple, economic and industrially scalable process for the preparation of Avanafil o Formula (I).
Summary of the invention
According to an aspect of present invention, there is provided a novel compound of Formula (II).

Formula (II)
wherein R is -OH, -CI or -OR and R is Q to C₃ alkyl group

The invention will be specifically described below with reference to Examples but it should not be construed that the scope of the invention is limited thereto. Since the starting compound was produced by a modified method from that described in prior art, it will be described as Referential Example 1 to 3. Here synthesis routes of Referential Example 1 to 3 and Example 1 to 10 are illustrated below in Scheme (V).
Scheme (V)

Formula (I) Referential Examples
Referential Example 1 – Preparation of ethyl 4-[(3-chloro-4-methoxybenzyl)amino]-2-(methyl sulfanyl)pyrimidine-5-carboxylate
To 600ml of methylene dichloride was added l OOg of ethyl 4-chloro-2-(methylsulfanyl) pyrimidine-5-carboxylate and 91.2g of 3-chloro-4-methoxybenzylamine. The reaction mixture was stirred and 500ml of water, 48g of sodium carbonate and Ig of tetra-butylammonium bromide were added to it. The reaction mixture was then maintained overnight at 25-30°C. After completion of reaction, methylene dichloride layer was separated, washed with water and evaporated to obtain 145g of ethyl 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfanyl) pyrimidine-5-carboxylate having 95% of HPLC purity.
Above reaction can also be carried out using ammonia or triethylamine in same reaction conditions and parameters, in place of sodium carbonate.
Referential Example 2 – Preparation of 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfanyl) pyrimidine-5-carboxylic acid
To 600ml of methanol was added l OOg of ethyl 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfanyl) pyrimidine-5-carboxylate (Referential Example 1) and an aqueous solution of sodium hydroxide (15g of NaOH in 140ml of water). The reaction mixture was heated to reflux temperature. After completion of reaction, the pH of mixture was adjusted to 1 -2 using concentrated hydrochloric acid followed by stirring the mixture for 1 hour at 10-15°C. The solid product obtained was filtered, washed sequentially with water and methanol, and dried overnight at 70-75°C to get 87g of 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfanyl) pyrimidine-5-carboxylic acid.
Referential Example 3 – Preparation of 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfinyl)-N-(pyrimidin-2-ylmethyl) pyrimidine-5-carboxiamide of Formula (III)
To a mixture of 400ml of toluene and 0.5ml of dimethyl formamide was added 50g of 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfanyl) pyrimidine-5-carboxylic acid (Referential Example 2) and 70g of thionyl chloride, and the reaction mixture was refluxed for 2.5 hours. After completion of reaction, solvent was distilled under vacuum and the residue was stripped with toluene to obtain yellow solid mass. The solid mass thus obtained, was cooled to 15-20°C followed by addition of 1 75ml of methylene dichloride, 36. l g of 2-amino methyl pyrimidine mesylate and 35.55g of triaethylamine. The reaction mixture was stirred overnight at 25-30°C. After completion of reaction, methylene dichloride was distilled out to get residue. The residue was washed sequentially with 2.5% sodium carbonate solution and water. The residue was then treated with methanol to obtain 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfinyl)-N-(pyrimidin-2-ylmethyl) pyrimidine-5-carboxiamide of Formula (III) having HPLC purity of more than 95% (yield: 80%)
Referential Example 4 – Preparation of 4-[(3-Chloro-4-methoxybenzyl)amino]-2-[(2S)-2-(hydroxymethyl)-l -pyrrolidinyl]-N-(2-pyrimidinylmethyl)-5-pyrimidinecarboxamide (Avanafil)
Step i)
To 200ml of dichloromethane was added lOg of 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfinyI)-N-(pyrimidin-2-ylmethyl) pyrimidine-5-carboxiamide and 6.5g of m-chloro per benzoic acid and the mixture was stirred for 1 hour at 25-30°C. After completion of reaction, the reaction mixture was washed with aqueous solution of sodium carbonate and water. The resulting dichloromethane layer comprising compound of Formula (IV) was taken to next step.
Step ii)
To the dichloromethane layer obtained in step i), was added 2.57g of triethylamine followed by slow addition of 125ml solution of L-prolinol in dichloromethane (2.46g of L-prolinol in 125ml of dichlromethane). The reaction mixture was maintained overnight. After completion of reaction, the reaction mixture was washed with water followed by evaporation of dichloromethane to obtain an oily mass. The oily mass thus obtained was treated with methanol to yield 8g of Avanafil.
Examples
Example 1 : Preparation of Compound of Formula (II) (wherein R is -OH)
Step i)
To 200ml of methylene dichloride was added lOg of 4-[(3-chloro-4-methoxybenzyl) amino]-2-(methyl sulfinyl)-N-(pyrimidin-2-ylmethyl) pyrimidine-5-carboxiamide of Formula (III) and 6.5g of m-chloro per benzoic acid and the mixture was stirred for 1 hour at 25-30°C. After completion of reaction, the reaction mixture was washed with aqueous solution of sodium carbonate and water. The resulting methylene dichloride layer comprising compound of Formula (IV) was taken to next step.
Step ii)
To the methylene dichloride layer comprising compound of Formula (IV) obtained in step i), was added 5g of triethylamine followed by slow addition of 125ml solution of L-proline in methylene dichloride (2.8g of L-proline in 125ml of methylene dichloride). The reaction mixture was maintained overnight. After completion of reaction, the reaction mixture was washed with water and 5% sodium carbonate solution, followed by evaporation of methylene dichloride to obtain an oily mass. The oily mass obtained was stripped with 50ml acetone to yield 9g of compound of Formula (II) having HPLC purity 98%.
Example 2: Preparation of Compound of Formula (II) (wherein R is -OC₂H₅)
To 100ml of ethanol was added 0.5ml of sulphuric acid and l Og of compound of Formula (II) obtained in example 1 , and the reaction mixture was maintained at reflux temperature till completion of reaction. The reaction mixture was then cooled to 25-30°C and the pH of reaction mixture was adjusted to 7-8 using sodium carbonate. Filter the reaction mixture and collect filtrate containing product. The ethanol in filtrate is completely distilled out to isolate 10.45g of esterified compound of Formula (II).
Example 3 : Preparation of Compound of Formula (II) (wherein R is -CI)
To a mixture of 400ml of toluene and 0.5ml of dimethylformamide was added 50g of compound of Formula (II) obtained in example 1 , and 70g of thionyl chloride. The reaction mixture was refluxed for 2.5 hours. After completion of reaction, solvent was distilled under vacuum and the residue was stripped with toluene to obtain 50.5g of oily carboxylic acid chloride compound of Formula (II).
Example 4: Preparation of Avanafil of Formula (I)
In an inert atmosphere, a solution of 30g of compound of Formula (II) obtained in example 1 or 2, in 150 ml of tetrahydrofuran was dropwise added to 180ml of suspension of 1.0M lithium aluminium hydride solution in tetrahydrofuran, The reaction mixture was refluxed for 5 hours. After completion of reaction, the mixture was cooled in ice-bath and saturated aqueous solution of sodium sulfate was added to decompose excess of lithium aluminium hydride. The mixture was then diluted with 200ml of methylene dichloride and thus formed organic layer was separated. The organic layer was washed with water (3 ^χ 100 ml), dried over MgS04 and concentrated to collect crude Avanafil of Formula (I) which was subjected to purification using methanol as solvent to yield 22.8g of Avanafil of Formula (I) having HPLC purity of 99.20%.
Example 5 : Preparation of Avanafil of Formula (I)
To a mixture of 1.3g sodium borohydride, 1 ml methanesulfonic acid and 50ml ethanol was added l Og of compound of Formula (II) obtained in example 1 or 2, and the mixture was stirred at 25-30°C for 5 hours. After completion of reaction, 100ml water was added and the mixture was extracted with 1 00ml methylene dichloride (50ml X 2). The methylene dichloride layer obtained was evaporated under reduced pressure to get an oily mass. The oily mass was stripped with ethyl acetate at 45- 50°C. To the oily residue formed was added 50ml of ethyl acetate and the mixture was cooled to 0-5°C. The solid obtained was filtered, washed with ethyl acetate and dried to yield crude Avanafil of Formula (I) which was subjected to purification using methanol as solvent to yield 7g of Avanafil of Formula (I) having HPLC purity of 99%.
Example 6 to Example 8
The procedure is carried out as in example 5 except for instead of methanesulfonic acid other reducing agents are used in combination with sodium borohydride. The results are given in Table I
Table I

Example 9: Preparation of Avanafil of Formula (I)
To 100ml of ethanol was added 0.5ml of sulphuric acid and l Og of compound of Formula (II) obtained in example 1 , and the reaction mixture was maintained at reflux temperature till completion of reaction. The reaction mixture was then cooled to 25-30°C and the pH of reaction mixture was adjusted to 7-8 using sodium carbonate. Filter the reaction mixture and collect filterate containing product. To the fi Iterate was added 1.2g of sodium borohydride and 2.6g of lithium bromide, and the mixture was stirred for 5 hours. After complete conversion of ester to final product, l OOml water was added and the mixture was extracted with 100ml methylene dichloride (50ml X 2). The methylene dichloride layer obtained was evaporated under reduced pressure to get an oily mass. The oily mass was stripped with 25ml ethyl acetate at 45-50°C. To the oily residue formed was added 50ml of ethyl acetate and the mixture was cooled to 0-5°C. The solid obtained was filtered, washed with ethyl acetate and dried to yield crude Avanafil of Formula (I) which was subjected to purification using methanol as solvent to yield 7.5g of Avanafil of Formula (I) having HPLC purity of 99%.
Example 10: Preparation of Avanafil of Formula (I) from Compound of Formula (II) (wherein R is -CI)
To a mixture of 400ml of tetrahydrofuran and 50g of carboxylic acid chloride compound of Formula (II) obtained in example 3, was added 12g sodium borohydride at 0-5°C. After completion of reaction, water was added to reaction mixture to decompose excess of sodium borohydride present. The reaction mixture was then concentrated and a solution of 30g of potassium hydroxide in 200 ml of water was added. The mixture was heated to 60-70°C and maintained for 15-18 hours. The mixture was then cooled to 25-30°C and 500 ml of methylene dichloride was added. The organic layer thus formed, was separated and evaporated to yield crude Avanafil
of Formula (I) which was then subjected to purification using methanol as solvent to obtain 40g of Avanafil of Formula (I) having HPLC purity of 99.01%.

Mr. K. Chandran
		Wholetime Director & Vice Chairman

Tarapur plant

MR K. CHANDRAN (left), Director, Wanbury, and Mr Asok Shinkar, Director-Corporate Finance, at a press conference held in Mumbai on Monday.

//////////////

Preparation method of rosuvastatin calcium, CN 102617481

ROSUVASTATIN CALCIUM

Inventors	林开朝
Applicant	湖南欧亚生物有限公司

SEE.........http://www.google.us/patents/CN102617481A?cl=en

'VPATAPP'.A free mobile based application for IPM related information

A free mobile based application

VPATAPP

October 2015 – Present (2 months)Android play store

It provides:
1. Worldwide patent blogs from different regions like USA, Europe, BRIC, Latin America, Africa, and Asia-pacific including India;
2. Worldwide full time LLM/Masters/ Graduate courses in IP;
3. Journals in the area of Intellectual Property Law especially patents;
4. Weekly or monthly official gazettes or registers published by different patent offices across the world;
5. Patent classification systems;
6. Patent search websites available from patent offices across the world;
7. Updated full text patent acts of different countries as published by the patent offices or WIPO.

Please See: https://play.google.com/store/apps/details?id=org.gunadhya.vpatapp

Please See: https://play.google.com/store/apps/details?id=org.gunadhya.vpatapp

This is Vijaykumar Shivpuje. My profile can be accessed here: https://in.linkedin.com/pub/vijaykumar-shivpuje/14/50a/75a. I am regular reader of http://newdrugapprovals.org/ and was part of Glenmark IPR team.

Recently, we have developed a simple android based mobile application called 'VPATAPP'. This app is available free of cost on Android Play Store. This tiny app provides the quick links for

1. Worldwide patent blogs from different regions like USA, Europe, BRIC, Latin America, Africa, and Asia-pacific including India;

2.  Worldwide full time LLM/Masters/ Graduate courses in IP;

3.  Journals in the area of Intellectual Property Law especially patents;

4.  Weekly or monthly official gazettes or registers published by different patent offices across the world;

5.  Patent classification systems;

6.  Patent search websites available from patent offices across the world;

7.  Updated full text patent acts of different countries as published by the patent offices or WIPO.

Please See: https://play.google.com/store/apps/details?id=org.gunadhya.vpatapp

Please See: https://play.google.com/store/apps/details?id=org.gunadhya.vpatapp

  

I would be pleased if you can publish about the app on your blog and spread the word if you feel it worth. Also, if you can download the app and suggest your comments and reviews, that would be great for the cause.

Thanks and Regards,

Vijaykumar Shivpuje

////////////

New patent, WO 2015155704, An improved process for the preparation of pramipexole dihydrochloride monohydrate

WO 2015155704, An improved process for the preparation of pramipexole dihydrochloride monohydrate

PIRAMAL ENTERPRISES LIMITED [IN/IN]; Piramal Tower, Ganpatrao Kadam Marg Lower Parel Mumbai 400013 (IN) Inventors: PATIL, Pravin; (IN). PANSARE, Prakash; (IN). JAGTAP, Ashutosh; (IN). KRISHNAMURTHY, Dhileepkumar; (IN)

Pramipexole, (S)-2-amino-4,5,6,7-tetrahydro-6-(propylamino)benzothiazole, represented by the following formula I (the compound of formula I), is a dopamine D2/D3 agonist used for treatment of Schizophrenia, and particularly for the treatment of Parkinson's disease. Pramipexole is marketed in the form of dihydrochloride monohydrate salt under the brand name Mirapex.

Formula I

The compound of formula I is disclosed in US Patent no. 4,886,812 (US '812 Patent). The US' 812 Patent also describes a process for the preparation of the compound of formula I and its dihydrochloride monohydrate salt involving the propylation reaction of the compound of formula II with n-propylbromide as a propylating agent in the presence of potassium carbonate by using methanol as a solvent to provide the reaction mixture. The resulting reaction mixture is then refluxed for 3 hours. After completion of the reaction, water is added to the reaction mixture. The reaction mixture is then extracted with ethyl acetate and concentrated to obtain the residue. The obtained residue is purified by silica gel chromatography and the corresponding fraction is concentrated under reduced pressure to obtain the compound of formula I which is then converted into its dihydrochloride monohydrate salt. Although, US '812 Patent describes the process for the preparation of the compound of formula I from the compound of formula II, it does not teach the process for converting the compound of formula I into its dihydrochloride monohydrate salt. Also, the process described in US '812 Patent involves propylation of the compound of formula II using 4 molar equivalents of n-propylbromide as the propylating agent. N-propylbromide is known to be carcinogenic compound and its average threshold limit value for 8 hours exposure is 10 parts per million. Therefore, on commercial scale, excess use of such a hazardous reagent is not desirable. Further, propylation of the compound of formula II using the process described in US '812 Patent generates one major impurity namely (6S)-2,6-benzothiazolediamine,4,5,6,7-tetrahydro-N²,N⁶-dipropyl. The US '812 Patent does not teach any purification method for removal of this impurity.

Indian Patent Application no. 694/MUM/2006 describes a process for the preparation of the dihydrochloride monohydrate salt of the compound of formula I involving treating the alcoholic solution of the compound of formula I with hydrochloric acid and precipitating the dihydrochloride monohydrate salt of the compound of formula I by addition of water. The process disclosed in this patent application does not involve any purification step for the purification of the compound of formula I or its dihydrochloride monohydrate salt and thus, the final active pharmaceutical ingredient (API), the dihydrochloride monohydrate salt of the compound of formula I prepared by this process does not have the desired pharmaceutically acceptable purity.

Indian patent application no. 605/MUM/2008 describes a process for the preparation of the dihydrochloride salt of the compound of formula I. The process for the preparation of the dihydrochloride salt of the compound of formula I involves the propylation reaction of the compound of formula II with n-propanal as a propylating agent by using a mixture of methanol and water as the solvent. To the resulting reaction mixture, glacial acetic acid and sodium borohydride are charged and the reaction mixture is stirred for 30-40 minutes at a temperature of 15 to 20°C. The reaction mixture is then cooled to -5 to 0°C and to the reaction mixture; second lot of n-propanal with methanol and sodium borohydride is added. The resulting reaction mixture is stirred for 30-40 minutes and quenched with brine solution. The reaction mixture is distilled under vacuum to obtain a residue. To the obtained residue, ethyl acetate and water are added. Two layers formed are separated and ethyl acetate layer is concentrated under vacuum to obtain the crude compound of formula I. The resulting crude compound of formula I is then recrystallised by using acetonitrile to yield the pure compound of formula I. To the pure compound of formula I; ethanolic hydrochloric acid solution is added. The reaction mixture is stirred for 1 hour to precipitate the solid. The precipitated solid is filtered and suspended in ethanol. The reaction mixture is then stirred at reflux temperature for 30 minutes and at room temperature for 1 hour to precipitate the dihydrochloride salt of the compound of formula I. The precipitated dihydrochloride salt of the compound of formula I is dissolved in a mixture of ethanol and water; and filtered through hyflo. The filtrate is then distilled under vacuum and recrystallised by using ethanol to obtain the pure dihydrochloride salt of the compound of formula I. The process disclosed in said patent involves the use of 3 molar equivalents of sodium borohydride and n-propanal which renders the process costlier and hence, this process is not viable for scale up.

The general process for producing the dihydrochloride monohydrate salt of the compound of formula I is depicted in the following Scheme I:

(S)-2-amino-6-propinamido-4, 5,6,7- tetrahydrobenzothiazole

sodium borohydride

o e compoun o ormu a

Scheme I

Scheme-II.

methanol-water purification

Scheme-II

Examples

Example 1:

Step A: Synthesis of compound of formula I:

To the reaction flask dichloromethane (1500 ml), methanol (1500 ml) and the compound of formula II (100 gm) were charged at a temperature of 25-30° C. The reaction mixture was cooled to a temperature of 3-8 °C and to the reaction mixture, sulphuric acid (8.69 gm); n-propanal (13.98 ml) and sodium borohydride (2.46 g) were charged. The reaction mixture was stirred for 20-30 minutes at a temperature of 3-8°C. To the reaction mixture, n-propanal (41.94g) followed by sodium borohydride (7.38g) were added in three different lots at a temperature of 3-8°C. After completion of the reaction, the reaction mixture was quenched with brine solution. The quenched reaction mixture was further concentrated up to 15-16 volumes at 50-55°C under vacuum. The reaction mixture was cooled to 15-20°C. To the reaction mixture potassium carbonate (150 g), ethyl acetate (900 ml) and methanol (100 ml) were charged. The two layers formed were separated. The organic layer was then concentrated up to 7 to 8 volumes. To the organic layer ethyl acetate (500 ml) and brine solution (240 g) were added. The two layers formed were separated. The organic layer was treated with activated charcoal and filtered through hyflo. The organic layer was then concentrated under vacuum to obtain residue. To the obtained residue diisopropyl ether (200 ml) was added and reaction mixture was stirred for 20-30 minutes at 45-50°C. The reaction mixture was then cooled at 25-30°C to precipitate solid. The precipitated solid was then filtered and washed with diisopropyl ether (200ml) to obtain the compound of formula I.

Step B: Synthesis of monohydrochlonde salt of the compound of formula I:

To the reaction flask, the compound of formula I (as obtained in the step A) and isopropyl alcohol (900 ml) were charged and the reaction mixture was stirred at a temperature of 25-35°C for 1 hour. The reaction mixture was then filtered through hyflo and washed with isopropyl alcohol (100 ml). To the filtrate cone, hydrochloric acid (42.20 ml) was added to obtain a solid. The obtained solid was then filtered and washed with isopropyl alcohol (200 ml) to yield the monohydrochloride salt of the compound of formula I.

Step C: Purification of the monohydrochloride salt of the compound of formula I:

To the reaction flask, the monohydrochloride salt of the compound of formula I (as obtained in the step B) and the mixture of methanol (300 ml) and water (5.01 ml) were charged and the reaction mixture was stirred at a temperature of 55-60°C for 2 hours. The resulting reaction mixture was then cooled to a temperature of 20-25°C to precipitate solid. The precipitated solid was then filtered and washed with isopropyl alcohol (200 ml) to obtain the pure monohydrochloride salt of the compound of formula I.

Step D: Synthesis of the dihydrochloride monohydrate salt of the compound of formula I:

To the reaction flask, the pure monohydrochloride salt of the compound of formula I (as obtained in the step C), methanol (600 ml) and cone, hydrochloric acid (33.67 ml) were charged and the reaction mass was stirred at a temperature of 3-8°C for 2 hours. To the reaction mass, activated charcoal (4g) was charged and the reaction mass was stirred for 30-45 minutes at temperature of 40-50°C. The activated charcoal was filtered through hyflo and filtrate was concentrated under vacuum to obtain residue. To the residue, isopropyl alcohol (700 ml) was charged and the reaction mass was maintained for 2-3 hours at 15-20°C to precipitate solid. The precipitated solid was then filtered and washed with isopropyl alcohol (100 ml). The solid was then dried under vacuum to yield dihydrochloride monohydrate salt of the compound of formula I. Yield 36%, purity 99.77%.

Details for HPLC analysis:

Column: Inertsil ODS-3, 125 X 4.0 mm, 5μιη

Part No: C/N 5020

Mobile phase

Mobile phase A: Buffer solution

Mobile phase B: Acetonitrile: Buffer (500:500 v/v)

Flow rate: 1.5 ml/min

Injection volume: 5 μΐ

Run time: 25 minutes

Detector: 264 nm.

Column temperature: 40°C

Diluent: Acetonitrile: Buffer (200:800 v/v)

Procedure:

For system suitability inject (5μί) of the system suitability solution. The resolution between Pramipexole (the compound of formula I) related compound and Pramipexole should not be less than 6.0. The tailing factor for Pramipexole should not be more than 2.0. Inject Standard solution in six replicates into the chromatograph. For the Pramipexole peak, the relative standard deviation should not be more than 5.0%.

Inject (5μί) of blank preparation and test solution into the chromatograph, measure the responses of all the peaks and calculate all known impurities and unknown impurities by the formula given below. In the sample chromatogram disregard any peak due to the blank. Retention time and relative retention times are given in the table below.

Calculation :- SPL (Area) Cone STD

% impurities = X X 100

STD (Area) Cone SPL

Where:

SPL (Area) - is area of peak due to impurities in sample preparation.

STD (Area) - is mean area of peak of Pramipexole in reference solution (a) for injections.

Cone SPL - concentration of Pramipexole in test solution in mg/mL

Cone STD - concentration of Pramipexole in test solution in mg/mL

Chairman of Piramal Enterprises Ltd. Ajay Piramal

Swati Piramal

WO2015155153, SYNTHESIS OF VORTIOXETINE VIA (2,4-DIMETHYLPHENYL)(2-IODOPHENYL)SULFANE INTERMEDIATE

WO2015155153,  SYNTHESIS OF VORTIOXETINE VIA (2,4-DIMETHYLPHENYL)(2-IODOPHENYL)SULFANE INTERMEDIATE

LEK PHARMACEUTICALS D.D. [SI/SI]; Verovskova 57 1526 Ljubljana (SI)
Inventors:ZUPANCIC, Borut; (SI)

Vortioxetine is disclosed as Example 1 e in WO 2003/029232 A1 and is described as being prepared analogously to Example 1 . The process used to prepare Example 1 involves the preparation of 1 -(2-((2-(trifluoromethyl)phenyl)thio)phenyl)piperazine on a solid polystyrene support, followed by decomplexation using visible light irradiation, and purification by preparative LC-MS and ion-exchange chromatography. The overall yield for the preparation of vortioxetine is described as 17%.

Several alternative palladium catalyzed processes for the preparation of vortioxetine are described in Examples 17 to 25 of WO 2007/144005 A1 . These processes describe the preparation of vortioxetine from 2,4-dimethylthiophenol and 2-bromoiodobenzene (or 1 ,2-dibromobenzene) starting materials via a 1 -(2-bromo-phenylsulfanyl)-2,4-dimethyl-benzene intermediate. Each of these processes involves the use of a palladium catalyst and a phosphine ligand.

The preparation of vortioxetine is also described by Bang-Andersen et al. in J. Med. Chem. (201 1 ), Vol. 54, 3206-3221 . Here, in a first step, te/t-butyl 4-(2-bromophenyl)piperazine-1 -carboxylate intermediate is prepared from Boc-piperazine and 2-bromoiodobenzene in a palladium catalyzed coupling reaction. te/t-Butyl 4-(2-bromophenyl)piperazine-1 -carboxylate is then reacted with 2,4-dimethylthiophenol, again in the presence of palladium catalyst and a phosphine ligand, to provide Boc-protected vortioxetine. In the final step, vortioxetine is deprotected using hydrochloric acid to give vortioxetine hydrochloride.

WO 2013/102573 A1 describes a reaction between 1 -halogen-2,4-dimethyl-phenyl, 2-halogen-thiophenol and an optionally protected piperazine in the presence of a base and a palladium catalyst consisting of a palladium source and a phosphine ligand.

Each of the above processes has disadvantages. The process described in WO 2003/029232 is low yielding and unsuitable for the large scale production of vortioxetine, whereas the processes described in WO 2007/144005 A1 , WO 2013/102573 A1 and by Bang-Andersen et al. require the use of expensive starting materials, palladium catalyst and phosphine ligand. In addition, the toxicity of palladium is well known, Liu et al. Toxicity of Palladium, Toxicology Letters, 4 (1979) 469-473, and the European Medicines Agency' s Guideline on the Specification for Residues of Metal Catalysts sets clear limits on the permitted daily exposure to palladium arising from palladium residue within drug substances, www.ema.europa.eu. Thus it would be desirable to avoid the use of a palladium catalyst in the synthesis of vortioxetine and the subsequent purification steps required to remove palladium residue from the final pharmaceutical product.

The invention is described below in further detail by embodiments, without being limited thereto.

A general concept of the process of the present invention may be represented in Scheme 1 .

Scheme 1 : General representation of the basic synthetic concept of the present invention.

Scheme 2.

X = NH₂: lb

Scheme 2: Representation of a particular synthetic embodiment of the present invention.

Compound III can also be prepared from 2,4-dimethylbenzenethiol (II) and 1 -fluoro-2-nitrobenzene (l"'a) or 1 -chloro-2-nitrobenzene (l'"b). In the first step (2,4-dimethylphenyl)(2- nitrophenyl)sulfane (III') is formed and in the second reaction step nitro group is reduced to ami

Z = F: l"'a

Z = CI: l"'b

Scheme 3: Representation of a particular synthetic embodiment of the present invention.

Example 7: Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine vortioxetine, VII)

Mixture of (2,4-dimethylphenyl)(2-iodophenyl)sulfane V (0.34 g, 1 .0 mmol), piperazine VI (0.13 g, 1 .5 mmol), K₃P0₃ (0.42 g, 2.0 mmol), Cul (19 mg, 0.1 mmol), and 2-phenylphenol (68 mg, 0.4 mmol) in dry and degassed DMSO (2 mL) was heated under nitrogen atmosphere at 120°C for 20 h. Water (10 mL) is then added and product is extracted to EtOAc (3 x 10 mL). Combined organic layers were washed with water (3 x 10 mL) and brine (2 x 10 mL) and dried over Na₂S0₄. After evaporation of the solvent crude product is purified by chromatography to afford title compound: H NMR (CDCI₃, 500 MHz) δ 1 .63 (br s, 1 H), 2.33 (s, 3H), 2.37 (s, 3H), 3.02-

3.09 (m, 8H), 6.52 (m, 1 H), 6.87 (m, 1 H), 7.04 (m, 1 H), 7.06-7.10 (m, 2H), 7.16 (m, 1 H), 7.39 (d, J= 7.8 Hz, 1 H); MS (ESI) m/z: 299 [MH]⁺.

Example 8: Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine (vortioxetine, VII)

Mixture of (2,4-dimethylphenyl)(2-iodophenyl)sulfane V (0.34 g, 1 .0 mmol), piperazine VI (0.13 g, 1 .5 mmol), K₃P0₃ (0.42 g, 2.0 mmol), Cul (19 mg, 0.1 mmol), and N,N-diethyl-2-hydroxybenzamide (39 mg, 0.2 mmol) in dry and degassed DMSO (2 mL) was heated under nitrogen atmosphere at 120 ^ for 20 h. Water (10 mL) is then added and product is extracted to EtOAc (3 x 10 mL). Combined organic layers were washed with water (3 x 10 mL) and brine (2 x 10 mL) and dried over Na₂S0₄. After evaporation of the solvent crude product is purified by chromatography to afford title compound: H NMR (CDCI₃, 500 MHz) δ 1 .63 (br s, 1 H), 2.33 (s, 3H), 2.37 (s, 3H), 3.02-3.09 (m, 8H), 6.52 (m, 1 H), 6.87 (m, 1 H), 7.04 (m, 1 H), 7.06-7.10 (m, 2H), 7.16 (m, 1 H), 7.39 (d, J= 7.8 Hz, 1 H); MS (ESI) m/z: 299 [MH]⁺.

Example 9: Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine hydrobromide

(vortioxetine HBr, VII.HBr)

To a solution of vortioxetine VII (1 .80 g, 6.03 mmol) in iPrOAc (20 mL) at room temperature 48% HBr (0.68 mL, 6.03 mmol) was slowly added. Obtained mixture was stirred at room temperature for 1 h, white precipitate was then filtered off, washed with acetone (2 x 20 mL), and dried to afford title compound VII.HBr as a white powder (2.15 g, 94% yield): H NMR (DMSO-d₆, 500 MHz) δ 2.23 (s, 3H), 2.32 (s, 3H), 3.15-3.27 (m, 8H), 6.40 (m, 1 H), 6.96 (m, 1 H), 7.08-7.17 (m, 3H), 7.24 (m, 1 H), 7.32 (d, J= 7.8 Hz, 1 H), 8.85 (br, 2H).

Reference Example 1 : Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine

(vortioxetine, VII)

Mixture of piperazine (1 .0 g, 1 1 .6 mmol), NaOtBu (1 .37 g, 13.8 mmol), Pddba₂ (40 mg, 0.07 mmol), and 1 ,3-bis(2,6-di-i-propylphenyl)imidazolium chloride (24 mg, 0,07 mmol) in dry and degassed toluene (10 mL) is stirred at room temperature for 1 h. (2,4-Dimethylphenyl)(2-iodophenyl)sulfane V (1 .32 g, 3.86 mmol) is then added, reaction mixture is heated to l OO'C and stirred for 24 h. After cooling to room temperature to the reaction mixture water (5 mL) and Celite (0.4 g) is added. After stirring for 20 min salts are filtered off, organic layer is separated, washed with brine (2 x 10 mL), dried over Na₂S0₄ and solvent is evaporated to afford crude product, which is then purified by chromatography to afford title compound as yellowish crystals: H NMR (CDCI₃, 500 MHz) δ 1 .63 (br s, 1 H), 2.33 (s, 3H), 2.37 (s, 3H),

Reference Example 2: Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine

(vortioxetine, VII)

Mixture of piperazine (1 .29 g, 15.0 mmol), NaOtBu (1 .77 g, 17.8 mmol), Pddba2 (52 mg, 0.09 mmol), and rac-BINAP (93 mg, 0,15 mmol) in dry and degassed toluene (10 mL) was stirred at room temperature for 1 h. (2,4-Dimethylphenyl)(2-iodophenyl)sulfane V (1 .70 g, 5.0 mmol) was then added, reaction mixture was heated to 100°C and stirred for 24 h. After cooled to room temperature to the reaction mixture water (5 mL) and Celite (0.4 g) were added. After stirring for 20 min salts were filtered off, organic layer was separated, washed with brine (2 x 10 mL), dried over Na₂S0₄ and solvent was evaporated to afford product as an orange oil (1 .41 g, 95% yield): H NMR (CDCI₃, 500 MHz) δ 1 .63 (br s, 1 H), 2.33 (s, 3H), 2.37 (s, 3H), 3.02-3.09 (m, 8H), 6.52 (m, 1 H), 6.87 (m, 1 H), 7.04 (m, 1 H), 7.06-7.10 (m, 2H), 7.16 (m, 1 H), 7.39 (d, J = 7.8 Hz, 1 H); MS (ESI) m/z: 299 [MH]⁺.

Comparative Example 1 : Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine

(vortioxetine, VII)

Mixture of (2,4-dimethylphenyl)(2-bromohenyl)sulfane V" (0.29 g, 1 .0 mmol), piperazine VI (0.13 g, 1 .5 mmol), K₃P0₃ (0.42 g, 2.0 mmol), Cul (19 mg, 0.1 mmol), and 2-phenylphenol (68 mg, 0.4 mmol) in dry and degassed DMSO (2 mL) was heated under nitrogen atmosphere at 120°C for 20 h. Vortioxetine VII was not formed.

Comparative Example 2: Preparation of 1 -(2-((2,4-dimethylphenyl)thio)phenyl)piperazine

(vortioxetine, VII)

Mixture of (2,4-dimethylphenyl)(2-bromophenyl)sulfane V (0.29 g, 1 .0 mmol), piperazine VI (0.13 g, 1 .5 mmol), K₃P0₃ (0.42 g, 2.0 mmol), Cul (19 mg, 0.1 mmol), and N,N-diethyl-2-hydroxybenzamide (39 mg, 0.2 mmol) in dry and degassed DMSO (2 mL) was heated under nitrogen atmosphere at 120 ^ for 20 h. Vortioxetine VII was not formed.


















Vojmir Urlep, President of the Lek Management Board,










//////