Title of Invention	A PROCESS FOR THE PREPARATION OF 6 ALPHA, 9 ALPHA-DIFLUORO-11 BETA-HYDROXY-16 ALPHA-METHYL-3-OXO-17 ALPHA-HYDROXY-ANDROSTA-1,4-DIENE-17 BETA-CARBOXYLIC ACID.
Abstract	TITLE: A PROCESS FPR THE PREPARATION OF 6 ALPHA, 9 ALPHA-DIFLUORO-11 BETA-HYDROXY-16 ALPHA-METHYL-3-OXO-17 ALPHA-HYDROXY-ANDROSTA-1,4-DIENE-15 BETA-CARBOXYLIC ACID. THE PRESENT INVENTION RELATES TO A PROCESS FOR THE PREPARATION OF 6ALPHA,9ALPHA-DIFLUORO-11BETA-HYDROXY-16ALPHA-METHYLO-3-OXO17ALPHA-HYDROXY-ANDROSTA-1,4-DIENE-17BETA-CARBOXYLIC ACID, COMPRISING A COMPOUND OF FORMULA, SAID PROCESS COMPRISING: FIGURE (a) OXIDATION IN THE MANNER SUCH AS HEREIN DESCRIBED, OF A SOLUTION, SUCH AS HEREIN DESCRIBED, CONTAINING THE COMPOUND OF FORMULA, WHEREIN THE SOLUTION OF THE COMPOUND OF FORMULA IS FORMED IN A MIXTURE OF WATER AND TETRAHYDROFURAN, AND; (b) PRECIPITATION OF THE COMPOUND OF FORMULA IN CRYSTALLINE FORM FROM THE REACTION MIXTURE BY ADDITION OF AN ANTI-SOLVENT UNDER TEMPERATURE CONDITIONS OF 10DEGREE C OR HIGHER.

Title of Invention

A PROCESS FOR THE PREPARATION OF 6 ALPHA, 9 ALPHA-DIFLUORO-11 BETA-HYDROXY-16 ALPHA-METHYL-3-OXO-17 ALPHA-HYDROXY-ANDROSTA-1,4-DIENE-17 BETA-CARBOXYLIC ACID.

Abstract

TITLE: A PROCESS FPR THE PREPARATION OF 6 ALPHA, 9 ALPHA-DIFLUORO-11 BETA-HYDROXY-16 ALPHA-METHYL-3-OXO-17 ALPHA-HYDROXY-ANDROSTA-1,4-DIENE-15 BETA-CARBOXYLIC ACID. THE PRESENT INVENTION RELATES TO A PROCESS FOR THE PREPARATION OF 6ALPHA,9ALPHA-DIFLUORO-11BETA-HYDROXY-16ALPHA-METHYLO-3-OXO17ALPHA-HYDROXY-ANDROSTA-1,4-DIENE-17BETA-CARBOXYLIC ACID, COMPRISING A COMPOUND OF FORMULA, SAID PROCESS COMPRISING: FIGURE (a) OXIDATION IN THE MANNER SUCH AS HEREIN DESCRIBED, OF A SOLUTION, SUCH AS HEREIN DESCRIBED, CONTAINING THE COMPOUND OF FORMULA, WHEREIN THE SOLUTION OF THE COMPOUND OF FORMULA IS FORMED IN A MIXTURE OF WATER AND TETRAHYDROFURAN, AND; (b) PRECIPITATION OF THE COMPOUND OF FORMULA IN CRYSTALLINE FORM FROM THE REACTION MIXTURE BY ADDITION OF AN ANTI-SOLVENT UNDER TEMPERATURE CONDITIONS OF 10DEGREE C OR HIGHER.

Full Text	A PROCESS FOR THE PREPARATION OF 6 ALPHA,9 ALPHA-DIFLURO-11BETA- HYDR0XY-16ALPHA-METHYL-3-OXO-17ALPHA-HYDROXY-ANDR0STA-l,4-DIENE-17 BETA -CARBOXYLIC ACID The present invention relates to a novel process for the synthesis of a known intermediate, useful in the preparation of anti-inflammatory steroids. There is also provided a new physical form of the intermediate which has improved handling properties 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-17a-propionyloxy-3-oxoandrosta-1, 4- diene-17ß-carbothioic acid, S-fluoromethyl ester (Formula A) was first described as an anti-inflammatory steroid by US Patent No. 4,335,121. This compound is also known by the generic name of fluticasone propionate and has since become widely known as a highly effective steroid in the treatment of inflammatory diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Additionally, 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-propionyloxy- androsta-1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahydro-furan-3-yl) ester (Formula B) was described in WO 97/24365 as a class of hydrolysable steroids with lactone derivatives. This compound possesses useful anti-inflammatory activity whilst having little or no systemic activity. Currently there is considerable interest in compounds of formula (A) and (B) as anti-inflammatory and anti-allergic compounds in the treatment of asthma and other inflammatory diseases. US 4,335,121 and WO 97/24365 describe preparations of fluticasone propionate and 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-propionyloxy-androsta- 1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahydro-furan-3-yl) ester, respectively which utilise a common starting material, namely 6a, 9a-difluoro-11ß-hydroxy- 16a-methyl-3-oxo-17a-hydroxy-androsta-1,4-diene-17ß-carboxylic acid (Formula I). However, this hydroxy acid androstane derivative compound is an extremely costly starting material for preparing quantities of steroids of formulae (A) and (B). Thus, according to a first aspect of the present invention we provide a novel process for the preparation of a compound of formula (I) which comprises the following step: wherein step (a) comprises oxidation of a solution containing the compound of formula (II). Preferably, step (a) will be performed in the presence of a solvent comprising methanol, water, tetrahydrofuran, dioxan or diethylene glygol dimethylether. For example, so as to enhance yield and throughput, preferred solvents are methanol, water or tetrahydrofuran, and more preferably are water or tetrahydrofuran, especially water and tetrahydrofuran as solvent. Dioxan and diethylene glygol dimethylether are also preferred solvents which may optionally (and preferably) be employed together with water. Preferably, the solvent will be present in an amount of between 3 and 10vol relative to the amount of the starting material (1wt), more preferably between 4 and 6 vol., especially 5 vol. If desired, the solution containing the compound of formula (II) may be cooled prior to oxidation eg. to a temperature less than approximately 10°C. Preferably the oxidising agent is present in an amount of 1-9 molar equivalents relative to the amount of the starting material. For example, when a 50% w/w aqueous solution of periodic acid is employed, the oxidising agent may be present in an amount of between 1.1 and 10wt. relative to the amount of the starting material (1wt.), more preferably between 1.1 and 3wt, especially 1.3wt. Preferably, the oxidation step will comprise the use of a chemical oxidising agent. More preferably, the oxidising agent will be periodic acid or iodic acid or a salt thereof. Most preferably, the oxidising agent will be periodic acid or sodium periodate, especially periodic acid. Alternatively (or in addition), it will also be appreciated that the oxidation step may comprise any suitable oxidation reaction, eg. one which utilises air and/or oxygen. When the oxidation reaction utilises air and/or oxygen, the solvent used in said reaction will preferably be methanol. Preferably, step (a) will involve incubating the reagents at room temperature or a little warmer, say around 25 °C eg for 2 hours. The compound of formula (I) may be isolated by crystallisation from the reaction mixture by addition of an anti-solvent. A suitable anti-solvent for compound of formula (I) is water. Surprisingly we have discovered that it is highly desirable to control the conditions under which the compound of formula (I) is precipitated by addition of anti-solvent eg water. When the crystallisation is performed using chilled water (eg water/ice mixture at a temperature of 0-5 °C) although better anti-solvent properties may be expected we have found that the crystalline product produced is very voluminous, resembles a soft gel and is very difficult to filter. Without being limited by theory we believe that this low density product contains a large amount of solvated solvent within the crystal lattice By contrast when conditions of around 10 °C or higher are used (eg around ambient temperature) a granular product of a sand like consistency which is very easily filtered is produced. Under these conditions, crystallisation typically commences after around 1 hour and is typically completed within a few hours (eg 2 hours). Without being limited by theory we believe that this granular product contains little or no of solvated solvent within the crystal lattice. As a further aspect of the invention we provide a process for preparing a compound of formula (I) which comprises the steps of (a) oxidation of a solution containing the compound of formula (II) followed by (b) precipitation of the compound of formula (I) in crystalline form from the reaction mixture by addition of an anti-solvent under temperature conditions of around 10 °C or higher. Preferably the anti-solvent is water. Preferably the temperature of step (b) is ambient temperature (eg around 18-22 °C) or higher (eg up to 40 °C). We also provide as an aspect of the invention the compound of formula (I) in the form of a granular solid which is readily filterable obtainable by a process comprising: (a) oxidising of a solution of a compound of formula (II) in water/tetrahydrofuran wth periodic acid in water at a temperature of around 20-30 °C; followed by (b) precipitating the compound of formula (I) by addition of water at a temperature of around 22°C. As a further aspect of the present invention we provide a novel process for the preparation of a compound of formula (A) which comprises the following step: wherein step (a) comprises oxidation of a solution containing the compound of formula (II). A preferred embodiment of the present invention is wherein the process for the preparation of a compound of formula (A) comprises the following steps: wherein step (a) comprises oxidation of a solution containing the compound of formula (II). Step (b) will typically comprise the addition of a reagent suitable for converting a carboxylic acid to a carbothioic acid eg. using hydrogen sulphide gas together with a suitable coupling agent eg. carbonyldiimidazole (CDI) in the presence of a suitable solvent eg. dimethylformamide. Step (c) typically comprises the addition of a reagent suitable for performing the esterification to the ethyl ester eg. propionyl chloride in the presence of suitable solvents eg. diethylamine, triethylamine, dichloromethane and acetone. Step (d) typically comprises the addition of a reagent suitable for performing alkylation eg. either by direct conversion by addition of a haloalkyl compound or via an iodinated intermediate compound. As a further aspect of the present invention we also provide a novel process for the preparation of a compound of formula (B) which comprises the following step: wherein step (a) comprises oxidation of a solution containing the compound of formula (II). A preferred embodiment of the present invention is wherein the process for the preparation of a compound of formula (B) comprises the following steps: wherein step (a) comprises oxidation of a solution containing the compound of formula (II). Typical conditions for step (b) and (c) are as previously described. Typically, step (e) will comprise reagents suitable to effect the coupling of compounds of formula (IV) with compounds of formula (V) eg. in the presence of a suitable solvent eg. dimethylformamide together with a suitable base eg. 2,4,6-collidine, pyridine or caesium carbonate. Compounds of formula (B) may then be optionally purified by suitable recrystallisation processes eg. recrystallisation from suitable solvents eg. isopropanol, diethylketone or methyl isobutyl ketone. Compounds of formula (V) may be prepared according to the following process: wherein step (i) typically comprises the addition of a suitable reagent eg. methanesulphonyl chloride in the presence of solvents eg. triethylamine, dimethylaminopyridine and ethyl acetate. In step (e), analogues of compounds of formula (V) in which the MsO-group is replaced with another leaving group may also be employed. It will be understood that this novel process makes use of an alternative starting material, flumethasone (formula (II)). Surprisingly, it has been shown that the use of such a starting material in the process for preparing fluticasone propionate and 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a- propionyloxy-androsta-1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahydro-furan- 3-yl) ester would substantially reduce production costs for these steroids. As a further aspect of the present invention we also provide the use of a compound of formula (II): in the preparation of a compound of formula (I): As a further aspect of the present invention we also provide the use of a compound of formula (II): in the preparation of a compound of formula (A): As a further aspect of the present invention we also provide the use of a compound of formula (II): in the preparation of a compound of formula (B): The present invention is illustrated by the following Examples: Intermediate 1: 6a, 9a-difluoro-11ß, 17a-dihvdroxv-16a-methvl-3-oxoandrosta- 1,4-diene-17ß-carbothioic acid A solution of Example 1 (12.0g) in dry dimethylformamide (250ml) was stirred and treated with N,N"-carbonyldiimidazole (9.94g) under nitrogen at room temperature. After 4 hours, hydrogen sulphide was passed through the solution for 0.5 hours. The reaction mixture was poured into 2M hydrochloric acid (500ml) containing ice (approximately 250g). The resulting precipitate was collected, washed with water and dried in vacuo to give the title compound as a white solid (11.47g), m.p. 230-232°C, [a]D +94°C (c 0.91). Intermediate 2: 6a, 9a-difluoro-1ß-hydroxv-16a-methvl-3-oxo-17a- propionvloxy-androsta-1,4-diene-17ß-carbothioic acid A solution of Intermediate 1 (5.0g) and triethylamine (6.15ml) in dichloromethane (140ml) was cooled with ice-salt and treated dropwise with propionyl chloride (4.74ml). The reaction mixture was stirred further at approximately 0°C for 0.75 hours then washed successively with 2M sodium carbonate, water, 2M hydrochloric acid, water and brine. After being dried, solvent was removed to give a white solid (6.35g). This was redissolved in acetone (120ml) and diethylamine (12.5ml): after being stirred at room temperature for 1 hour the volume was reduced to approximately 75ml. The solution was poured into 2M hydrochloric acid (200ml) containing ice (approximately 300g) and the resulting precipitate was collected, washed with water and dried in vacuo to a white solid (5.17g) m.p. 152-155°C. Recrystallisation of a portion (400mg) from ethyl acetate gave the analytically pure title compound as colourless crystals (290mg), m.p. 161-164°C, [a]D -27°C (c 0.95). Intermediate 3: Methansulfonic acid 2-oxo-tetrahydro-furan-3R-yl ester Triethylamine (1.5vol, 1.1eq) and 4-N,N-dimethylaminopyridine (0.012wt, 0.01 eq) in ethylacetate (2vol) is added to a stirred solution of (R)-(+)-a-hydroxy- Y-butyrolactone (1wt, 1eq) in ethyl acetate (12vol) under nitrogen at 20°C +/-3°C. The solution is cooled to below 10°C and methanesulphonyl chloride (0.79vol, 1.05eq) is cautiously added to the reaction mixture over a period of at least 15 minutes at a rate sufficient to maintain the reaction temperature below 35°C. After complete addition, the reaction mixture is cooled to 20°C +/-3°C and stirred for up to 7h at 20°C +/-3°C under nitrogen, monitoring for completion by TLC (EtOAc, cyclohexane; 1:1; staining solution: 3g KMnO4, 20g K2CO3, 0.5g NaOH, and 300ml water) or GC. Upon completion, the reaction mixture is treated with 1M HCI (3vol) and stirred until all solids have dissolved. The phases are separated and the organic phase is washed with further 1M HCI (3vol). The phases are separated and the organic phase is distilled under reduced pressure to approximately 4vol using a rotary evaporator. The organic solution is heated to 40-50°C and treated with cyclohexane (12vol). The mixture is cooled to below 15°C and aged at 10-15°C for at least 15 minutes. The mixture is filtered, the collected solid is washed with cyclohexane (2x3vol) and dried under vacuum at 30-35°C to yield the title compound as a white solid. Expected yield: 150%w/w, 85%theory. Example 1: 6a, 9a-difluoro-11ß-hvdroxv-16a-methvl-3-oxo-17a-hydroxy- androsta-1,4-diene-17ß-carboxylic acid A suspension of flumethasone (40g) in tetrahydrofuran (199ml) was treated with lab grade water (13.2ml) and stirred at 20°C until a clear solution was achieved (approximately 2 minutes). The solution was cooled to less than 10°C and an aqueous solution of periodic acid (99% purity, 33.32g (1.5mole equivs) in water (68ml)) was added dropwise over a period of 6 minutes. The clear solution was allowed to warm to ambient (approximately 20°C) and stirred at ambient for 2 hours and 5 minutes. HPLC analysis at 90minutes showed 97.4area% title compound present in the reaction mixture. Water (1000ml) was added dropwise over a period of 15 minutes causing crystallisation/precipitation of the product. After complete addition, the mixture was externally cooled and aged at approximately 10°C for 100minutes and the product filtered off. The bed was washed with water (3x140ml) and dried at 70°C (house vacuum) for 26hours and 40 minutes leaving the title compound as a white granular solid (37.98g, 98.3%th). Example 1A: 6a, 9a-difluoro-1ß-hydroxy-16a-methvl-3-oxo-17a-hydroxy- androsta-1,4-diene-17ß-carboxylic acid A suspension of flumethasone (5g, 12.2mmol) in dioxan (22ml) and lab grade water (3ml) was treated with an aqueous solution of periodic acid (50%w/w purity, 6.65g, 14.6mmol (1.2mole equivs)) over a period of 45 minutes keeping the temperature in the range 25-30°C. The suspension was stirred at ambient for 2 hours. HPLC analysis at near 2 hours showed 98.1area% title compound present in the reaction mixture. Water (70ml) was added dropwise over a period of 45 minutes. After complete addition, the mixture was stirred 20°C for 1 hour and the product filtered off. The bed was washed with water (2x15ml) and dried at 60°C (house vacuum) for 18 hours leaving the title compound as a white granular solid (4.65g, 96.3%th). Example 1B: 6a, 9a-difluoro-11ß-hydroxy-16a-methvl-3-oxo-17a-hydroxy- androsta-1,4-diene-17ß-carboxvlic acid A suspension of flumethasone (5g, 12.2mmol) in diethylene glygol dimethyl ether (22ml) and lab grade water (4.4ml) was treated with an aqueous solution of periodic acid (50%w/w purity, 6.65g, 14.6mmol (1.2mole equivs)) over a period of 45 minutes keeping the temperature in the range 25-30°C. The suspension was stirred at ambient for 5 hours. HPLC analysis at near 5 hours showed 95.8area% title compound present in the reaction mixture. Water (70ml) was added dropwise over a period of 45 minutes. After complete addition, the mixture was stirred at 20°C for 1 hour and the product filtered off. The bed was washed with water (2x15ml) and dried at 60°C (house vacuum) for 72 hours leaving the title compound as a white granular solid (4.66g, 96.5%th). Example 1C: 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-hydroxy- androsta-1,4-diene-17a-carboxylic acid A suspension of flumethasone (5g, 12.2mmol) in tetrahydrofuran (22ml) and lab grade water (4.4ml) was treated with an aqueous solution of sodium periodate (99% purity, 3.13g, 14.6mmol (1.2mole equivs)) in hydrochloric acid (12 molar, 1.46ml 17.5mmol (1.43 equiv)) and water (8.5ml) over a period of 30 minutes keeping the temperature in the range 25-30°C. The suspension was stirred at ambient for 2 hours. HPLC analysis at near 2 hours showed 98.4area% title compound present in the reaction mixture. Water (65ml) was added dropwise over a period of 20 minutes. After complete addition, the mixture was cooled to 10°C, was stirred at 20°C for 2 hours and the product filtered off. The bed was washed with water (2x15ml) and then dried at 60°C (house vacuum) for 18 hours leaving the title compound as a white granular solid (4.65g, 96.3%th). Example 1D: 6a, 9a-difluoro-11ß-hydroxv-16a-methyl-3-oxo-17a-hydroxy- androsta-1,4-diene-17ß-carboxvlic acid A suspension of flumethasone (1weight) in tetrahydrofuran (4.4vol) and water (0.9vol) was stirred at 22+/- 3°C until a clear solution was achieved. An aqueous solution of periodic acid (50%w/w, 1.33 weights, 1.2equivalents) was added over approximately 45 minutes at a rate sufficient to maintain a reaction temperature of 25+/-5°C. A further portion of water (0.1 vol) was added as a line wash and the mixture was stirred at 22+/-3°C for 2 hours (note, the hydroxyacid product starts to crystallise after approximately 1 hour of this stir period). Water (14vol) was added to the suspension over at least 30 minutes maintaining a reaction temperature in the range 22+/-3°C. The mixture was cooled to approximately 10 °C and stirred for at least 1 hour at this temperature. The solid was filtered off and the bed washed with water (2x3vol) at 22+/-5°C. The product was dried under vacuum at 60+/-5°C to afford hydroxyacid as a white granular solid (expected yield 97%th). Example 2: 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-17a-propionyloxv-3- oxoandrosta-1, 4-diene-17ß-carbothioic acid, S-fiuoromethyl ester The compound of Example 2 may be prepared from Intermediate 2 following the processes described in GB Patent No. 2288877B. Example 3: 6a, 9a-difluoro-11a-hvdroxy-16a-methvl-3-oxo-17a-propionvloxv- androsta-1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahvdro-furan-3-yl) ester A mixture of Intermediate 2 (1wt), Intermediate 3, and DMF (3.5vol) is treated with 2,4,6-collidine (0.268wt, 1.04eq). The resulting solution is heated at 39- 43°C for approximately 4h until complete by HPLC. 2M Hydrochloric acid (0.2vol) is added and residual ethyl acetate is removed by vacuum distillation. The solution is warmed to 60°C and water (approximately 2vol) is added over 5- 30 min at 60-65°C, seeding when a fine suspension has formed. The suspension is aged at 55-65°C for at least 5 min and water (approximately 8vol; total water added 10vol) is added slowly at 49-60°C. The suspension is allowed to cool to room temperature and is aged for at least 30min (typically overnight). The title compound is filtered off, washed with water (3 x 2vol), and pulled dry. The title compound is then purified using isopropanol recrystallisation, which comprises heating to reflux a suspension of the title compound in isopropanol (13.4 vol) and holding at reflux for at least 5 minutes. (At this stage the reaction mixture may be given a hot filtration). The solution is heated and maintained above 60°C whilst filtered, purified water (5.6vol) is added dropwise over at least 10 minutes. The suspension is cooled to 0-10°C and then aged at least 30 minutes. The solid is collected by vacuum filtration, washed with filtered purified water (2 x 3.4vol) and dried under vacuum using a filter bed for at least 15 minutes. The product is dried in vacuo at up to 70°C overnight. Expected yield: 99% w/w, 84% theory (uncorrected) from Intermediate 2. The merits of the present invention may be seen by reference to the following Comparative Example: Comparative Example Example was prepared following a procedure analogous to that described in J. Med. Chem. (1994), 37, 3717, example 2b, (half scale), which describes conversion of des-16 alpha methyl dexamethasone to corresponding hydroxyacid via a cold isolation. A suspension of flumethasone (5.42g, 13.2mmol) in tetrahydrofuran (27.5ml) and lab grade water (3ml) was treated with an solution of periodic acid (99% purity, 4.5g, 19.8mmol (1.5mole equivs)) in lab grade water (45ml) over a period of 15 minutes keeping the temperature in the range 20-30°C. The suspension was stirred at ambient for 2 hours and an essentially clear solution resulted. HPLC analysis at near 2 hours showed 98.9area% title compound present in the reaction mixture. The reaction mixture was then added to a stirred mixture of water (75ml) and crushed ice (125g) over 5 minutes. The suspension was then stirred at 0-2°C for 10 minutes and the solid was filtered off to give a very volumous gel (ca100ml). This comparative example resulted in a voluminous product with a high level of associated solvent and it was not possible to remove this solvent by conventional solvent removal techniques, such as low temperature filtration. By contrast, in Example 1A, 1B, 1C and 1D, the title compound was obtained in a relatively low volume (ca 4 ml) as a granular solid in a form which was readily filterable. In Example 1 which was performed on a larger scale the same low volume solid was obtained (ca 32 ml). Throughout the 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 but not to the exclusion of any other integer or step or group of integers or steps. The above mentioned patents and patent applications are herein incorporated by reference. WE CLAIM : 1. A process for the preparation of 6a,9a-difluoro-11ß-hydroxy-16a- methyl-3-oxo-17a-hydroxy-androsta-1,4-diene-17ß-carboxylic acid, comprising a compound of formula (I), said process comprising : (a) oxidation, in the manner such as herein described, of a solution, such as herein described, containing the compound of formula (II), wherein the solution of the compound of formula (II) is formed in a mixture of water and tetrahydrofuran, and; (b) precipitation of the compound of formula (II) in crystalline form from the reaction mixture by addition of an anti-solvent under temperature conditions of 10 °C or higher. 2. A process as claimed in claim 1, wherein the oxidation step comprises the use of a chemical oxidising agent, such as herein described. 3. A process as claimed in claim 2, wherein the oxidising agent is selected from amongst periodic acid or iodic acid or a salt thereof. 4. A process as claimed in claim 3, wherein the oxidising agent is periodic acid or sodium periodate. 5. A process as claimed in claim 4, wherein the oxidising agent is periodic acid. 6. A process as claimed in any one of claims 1 to 5, wherein the anti-solvent is water. 7. A process as claimed in claim 6, wherein the temperature of step (b) is 25°C or higher. 8. A process as claimed in claim 1, wherein the oxidation step comprises an oxidation reaction which utilises air and/or oxygen, followed by step (b) precipitation of the compound of formula (I) in crystalline form from the reaction mixture by addition of water under temperature conditions of 10 °C or higher. 9. A process as claimed in claim 8, wherein the temperature of step (b) is 25°C or higher. 10. A process as claimed in any one of the preceding claims wherein step (a) is incubated at 25°C. The present invention relates to a process for the preparation of 6a,9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-hydroxy-androsta-1,4- diene-17ß-carboxylic acid, comprising a compound of formula (I), said process comprising : (a) oxidation, in the manner such as herein described, of a solution, such as herein described, containing the compound of formula (II), wherein the solution of the compound of formula (II) is formed in a mixture of water and tetrahydrofuran, and; (b) precipitation of the compound of formula (II) in crystalline form from the reaction mixture by addition of an anti-solvent under temperature conditions of 10 °C or higher.

Full Text

A PROCESS FOR THE PREPARATION OF 6 ALPHA,9 ALPHA-DIFLURO-11BETA-
HYDR0XY-16ALPHA-METHYL-3-OXO-17ALPHA-HYDROXY-ANDR0STA-l,4-DIENE-17 BETA
-CARBOXYLIC ACID
The present invention relates to a novel process for the synthesis of a known
intermediate, useful in the preparation of anti-inflammatory steroids. There is
also provided a new physical form of the intermediate which has improved
handling properties
6a, 9a-difluoro-11ß-hydroxy-16a-methyl-17a-propionyloxy-3-oxoandrosta-1, 4-
diene-17ß-carbothioic acid, S-fluoromethyl ester (Formula A) was first described
as an anti-inflammatory steroid by US Patent No. 4,335,121. This compound is
also known by the generic name of fluticasone propionate and has since
become widely known as a highly effective steroid in the treatment of
inflammatory diseases, such as asthma and chronic obstructive pulmonary
disease (COPD).
Additionally, 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-propionyloxy-
androsta-1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahydro-furan-3-yl) ester
(Formula B) was described in WO 97/24365 as a class of hydrolysable steroids
with lactone derivatives. This compound possesses useful anti-inflammatory
activity whilst having little or no systemic activity.
Currently there is considerable interest in compounds of formula (A) and (B) as
anti-inflammatory and anti-allergic compounds in the treatment of asthma and
other inflammatory diseases.
US 4,335,121 and WO 97/24365 describe preparations of fluticasone propionate
and 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-propionyloxy-androsta-
1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahydro-furan-3-yl) ester, respectively
which utilise a common starting material, namely 6a, 9a-difluoro-11ß-hydroxy-
16a-methyl-3-oxo-17a-hydroxy-androsta-1,4-diene-17ß-carboxylic acid (Formula
I). However, this hydroxy acid androstane derivative compound is an extremely
costly starting material for preparing quantities of steroids of formulae (A) and
(B).
Thus, according to a first aspect of the present invention we provide a novel
process for the preparation of a compound of formula (I) which comprises the
following step:
wherein step (a) comprises oxidation of a solution containing the compound of
formula (II).
Preferably, step (a) will be performed in the presence of a solvent comprising
methanol, water, tetrahydrofuran, dioxan or diethylene glygol dimethylether. For
example, so as to enhance yield and throughput, preferred solvents are
methanol, water or tetrahydrofuran, and more preferably are water or
tetrahydrofuran, especially water and tetrahydrofuran as solvent. Dioxan and
diethylene glygol dimethylether are also preferred solvents which may optionally
(and preferably) be employed together with water.
Preferably, the solvent will be present in an amount of between 3 and 10vol
relative to the amount of the starting material (1wt), more preferably between 4
and 6 vol., especially 5 vol.
If desired, the solution containing the compound of formula (II) may be cooled
prior to oxidation eg. to a temperature less than approximately 10°C.
Preferably the oxidising agent is present in an amount of 1-9 molar equivalents
relative to the amount of the starting material. For example, when a 50% w/w
aqueous solution of periodic acid is employed, the oxidising agent may be
present in an amount of between 1.1 and 10wt. relative to the amount of the
starting material (1wt.), more preferably between 1.1 and 3wt, especially 1.3wt.
Preferably, the oxidation step will comprise the use of a chemical oxidising
agent. More preferably, the oxidising agent will be periodic acid or iodic acid or a
salt thereof. Most preferably, the oxidising agent will be periodic acid or sodium
periodate, especially periodic acid. Alternatively (or in addition), it will also be
appreciated that the oxidation step may comprise any suitable oxidation
reaction, eg. one which utilises air and/or oxygen. When the oxidation reaction
utilises air and/or oxygen, the solvent used in said reaction will preferably be
methanol.
Preferably, step (a) will involve incubating the reagents at room temperature or a
little warmer, say around 25 °C eg for 2 hours.
The compound of formula (I) may be isolated by crystallisation from the reaction
mixture by addition of an anti-solvent. A suitable anti-solvent for compound of
formula (I) is water. Surprisingly we have discovered that it is highly desirable to
control the conditions under which the compound of formula (I) is precipitated by
addition of anti-solvent eg water. When the crystallisation is performed using
chilled water (eg water/ice mixture at a temperature of 0-5 °C) although better
anti-solvent properties may be expected we have found that the crystalline
product produced is very voluminous, resembles a soft gel and is very difficult to
filter. Without being limited by theory we believe that this low density product
contains a large amount of solvated solvent within the crystal lattice By contrast
when conditions of around 10 °C or higher are used (eg around ambient
temperature) a granular product of a sand like consistency which is very easily
filtered is produced. Under these conditions, crystallisation typically commences
after around 1 hour and is typically completed within a few hours (eg 2 hours).
Without being limited by theory we believe that this granular product contains
little or no of solvated solvent within the crystal lattice.
As a further aspect of the invention we provide a process for preparing a
compound of formula (I) which comprises the steps of
(a) oxidation of a solution containing the compound of formula (II) followed by
(b) precipitation of the compound of formula (I) in crystalline form from the
reaction mixture by addition of an anti-solvent under temperature conditions
of around 10 °C or higher.
Preferably the anti-solvent is water. Preferably the temperature of step (b) is
ambient temperature (eg around 18-22 °C) or higher (eg up to 40 °C).
We also provide as an aspect of the invention the compound of formula (I) in the
form of a granular solid which is readily filterable obtainable by a process
comprising:
(a) oxidising of a solution of a compound of formula (II) in water/tetrahydrofuran
wth periodic acid in water at a temperature of around 20-30 °C; followed by
(b) precipitating the compound of formula (I) by addition of water at a
temperature of around 22°C.
As a further aspect of the present invention we provide a novel process for the
preparation of a compound of formula (A) which comprises the following step:

wherein step (a) comprises oxidation of a solution containing the compound of
formula (II).
A preferred embodiment of the present invention is wherein the process for the
preparation of a compound of formula (A) comprises the following steps:
wherein step (a) comprises oxidation of a solution containing the compound of
formula (II).
Step (b) will typically comprise the addition of a reagent suitable for converting a
carboxylic acid to a carbothioic acid eg. using hydrogen sulphide gas together
with a suitable coupling agent eg. carbonyldiimidazole (CDI) in the presence of a
suitable solvent eg. dimethylformamide.
Step (c) typically comprises the addition of a reagent suitable for performing the
esterification to the ethyl ester eg. propionyl chloride in the presence of suitable
solvents eg. diethylamine, triethylamine, dichloromethane and acetone. Step (d)
typically comprises the addition of a reagent suitable for performing alkylation
eg. either by direct conversion by addition of a haloalkyl compound or via an
iodinated intermediate compound.
As a further aspect of the present invention we also provide a novel process for
the preparation of a compound of formula (B) which comprises the following
step:

wherein step (a) comprises oxidation of a solution containing the compound of
formula (II).
A preferred embodiment of the present invention is wherein the process for the
preparation of a compound of formula (B) comprises the following steps:

wherein step (a) comprises oxidation of a solution containing the compound of
formula (II).
Typical conditions for step (b) and (c) are as previously described. Typically,
step (e) will comprise reagents suitable to effect the coupling of compounds of
formula (IV) with compounds of formula (V) eg. in the presence of a suitable
solvent eg. dimethylformamide together with a suitable base eg. 2,4,6-collidine,
pyridine or caesium carbonate. Compounds of formula (B) may then be
optionally purified by suitable recrystallisation processes eg. recrystallisation
from suitable solvents eg. isopropanol, diethylketone or methyl isobutyl ketone.
Compounds of formula (V) may be prepared according to the following process:

wherein step (i) typically comprises the addition of a suitable reagent eg.
methanesulphonyl chloride in the presence of solvents eg. triethylamine,
dimethylaminopyridine and ethyl acetate.
In step (e), analogues of compounds of formula (V) in which the MsO-group is
replaced with another leaving group may also be employed.
It will be understood that this novel process makes use of an alternative starting
material, flumethasone (formula (II)). Surprisingly, it has been shown that the
use of such a starting material in the process for preparing fluticasone
propionate and 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-
propionyloxy-androsta-1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahydro-furan-
3-yl) ester would substantially reduce production costs for these steroids.
As a further aspect of the present invention we also provide the use of a
compound of formula (II):

in the preparation of a compound of formula (I):

As a further aspect of the present invention we also provide the use of a
compound of formula (II):

in the preparation of a compound of formula (A):

As a further aspect of the present invention we also provide the use of a
compound of formula (II):

in the preparation of a compound of formula (B):

The present invention is illustrated by the following Examples:
Intermediate 1: 6a, 9a-difluoro-11ß, 17a-dihvdroxv-16a-methvl-3-oxoandrosta-
1,4-diene-17ß-carbothioic acid
A solution of Example 1 (12.0g) in dry dimethylformamide (250ml) was stirred
and treated with N,N"-carbonyldiimidazole (9.94g) under nitrogen at room
temperature. After 4 hours, hydrogen sulphide was passed through the solution
for 0.5 hours. The reaction mixture was poured into 2M hydrochloric acid (500ml)
containing ice (approximately 250g). The resulting precipitate was collected,
washed with water and dried in vacuo to give the title compound as a white solid
(11.47g), m.p. 230-232°C, [a]D +94°C (c 0.91).
Intermediate 2: 6a, 9a-difluoro-1ß-hydroxv-16a-methvl-3-oxo-17a-
propionvloxy-androsta-1,4-diene-17ß-carbothioic acid
A solution of Intermediate 1 (5.0g) and triethylamine (6.15ml) in dichloromethane
(140ml) was cooled with ice-salt and treated dropwise with propionyl chloride
(4.74ml). The reaction mixture was stirred further at approximately 0°C for 0.75
hours then washed successively with 2M sodium carbonate, water, 2M
hydrochloric acid, water and brine. After being dried, solvent was removed to
give a white solid (6.35g). This was redissolved in acetone (120ml) and
diethylamine (12.5ml): after being stirred at room temperature for 1 hour the
volume was reduced to approximately 75ml. The solution was poured into 2M
hydrochloric acid (200ml) containing ice (approximately 300g) and the resulting
precipitate was collected, washed with water and dried in vacuo to a white solid
(5.17g) m.p. 152-155°C. Recrystallisation of a portion (400mg) from ethyl
acetate gave the analytically pure title compound as colourless crystals (290mg),
m.p. 161-164°C, [a]D -27°C (c 0.95).
Intermediate 3: Methansulfonic acid 2-oxo-tetrahydro-furan-3R-yl ester
Triethylamine (1.5vol, 1.1eq) and 4-N,N-dimethylaminopyridine (0.012wt,
0.01 eq) in ethylacetate (2vol) is added to a stirred solution of (R)-(+)-a-hydroxy-
Y-butyrolactone (1wt, 1eq) in ethyl acetate (12vol) under nitrogen at 20°C +/-3°C.
The solution is cooled to below 10°C and methanesulphonyl chloride (0.79vol,
1.05eq) is cautiously added to the reaction mixture over a period of at least 15
minutes at a rate sufficient to maintain the reaction temperature below 35°C.
After complete addition, the reaction mixture is cooled to 20°C +/-3°C and stirred
for up to 7h at 20°C +/-3°C under nitrogen, monitoring for completion by TLC
(EtOAc, cyclohexane; 1:1; staining solution: 3g KMnO4, 20g K2CO3, 0.5g NaOH,
and 300ml water) or GC. Upon completion, the reaction mixture is treated with
1M HCI (3vol) and stirred until all solids have dissolved. The phases are
separated and the organic phase is washed with further 1M HCI (3vol). The
phases are separated and the organic phase is distilled under reduced pressure
to approximately 4vol using a rotary evaporator. The organic solution is heated
to 40-50°C and treated with cyclohexane (12vol). The mixture is cooled to below
15°C and aged at 10-15°C for at least 15 minutes. The mixture is filtered, the
collected solid is washed with cyclohexane (2x3vol) and dried under vacuum at
30-35°C to yield the title compound as a white solid. Expected yield: 150%w/w,
85%theory.
Example 1: 6a, 9a-difluoro-11ß-hvdroxv-16a-methvl-3-oxo-17a-hydroxy-
androsta-1,4-diene-17ß-carboxylic acid
A suspension of flumethasone (40g) in tetrahydrofuran (199ml) was treated with
lab grade water (13.2ml) and stirred at 20°C until a clear solution was achieved
(approximately 2 minutes). The solution was cooled to less than 10°C and an
aqueous solution of periodic acid (99% purity, 33.32g (1.5mole equivs) in water
(68ml)) was added dropwise over a period of 6 minutes. The clear solution was
allowed to warm to ambient (approximately 20°C) and stirred at ambient for 2
hours and 5 minutes. HPLC analysis at 90minutes showed 97.4area% title
compound present in the reaction mixture. Water (1000ml) was added dropwise
over a period of 15 minutes causing crystallisation/precipitation of the product.
After complete addition, the mixture was externally cooled and aged at
approximately 10°C for 100minutes and the product filtered off. The bed was
washed with water (3x140ml) and dried at 70°C (house vacuum) for 26hours and
40 minutes leaving the title compound as a white granular solid (37.98g,
98.3%th).
Example 1A: 6a, 9a-difluoro-1ß-hydroxy-16a-methvl-3-oxo-17a-hydroxy-
androsta-1,4-diene-17ß-carboxylic acid
A suspension of flumethasone (5g, 12.2mmol) in dioxan (22ml) and lab grade
water (3ml) was treated with an aqueous solution of periodic acid (50%w/w
purity, 6.65g, 14.6mmol (1.2mole equivs)) over a period of 45 minutes keeping
the temperature in the range 25-30°C. The suspension was stirred at ambient
for 2 hours. HPLC analysis at near 2 hours showed 98.1area% title compound
present in the reaction mixture. Water (70ml) was added dropwise over a period
of 45 minutes. After complete addition, the mixture was stirred 20°C for 1 hour
and the product filtered off. The bed was washed with water (2x15ml) and dried
at 60°C (house vacuum) for 18 hours leaving the title compound as a white
granular solid (4.65g, 96.3%th).
Example 1B: 6a, 9a-difluoro-11ß-hydroxy-16a-methvl-3-oxo-17a-hydroxy-
androsta-1,4-diene-17ß-carboxvlic acid
A suspension of flumethasone (5g, 12.2mmol) in diethylene glygol dimethyl ether
(22ml) and lab grade water (4.4ml) was treated with an aqueous solution of
periodic acid (50%w/w purity, 6.65g, 14.6mmol (1.2mole equivs)) over a period
of 45 minutes keeping the temperature in the range 25-30°C. The suspension
was stirred at ambient for 5 hours. HPLC analysis at near 5 hours showed
95.8area% title compound present in the reaction mixture. Water (70ml) was
added dropwise over a period of 45 minutes. After complete addition, the
mixture was stirred at 20°C for 1 hour and the product filtered off. The bed was
washed with water (2x15ml) and dried at 60°C (house vacuum) for 72 hours
leaving the title compound as a white granular solid (4.66g, 96.5%th).
Example 1C: 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-hydroxy-
androsta-1,4-diene-17a-carboxylic acid
A suspension of flumethasone (5g, 12.2mmol) in tetrahydrofuran (22ml) and lab
grade water (4.4ml) was treated with an aqueous solution of sodium periodate
(99% purity, 3.13g, 14.6mmol (1.2mole equivs)) in hydrochloric acid (12 molar,
1.46ml 17.5mmol (1.43 equiv)) and water (8.5ml) over a period of 30 minutes
keeping the temperature in the range 25-30°C. The suspension was stirred at
ambient for 2 hours. HPLC analysis at near 2 hours showed 98.4area% title
compound present in the reaction mixture. Water (65ml) was added dropwise
over a period of 20 minutes. After complete addition, the mixture was cooled to
10°C, was stirred at 20°C for 2 hours and the product filtered off. The bed was
washed with water (2x15ml) and then dried at 60°C (house vacuum) for 18 hours
leaving the title compound as a white granular solid (4.65g, 96.3%th).
Example 1D: 6a, 9a-difluoro-11ß-hydroxv-16a-methyl-3-oxo-17a-hydroxy-
androsta-1,4-diene-17ß-carboxvlic acid
A suspension of flumethasone (1weight) in tetrahydrofuran (4.4vol) and water
(0.9vol) was stirred at 22+/- 3°C until a clear solution was achieved. An aqueous
solution of periodic acid (50%w/w, 1.33 weights, 1.2equivalents) was added over
approximately 45 minutes at a rate sufficient to maintain a reaction temperature
of 25+/-5°C. A further portion of water (0.1 vol) was added as a line wash and
the mixture was stirred at 22+/-3°C for 2 hours (note, the hydroxyacid product
starts to crystallise after approximately 1 hour of this stir period). Water (14vol)
was added to the suspension over at least 30 minutes maintaining a reaction
temperature in the range 22+/-3°C. The mixture was cooled to approximately 10
°C and stirred for at least 1 hour at this temperature. The solid was filtered off
and the bed washed with water (2x3vol) at 22+/-5°C. The product was dried
under vacuum at 60+/-5°C to afford hydroxyacid as a white granular solid
(expected yield 97%th).
Example 2: 6a, 9a-difluoro-11ß-hydroxy-16a-methyl-17a-propionyloxv-3-
oxoandrosta-1, 4-diene-17ß-carbothioic acid, S-fiuoromethyl ester
The compound of Example 2 may be prepared from Intermediate 2 following the
processes described in GB Patent No. 2288877B.
Example 3: 6a, 9a-difluoro-11a-hvdroxy-16a-methvl-3-oxo-17a-propionvloxv-
androsta-1,4-diene-17ß-carbothioic acid S-(2-oxo-tetrahvdro-furan-3-yl) ester
A mixture of Intermediate 2 (1wt), Intermediate 3, and DMF (3.5vol) is treated
with 2,4,6-collidine (0.268wt, 1.04eq). The resulting solution is heated at 39-
43°C for approximately 4h until complete by HPLC. 2M Hydrochloric acid
(0.2vol) is added and residual ethyl acetate is removed by vacuum distillation.
The solution is warmed to 60°C and water (approximately 2vol) is added over 5-
30 min at 60-65°C, seeding when a fine suspension has formed. The
suspension is aged at 55-65°C for at least 5 min and water (approximately 8vol;
total water added 10vol) is added slowly at 49-60°C. The suspension is allowed
to cool to room temperature and is aged for at least 30min (typically overnight).
The title compound is filtered off, washed with water (3 x 2vol), and pulled dry.
The title compound is then purified using isopropanol recrystallisation, which
comprises heating to reflux a suspension of the title compound in isopropanol
(13.4 vol) and holding at reflux for at least 5 minutes. (At this stage the reaction
mixture may be given a hot filtration). The solution is heated and maintained
above 60°C whilst filtered, purified water (5.6vol) is added dropwise over at least
10 minutes. The suspension is cooled to 0-10°C and then aged at least 30 minutes. The solid is collected by vacuum filtration, washed with filtered
purified water (2 x 3.4vol) and dried under vacuum using a filter bed for at least
15 minutes. The product is dried in vacuo at up to 70°C overnight. Expected
yield: 99% w/w, 84% theory (uncorrected) from Intermediate 2.
The merits of the present invention may be seen by reference to the following
Comparative Example:
Comparative Example
Example was prepared following a procedure analogous to that described in J.
Med. Chem. (1994), 37, 3717, example 2b, (half scale), which describes
conversion of des-16 alpha methyl dexamethasone to corresponding
hydroxyacid via a cold isolation.
A suspension of flumethasone (5.42g, 13.2mmol) in tetrahydrofuran (27.5ml)
and lab grade water (3ml) was treated with an solution of periodic acid (99%
purity, 4.5g, 19.8mmol (1.5mole equivs)) in lab grade water (45ml) over a period
of 15 minutes keeping the temperature in the range 20-30°C. The suspension
was stirred at ambient for 2 hours and an essentially clear solution resulted.
HPLC analysis at near 2 hours showed 98.9area% title compound present in the
reaction mixture. The reaction mixture was then added to a stirred mixture of
water (75ml) and crushed ice (125g) over 5 minutes. The suspension was then
stirred at 0-2°C for 10 minutes and the solid was filtered off to give a very
volumous gel (ca100ml).
This comparative example resulted in a voluminous product with a high level of
associated solvent and it was not possible to remove this solvent by
conventional solvent removal techniques, such as low temperature filtration. By
contrast, in Example 1A, 1B, 1C and 1D, the title compound was obtained in a
relatively low volume (ca 4 ml) as a granular solid in a form which was readily
filterable. In Example 1 which was performed on a larger scale the same low
volume solid was obtained (ca 32 ml).
Throughout the 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 but not to the exclusion of any other integer or step or group
of integers or steps.
The above mentioned patents and patent applications are herein incorporated by
reference.
WE CLAIM :
1. A process for the preparation of 6a,9a-difluoro-11ß-hydroxy-16a-
methyl-3-oxo-17a-hydroxy-androsta-1,4-diene-17ß-carboxylic acid,
comprising a compound of formula (I), said process comprising :

(a) oxidation, in the manner such as herein described, of a solution, such
as herein described, containing the compound of formula (II), wherein the
solution of the compound of formula (II) is formed in a mixture of water
and tetrahydrofuran, and;
(b) precipitation of the compound of formula (II) in crystalline form from
the reaction mixture by addition of an anti-solvent under temperature
conditions of 10 °C or higher.
2. A process as claimed in claim 1, wherein the oxidation step
comprises the use of a chemical oxidising agent, such as herein
described.
3. A process as claimed in claim 2, wherein the oxidising agent is
selected from amongst periodic acid or iodic acid or a salt thereof.
4. A process as claimed in claim 3, wherein the oxidising agent is
periodic acid or sodium periodate.
5. A process as claimed in claim 4, wherein the oxidising agent is
periodic acid.
6. A process as claimed in any one of claims 1 to 5, wherein the
anti-solvent is water.
7. A process as claimed in claim 6, wherein the temperature of step
(b) is 25°C or higher.
8. A process as claimed in claim 1, wherein the oxidation step
comprises an oxidation reaction which utilises air and/or oxygen, followed
by step (b) precipitation of the compound of formula (I) in crystalline form
from the reaction mixture by addition of water under temperature
conditions of 10 °C or higher.
9. A process as claimed in claim 8, wherein the temperature of step
(b) is 25°C or higher.
10. A process as claimed in any one of the preceding claims wherein
step (a) is incubated at 25°C.
The present invention relates to a process for the preparation of
6a,9a-difluoro-11ß-hydroxy-16a-methyl-3-oxo-17a-hydroxy-androsta-1,4-
diene-17ß-carboxylic acid, comprising a compound of formula (I), said
process comprising :
(a) oxidation, in the manner such as herein described, of a solution, such
as herein described, containing the compound of formula (II), wherein the
solution of the compound of formula (II) is formed in a mixture of water
and tetrahydrofuran, and;
(b) precipitation of the compound of formula (II) in crystalline form from
the reaction mixture by addition of an anti-solvent under temperature
conditions of 10 °C or higher.

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Patent Number

213999

Indian Patent Application Number

IN/PCT/2002/01303/KOL

PG Journal Number

04/2008

Publication Date

25-Jan-2008

Grant Date

23-Jan-2008

Date of Filing

18-Oct-2002

Name of Patentee

GLAXO GROUP LIMITED

Applicant Address

GLAXO WELCOME HOUSE, BERKELEY AVENUE, GREENFORD, MIDDLESEX, UB6 0NN, UNITED KINGDOM, A BRITISH COMPANY.

Inventors:

#	Inventor's Name	Inventor's Address
1	ROBINSON JOHN MALCOLM	-DO-
2	ALBINSON FREDERICK	C/O GLAXOSMITHKLINE,GUNNELS WOOD ROAD, STEVENAGE, HERTFORDSHIRE,SG1 2NY, UNITED KINGDOM.
3	COOTE STEVEN JOHN	-DO-

PCT International Classification Number

C07J5/00,31/00,3/00

PCT International Application Number

PCT/GB01/03289

PCT International Filing date

2001-07-20

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA