GB2357082A - Pharmaceutically active indanylidene-acetamide derivatives - Google Patents

Abstract

The amide derivatives (+)-(E)-2-(4,6-difluoro-3-hydroxy-1-indanylidene) acetamide and (-)-(E)-2-(4,6-difluoro-3-hydroxy-1-indanylidene)acetamide and pharmaceutically acceptable salts and solvates thereof are disclosed for use in therapy. The (+) enantiomer has muscle relaxant, analgesic and anti-inflammatory activity, whereas the (-) enantiomer has analgesic and anti-inflammatory, but not muscle relaxant activity.

Description

1 PU3833 2357082 1 Bicyclic Amide Derivatives This invention relates to

optically pure indanylidenes, salts and solvates thereof, pharmaceutical formulations containing them and their use in medicine.

US 5,872,118 discloses bicyclic amide derivatives that are useful as potent central muscle relaxants, analgesic agents or anti-inflammatory conditions. One such amide derivative is (+/-)-(E)-2-(4,6-difluoro-3-hydroxy-l- indanyiidene)acetamide.

Surprisingly, it has now been found that the pharmacological profile of the (+)-enantiomer differs from that of the (+enantiomer.

The (+)-enantiomer has been found to exhibit muscle relaxant, aria lgesic and anti-inflammatory activity; that is the same qualitative activity as the corresponding racemate. In contrast and quite unexpectedly, the (+ enantiomer has been found to exhibit analgesic and anti-inflammatory activity, but does not exhibit muscle relaxant activity. The skilled person will appreciate that it may be desirable to provide an analgesic andlor anti-inflammatory without unwanted side effects, such as muscle relaxant activity.

Moreover, for those activities shared by the enantiomers, the (+)enantiomer is, surprisingly, found to be significantly more potent than the (+enantiomer. For example, in the analgesia activity assay, the (+)-enantiomer is 330 times more potent than the (+enantiomer.

According to the present invention therefore, there is provided:

(i) (+)-(E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene)acetamide, hereinafter referred to as "(+)-enantiomer"; (ii) (-)-(E)-2-(4,6-difluoro-3-hydroxy-1 -indanyiidene)acetamide, hereinafter referred to as "(-)-enantiomer"; and PU3833 2 salts and solvates thereof.

Such salts and solvates will normally be pharmaceutically acceptable. Thus, pharmaceutically acceptable salts include, but are not limited to, ammonium salts; alkali metal salts, for example sodium or potassium salts; and alkaline earth metal salts, for example magnesium or calcium salts.

The enantiomers can be provided in pure form or substantially pure form. Thus, the ratio (+)-enantiomer:(-)-enantiomer may be at least 80:20, such as at least 95:5 or at least 99:1. Preferably the enantiomers are provided having an enantiomeric purity of at least 99.4%.

The (+)-enantiomer or the (-)-enantiomer and pharmaceutically acceptable salts and solvates thereof may be prepared in any manner known in the art for the preparation of compounds of analogous structure by those methods hereinafter described.

Racemic (E)-2-(4,6-difluoro-3-hydroxy-1 -indanylidene)acetamide can be prepared via a process described in US 5,872,118, incorporated herein by reference.

The (+)-enantiomer or the (-)-enantiomer and pharmaceutically acceptable salts and solvates thereof according to the invention can be prepared by a process as described in the Journal of Chromatography, (1998), 826, pp217-225 (Villeneuve, M.S. and Anderegg, R.J.), which is incorporated herein by reference.

PU3833 3 The present invention further provides the use of the (+)-enantiomer or the -enantiomer and pharmaceutically acceptable salts and solvates thereof in therapy.

There is also provided as a further aspect of the invention the use of the (+)-enantiomer or the (-)-enantiomer and pharmaceutically acceptable salts and solvates thereof, in the manufacture of a medicament for use in the treatment of a mammal, including a human being.

In an alternative or further aspect of the invention, there is provided a method for the treatment of a mammal, including man, comprising administration of an effective amount of the (+)-enantiomer or the (+enantiomer and pharmaceutically acceptable salts and solvates thereof.

It will be appreciated that reference to treatment is intended to include prophylaxis as well as the alleviation of established symptoms. The (+)-enantiomer or the (+enantiomer may be administered as the raw chemical but the active ingredient is preferably presented as a pharmaceutical formulation.

The (+)-enantiomer together with its pharmaceutically acceptable salts or solvates, is useful in medicine as a central muscle relaxant and may thus be used in the treatment of conditions associated With abnormally raised skeletal muscle tone.

It is of especial value in the relaxation of skeletal muscle in spastic, hypertonic or hyperkinetic conditions. In particular, it may be used in the treatment or symptomatic relief of exertion-induced skeletal muscle spasm, for example, in lower back pain. It may also be used in conditions such as spinal cord injury, parkinsonism, chorea, arthritis, athetosis, status epilepticus or tetanus or PU3833 4 especially in the relief of muscle spasm in conditions such as spasticity, myositis, spondylitis, cerebral palsy, cerebrovascular disease or multiple sclerosis. It may also be used as a pre-surgical muscle relaxant.

The (+)-enantiomer or the (-)-enantiomer, together with their pharmaceutically acceptable salts and solvates, are also useful in the treatment of pain, for example that associated with inflammation and/or trauma, and have utility as a mild and strong analgesic.

The (+)-enantiomer or the (-)-enantiomer, together with their pharmaceutically acceptable salts or solvates, are also useful in the treatment of inflammatory conditions including inflammatory arthritic conditions, for example rheumatoid arthritis, rheumatoid spondylitis, osteoarthritis or gouty arthritis; or non-articular inflammatory conditions, for example herniated/ruptured/prolapsed intervertebral disk syndrome, bursitis, tendinitis, tenosynovitis, fibromyalgia syndrome or other inflammatory conditions associated with ligamentous sprain or regional musculoskeletal strain. It is particularly notable that they are less ulcerogenic than other anti-inflammatory agents such as ibuprofen, naproxen or aspirin.

The (+)-enantiomer or the (-)-enantiomer and their pharmaceutically acceptable salts and solvates may be administered concomitantly with other therapeutic agents for the treatment of the above-recited conditions. For inflammatory conditions (for example, arthritis) and/or pain, such other agents include analgesics, such as codeine, oxycodone, acetaminophen, phenacetin or ibuprofen; anti-arthritics, such as methotrexate or azathioprine; or decongestants, such as ephedrine or pseudoephedrine. For conditions associated with abnormally raised skeletal muscle tone, the (+)- enantiomer only, such other agents include analgesics such as codeine, acetaminophen, phenacetin or ibuprofen.

PU3833 The (+)-enantiomer or the (-)-enantiomer, salt or solvate, (hereinafter together referred to as the active ingredient) may be administered by any suitable route including oral, rectal, nasal, topical (including buccal and sublingual), vaginal, parenteral (including subcutaneous, intramuscular, intravenous and intradermal).

It will be appreciated that the preferred route will be determined by, for example, the condition and age of the recipient and the identity of the condition to be treated.

The amount required of the active ingredient depends upon a number of factors including the identity of the condition and its severity, the identity of the recipient and the route of administration and will ultimately be at the discretion of the attendant physician.

In general, for each of the above-recited conditions, a suitable dose of the active ingredient is in the range of 0.05 to 100 mg per kilogram body weight of the recipient per day, preferably in the range of 0.1 to 50 mg per kilogram body weight per day, most preferably in the range of 0.5 to 20 mg per kilogram body weight per day and optimally 1 to 10 mg per kilogram body weight per day. The desired dose is preferably presented as two, three, four, five, six or more sub doses administered at appropriate intervals throughout the day.

While it is possible for the active ingredient to be administered alone it is preferable to present it as a pharmaceutical composition comprising an active ingredient, as defined above, together with an acceptable carrier therefor. Each carrier must be "acceptable" in the sense of being compatible with the other ingredients of the composition and not injurious to the recipient.

The compositions include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal, parenteral (including subcutaneous, intramuscular, intravenous and intradermal) or transdermal administration. The PU3833 6 compositions may conveniently be presented in unit dosage form and may be prepared by and methods well known in the art of pharmacy. Such methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more accessory ingredients. In general the compositions are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then if necessary shaping the product.

Compositions of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or suspension in an aqueous or non-aqueous)iquid; or as an oil- in-water liquid emulsion or a water-in-oil liquid emulsion. The active ingredient may also be presented as a bolus, electuary or paste.

A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder (e.g. povidone, gelatin, hydroxypropyimethyl cellulose), lubricant, inert diluent, preservative, disintegrant (e.g. sodium starch glycollate, cross-linked povidone, cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Moulded tablets may be made by moulding in a suitable machine a mixture of the powered compound moistened with an inert liquid diluent. The tables may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropyimethyl cellulose in varying proportions to provide the desired release profile. Tablets may optionally be provided with an enteric coating, to provide release in parts of the gut other than the stomach.

PU3833 7 Compositions suitable for oral use as described above may also include buffering agents designed to neutralize stomach acidity. Such buffers may be chosen from a variety of organic or inorganic agents such as weak acids or bases admixed with their conjugated salts.

Compositions suitable for topical administration in the mouth include lozenges comprising the active ingredient in a flavoured basis, usually sucrose and acacia or tragacanth; pastilles comprising the active ingredient in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising the active ingredient in a suitable liquid carrier.

Compositions for rectal administration may be presented as a suppository with a suitable base comprising for example cocoa butter or a salicylate.

Compositions suitable for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams or spray formulations containing in addition to the active ingredient such carriers as are known in the art to be appropriate.

Compositions suitable for parenteral administration include aqueous and non aqueous isotonic sterile injection solutions which may contain antioxidants, buffers, bacteriostats and solutes which render the compositions isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents, as liposomes or other micropa rticu late systems which are designed to target the compounds to blood components or one or more organs. The compositions may be presented in unit-dose or multi-dose sealed containers, for example, ampoules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water injections, immediately prior to use. Extemporaneous injection solutions and PU3833 8 suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.

Compositions suitable for transdermal administration may be presented as discrete patches adapted to remain in intimate contact with the epidermis of the recipient for a prolonged period of time. Such patches suitably contain the active ingredient as an optionally buffered, aqueous solution of, for example, 0. 1 to 0.2M concentration with respect to the said compound. As one particular possibility, the active ingredient may be delivered from the patch by iontophoresis as generally described in Pharmaceutical Research, 3(6), 318 (1986).

Preferred unit dosage compositions are those containing a daily dose or unit, daily sub-dose, or an appropriate fraction thereof, of active ingredient, for example 1 to 1500 mg, preferably 5 to 1000 mg and most preferably 10 to 700 mg of active ingredient, estimated as the parent compound.

It should be understood that in addition to the ingredients particularly mentioned above the composition of this invention may include other agents conventional in the art having regard to the type of composition in question, for example, those suitable for oral administration may include such further agents as sweeteners, thickeners and flavouring agents.

The present invention thus also provides a pharmaceutical composition comprising the (+)-enantiomer or the (-)-enantiomer or pharmaceutically acceptable salts or solvates thereof together with an acceptable carrier thereof.

The following Examples illustrate the invention. Reference Examples are provided.

PU3833 9 REFERENCE EXAMPLE 1: Preparation of (+/-)-(E)-2-(4,6-Difluoro-3-hydroxy-l- indanylidene)acetamide 1. Preparation of 2,4,Dicarbethoxy-3-(3,5-difluorophenyl)-5-hydroxy-5methyl-l- cyclohexanone Slightly warm, liquid 3,5-difluorobenzaldehyde (5.0) g, 0.0352 mol, Aldrich). 95% ethanol (1.75 ml). and piperidine (0.7 ml) were added, with stirring, to ethyl acetoacetate (9.2g, 0.0704 mol, Aldrich). The solution was stirred until homogeneous and was then placed in a water bath to control the slightly exothermic reaction. After 4 hours, the crystalline mass was dissolved in warm dichloromethane (100 mi). Dilution with hexanes (300 ml) gave a turbid solution.

After standing for 24 hours, the crystalline product was collected by filtration and washed with hexanes to give 8.Og (59%) of 2,4-dicarbethoxy-3-(3,5 difluorophenyl)-5-hydroxy-5-methyl-l-cyclohexanone: m.p.. 1850-186 C; 2. Preparation of 3-(3,5-Difluorophenyl)glutaric acid To a hot (95 C) solution prepared from sodium hydroxide (322 g, 8.1 mol) and deionized water (322 ml) was added a mixture of 2,4-diacetyl-3-(3,5 difluorophenyl)-5-hydroxy-5-methyl-l-cyclohexanone (43 g, 0.112 mol) in ethanol (322 ml) with rapid stirring. The resulting mixture was refluxed for 4 hours using an oil bath at 140 C. The ethanol was removed by spin evaporation in vacuo and the resulting slurry was cooled in an ice bath, and concentrated hydrochloric acid (12N) was added to adjust the pH to approximately 1. The precipitate was dissolved by the addition of water, and this aqueous solution was extracted with ethyl acetate (total volume 1500 ml). The ethyl -acetate extracts were combined, washed with water, dried with MgS04 and the volatiles were removed by spin evaporation in vacuo. Recrystallization of the residue from dichloromethane and hexanes gave 9.1 Og (33%) of 3-(3.5- difluorophenyl)glutaric acid: m.p.. 170 -172 C; PU3833 3. Preparation of 2-(4,6-Difluoro-3-oxo-1 -indanyl)acetic acid Polyphosphoric acid (54 g, Aldrich) and 3-(3,5-difluorophenyl) glutaric acid (9.02g, 36.9 mmol) were combined and the mixture heated with an oil bath at 120'C for 30 min. The now red solution was cooled to approximately 60C and water (approximately 100 ml) was added dropwise, with efficient stirring. The resulting precipitate was collected and washed with water. Chromatography of the collected product on a column of Silica Gel 60 (51 x 450 mm) with methanol:

dichloromethane (4:96) gave a material which was recrystallized from water to give 1.93g (23%) of 2-(4,6-difluoro-3-oxo-1 -indanyl)acetic acid: m.p.. 170 -172 C; 4. Preparation of 2-(4,6-Difluoro-3-oxo-l-indanyl)acetyI chloride Oxalyl chloride (2.69g, 0.021 mol, Aldrich) was added to an ice cold stirring mixture of 2-(4,6-difluoro-3-oxo-l-indanyl)acetic acid (3.85g, 0.017 mol) in dichloromethane (200 ml) under a nitrogen atmosphere. The mixture was allowed to warm to room temperature and stirring was continued for 48 hours.

The volatiles were removed from the solution by spin evaporation in vacuo with the addition of dichloromethane (3 x 50ml) to give 2-(4,6-difluoro-3-oxo- l indanyl)acetyl chloride which was used without purification or analysis; 5. Preparation of 2-(4,6-Difluoro-3-oxo-l-indanyl)acetamide A solution of 2-(4,6-difluoro-3-oxo-l-indanyl)acetyI chloride (4.2 g, 17 mmol) in dichloromethane (100 ml) was cooled to OOC and stirred rapidly while 20 ml of ammonium hydroxide, 28-30%, was added. The resulting mixture was allowed to warm to room temperature and stirring was continued for 18 hours. The volatiles from this mixture were removed by spin evaporation in vacuo and the residue was dissolved in methanol (250 ml) and washed with water (3 x 50 ml).

The dichloromethane phase was then slurried with Silica Gel 60 and the volatiles were removed by spin evaporation in vacuo. This silica was then applied to a column of Silica Gel 60 (51 x 400 mm) wet with dichloromethane and the product was removed by elution with methanol:dichloromethane (3:97) to give, after PU3833 recrystallization twice from dichloromethane:hexanes 2.8g (77%) of 2-(4,6 Difluoro-3-oxo-l-indanyl)acetamide: m.p.. 155 -157 C; 6. Preparation of (E)-2-(4,6-Difluoro-3-oxo-l-indanylidene)acetamide A mixture of 2-(4,6-difluoro-3-oxo-l-indanyl)acetamide (1.0 g, 0.0044 mol),N bromosuccinimide (0.950g, 0.00533 mol), 2.21-azobis(2methylpropionitrile) (0.350 g, 0.00213 mol, Kodak), tetrachloromethane (50 ml) and benzene (50 ml) was heated with an oil bath at 120 C for 1 hour. The reaction solution was diluted with dichloromethane, slurried with Silica Gel 60 and the volatiles were removed by spin evaporation in vacuo. This silica was then applied to a column of Silica Gel 60 (51 x 450 mm) wet with dichloromethane and the product was removed by elution with methanol:dichloromethane (2:98). The volatiles were removed by spin evaporation in vacuo to give 0.613 g of a residue. This residue was recrystallized from methanol to give 0.302 g (31%) of (E)-2-(4,6difluoro-3 oxo-l-indanylidene)acetamide: m.p 2500 C (dec.); 7. Preparation of (E)-2-(4,6-Difluoro-3-hydroxy-l-indanylidene)acetamide A suspension of (E)-2-(4,6-difluoro-3-oxo-l-indanylidene)acetamide (0.100 g, 0.45 mmol) and sodium borohydride (0.017 g. 0.45 mmol) in 95% ethanol was stirred at ambient temperature for 2 hours. The mixture was cooled in an ice bath and quenched with OAN hydrochloric acid (3 ml). The ethanol was evaporated in vacuo, and the residue was dissolved in ethyl acetate (50 ml), washed successively with water (2 x 3 ml) and brine (30 ml), dried over sodium sulfate, filtered and evaporated in vacuo. The residue was washed successively with cold ethyl acetate, hexane, and diethyl ether to give 0.046 g (45%) if (E)-2 (4,6-difluoro-3-hydroxy-l-indanylidene)acetamide as a while solid; mp 2320-237' C (dec.) 1 H-NMR (DMSO-d6): 67.06-7.42 (m, 4H), 6.49 (s, 1 H), 5.52 (d, 1 H), 5.30 (m, 1 H), 3.44 (m, 1 H). 3.03 (d, 1 H).

PU3833 12 REFERENCE EXAMPLE 2: Alternative synthesis of (E)-2-(4,6-Difluoro-3 hydroxy-1 -indanylidene)acetamide 1. Preparation of 2,4,Dicarbethoxy-3-(3,5-difluorophenyl)-5-hydroxy-5- methyl-1 cyclohexanone Slightly warm, liquid 3,5-difluorobenzaldehyde (5.0g, 0.0352mol, Aldrich). 95% ethanol (1.75ml). and piperidine (0.7ml) were added, with stirring, to ethyl acetoacetate (9.2g, 0.0704mol, Aldrich). The solution was stirred until homogeneous and was then placed in a water bath to control the slightly exothermic reaction. After 4 hours the crystalline mass was dissolved in warm dichloromethane (100mi). Dilution with hexanes (300ml) gave a turbid solution.

After standing for 24 hours the crystalline product was collected by filtration and washed with hexanes to give 8.Og (59%) of 2,4-dicarbethoxy-3-(3,5 d ifl uo rop hen yl)-5-hyd roxy-5-methyl- 1 -cyclohexa none: m.p. 1850- 1860 C.; 2. Preparation of 3-(3,5-Difluorophenyl)glutaric acid To a hot (950 C) solution prepared from sodium hydroxide (322g, 8.1mol) and deionized water (322ml) was added a mixture of 2,4-diacetyl-3-(3,5 d ifl u oro ph eny 1) -5-hyd roxy-5-methyl- 1 -cyclo hexa none (43g, 0. 112mol) in ethanol (322ml) with rapid stirring. The resulting mixture was refluxed for 4 hours using an oil bath at 1400C. The ethanol was removed by spin evaporation in vacuo and the resulting slurry was cooled in an ice bath, and concentrated hydrochloric acid (1 2N) was added to adjust the pH to approximately 1. The precipitate was dissolved by the addition of water,and this aqueous solution was extracted with ethyl acetate (total volume 1500ml). The ethyl acetate extracts were combined, washed with water, dried withMgS04 and the volatiles were removed by spin evaporation in vacuo. Recrystallization of the residue from dichloromethane and hexanes gave 9.10g (33%) of 3-(3.5-difluorophenyl)glutaric acid: m.p. 1700-1720 C.

PU3833 13 3. Preparation of 2-(4,6-Difluoro-3-oxo-lindanyi)acetic acid Sulfuric acid (460mi, BIDH) and 3-(3,5-difluorophenyi)giutaric acid (153g 0.62mol) were combined and the mixture heated at 1OTC for 90 min. The now red solution was cooled to approximately 200C and added dropwise, with efficient stirring, to water (approximately 4.61) at <200C. The resulting precipitate was collected and washed with water to give 124g (88%) of 2-(4,6-difluoro- 3 oxo-l-indanyi)acetic acid.

4. Preparation of Methyl 2-(4,6-difluoro-3-oxo-l-indanyi)acetate Acetyl chloride (4mi, 0.056mol Fluka) was added to a stirred mixture of 2- (4,6 difluoro-3-oxo-l-indanyi) acetic acid (122.5g. 0.54mol) in methanol (1. 21) under a nitrogen atmosphere. The mixture was stirred at room temperature for 48 hours.

The volatiles were removed from the solution by spin evaporation in vacuo and the residue dissolved in ethyl acetate (370mi). The solution was washed with sodium carbonate solution (50mi) followed by sodium chloride solution (2x50mi) then dried (M9S04) and concentrated to a volume of 240mi. The solution was cooled to ca. 5'C and iso-hexane (610mi) added dropwise. The resulting crystalline slurry was filtered and washed with 5% ethyl acetate in iso- hexane to give 94.4g (73%) of methyl 2-(4,6difluoro-3-oxo-1 indanyl)acetate.

5. Preparation of Methyl (E)-2-(4,6-difluoro-3-oxo-l-indanylidene)acetate A mixture of methyl 2-(4,6-d ifi uoro-3-oxo- 1 -inda nyi) acetate (110g, 0.45mol), N bromosuccinimide (90g, 0.5mol) and 2,2-azobis(2-methylpropionitrile) (7. 5g, 46mmol) in tetrachloromethane (1.651) was heated at reflux for 2 hours. The suspension was cooled to 200C and filtered to remove succinimide. The filtrate was stirred at 2TC and triethylamine (76mi, 0.55mol) added dropwise. The resulting suspension was stirred for 30 mins and then water (400mi) added, After stirring for an additional 30 mins, the biphasic mixture was filtered and the solid product washed with tetrachloromethane (1 00mi) and water (200mi) to give 94.7g (86.5%) of methyl (E)-2-(4,6-difluoro-3-oxo-l-indanylidene)acetate.

PU3833 14 6. Preparation of racemic (+/-) methyl (E)-2-(4,6-difluoro-3-hydroxy-1 indanylidene)acetate A suspension of methyl 2-(4,6-difluoro-3-oxo-l-indanylidene)acetate (0. 261g, 1.096mmol) in methanol (5mi) was cooled in an ice bath and sodium borohydride (0.042g, 1Ammol) added. After stirring for 1 hour, the mixture was partitioned between 0.5N hydrochloric acid (50mi) and ethyl acetate (50mi) The organic layer was dried over sodium sulphate, filtered and evaporated in vacuo to give 0.253g (96%) of (+/-) methyl (E)-2-(4,6-difluoro-3-hydroxy-l indanylidene)acetate.

7. Preparation of racemic (E)-2-(4,6-difluoro-3-hydroxy-1 indanyiidene)acetamide A stirred suspension of ammonium chloride (1.07g, 20mmol) in toluene (5mi) was treated with trimethylaluminium in toluene (10m], 20mmol, Aldrich) at 5'C.

After stirring at 200C for 2 hours, the cloudy solution was added to (+/) methyl (E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene)acetate (0.847g, 3.55mmol) and the mixture stirred at 55C under nitrogen for 14 hours. The mixture was cooled in an ice bath and quenched with isopropanol (5mi). Solvents were removed by evaporation in vacuo and the residue treated with 0.5N hydrochloric acid (40mi).

After stirring for 10 min., the solid was collected by filtration and washed with water (2x20mi) to give a pale brown solid. This was slurried in hot ethanol (5mi) then cooled to 50C for 16 hours. The product was collected by filtration, washed with ethyl acetate (2x2mi) and dried to give 0.452g (56%) of (+/-) (E)-2- (4,6 difluoro-3-hydroxy-l-indanylidene)acetamide as a off-white solid; 'H-NMR (DIVISO-d6): 7.06-7.42 (m.41-1) 6.49 (s.11-1) 5.52 (d.11-1) 5.30 (m.1H) 3. 44 (m.1H) 3.03 (d. 1 H).

PU3833 REFERENCE EXAMPLE 3: Alternative synthesis of (E)-2-(4,6-Difluoro-3 hydroxy-1 -indanylidene)acetamide 1. Preparation of chiral Methyl (E)-2-(4,6-difluoro-3-hydroxy-1 - indanylidene)acetate.

(S)-2-Methyl-CBS-oxazaborolidine (0. 21 m 1, 0.21 mmol, Aldrich) in dichloromethane (4ml) was treated with borane-methyl sulphide complex (0. 1 ml) at OOC and methyl 2-(4,6-difluoro-3-oxo-l-indanylidene)acetate (0.2g, 0. 84mmol) in dichloromethane (4ml) added. After 30 mins methanol (5ml) was added and solvents removed by evaporation in vacuo. The residue was dissolved in dichloromethane (20ml) and washed with 1N hydrochloric acid (2xlOml) and sodium chloride solution (10ml). The solution is dried with magnesium sulphate and evaporated in vacuo to afford 0.188g (93%) of chiral methyl (E)-2-(4, 6 difluoro-3-hydroxy-1 A ndanyl id e ne) acetate.

2. Preparation of chiral (E)-2-(4,6-difluoro-3-hydroxy-lindanylidene)acetamide.

A stirred suspension of ammonium chloride (6.95g, 0.13mol) in toluene (35ml) was treated with trimethylaluminium in toluene (65ml, 0.13mol, Aldrich) at 50C.

After stirring at 200C for 2 hours, the cloudy solution was diluted with further toluene (35ml) and a portion (96ml) added to chiral methyl (E)-2-(4,6- difluoro-3 hydroxy-l-indanylidene)acetate (4g, - 16.6mmol). The mixture was stirred at 550C under nitrogen for 19 hours. The mixture was cooled in an ice bath and quenched with isopropanol (75ml). Solvents were removed by evaporation in vacuo and the residue treated with 0.5N hydrochloric acid (220ml). After stirring for 30 min., the solid was collected by filtration and washed with water (2x2Oml) to afford Ug (35%) of chiral (E)-2-(4,6-difluoro-3-hydroxy-l- indanylidene)acetamide.

PU3833 16 EXAMPLE 1: Preparation of (+)-(E)-2-(4,6-Difluoro-3-hydroxy-1 indanylidene)acetamide The (+)-enantiomer of (+/-)-(E)-2-(4,6-difluoro-3-hydroxy-1 - indanylidene) acetamide was isolated by supercritical fluid chromatography (Super C-20 Instrument from Prochrom, France). The instrument is equipped with a C02 pump, a modifier pump, an automated injector, a column oven and an UV detector. The (+)-enantiomer was isolated on a Chiralcel OID column (20 x 250 mm). Chromatographic conditions: 45 g/min Of C02, 5.0 ml/min of methanol, pressure of 21 Mpa, 400C and 300nm. Several runs were performed but for one run, 501.7 mg of the racemate was dissolved in 90 ml of methanol to give a concentration of 5.57 mg/ml. 0.6 ml of this solution was injected into the Super C-20 which gave the (+)-enantiomer as an off-white solid (204.2mg, 100% pure).

EXAMPLE 2: Preparation of (-)-(E)-2-(4,6-Difluoro-3-hydroxy-lindanylidene)acetamide The (-)-enantiomer of(+/-)-(E)-2-(4,6-difluoro-3-hydroxy-1 - indanylidene) acetamide was isolated by supercritical fluid chromatography (Super C-20 Instrument from Prochrom, France). The instrument is equipped with a C02 pump, a modifier pump, an automated injector, a column oven and an UV detector. The (-)-enantiomer was isolated on a Chiralcel OID column (20 x 250 mm). Chromatographic conditions: 45 g/min Of C02, 5.0 ml/min of methanol, pressure of 21 Mpa, 40'C and 300nm. Several runs were performed, for one run 501.7 mg was dissolved in 90 ml of methanol to give a concentration of 5.57 mg/ml. 0.6ml of this solution was injected into the Super C-20 which gave the(-) enantiomer as an off-white solid (1 90mg, at least 96% pure).

PU3833 17 Properties of (+)-(E)-2-(4,6-Difluoro-3-hydroxy-l-indanylidene)acetamide 1. Chemical/Physico-chemical Properties Physical Appearance: off-white solid Molecular Formula: C11H9F2NO2 Molecular Weight: 225.19 Optical Rotation: [(XID = +30.0' (c =0. 19, MeOH, taken at 21 0) NMR data (1 H NMR, 300MHz, d6-DMSO) 3 7.42 (s, 1 H), 7.25 (m, 21-1), 7.06 (s, 1 H), 6.49 (s, 1 H), 5.52 (m, 1 H), 5.30 (brd s, 1 H), 3.50 (dd, 1 H J=7.1, 2.4 Hz), 3.44 (dd, 1 H J=7.1, 2.4 Hz), 3.04 (d, 1 H, J=19.4 Hz) ppm.

2. Analgesic Activity (+)-(E)-2-(4,6-Difluoro-3-hydroxy-l-indanylidene)acetamide was assayed for activity using the 90' Trypsin Hyperalgesia Assay in rats (NSAID sensitive), (Vinegar, et al., J. Pharmacol. Meth., 23:51-61, 1990). The ED5o was 1.7 mglkg ip or an 1C50 of 4 ng/mi (plasma level).

3. Muscle Relaxant Activity (+)-(E)-2-(4,6-Difluoro-3-hydroxy-l-indanylidene)acetamide was assessed for activity using the rat pull up test (Deacon and Gardner, 1984). The ED50 was 15 mglkg ip.

Properties of (-)-(E)-2-(4,6-Difluoro-3-hyd roxy-1 indanylidene)acetamide 1. Chemical/Physico-chemical Properties Physical Appearance: off-white solid Molecular Formula: C11H9F2NO2 Molecular Weight: 225. 19 Optical Rotation: [a]c) = -37.6' (c =0.17, MeOH, taken at 21') PU3833 18 2. Analgesic Activi (-)-(E)-2-(4,6-Difluoro-3-hydroxy-l-indanylidene)acetamide was assayed for activity using the 90' Trypsin Hyperalgesia Assay in rats (NSAID sensitive), (Vinegar, et al., J. Pharmacol. Meth., 23:51-61, 1990). The ED5o was 7 mg/kg ip, or an IC50 of 1300 ng/ml (plasma level).

3. Muscle Relaxant Activi (-)-(E)-2-(4,6-Difluoro-3-hydroxy-l-indanylidene)acetamide was assessed for activity using the rat pull up test (Deacon and Gardner, 1984). The -enantiomer did not exhibit any-activity up to 45 mg/kg ip.

PU3833 19

Claims (10)

Claims

1. (+)-(E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene)acetamide and pharmaceutically acceptable salts and solvates thereof.

2. Pharmaceutical compositions comprising (+)-(E)-2-(4,6-difluoro-3hydroxy-l- indanylidene)acetamide and pharmaceutically acceptable salts and solvates thereof together with one or more pharmaceutically acceptable carriers, diluents or excipients.

3. (+)-(E)-2-(4,6-difluoro-3-hydroxy-1 -indanylidene)acetamide or a pharmaceutically acceptable salt or solvate thereof for use in therapy.

4. The use (+)-(E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene) acetamide or a pharmaceutically acceptable salt or solvate thereof, (or a pharmaceutical composition thereof), in the preparation of a medicament for the treatment of conditions associated with abnormally raised skeletal muscle tone, pain or inflammatory conditions.

5. A method of treating conditions associated with abnormally raised skeletal muscle tone, pain or inflammatory conditions in a human or animal subject comprising the administration to said subject of an effective amount of (+ )-(E)-2 (4,6-difluoro-3-hydroxy-l-indanylidene)acetamide, (or a pharmaceutically acceptable salt or solvate thereof), or a pharmaceutical composition thereof.

6. (-)-(E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene)acetamide and pharmaceutically acceptable salts and solvates thereof.

7. Pharmaceutical compositions comprising (-)-(E)-2-(4,6-difluoro-3hydroxy-l- indanylidene)acetamide or pharmaceutically acceptable salts or solvates thereof PU3833 together with one or more pharmaceutically acceptable carriers, diluents or excipients.

8. (-)-(E)-2-(4,6-difluoro-3-hydroxy-1 -indanylidene)acetamide or a pharmaceutically acceptable salt or solvate thereof for use in therapy.

9. The use of (-)-(E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene) acetamide or a pharmaceutically acceptable salt or solvate thereof, (or a pharmaceutical composition thereof), in the preparation of a medicament for the treatment of pain or inflammatory conditions.

10. A method of treating pain or inflammatory conditions in a human or animal subject comprising the administration to said subject of an effective amount of (-) -(E)-2-(4,6-difluoro-3-hydroxy-l-indanylidene)acetamide or a pharmaceutically acceptable salt or solvate thereof (or a pharmaceutical composition thereof).