WO2004099196A1 - Benzoxazinone derivatives, their preparation and use - Google Patents

Abstract

Compounds of formula (I) and pharmaceutically acceptable salts thereof are disclosed, wherein R1 is hydrogen or C1-6alkyl; and R2 is fluoro or chloro. Methods of preparation and uses thereof in treatment of CNS disorders, such as depression or anxiety, are also disclosed.

Description

Benzoxazinone derivatives, their preparation and use

The present invention relates to^' novel compounds, processes for their preparation, pharmaceutical compositions containing the same and their use as medicaments. More particularly this invention relates to novel benzoxazinone derivatives and their utility in the treatment of CNS and other disorders.

Artigas (Trends in Pharmacological Sciences, Vol. 14, 262, 1993) suggests that the co- administration of a 5-HT-I A receptor antagonist and a selective serotonin reuptake inhibitor (SSRI) may give rise to an improvement in anti-depressant efficacy. WO02/34754 discloses a series of benzoxazinone compounds as being useful for treating certain CNS disorders such as depression.

A novel class of compounds has now been discovered. These compounds fall within the generic scope of WO02/34754, but are not specifically disclosed therein, and have been found to exhibit a surprisingly enhanced SSRI activity and excellent pharmacokinetics.

Thus, the present invention provides, in a first aspect, a compound of formula (I) or a pharmaceutically acceptable salt thereof:

(I) wherein

R1 is hydrogen or C-ι_galkyl; and R2 is fluoro or chloro.

The term "C-i. alkyl", whether alone or part of another group, refers to alkyl groups having from one to six carbon atoms, in all isomeric forms, including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, sec-pentyl, n-pentyl, isopentyl, tert-pentyl and hexyl.

Preferably R1 is hydrogen or methyl.

Preferably R2 is fluoro. A preferred compound of this invention is 8-Fluoro-6-{1-[2-(7-fluoro-2-methyl-quinolin-5- yloxy)-ethyl]-piperidin-4-ylmethyl}-4H-benzo[1 ,4]oxazin-3-one, and pharmaceutically acceptable salts thereof.

The compounds of formula (I) can form acid addition salts thereof. It will be appreciated that for use in medicine the salts of the compounds of formula (I) should be pharmaceutically acceptable. Suitable pharmaceutically acceptable salts will be apparent to those skilled in the art and include those described in J. Pharm. Sci., 1977, 66, 1-19, such as acid addition salts formed with inorganic acids e.g. hydrochloric, hydrobromic, sulfuric, nitric or phosphoric acid; and organic acids e.g. succinic, maleic, acetic, fumaric, citric, tartaric, benzoic, p-toluenesulfonic, methanesulfonic or naphthalenesulfonic acid. Certain of the compounds of formula (I) may form acid addition salts with one or more equivalents of the acid. The present invention includes within its scope all possible stoichiomet c and non-stoichiometric forms.

The compounds of formula (I) may be prepared in crystalline or non-crystalline form, and, if crystalline, may optionally be hydrated or solvated. This invention includes within its scope stoichiometric hydrates or solvates as well as compounds containing variable amounts of water and/or solvent.

The compounds of the present invenion may be prepared in an analogous manner to the processes disclosed in WO02/34754. Pharmaceutically acceptable salts may be prepared conventionally by reaction with the appropriate acid or acid derivative.

The affinities of the compounds of this invention for 5-HTIA, 5-HT^<| B and 5-HT-I D receptors can be determined by the following assay. CHO cells expressing 5-HT-|A receptors (4 x 10^ cells/ml) are homogenised in Tris buffer and stored in 1 ml aliquots. CHO cells expressing 5-HT^ β receptors (4 x 10^ cells/ml) are homogenised in Tris buffer and stored in 1.5 ml aliquots. CHO cells expressing 5-HT-| fj receptors (1 x lO^/tnl) are homogenised in Tris buffer and stored in 1 ml aliquots. 0.4 ml of a cell suspension is incubated with [³H]-5-HT (4nM) for 5-HT_{1 B}/1 D receptors and [³H]WAY100635 (1 nM) for 5-HT-IA receptors in Tris Mg HCI buffer (pH 7.7) and test drug, at 37°C for 45 minutes. Each test drug is tested at 10 concentrations (0.01 mM to 0.3 nM final concentration), with non-specific binding defined using 0.01 mM 5-HT. The total assay volume is 0.5 ml. Incubation is stopped by rapid filtration using a Packard Filtermate and radioactivity measured by Topcount scintillation counting. pKi values are calculated from the IC50 generated by an iterative least squares curve fitting programme.

The Example compound shown below was tested according to the radioligand binding assay described above and was found to have a pKi value of 8.4. It is selective for the 5- H M A receptor over the 5-HT-j g and 5-HT-j rj receptors. The intrinsic activity of the compounds of this invention can be determined according to the following assay. HEK293 cell membranes stably expressing human 5-HT-JA receptors and CHO cell membranes stably expressing human 5-HT-J B receptors are homogenised in HEPES/EDTA buffer and stored in 1ml aliquots, and [³⁵S]GTPγS binding studies are carried out essentially as described by Lazareno et. al., (Life Sci., 1993, 52, 449) with some minor modifications. Membranes from 10^ cells are pre-incubated at 30°C for 30 minutes in 20 mM HEPES buffer (pH 7.4) in the presence of MgC^'2 (3 mM), NaCI (100 mM), GDP (10 μM) and ascorbate (0.2 mM), with or without test compounds. The reaction is started by the addition of 50 μl of [³^S]GTPγS (100 pM, assay concentration) followed by a further 30 minutes incubation at 30°C. Non-specific binding is determined using nonradiolabelled GTPγS (20 μM) added prior to the membranes. The reaction is terminated by rapid filtration through Whatman GF/B grade filters followed by 5 x 1 ml washes with ice cold HEPES (20 mM) /MgCl2 (3 mM) buffer. Radioactivity is measured using liquid scintillation spectrometry. This procedure is hereafter referred to as the [³⁵S]GTPγS functional assay.

It has been found, using the [³^S]GTPγS functional assay, that the Example compound below appears to be an antagonist at 5-HT-] type receptors.

The efficacy of the compounds of this invention to inhibit the re-uptake of serotonin can be measured in a 5-HT uptake assay by measurement of uptake of [³H]-5-HT into LLCPK cells expressing human or rat serotonin transporters. In brief, cells are harvested and plated onto 96-well plates (10,000 cells per well). 24hr later cells are washed 2x with HBSSH (Hanks'balanced salt solution + 20mM HEPES). 50ul of test compound or vehicle is added to each well and incubated for 10min. Subsequently, [³H]5-HT (final concentration 25nM) is added and the test mixture is incubated for a further 7min. The reaction is terminated by aspiration of test mixture and the cells are washed 6x with HBSSH. 50ul of scintillation cocktail (Microscint-20, Packard) is added onto the cells and the top and bottom of the plate is sealed. Plates are read, 30min later, in a Packard TopCount.

The Example compound below was tested according to this uptake assay and was found to have potency at the uptake site of PIC50 of 7.7 and 8.4 at human and rat transporters respectively.

Compounds of the present invention are of use in the treatment of certain CNS disorders, particularly serotonin-related disorders such as depression (which term is used herein to include bipolar depression, unipolar depression, single or recurrent major depressive episodes with or without psychotic features, catatonic features, melancholic features, atypical features or postpartum onset, seasonal affective disorder, dysthymic disorders with early or late onset and with or without atypical features, neurotic depression and social phobia, depression accompanying dementia for example of the Alzheimer's type, vascular dementia with depressed mood, schizoaffective disorder or the depressed type, and depressive disorders resulting from general medical conditions including, but not limited to, myocardial infarction, diabetes, miscarriage or abortion, etc), anxiety disorders (including generalised anxiety disorder and social anxiety disorder), schizophrenia, panic disorder, agoraphobia, social phobia, obsessive compulsive disorder and post-traumatic stress disorder, pain (particularly neuropathic pain), memory disorders, including dementia, amnesic disorders and age-associated memory impairment, disorders of eating behaviours, including anorexia nervosa and bulimia nervosa, sexual dysfunction, sleep disorders (including disturbances of circadian rhythm, dyssomnia, insomnia, sleep apnea and narcolepsy), withdrawal from abuse of drugs such as of cocaine, ethanol, nicotine, benzodiazepines, alcohol, caffeine, phencyclidine (phencyclidine-like compounds), opiates (e.g. cannabis, heroin, morphine), amphetamine or amphetamine-related drugs (e.g. dextroamphetamine, methylamphetamine) or a combination thereof, motor disorders such as Parkinson's disease, dementia in Parkinson's disease, neuroleptic-induced Parkinsonism and tardive dyskinesias, as well as other psychiatric disorders. Compounds of formula (I) may also have utility in the treatment of certain gastrointestinal disorders such as irritable bowel syndrome, Crohn's disease, ulcerative colitis, non-steroidal anti- inflammatory drug induced damage.

Thus the invention also provides a compound of formula (I) or a pharmaceutically acceptable salt thereof, for use as a therapeutic substance, in particular in the treatment of the above disorders. In particular the invention provides a compound of formula (I) or a pharmaceutically acceptable salt thereof for use in the treatment of depression or anxiety.

It is to be understood that the term "treatment" as used herein includes amelioration of established symptoms as well as prophylaxis.

Compounds of the invention may be administered in combination with other active substances such as 5HT3 antagonists, NK-1 antagonists, serotonin agonists, selective serotonin reuptake inhibitors (SSRI), noradrenaline re-uptake inhibitors (SNRI), tricyclic antidepressants and/or dopaminergic antidepressants.

Suitable 5HT3 antagonists which may be used in combination of the compounds of the inventions include for example ondansetron, granisetron, metoclopramide.

Suitable serotonin agonists which may be used in combination with the compounds of the invention include sumat ptan, rauwolscine, yohimbine, metoclopramide. Suitable SSRIs which may be used in combination with the compounds of the invention include fluoxetine, citalopram, femoxetine, fluvoxamine, paroxetine, indalpine, sertraline, zimeldine.

Suitable SNRIs which may be used in combination with the compounds of the invention include venlafaxine and reboxetine.

Suitable tricyclic antidepressants which may be used in combination with a compound of the invention include imipramine, amitriptiline, chlomipramine and nortriptiline.

Suitable dopaminergic antidepressants which may be used in combination with a compound of the invention include bupropion and amineptine.

It will be appreciated that the compounds of the combination or composition may be administered simultaneously (either in the same or different pharmaceutical formulations), separately or sequentially.

The invention further provides a method of treatment of the above disorders, particularly a CNS disorder such as depression or anxiety, in mammals including humans, which comprises administering to the sufferer a therapeutically safe and effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof.

In another aspect, the invention provides for the use of a compound of formula (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for use in the treatment of the above disorders, particularly a CNS disorder such as depression or anxiety.

In order to use the compounds of formula (I) in therapy, they will normally be formulated into a pharmaceutical composition in accordance with standard pharmaceutical practice. The present invention also provides a pharmaceutical composition, which comprises a compound of formula (I) or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.

In a further aspect, the present invention provides a process for preparing a pharmaceutical composition, the process comprising mixing a compound of formula (I) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier or excipient.

A pharmaceutical composition of the invention, which may be prepared by admixture, suitably at ambient temperature and atmospheric pressure, is usually adapted for oral, parenteral or rectal administration and, as such, may be in the form of tablets, capsules, oral liquid preparations, powders, granules, lozenges, reconstitutable powders, injectable or infusible solutions or suspensions or suppositories. Orally administrable compositions are generally preferred.

Tablets and capsules for oral administration may be in unit dose form, and may contain conventional excipients, such as binding agents (e.g. pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose);, fillers (e.g. lactose, microcrystalline cellulose or calcium hydrogen phosphate);, tabletting lubricants lubricants (e.g. magnesium stearate, talc or silica);, disintegrants (e.g. potato starch or sodium starch glycollate); and acceptable wetting agents (e.g. sodium lauryl sulphate). The tablets may be coated according to methods well known in normal pharmaceutical practice.

Oral liquid preparations may be in the form of, for example, aqueous or oily suspension, solutions, emulsions, syrups or elixirs, or may be in the form of a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents (e.g. sorbitol syrup, cellulose derivatives or hydrogenated edible fats), emulsifying agents (e.g. lecithin or acacia), non-aqueous vehicles (which may include edible oils e.g. almond oil, oily esters, ethyl alcohol or fractionated vegetable oils), preservatives (e.g. methyl or propyl-p- hydroxybenzoates or sorbic acid), and, if desired, conventional flavourings or colorants, buffer salts and sweetening agents as appropriate. Preparations for oral administration may be suitably formulated to give controlled release of the active compound.

For parenteral administration, fluid unit dosage forms are prepared utilising a compound of the invention or pharmaceutically acceptable salt thereof and a sterile vehicle. Formulations for injection may be presented in unit dosage form e.g. in ampoules or in multi-dose, utilising a compound of the invention or pharmaceutically acceptable salt thereof and a sterile vehicle, optionally with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g. sterile pyrogen-free water, before use. The compound, depending on the vehicle and concentration used, can be either suspended or dissolved in the vehicle. In preparing solutions, the compound can be dissolved for injection and filter sterilised before filling into a suitable vial or ampoule and sealing. Advantageously, adjuvants such as a local anaesthetic, preservatives and buffering agents are dissolved in the vehicle. To enhance the stability, the composition can be frozen after filling into the vial and the water removed under vacuum. Parenteral suspensions are prepared in substantially the same manner, except that the compound is suspended in the vehicle instead of being dissolved, and sterilisation cannot be accomplished by filtration. The compound can be sterilised by exposure to ethylene oxide before suspension in a sterile vehicle. Advantageously, a surfactant or wetting agent is included in the composition to facilitate uniform distribution of the compound.

Lotions may be formulated with an aqueous or oily base and will in general also contain one or more emulsifying agents, stabilising agents, dispersing agents, suspending agents, thickening agents, or colouring agents. Drops may be formulated with an aqueous or non- aqueous base also comprising one or more dispersing agents, stabilising agents, solubilising agents or suspending agents. They may also contain a preservative.

The compounds of the invention may also be formulated in rectal compositions such as suppositories or retention enemas, e.g. containing conventional suppository bases such as cocoa butter or other glycerides.

The compounds of the invention may also be formulated as depot preparations. Such long acting formulations may be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the compounds of the invention may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

For intranasal administration, the compounds of the invention may be formulated as solutions for administration via a suitable metered or unitary dose device or alternatively as a powder mix with a suitable carrier for administration using a suitable delivery device. Thus compounds of formula (I) may be formulated for oral, buccal, parenteral, topical (including ophthalmic and nasal), depot or rectal administration or in a form suitable for administration by inhalation or insufflation (either through the mouth or nose).

The compounds of the invention may be formulated for topical administration in the form of ointments, creams, gels, lotions, pessaries, aerosols or drops (e.g. eye, ear or nose drops). Ointments and creams may, for example, be formulated with an aqueous or oily base with the addition of suitable thickening and/or gelling agents. Ointments for administration to the eye may be manufactured in a sterile manner using sterilised components.

The composition may contain from 0.1% to 99% by weight, preferably from 10 to 60% by weight, of the active material, depending on the method of administration. The dose of the compound used in the treatment of the aforementioned disorders will vary in the usual way with the seriousness of the disorders, the weight of the sufferer, and other similar factors. However, as a general guide suitable unit doses may be 0.05 to 1000 mg, more suitably 1.0 to 200 mg, and such unit doses may be administered more than once a day, for example two or three times a day. Such therapy may extend for a number of weeks or months. All publications, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference as if each individual publication were specifically and individually indicated to be incorporated by reference herein as though fully set forth.

The following Descriptions and Examples illustrate the preparation of the compounds of the invention.

Description 1

3-Fluoro-4-methoxy-5-nitro-benzaldehyde (D1 )

3-Fluoro-4-methoxy-benzaldehyde (17.6g, 114mmol) was added to stirred concentrated sulfuric acid (200mL) at -10°C. Nitric acid (70% w/w) (10.5g) was added dropwise. After 60 mins. of stirring, the mixture was poured onto ice. The precipitate was filtered and partitioned between sodium hydrogen carbonate solution and dichloromethane. The aqueous layer was extracted with more dichloromethane (200mL) and the combined organic layer was dried (Na₂SO₄) and evaporated in vacuo to give the title compound as a crude solid (19g).

¹ H NMR (CDCI3) δ: 4.21 (3H, d, J = 5 Hz), 7.86 (1 H, dd, J = 17, 3 Hz), 8.09 (1 H, t, J = 3 Hz), 9.92 (1 H, d, J = 3 Hz).

Description 2 (3-Fluoro-4-methoxy-5-nitro-phenyl)-methanol (D2)

Sodium borohydride (5g) was added portionwise to a stirring solution of crude 3-fluoro-4- methoxy-3-nitro-benzaldehyde (19g) in methanol (200mL) at 5°C. After 2 hours, the methanol was removed in vacuo. The residue was treated with cold water (150mL) and extracted with dichloromethane (2x150mL). The combined organic layer was evaporated in vacuo to give a crude oil. Silica gel chromatography eluting with ethyl acetate in petroleum ether (10-20%) gave the title compound as a solid (15g). H NMR (CDCI3) δ: 1.86 (1 H, t, J = 6 Hz), 4.06 (3H, d, J = 2 Hz), 4.72 (2H, d, J = 6 Hz), 7.38 (1 H, dd, J = 10, 2 Hz), 7.58 (1 H, s).

Description 3

1 -Bromomethyl-3-f luoro-4-methoxy-5-nitro-benzene (D3)

Carbon tetrabromide (62g, 187mmol) and triphenyl phosphine (49g, 187mmol) were added to a stirred solution of (3-fluoro-4-methoxy-3-nitro-phenyl)-methanol (15g, 74.6mmol) in anhydrous diethyl ether (500mL). After 2 hours, the mixture was filtered and the filtrate was evaporated in vacuo. Silica gel chromatography of the crude residue eluting with diethyl ether in petroleum ether (10-20%) gave the title compound (14g). H NMR (CDCI3) δ: 4.08 (3H, d, J = 2 Hz), 4.42 (2H, s), 7.39 (1 H, dd, J = 11 , 2 Hz), 7.61 (1 H, t, J = 2 Hz).

Description 4

(3-Fluoro-4-methoxy-5-nitro-benzyl)-phosphonic acid diethyl ester (D4)

A mixture of 1-bromomethyl-3-fluoro-4-methoxy-3-nitro-benzene (22.2g, 84mmol) and triethyl phosphite (16.8g) was heated to 160°C for 4 hours to give the title compound as a brown oil (29.6g).

¹ H NMR (CDCI3) δ: 1.26-1.36 (6H, m), 3.10 (2H, d, J = 21 Hz), 4.05 (3H, d, J = 2Hz), 4.05-4.16 (4H, m), 7.33 (1 H, dt, J = 12, 2 Hz), 7.50 (1 H, m).

Description 5

4-(3-Fluoro-4-methoxy-5-nitro-benzylidene)-piperidine-1 -carboxylic acid te/τ-butyl ester (D5)

A solution of (3-fluoro-4-methoxy-3-nitro-benzyl)-phosphonic acid diethyl ester (29.6g) in anhydrous THF (40mL) was added to a stirred suspension of sodium hydride (60%) (3.5g) in anhydrous THF (250mL) at 0°C. The mixture was left to stir for 30min. 4-Oxo- piperidine-1-carboxylic acid fe/τ-butyl ester (17.6g) in anhydrous THF (10mL) was added to the mixture. Stirring was continued at room temperature until no starting material remains. The mixture was poured into saturated ammonium chloride (250mL) and extracted with ethyl acetate (2x200mL). The combined organic layer was evaporated in vacuo to give a crude oil. Silica gel chromatography eluting with ethyl acetate in petroleum ether (5-10%) gave the title compound as an oil (25.2g). H NMR (CDCI₃) δ: 1.48 (9H, s), 2.34 (2H, m), 2.42 (2H, m), 3.42 (2H, m), 3.51 (2H, m), 4.06 (3H, d, J = 2 Hz), 6.24 (1 H, s), 7.15 (1 H, dd, J = 12, 2 Hz), 7.38 (1 H, m).

Description 6

4-(3-Fluoro-4-hydroxy-3-nitro-benzylidene)-piperidine-1-carboxylic acid tert-butyl ester (D6)

A mixture of 4-(3-fluoro-4-methoxy-3-nitro-benzylidene)-piperidine-1-carboxylic acid tert- butyl ester (6g, 16.4mmo!) and lithium chloride (2.8g) in DMF was stirred at 140°C for 4 hours. It was allowed to cool to room temperature and evaporated in vacuo. The residue was triturated with dichloromethane. Evaporation of the dichloromethane gave the title compound as an oil (2g). H NMR (CDCI3) δ: 1.48 (9H, s), 2.34 (2H, m), 2.42 (2H, m), 3.42 (2H, m), 3.51 (2H, m), 6.23 (1 H, s), 7.24-7.29 (1 H, m), 7.72 (1 H, m).

Description 7 4-(3-Amino-5-fluoro-4-hydroxy-benzyl)-piperidine-1-carboxylic acid ferf-butyl ester (D7)

A solution of 4-(3-fluoro-4-hydroxy-3-nitro-benzylidene)-piperidine-1-carboxylic acid tert- butyl ester (5g) in methanol (500mL) was stirred under atmospheric hydrogen in the presence of 10% palladium on charcoal (0.5g) for 2.75 hours. The catalyst was removed and the filtrate was evaporated in vacuo to give the title compound as an oil (3.6g, 78%). 1 H NMR (CDCI3) δ: 1.05-1.18 (2H, m), 1.45 (9H, s), 1.52-1.70 (3H, m), 2.36 (2H, m), 2.63 (2H, m), 3.77 (2H, m), 4.06 (2H, m), 6.25-6.35 (2H, m).

Description 8

6-(4-(Λ/-(f-Butyloxycarbonyl)piperidinyl)methyl)-8-fluoro-4H-benzo[1,4]oxazin-3-one

(D8)

Chloroacetyl chloride (1.5g) was added dropwise to a stirring mixture of 4-(3-amino-5- fluoro-4-hydroxy-benzyl)-piperidine-1-carboxylic acid te/t-butyl ester (3.6g) in 2-butanone (30mL) and sodium hydrogen carbonate (2.34g) in water (10mL) at 0°C. The mixture was stirred from 0°C to room temperature over 4 hours and then at 80°C for 4 hours. The layers were allowed to separate and the aqueous layer was extracted with dichloromethane (2x100mL). The combined organic layer was evaporated in vacuo. Silica gel chromatography of the resulting residue eluting with ethyl acetate in petroleum ether (10-30%) gave the title compound as an oil (3.4g, 84%).

¹ H NMR (CDCI3) δ: 1.05-1.20 (2H, m), 1.45 (9H, s), 1.55-1.70 (3H, m), 2.44 (2H, d, J = 6 Hz), 2.73 (2H, m), 4.00-4.15 (2H, m), 4.66 (2H, s), 6.35 (1 H, s), 6.60 (1 H, m), 7.90 (1 H, br s).

Description 9

8-Fluoro-6-piperidin-4-ylmethyl-4H-benzo[1 ,4]oxazin-3-one hydrochloride (D9)

6-(4-(Λ/-(f-Butyloxycarbonyl)piperidinyl)methyl)-8-fluoro-4H-benzo[1 ,4]oxazin-3-one (1.0g, 2.75rτimol) was dissolved in ethanol (16 mL) and 1 M hydrochloride solution in diethyl ether (26 mL) was added. The mixture was heated at 45°C for 2.5 hours. The solvents were removed under reduced pressure, the solid triturated with diethyl ether and dried to give the title compound as a beige coloured solid (0.783g, 95%). Mass spectrum (AP⁺): Found 265 (MH⁺). C-14H17N2O2F requires 264. ¹H NMR (MeOD) δ: 1.36-1.47 (2H, m), 1.82-1.91 (3H, m), 2.53 (2H, d, J = 7 Hz), 2.91- 2.97 (2H, m), 3.35-3.38 (2H, m), 4.60 (2H, s), 6.55 (1H, d, J = 1 Hz), 6.68 (1 H, dd, J = 11 Hz, 2 Hz).

Example

8-Fluoro-6-{1-[2-(7-fluoro-2-methyl-quinolin-5-yloxy)-ethyl]-piperidin-4-ylmethyl}-4H- benzo[1 ,4]oxazin-3-one

A mixture of 8-fluoro-6-piperidin-4-ylmethyl-4H-benzo[1 ,4]oxazin-3-one hydrochloride (0.170 g, 0.57 mmol), 5-(2-bromo-ethoxy)-7-fluoro-2-methyl-quinoline (0.160 g, 0.57 mmol) and sodium iodide (0.085 g, 0.57 mmol) in lPA (5 mL) and N,N'- diisopropylethylamine (0.5 mL) was heated at 85°C for 18 hours under a stream of argon.

The solvents were removed under reduced pressure and the residue partitioned between ethyl acetate and saturated aqueous sodium bicarbonate solution. The organic phase was separated, washed with brine, dried over anhydrous magnesium sulphate, filtered and concentrated under reduced pressure. The crude compound was purified by column chromatography on silica gel eluting with 4% methanol in dichloromethane to give the title compound as a cream coloured foam (0.196 g, 74%)

Mass spectrum (ES⁺): Found 468 (MH⁺). C26H27N3O3F2 requires 467. ¹H NMR (CDCI3) δ: 1.32 (2H, dq, J = 12 Hz, 3 Hz, ), 1.47-1.51 (1 H, m), 1.63 (2H, bd, J =

13Hz), 2.14 (2H, dt, J =12 Hz, 2 Hz), 2.43 (2H, d, J = 7 Hz), 2.70 (3H, s), 2.93 (2H, t, J = 6

Hz), 3.04 (2H, d, J = 12 Hz), 4.24 (2H, t, J = 6 Hz), 4.64 (2H, s), 6.35 (1 H, s), 6.58 (2H, dd, J = 11 Hz, 2 Hz), 7.17 (1H, d, J = 8 Hz), 7.22 (1H, dd, J = 10 Hz, 2 Hz), 8.33 (1 H, d, J = 8 Hz), 8.61 (1 H, bs).

Claims

Claims

1. A compound of formula (I) or a pharmaceutically acceptable salt thereof:

(I)

wherein

R1 is hydrogen or C-i.galkyl; and

R2 is fluoro or chloro.

2. A compound as claimed in claim 1 , wherein R1 is hydrogen or methyl.

3. A compound as claimed in claim 1 or claim 2, wherein R2 is fluoro.

4. A compound as claimed in claim 1 , which is 8-Fluoro-6-{1-[2-(7-fluoro-2-methyl- quinolin-5-yloxy)-ethyl]-piperidin-4-ylmethyl}-4/- -benzo[1 ,4]oxazin-3-one, or a pharmaceutically acceptable salt thereof.

5. A compound as claimed in any of claims 1-4, for use as a therapeutic substance.

6. A compound as claimed in any of claims 1-4, for use in the treatment of a CNS disorder.

7. A compound as claimed in any of claims 1-4, for use in the treatment of depression or anxiety.

8. A method of treatment of a CNS disorder in mammals including humans, which comprises administering to the sufferer a therapeutically safe and effective amount of a compound as claimed in any of claims 1-4.

9. A method as claimed in claim 8, wherein the CNS disorder is depression or anxiety.

10. Use of a compound as claimed in any of claims 1-4 in the manufacture of a medicament for use in the treatment of a CNS disorder.

11. The use as claimed in claim 10, wherein the CNS disorder is depression or anxiety.

12. A pharmaceutical composition, which comprises a compound as defined in any of claims 1-4 and a pharmaceutically acceptable carrier or excipient.