WO2000048998A1

WO2000048998A1 - Amino(thio)phenols and their therapeutic use

Info

Publication number: WO2000048998A1
Application number: PCT/GB2000/000484
Authority: WO
Inventors: Andrew Sharpe; Hannah Jayne Kendall
Original assignee: Darwin Discovery Limited
Priority date: 1999-02-19
Filing date: 2000-02-14
Publication date: 2000-08-24
Also published as: AU2557400A; GB9903919D0

Abstract

Compounds having therapeutic utility, as inhibitors of PDE and TNF, are of formula (i) wherein R1 is alkyl optionally substituted with one or more halogens; R2 is a carboxylate, carboxamide, sulfinyl or sulfonyl group; R3, R4 and R6 are each H or alkyl; R5 is optionally substituted aryl or heteroaryl; and X is O or S.

Description

AMINOΠΉIO^PHENOLS AND THEIR THERAPEUTIC USE Field of the Invention

The present invention relates to novel amino(thio)phenol (and phenol ether) compounds and to their formulation and use as pharmaceuticals. Background of the Invention

WO-A-9631476 and WO-A-9640636 disclose aromatic ethers having therapeutic utility, as inhibitors of tumour necrosis factor (TNF) and phosphodiesterases (PDE). Other such compounds and their uses are described in US-A-5804588, and in WO-A- 9924404 (published 20 May 1999). Summary of the Invention

This invention provides novel compounds having therapeutic utility, in particular for the treatment of disease states associated with proteins which mediate cellular activity, for example by inhibiting TNF and/or PDE IV. According to the invention, the compounds are of formula (i):

wherein Rj is alkyl optionally substituted with one or more halogens;

R₂ is COjRj, COR, , CONRjR,,, or S(O)_pR,;

R₃ is H or alkyl;

R₄ is H or alkyl;

Rs is aryl or heteroaryl either of which may be substituted at any position with (one or more) substituents R_M or alkyl-R₁₄;

Re is H or alkyl;

R₇ is OR_u> NR₁₅Ri₂, CN, COjRu, CONR^^ or COR_ls; R_g is R,₃ optionally substituted with R₇;

R_j, and Rι₀ are the same or different and are each H, alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl, or represents a heterocyclic ring optionally substituted with alkyl, arylalkyl or heteroarylalkyl;

R_u is H, alkyl (optionally substituted with one or more halogens), cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl;

Rj₂ is H, alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl, heterocycloalkyl, alkylcarbonyl, alkoxycarbonyl, arylcarbonyl, heteroarylcarbonyl, heterocyclocarbonyl, alkylsulphonyl, arylsulphonyl, heteroarylsulphonyl or heterocyclosulphonyl;

R₁₃ is alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl;

R₁₄ is alkyl, aryl, heteroaryl, heterocyclo,

SO₂N ₉R_K,, OR_n, halogen, CN, NR,₅R₁₂, COR_ls or S(O)_pR_u;

R_1$ is H, alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl;

X is O or S; and p = 1 or 2; including N-oxides and pharmaceutically acceptable salts.

This invention provides also a method for mediating or inhibiting the enzymatic activity or catalytic activity of PDE IV in a mammal in need thereof and for inhibiting the production of TNF in a mammal in need thereof, which comprises administering to said mammal an effective amount of a compound of Formula (i) or a pharmaceutically- acceptable salt thereof.

Description of the Invention

Certain compounds of the invention are preferred. X is preferably O. - g is preferably H. Rj is preferably phenyl, pyrimidinyl, pyridyl or pyridyl-N-oxide, any of which may be substituted at any position with (one or more) substitutents R₁₄ (in which R₁₄ is alkyl optionally substituted with one or more halogens, halogen, OR_u or CN).

Suitable pharmaceutically-acceptable salts are pharmaceutically-acceptable base salts and pharmaceutically-acceptable acid addition salts. Certain of the compounds of formula (i) which contain an acidic group form base salts. Suitable pharmaceutically- acceptable base salts include metal salts, such as alkali metal salts, for example sodium salts, or organic amine salts such as that provided with ethylenediamine.

Certain of the compounds of formula (i) which contain a basic group form acid addition salts. Suitable acid addition salts include pharmaceutically-acceptable inorganic salts such as the sulphate, nitrate, phosphate, borate, hydrochloride and hydrobromide, and pharmaceutically-acceptable organic acid addition salts such as acetate, tartrate, maleate, citrate, succinate, benzoate, ascorbate, methanesulphate, α-ketoglutarate, α-glycerophosphate and glucose- 1 -phosphate. The pharmaceutically-acceptable salts of the compounds of formula (i) are prepared using conventional procedures.

It will be appreciated by those skilled in the art that some of the compounds of formula (i) may exist in more than one tautomeric or geometric form. This invention extends to all tautomeric forms.

It will be appreciated that the compounds according to the invention can contain one or more asymmetrically substituted carbon atoms. The presence ofone or more of these asymmetric centers in a compound of formula (i) can give rise to stereoisomers, and in each case the invention is to be understood to extend to all such stereoisomers, including enantiomers, and diastereoisomers and mixtures including racemic mixtures thereof. When used herein the term alkyl whether used alone or when used as a part of another group includes straight and branched chain alkyl groups containing up to 6 carbon atoms. Alkoxy means an alkyl-O- group in which the alkyl group is as previously described, and thioalkyl means an alkyl-S- group. Cycloalkyl includes a non-aromatic cyclic or multicyclic ring system of 3 to 10 carbon atoms. The cyclic alkyl may optionally be partially unsaturated. Aryl indicates mono- or multicyclic carbocyclic radicals containing 6 to 10 carbon atoms. Arylalkyl means an aryl-alkyl- group wherein the aryl and alkyl are as described herein. Heteroaryl means a 5 to 10 membered aromatic monocyclic or multicyclic hydrocarbon ring system in which one or more of the atoms in the ring system is an element other than carbon, chosen from amongst nitrogen, oxygen or sulphur. Heterocyclo means a 4 to 10 membered saturated or partially saturated monocyclic or multicyclic hydrocarbon ring system in which one or more of the atoms in the ring system is an element other than carbon, chosen from amongst nitrogen, oxygen or sulphur. Heteroarylalkyl means a heteroaryl-alkyl- group and heterocycloalkyl means a heterocycloalkyl- group. Alkylcarbonyl means an alkyl-CO- group in which the alkyl group is as previously described. Arylcarbonyl means an aryl-CO- group in which the aryl group is as previously described. Heteroarylcarbonyl means a heteroaryl-CO- group and heterocyclocarbonyl means a heterocyclo-CO- group. Arylsulphonyl means an aryl-SO₂- group in which the aryl group is as previously described. Heteroarylsulphonyl means a heteroaryl-SO₂- group and heterocyclosulponyl means a heterocyclo-SO₂- group. Alkoxycarbonyl means an alkoxy-CO- group in wich the alkoxy group is as previously desribed. Alkylsulphonyl means an alkyl-SO₂- group in which the alkyl group is as previously described. Carbonyl oxygen means a -CO- group. It will be appreciated that a carbonyl oxygen can not be a substituent on an aryl ring. Heterocyclic ring means a 4 to 10 membered monocyclic or multicyclic ring system (which may saturated or partially unsaturated) wherein one or more of the atoms in the ring system is an element other than carbon chosen from amongst nitrogen, oxygen or sulphur atoms. Halogen means fluorine, chlorine, bromine or iodine.

The invention further provides a process for the preparation of a compound of formula (i), in which

and p are as defined above. It will be appreciated that functional groups such as amino, hydroxyl or carboxyl groups present in the various compounds described below, and which it is desired to retain, may need to be in protected forms before any reaction is initiated. In such circumstances, removal of the protecting group may be the final step in a particular reaction. Suitable protecting groups for such functionality will be apparent to those skilled in the art. For specific details, see Protective Groups in Organic Synthesis, Wiley Interscience, T W Greene or Chem. Ber. (1925), 58, 44. Thus the process for preparing compounds of formula (i) in which R₇ contains an -OH comprises deprotecting (for example by hydrogenolysis or hydrolysis) a compound of formula (i) in which R₇ contains an appropriate -OP wherein P represents a suitable protecting group (e.g. benzyl or acetyl).

A process for the preparation of a compound of formula (i) comprises reaction of an appropriate carboxylic acid of formula (ii) with a suitable amine of formula (iϋ)

(ii) (ia)

wherein Ri.-Rg, represent Ri-Rg as defined in relation to formula (i) or a group convertible to R Rg respectively. The reaction of a carboxyuc acid of formula (ii) with an amine of formula (ϋi) may be carried out under suitable conditions known to those skilled in the art. Preferably, the carboxyuc acid is converted into an acid chloride, mixed anhydride or other activated intermediate prior to reaction with an amine of formula (iii). Preferably, the reaction with the amine of formula (iii) is carried out in the presence of a suitable base, for example an amine base such as triethylamine, preferably in an appropriate solvent such as dichloromethane. In some cases a stronger base, such as sodium hydride, and a polar solvent such as dimethylformamide, will be required.

Carboxylic acids of formula (ii) are either commercially available, previously described compounds or are prepared using standard conditions known to those skilled in the art. For example, a carboxylic acid of formula (ii) is conveniently prepared from a compound of formula (iv), either by formylation to provide an aldehyde of formula (v) followed by oxidation to provide the acid of formula (ii), or by bromination to provide a bromide of formula (vi) followed by carboxylation to provide an acid of formula (ii).

Formylation Carboxylation

Oxidation

(v) (ii)

Formylation of a compound of formula (iv) may be carried out under any standard conditions known to those skilled in the art, for example by using phosphorus oxychloride and dimethylformamide at elevated temperature. Oxidation of an aldehyde of formula (v) may be carried out using any appropriate conditions known to those skilled in the art, for example by using sodium chlorite and sodium phosphate in water/t-butanol in the presence of an acid scavenger such as 2-methyl-2-butene. Bromination of a compound of formula (iv) can be carried out using standard conditions, for example by using bromine in an appropriate solvent such as methanol. Carboxylation of a bromide of formula (vi) can conveniently be achieved by the use of an organometal catalyst, such as a palladium catalyst in the presence of an appropriate base in a suitable solvent.

A compound of formula (iv) may be commercially available, a previously described compound or may be prepared using standard conditions known to those skilled in the art. Procedures for their preparation are described in Bull. Soc. Chim. Fr. (1974), 2628.

Amines of formula (ϋi) are either commercially available or are prepared using standard conditions known to those skilled in the art. Compounds of formula (i) in which R₃ and R₄ are both H may be prepared by the acid-mediated ring opening of a benzoxazole of formula (vii) as shown in the following scheme and described in Chem. Ber. (1925) 58, 44. Q represents a suitable substituent such that COQ represents R₂ or may be converted to R₂. Benzoxazoles of formula (vϋ) may be prepared as described in WO-A-9822460.

Alkylation

Compounds of formula (i) in which R₃ and /or R₄ are alkyl may be prepared from compounds of formula (i) in which R₃ and/or R₄ are H, respectively. This transformation may be carried out using appropriate alkylation conditions known to those skilled in the art, for example by the use of an alkyl halide and appropriate base, such as sodium hydride, in a suitable solvent such as THF.

It will be appreciated that where a particular stereoisomer of formula (i) is required, this may be obtained by conventional resolution techniques such as high performance liquid chromatography or the synthetic processes herein described may be performed using the appropriate homochiral starting material. The invention includes the prevention and treatment of TNF-mediated disease or disease states, by which is meant any and all disease states in which TNF plays a role, either by production of TNF itself, or by TNF causing another cytokine to be released, such as but not limited to IL-1 or IL-6. A disease state in which IL-1, for instance, is a major component, and whose production or action is exacerbated or secreted in response to TNF, would therefore be considered a disease state mediated by TNF. As TNF-β (also known as lymphotoxin) has close structural homology with TNF-α (also known as cachectin), and since each induces similar biological responses and binds to the same cellular receptor, both TNF-α and TNF-β are considered to be inhibited by compounds of the present invention and thus are herein referred to collectively as "TNF" unless specifically dehneated otherwise.

PDE IV inhibitors are useful in the treatment of a variety of allergic and inflammatory diseases, including: asthma, chronic bronchitis, chronic pulmonary inflammatory disease, chronic obstructive pulmonary disease, atopic dermatitis, atopic eczema, urticaria, allergic rhinitis, allergic conjunctivitis, vernal conjunctivitis, inflammation of the eye, allergic responses in the eye, eosinophUic granuloma, psoriasis, Bechet's disease, erythematosis, anaphylactoid purpura nephritis, joint inflammation, arthritis, rheumatoid arthritis and other arthritic conditions such as rheumatoid spondylitis and osteoarthritis, septic shock, ulcerative coϋtis, Crohn's disease, reperfiision injury of the myocardium and brain, chronic glomerulonephritis, endotoxic shock and adult respiratory distress syndrome. In addition, PDE IV inhibitors are useful in the treatment of diabetes insipidus and conditions associated with cerebral metabolic inhibition, such as cerebral senility, senile dementia (Alzheimer's disease), memory impairment associated with Parkinson's disease, depression and multi-infarct dementia. PDE IV inhibitors are also useful in conditions ameliorated by neuroprotectant activity, such as cardiac arrest, stroke and intermittent claudication. PDE IV inhibitors may be useful in the treatment of tarditive dyskinesia, ischaemia and Huntingdon's disease. Additionally, PDE IV inhibitors may have utility as gastroprotectants. A special embodiment of the therapeutic methods of the present invention is the treatment of asthma. TNF release inhibitors are useful in the treatment of viral infections. The viruses contemplated for treatment here are those that produce TNF as a result of infection, or those which are sensitive to inhibition, such as by decreased replication, directly or indirectly, by the TNF release inhibitors of Formula (i). Such viruses include, but are not limited to HTV-l, HIV-2 and HTV-3, cytomegalo virus (CMV), influenza, adenovirus and the Herpes group of viruses, such as, but not ϋmited to, Herpes zoster and Herpes simplex. This invention more specifically relates to a method of treating a mammal, afflicted with a human immunodeficiency virus (HTV), which comprises administering to such mammal an effective TNF release-inhibiting amount of a compound of Formula (i) or a pharmaceutically-acceptable salt thereof.

The compounds of this invention may also be used in association with the veterinary treatment of animals, other than humans, in need of inhibition of TNF production. TNF mediated diseases for treatment, therapeutically or prophylactically, in animals include disease states such as those noted above, but in particular viral infections. Examples of such viruses include, but are not ϋmited to feϋne immunodeficiency virus (FIV) or other retroviral infection such as equine infectious anaemia virus, caprine arthritis vϋus, visna virus, maedi virus and other lentiviruses.

The compounds of this invention are also useful in treating parasite, yeast and fungal infections, where such yeast and fungi are sensitive to upregulation by TNF or will eϋcit TNF production in vivo. A preferred disease state for treatment is fungal meningitis.

The compounds of formula (i) are preferably in pharmaceutically-acceptable form. By pharmaceutically-acceptable form is meant, inter alia, a pharmaceutically-acceptable level of purity excluding normal pharmaceutical additives such as diluents and carriers, and including no material considered toxic at normal dosage levels. A pharmaceutically- acceptable level of purity will generally be at least 50% excluding normal pharmaceutical additives, preferably 75%, more preferably 90% and still more preferably 95%. When used herein the term "pharmaceutically-acceptable" encompasses materials suitable for both human and veterinary use.

A compound of formula (i) or where appropriate a pharmaceutically-acceptable salt thereof and/or a pharmaceutically-acceptable solvate thereof, may be administered/jer se or, preferably, as a pharmaceutical composition also comprising a pharmaceutically- acceptable carrier.

Accordingly, the present invention provides a pharmaceutical composition comprising a compound of formula (i) or where appropriate a pharmaceutically-acceptable salt thereof and/or a pharmaceutically-acceptable solvate thereof, and a pharmaceutically- acceptable carrier.

The active compound may be formulated for administration by any suitable route, the preferred route depending upon the disorder for which treatment is required, and is preferably in unit dosage form or in a form that a human patient may administer to himself in a single dosage. Advantageously, the composition is suitable for oral, rectal, topical, parenteral administration or through the respiratory tract. Preparations may be designed to give slow release of the active ingredient.

The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. In addition to the treatment of warm-blooded animals such as mice, rats, horses, cattle, sheep, dogs, cats, etc, the compounds of the invention are effective in the treatment of humans.

The compositions of the invention may be in the form of tablets, capsules, sachets, vials, powders, granules, lozenges, suppositories, reconstitutable powders, or liquid preparations such as oral or sterile parenteral solutions or suspensions. Topical formulations are also envisaged where appropriate.

In order to obtain consistency of administration it is preferred that a composition of the invention is in the form of a unit dose. Unit dose presentation forms for oral administration may be tablets and capsules and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrroUdone; fillers for example microcrystalϋne cellulose, lactose, sugar, maize- starch, calcium phosphate, sorbitol or glycine; tabletting lubricants, for example magnesium stearate; disintegrants, for example starch, polyvinylpyrrolidone, sodium starch glycollate or microcrystalline cellulose; or pharmaceutically-acceptable wetting agents such as sodium lauryl sulphate.

Soϋd oral compositions may be prepared by conventional methods of blending, filling, tabletting or the like. Repeated blending operations may be used to distribute the active agent throughout those compositions employing large quantities of fillers.

Such operations are of course conventional in the art. The tablets may be coated according to methods weU known in normal pharmaceutical practice, in particular with an enteric coating. Oral liquid preparations may be in the form of, for example, emulsions, syrups or eϋxirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such Uquid preparations may contain conventional additives such as suspending agents, for example sorbitol, syrup, methyl cellulose, gelatin, hydroxyethylcellulose, carboxymethylcellulose, aluminium stearate gel, hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia, non- aqueous vehicles (which may include edible oϋs), for example almond oil, fractionated coconut oϋ, oily esters such as esters of glycerine, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid; and if desired conventional flavouring or colouring agents.

Compositions may also suitably be presented for administration to the respiratory tract as a snuff or an aerosol or solution for a nebuliser, or as a microfine powder for insufflation, alone or in combination with an inert carrier such as lactose. In such a case the particles of active compound suitably have diameters of less than 50 μm, such as from 0.1 to 50 μm, preferably less than 10 μm, for example from 1 to 10 μm, 1 to 5 μm or from 2 to 5 μm. Where appropriate, small amounts of other anti-asthmatics and bronchodilators for example sympathomimetic amines such as isoprenaϋne, isoetharine, salbutamol, phenylephrine and ephedrine; corticosteroids such as prednisolone and adrenal stimulants such as ACTH may be included. For parenteral administration, fluid unit dosage forms are prepared utilizing the compound and a sterile vehicle, and, depending on the concentration used, can be either suspended or dissolved in the vehicle. In preparing solutions, the compound can be dissolved in water for injection and filter-sterilised before filling into a suitable vial or ampoule and sealing. Advantageously, adjuvants such as a local anaesthetic, a preservative and buffering agents can be 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 accompϋshed by filtration. The compound can be sterilised by exposure to ethylene oxide before suspending in the sterile vehicle. Advantageously, a surfactant or wetting agent is included in the composition to facilitate uniform distribution of the compound. The compositions may contain from 0.1% to 99% by weight, preferably from 10- 60% by weight, of the active material, depending on the method of administration.

Compounds of formula (i), or if appropriate a pharmaceutically-acceptable salt thereof and/or a pharmaceuticaUy-acceptable solvate thereof, may also be administered as a topical formulation in combination with conventional topical excipients.

Topical formulations may be presented as, for instance, ointments, creams or lotions, impregnated dressings, gels, gel sticks, spray and aerosols, and may contain appropriate conventional additives such as preservatives, solvents to assist drug penetration and emoUients in ointments and creams. The formulations may contain compatible conventional carriers, such as cream or ointment bases and ethanol or oleyl alcohol for lotions.

Suitable cream, lotion, gel, stick, ointment, spray or aerosol formulations that may be used for compounds of formula (i) or if appropriate a pharmaceuticaUy-acceptable salt thereof, are conventional formulations weU known in the art, for example, as described in standard text books such as Harry's Cosmeticology pubϋshed by Leonard Hill Books,

Remington's Pharmaceutical Sciences, and the British and US Pharmacopoeias.

Suitably, the compound of formula (i), or if appropriate a pharmaceutically- acceptable salt thereof, wiU compromise from about 0.5 to 20% by weight of the formulation, favourably from about 1 to 10%, for example 2 to 5%. The dose of the compound used in the treatment of the invention will vary in the usual way with the seriousness of the disorders, the weight of the sufferer, and the relative efficacy of the compound. However, as a general guide suitable unit doses may be 0.1 to 1000 mg, such as 0.5 to 200, 0.5 to 100 or 0.5 to 10 mg, for example 0.5, 1, 2, 3, 4 or 5 mg; and such unit doses may be administered more than once a day, for example 2, 3, 4, 5 or 6 tunes a day, but preferably 1 or 2 times per day, so that the total daily dosage for a 70 kg adult is in the range of about 0.1 to 1000 mg, that is in the range of about 0.001 to 20 mg/kg/day, such as 0.007 to 3, 0.007 to 1.4, 0.007 to 0.14 or 0.01 to 0.5 mg/kg day, for example 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1 or 0.2 mg/kg day, and such therapy may extend for a number of weeks or months. The following Examples illustrate the invention. Intermediate 1 7-Bromo-2-ethyIbenzox---zol-4-ol

To a stirred suspension of sodium hydride (1.6g) (60% dispersion in mineral oϋ) in dry DMF (20ml) under an atmosphere of nitrogen was added dropwise a solution of ethanethiol (2.9ml) in DMF (3ml). After stirring at room temperature for 15 mins a solution of 2-ethyl-7-methoxybenzoxazole (l.Og) in DMF (10ml) was added slowly. The reaction mixture was heated at 150°C for 90 mins. The solvent was removed in vacuo and the residue dissolved in saturated ammonium chloride solution (50ml) and extracted with ethyl acetate (100ml). The aqueous layer was acidified to pH4 with 1M hydrochloric acid and extracted with ethyl acetate ( 100ml). The organic layers were combined, washed with brine (50ml), separated, died over magnesium sulphate, filtered and the solvent removed in vacuo. Purification by column chromatography on silica eluting with 20-30% ethyl acetate in hexane afforded the title compound as an off-white solid (0.62g). TLC R_f 0.21 (20% ethyl acetate in hexane). Intermediate 2 7-Bromo-4-difluorometho-cy-2-ethylbenzoxazole

To a stirred solution of 7-bromo-2-ethylbenzoxazol-4-ol (2.0g) in dioxane (60ml) heated to 100°C was added dropwise a solution of sodium hydroxide (l.Og) in water (3ml). Chlorodifluoromethane was bubbled through the reaction mixture for 20 mins after which the mixture was allowed to cool to room temperature and stirred for 18 hours. The solvent was removed in vacuo and the residue dϋuted with water (30ml) and acidified to pH3 with 1M hydrochloric acid. This was extracted with ethyl acetate (200ml), washed with brine (30ml), the organic layer separated, dried over magnesium sulphate, filtered and the solvent removed in vacuo. Purification by column chromatography on siϋca eluting with 10% ethyl acetate in hexane afforded the title compound as a colourless oϋ (1.9g). TLC R_f 0.72 (20% ethyl acetate in hexane).

Intermediate 3 4-Difluoromethoxy-2-ethylbenzoxazole-7-carboxyIic acid

To a solution of 7-bromo-4-difluoromethoxy-2-ethylbenzoxazole (0.7g) in THF/water (30ml 15ml) was added palladium (II) acetate (54mg), 1,3- bis(diphenylphosphino)propane (198mg) and triethylamine (3.3ml). The mixture was heated at 90°C under a 100 psi atmosphere of carbon monoxide for 4 days. The reaction mixture was allowed to cool to room temperature and the pressure released. The THF was removed in vacuo and the residue diluted with water ( 10ml) and washed with ethyl acetate (50ml). The aqueous layer was acidified to pH3 with 2M hydrochloric acid and extracted with ethyl acetate (150ml). Separation of the organic layer, drying over magnesium sulphate, filtering and removal of the solvent in vacuo afforded the title compound as an off-white soϋd (0.47g). TLC R_f 0.37 (50% ethyl acetate in hexane).

Intermediate 4 4-Difluoromethoxy-2-ethylbenzoxazoIe-7-carboxyIic acid 4- nitrophenyl ester To a stirred suspension of 4-difluoromethoxy-2-ethylbenzoxazole-7-carboxyUc acid (1.6g) in dry dichloromethane (60ml) under an atmosphere of nitrogen was added p- nitrophenol (0.95g), 4-dimethylaminopyridine (80mg) and l-(3-dimethylaminopropyl)-3- ethylcarbodiimide hydrochloride (2.4g). The reaction mixture was stirred at room temperature for 18 hours. Water (20ml) was added and the aqueous layer extracted with dichloromethane (400ml). The organic layer was washed with water (80ml), separated, dried over magnesium sulphate, filtered and the solvent removed in vacuo. Purification by column chromatography on siϋca eluting with 1:4 ethyl acetate/heptane to 1:1:2 ethyl acetate/dichloromethane/heptane afforded the title compound as a pale yellow solid (1.9g). TLC R_f 0.39 (20% ethyl acetate in hexane).

Intermediates 4-Difluoromethoxy-2-ethyIbenzoxazoIe-7-carboxyIicacid (3,5- dichloropyridin-4-yl)amide To a stirred solution of 4-amino-3,5-dichloropyridine (216mg) in dry DMF(5ml) under an atmosphere of nitrogen was added sodium hydride (53 mg) (60% dispersion in mineral oil) and the mixture stired at room temperature for 30 mins. A solution of 4- difluoromethoxy-2-ethylbenzoxazole-7-carboxylic acid 4-nitrophenyl ester (250mg) in DMF (10ml) was added dropwise and the reaction mixture stirred for 18 hours. Water (5ml) was added and the solvents removed in vacuo. The residue was dissolved in ethyl acetate (150ml), washed with water (3 X 50ml), washed with brine (50ml), the organic layer separated, dried over magnesium sulphate, filtered and the solvent removed in vacuo. Purification by flash chromatography on siϋca eluting with 20 to 40% ethyl acetate in hexane afforded the title compound as a white soϋd (180mg). TLC R_f 0.43 (50% ethyl acetate in hexane). Example 1 N-(3,5-Dichloropyridin-4-yl)-2-hydroxy-4-methoxy-3- propionylaminobenzamide

A solution of 4-methoxy-2-ethylbenzoxazole-7-carboxyϋc acid (3,5-dichloro- pyridin-4-yl)-amide (see WO-A-9822460; 10 mg) in methanol/2M hydrochloric acid (4ml/4ml) was stured at room temperature for 18 hours. The methanol was removed in vacuo and the aqueous residue neutraϋsed with 25% sodium hydroxide solution. This was extracted with ethyl acetate (2 x 15ml), dried over magnesium sulphate, filtered and the solvent removed in vacuo. Trituration in ethyl acetate/hexane afforded the title compound as an off-white soϋd. TLC R_f 0.39 (ethyl acetate).

Mass spectrum 384 [M+H]⁺.

Example 2 N-(3,5-Dichloropyridin-4-yl)-4-difluoromethoxy-2-hydroxy-3- propionylaminobenzamide A solution of 4-difluoromethoxy-2-ethylbenzoxazole-7-carboxyϋc acid (3,5- dichloropyridin-4-yl)-amide (140mg) and peracetic acid (65μl) (36-40% solution in acetic acid) was stirred at room temperature for 3 weeks. Removal of the solvent in vacuo and purification by column chromatography on silica eluting with 40% ethyl acetate in hexane afforded the title compound as a white soϋd (37mg).

TLC R_f 0.28 (50% ethyl acetate in hexane). Mass spectrum 418 [M-H]\

Example 3 N-(3,5-Dichloro-l-oxypyridin-4-yl)-4-difluoromethoxy-2-hydroxy-3- propanylaminobenzamide To a stirred solution of 4-difluoromethoxy-2-ethylbenzoxazole-7-carboxyϋc acid

(3,5-dichloropyridin-4-yl)amide (50mg) in methanol (5ml) was added methyltrioxorhenium (VQ) (2mg) and hydrogen peroxide (80μl) (27.5% solution in water). The reaction mixture was heated at 50°C for 48 hours. The methanol was removed in vacuo and the residue dissolved in ethyl acetate (75ml) and washed with water (15ml). The organic layer was separated, dried over magnesium sulphate, filtered, and the solvent removed in vacuo.

Purification by column chromatography on silica eluting with 5% methanol in dichloromethane afforded the title compound as a white solid (1 lmg).

TLC R_f 0.34 (10% methanol in dichloromethane).

Mass spectrum 436 [M+H]⁺. Assay Methods

The assays used to confirm the phosphodiesterase IV inhibitory activity of compounds of formula (I) are standard assay procedures as disclosed by Schilϋng et al, Anal. Biochem. 216:154 (1994), Thompson and Strada, Adv. Cycl. Nucl. Res. 8:119 (1979) and Gristwood and Owen, Br. J. Pharmacol. 87:91P (1986).

Compounds of formula (i) have exhibited activity at levels consistent with those beϋeved to be useful in treating phosphodiesterase IV-related disease states in those assays.

The abiϋty of compounds of formula (i) to inhibit TNF production in human peripheral blood mononuclear cells (PMBC's) is measured as follows. PMBC's are prepared from freshly taken blood or "Bufiy coats" by standard procedures. Cells are plated out in RPMI1640 +1% foetal calf serum in the presence and absence of inhibitors. Lipopolysaccharide (endotoxin) (100 ng/ml) is added and cultures are incubated for 22 h at 37°C in an atmosphere of 95% air/5% CO₂. Supernatants are tested for TNFα by enzyme-linked immunosorbent assay, using commerciaUy available kits.

Claims

1. A compound of formula (i)

(D

wherein Ri is alkyl optionaϋy substituted with one or more halogens; R₂ is COjRj, CORg, CONR^o or S(O)_pR,; R₃ is H or alkyl; R₄ is H or alkyl;

Rj is aryl or heteroaryl either of which may be substituted at any position with (one or more) substituents R₁₄ or alkyl-R,₄; ^ is H or alkyl;

R₇ is OR,,, NR^Ru, CN, COjRu, CONRsR,,, or COR,₅; Rg is R,₃ optionally substituted with R₇;

R, and R,₀ are the same or different and are each H, alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl, or NR^R_JO represents a heterocyc c ring optionally substituted with alkyl, arylalkyl or heteroarylalkyl;

Rj, is H, alkyl (optionally substituted with one or more halogens), cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl; Rj₂ is H, alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl, heterocycloalkyl, alkylcarbonyl, alkoxycarbonyl, arylcarbonyl, heteroarylcarbonyl, heterocyclocarbonyl, alkylsulphonyl, arylsulphonyl, heteroarylsulphonyl or heterocyclosulphonyl; R_j3 is alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl;

R,₄ is alkyl, aryl, heteroaryl, heterocyclo, CO^, CONR^_o, SO-_JNR_JR_JO, OR,,, halogen, CN, NR,₅R₁₂, COR,₅ or SCO)^, R,₅ is H, alkyl, cycloalkyl, aryl, heteroaryl, heterocyclo, cycloalkylalkyl, arylalkyl, heteroarylalkyl or heterocycloalkyl;

X is O or S; and p = 1 or 2; or an N-oxide or pharmaceutically acceptable salt thereof.

2. A compound of claim 1, wherein R_<; is H.

3. A compound of claim 1 or claim 2, wherein Rj is phenyl, pyrimidinyl, pyridyl or pyridyl-N-oxide, any of which may be substituted at any position with (one or more) substitutents R,₄ (in which R₁₄ is alkyl optionaϋy substituted with one or more halogens, halogen, OR,, or CN).

4. A compound of any preceding claim, wherein X is O.

5. A compound of claim 1, selected from N-(3,5-dichloropyrid -4-yl)-2-hydroxy-4-methoxy-3-propionylaminobenzamide; N-(3,5-dichloropyridin-4-yl)-4-difluoromethoxy-2-hydroxy-3-propionylamino- benzamide; and N-(3,5-dichloro-l-oxypyridin-4-yl)-4-difluoromethoxy-2-hydroxy-3- propanylaminobenzamide.

6. A pharmaceutical composition for therapeutic use comprising a compound of any preceding claim and a pharmaceutically-acceptable carrier or excipient.

7. Use of a compound of any of claims 1 to 5, for the manufacture of a medicament for use in the treatment of a disease state that is capable of being modulated by inhibition of phosphodiesterase IV or Tumour Necrosis Factor, or that is a pathological condition associated with a function of phosphodiesterase IV, eosinophil accumulation or a function of the eosinophil.

8. The use of claim 7, wherein the disease state is an inflammatory disease or autoimmune disease.

9. The use of claim 7, wherein the disease state is selected from asthma, chronic bronchitis, chronic pulmonary inflammatory disease, chronic obstructive pulmonary disease, atopic dermatitis, allergic rhinitis, psoriasis, arthritis, rheumatoid arthritis, joint inflammation, ulcerative coϋtis, Crohn's disease, atopic eczema, stroke, bone resorption disease, multiple sclerosis and inflammatory bowel disease.

10. The use of claim 8, wherein the disease state is asthma.

11. The use of claim 8, wherein the disease state is chronic obstructive pulmonary disease or chronic bronchitis.