WO2007062677A1 - Thiazolyl- and pyrimidinyl-acetic acids and their use as crth2 receptor ligands - Google Patents

Abstract

[2-[Bis-(4-fluoro-phenyl)methyl]-4-(2-methylpyridin-4-yl)thiazol-5-yl]acetic acid, {4-(2­aminopyridin-4-yl)-2-[bis-(4-fluorophenyl)methyl]thiazol-5-yl}acetic acid, [2-[bis-(4-fluoro­phenyl)-methyl]-4-(3-fluoro-phenyl)-pyrimidin-5-yl]acetic acid, and salts, hydrates and solvates thereof are ligands of the CRTH2 receptor, and of value for the treatment of, inter alia, asthma, rhinitis, allergic airway syndrome, or allergic rhinobronchitis.

Description

THIAZOLYL- AND PYRIMIDINYL-ACETIC ACIDS AND THEIR USE AS CRTH2 RECEPTOR LIGANDS

This invention relates to the use of a class of compounds which are ligands of the CRTH2 receptor (Chemoattractant Receptor-homologous molecule expressed on T Helper cells type 2), in the treatment of diseases responsive to modulation of CRTH2 receptor activity, principally diseases having a significant inflammatory component. The invention also relates to novel members of that class of ligands and pharmaceutical compositions containing them.

Many classes of antiinflammatory agents are known, including the non-steroidal antiinflammatory compounds known as NSAIDs and the inhibitors of cyclooxygenase (COX-1 and COX-2). Benzoylphenylacetic acid and some benzophenone derivatives with carboxymethoxy substituents in one of the rings have been identiified as antiinfammatory agents (see, for example, Khanum et. al. Bioorganic Chemistry VoI 32, No. 4, 2004, pages 211-222 and the references cited therein). Some o-phenyl carbamoyl-phenoxyacetic acids and o-benzamido-phenoxymethyl tetrazoles have been reported as potential antiinflammatory agent, see for example Drain et. al. J. Pharm. Pharmaα, 1971 , 23, 857-864, and ibid 1970, 22, 684-693. WO 99/15520 discloses a few benzophenone derivatives with carboxymethoxy or tetrazolylmethoxy substituents in one of the rings, synthesised as members of a group of compounds said to have activity as inhibitors of peroxisome proliferator-activated receptor (PPAR), and utility in a variety of disease states including diabetes, cardiac disease, andcirculatory disease.

The natural ligand of the G-protein coupled receptor CRTH2 is prostaglandin D2. As its name implies, CRTH2 is expressed on T helper cells type 2 (Th2 cells) but it is also known to be expressed on eosinophils and basophil cells. Cell activation as a result of binding of PGD2 to the CRTH2 receptor results in a complex biological response, including release of inflammatory mediators. Elevated levels of PGD2 are therefore associated with many diseases which have a strong inflammatory component, such as asthma, rhinitis and allergies. Blocking binding of PGD2 to the CRTH2 receptor is therefore a useful therapeutic strategy for treatment of such diseases.

Some small molecule ligands of CRTH2, apparently acting as antagonists of PGD2, are known, for example as proposed in the following patent publications: WO 03/097042, WO 03/097598, WO 03/066046, WO 03/066047, WO 03/101961 , WO 03/101981 , GB 2388540, WO 04/089885 and WO 05/018529. Our copending international application PCT/EP2005/005882 is concerned with the use of a compound of formula (IA) or a salt, hydrate or solvate thereof in the manufacture of a composition for the treatment of disease responsive to modulation of CRTH2 receptor activity

wherein

X₁ is -S-, -O-, -N=N-. -NR₇-, -CR₇=CR₈-, -CR₇=N-, wherein R₇ and R₈ are independently hydrogen or Ci-C₃ alkyl;

A is a carboxyl group -COOH, or a carboxyl bioisostere;

rings Ar² and Ar³ each independently represent a phenyl or 5- or 6-membered monocyclic heteroaryl ring, or a bicyclic ring system consisting of a 5- or 6-membered carbocyclic or heterocyclic ring which is benz-fused or fused to a 5- or 6-membered monocyclic heteroaryl ring, said ring or ring system being optionally substituted;

ring B is as defined for Ar² and Ar³, or an optionally substituted N-pyrrolidinyl, N-piperidinyl or N-azepinyl ring;

s is O or 1 ;

L1 represents a divalent radical of formula -(Alk¹)_m- and L2 and L4 each independently represents a divalent radical of formula -(Alk¹)_m-(Z)_n-(Alk²)_p- wherein

m, n and p are independently O or 1 , AIk¹ and AIk² are independently optionally substituted straight or branched chain C₁-C₃ alkylene or C₂-C₃ alkenylene radicals which may contain a compatible -O-, -S- or -NR- link wherein R is hydrogen or C₁-C₃ alkyl, and

Z is -O-; -S-; -C(=O)-; -SO₂-; -SO-; -NR-, -NRSO₂-, -C(=O)NR-, -NRCONH-, NRC(=NR)NH-, or =N-NR- wherein R is hydrogen or C₁-C₃ alkyl; or a divalent 5- or 6- membered monocyclic carbocyclic or heterocyclic radical;

L3 represents a divalent radical of formula -(Alk³)_m-(Z)_n-(Alk²)_p- wherein m, n, p, AIk² and Z are as defined in relation to L2 and L4, and Alk3 is an optionally substituted straight or branched chain C₁-C₂ alkylene or C₁-C₂ alkenylene radical which may contain a compatible -0-, -S- or - NR- link wherein R is hydrogen or C₁-C₃ alkyl;

Qi represents hydrogen or (C_rC₆)alkyl;

Q₂ represents

(i) (CrC₆)alkyl, (CrC₆)alkoxy, hydroxy, hydroxy(C₁-C₆)alkyl, nitrile (-CN), phenyl, phenoxy, monocyclic heteroaryl or heteroaryloxy with 5 or 6 ring atoms, -CONR^AR^B,

-NR^BCOR^A, -NR^BSO₂R^A or -NR^ACONR^AR^B wherein R^A and R^B are independently hydrogen or a (CrC^alkyl group, or R^A and R^B are linked to the same N atom to form a cyclic amino ring, and when Q is phenyl, phenoxy or monocyclic heteroaryl or heteroaryloxy with 5 or 6 ring atoms the phenyl or heteroaryl ring is optionally substituted by any of (d-CβJalkyl, (C₁-

C₆)alkoxy, hydroxy, hydroxy(C₁-C₆)alkyl, (CrC^alkylthio, halo, fully or partially fluorinated (C₁-

C₃)alkyl, (C₁-C₃)alkoxy or (d-CaJalkylthio, trifluoromethylthio, nitro, nitrile (-CN), -COOR^A, -

COR^A, -OCOR^A, -SO₂R^A, -CONR^AR^B, -SO₂NR^AR^B, -NR^AR^B, -NR^BCOR^A, -NR^BCOOR^A, -

NR^BSO₂R^A or

-NR^ACONR^AR^B wherein R^A and R^B are independently hydrogen or a (C₁-C₆)alkyl group, or R^A and R^B are linked to the same N atom to form a cyclic amino ring, or

(ii) hydrogen, but only when, in L3, Z represents an optionally substituted divalent 5- or 6- membered monocyclic carbocyclic or heterocyclic radical;

or Qi and Q₂ taken together with the carbon atom to which they are attached form a C₃-C₆ cycloalkyl ring or a monocyclic non-aromatic heterocyclic ring with 4-6 ring atoms; and wherein the total length of L2 and L3 does not exceed that of an unbranched saturated chain of 10 carbon atoms.

This invention relates to certain compounds falling withinthe general ambit of, but not specifically disclosed in PCT/EP2005/005882, and which have the CRTH2 receptor activity and utilities described in that application.

According to the present invention, there is provided a compound selected from the group consisting of [2-[bis-(4-fluoro-phenyl)methyl]-4-(2-methylpyridin-4-yl)thiazol-5-yl]acetic acid, {4- (2-aminopyridin-4-yl)-2-[bis-(4-fluorophenyl)methyl]thiazol-5-yl}acetic acid, [2-[bis-(4-fluoro-phenyl)-methyl]-4-(3-fluoro-phenyl)-pyrimidin-5-yl]acetic acid, and salts, hydrates and solvates thereof. Pharmaceutical compositions comprising a compound selected from the foregoing group together with a pharmaceutically acceptable carrier, also form part of the invention.

In a further aspect, the invention provides the use of a compound selected from the foregoing group in medicine, particularly in the manufacture of a medicament for treatment diseases responsive to modulation of CRTH2 receptor activity,

In another aspect, the invention provides a method of treatment of a subject suffering from a disease responsive to modulation of CRTH2 receptor activity, which comprised administering to the subject an amount of a compound selected from the foregoing group effective to ameliorate the disease.

In particular, compounds with which the invention is concerned are useful in the treatment of disease associated with elevated levels of prostaglandin D2 (PGD2) or one or more active metabolites thereof.

Examples of such diseases include asthma, rhinitis, allergic airway syndrome, allergic rhinobronchitis, bronchitis, chronic obstructive pulmonary disease (COPD), nasal polyposis, sarcoidosis, farmer^'s lung, fibroid lung, cystic fibrosis, chronic cough, conjunctivitis, atopic dermatitis, Alzheimer's disease, amyotrophic lateral sclerosis, AIDS dementia complex, Huntington's disease, frontotemporal dementia, Lewy body dementia, vascular dementia, Guillain-Barre syndrome, chronic demyelinating polyradiculoneurophathy, multifocal motor neuropathy, plexopathy, multiple sclerosis, encephalomyelitis, panencephalitis, cerebellar degeneration and encephalomyelitis, CNS trauma, migraine, stroke, rheumatoid arthritis, ankylosing spondylitis, Behςet's Disease, bursitis, carpal tunnel syndrome, inflammatory bowel disease, Crohn^'s disease, ulcerative colitis, dermatomyositis, Ehlers-Danlos Syndrome (EDS), fibromyalgia, myofascial pain, osteoarthritis (OA), osteonecrosis, psoriatic arthritis, Reiter's syndrome (reactive arthritis), sarcoidosis, scleroderma, Sjogren's Syndrome, soft tissue disease, Still's Disease, tendinitis, polyarteritis Nodossa, Wegener's Granulomatosis, myositis (polymyositis dermatomyositis), gout, atherosclerosis, lupus erythematosus, systemic lupus erythematosus (SLE), type I diabetes, nephritic syndrome, glomerulonephritis, acute and chronic renal failure, eosinophilia fascitis, hyper IgE syndrome, sepsis, septic shock, ischemic reperfusion injury in the heart, allograft rejection after transplantations, and graft versus host disease.

However, the compounds with which the invention is concerned are primarily of value for the treatment of asthma, rhinitis, allergic airway syndrome, and allergic rhinobronchitis.

As used herein, the term "treatment" includes prophylactic treatment.

As used herein the term "salt" includes base addition, acid addition and quaternary salts. Compounds of the invention which are acidic can form salts, including pharmaceutically acceptable salts, with bases such as ammonium hydroxide; alkali metal hydroxides, e.g. sodium and potassium hydroxides; alkaline earth metal hydroxides e.g. calcium, barium and magnesium hydroxides; with organic bases e.g. N-methyl-D-glucamine, choline tris(hydroxymethyl)amino-methane, L-arginine, L-lysine, N-ethyl piperidine, dibenzylamine and the like. Those compounds (I) which are basic can form salts, including pharmaceutically acceptable salts with inorganic acids, e.g. with hydrohalic acids such as hydrochloric or hydrobromic acids, sulphuric acid, nitric acid or phosphoric acid and the like, and with organic acids e.g. with acetic, tartaric, succinic, fumaric, maleic, malic, salicylic, citric, methanesulphonic, p-toluenesulphonic, benzoic, benzenesunfonic, glutamic, lactic, and mandelic acids and the like.

Compositions

As mentioned above, the compounds with which the invention is concerned are capable of modulating CRTH2 activity, and are useful in the treatment of diseases which benefit from such modulation. Examples of such diseases are referred to above, and include asthma, allergy and rhinitis. It will be understood that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the particular disease undergoing treatment. Optimum dose levels and frequency of dosing will be determined by clinical trial, as is required in the pharmaceutical art.

The compounds with which the invention is concerned may be prepared for administration by any route consistent with their pharmacokinetic properties. The orally administrable compositions may be in the form of tablets, capsules, powders, granules, lozenges, liquid or gel preparations, such as oral, topical, or sterile parenteral solutions or suspensions. Tablets and capsules for oral administration may be in unit dose presentation form, and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers for example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tabletting lubricant, for example magnesium stearate, talc, polyethylene glycol or silica; disintegrants for example potato starch, or acceptable wetting agents such as 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 suspensions, solutions, emulsions, syrups or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, for example sorbitol, syrup, methyl cellulose, glucose syrup, gelatin hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia; non-aqueous vehicles (which may include edible oils), for example almond oil, fractionated coconut oil, oily esters such as 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.

For topical application to the skin, the drug may be made up into a cream, lotion or ointment. Cream or ointment formulations which may be used for the drug are conventional formulations well known in the art, for example as described in standard textbooks of pharmaceutics such as the British Pharmacopoeia.

For topical application to the eye, the drug may be made up into a solution or suspension in a suitable sterile aqueous or non aqueous vehicle. Additives, for instance buffers such as sodium metabisulphite or disodium edeate; preservatives including bactericidal and fungicidal agents such as phenyl mercuric acetate or nitrate, benzalkonium chloride or chlorhexidine, and thickening agents such as hypromellose may also be included.

The drug may also be formulated for inhalation, for example as a nasal spray, or dry powder or aerosol inhalers.

The active ingredient may also be administered parenterally in a sterile medium. Depending on the vehicle and concentration used, the drug can either be suspended or dissolved in the vehicle. Advantageously, adjuvants such as a local anaesthetic, preservative and buffering agents can be dissolved in the vehicle.

The compounds with which the invention is concerned may be administered alone, or as part of a combination therapy with other drugs used for treatment of diseases with a major inflammatory component. In the case of asthma, rhinitis, and allergic airway syndrome such drugs include corticosteroids, long-acting inhaled beta agonists, cromolyn, nedocromil, theophylline, leukotriene receptor antagonists, antihistamines, and anticholinergics (e.g. ipratropium), and are often administered as nasal sprays, dry powder or aerosol inhalers.

In the case of arthritis and related inflammatory diseases other known drugs include glucocorticoids, NSAIDs (Non Steroidal Anti-Inflammatory Drugs - conventional prostaglandin synthesis inhibitors, COX-2 inhibitors, salicylates), and DMARDs (disease-modifying antirheumatic drugs such as methotrexate, sulfasalazine, gold, cyclosporine).

Synthesis of compounds of the invention:

General comments:

Microwave chemistry was performed in a Personal Chemistry Emrys Optimizer. NMR spectra were obtained on a Bruker Avance AMX 300 MHz instrument. LC/MS was performed on an

Agilent 1100-series instrument. LC/MS methods are as follows:

Analytical an20p5: Column: Gemini 5μ C18 2.0x50 mm; Flow: 1.2 mL/min; Gradient: 0-3.5 min: 10-95% MeCN in water, 3.5-4.5 min: 95% , MeCN; Modifier: 5 mM ammonium formate;

MS-ionisation mode: API-ES (pos.)

Analytical an20n5: Column: Gemini 5μ C18 2.0x50 mm; Flow: 1.2 mL/min; Gradient: 0-3.5 min: 10-95% MeCN in water, 3.5-4.5 min: 95% MeCN; Modifier: 5 mM ammonium formate;

MS-ionisation mode: API-ES (neg.) Analytical tfa20p5: Column: Gemini 5μ C18 2.0x50 mm; Flow: 1.2 mL/min; Gradient: 0-3.5 min: 10-95% MeCN in water, 3.5-4.5 min: 95% MeCN; Modifier: 0.1% TFA; MS-ionisation mode: API-ES (pos.)

General Synthetic Route 1

Step 1.1 Step 1.2

Step 1.3 Step 1.4

lntermediate-1 (prepared by Step 1.1)

Synthesis of nitrile

Bis-(4-fluorophenyl)acetonitrile. 4,4'-Fluorodiphenylhydrol (5.0 g, 22.70mmol) was suspended in TFA (25 ml_) and potassium cyanide (3.2 g, 49.94 mmol) was added. The reaction mixture was cooled to 0 °C on ice bath and cone. H₂SO₄ (10 ml.) was added dropwise under cooling. The reaction mixture was stirred at room temperature for 2 h. Then poured into ice/water (100 ml_) and extracted with EtOAc (3 x 60 ml_). The combined organic extracts were dried over MgSO₄ and concentrated. Purification on a SiO₂ column (100% DCM) gave the crude product as an oil (3.0 g, 58%). LC/MS (an20n5): Rt = 2.9 min, m/z 228 [M-H]^'. ¹H NMR (CDCI₃): δ 5.02 (s, 1 H), 6.95 (t, 4H), 7.19 (t, 4H)

lntermediate-2 (prepared by Step 1.2)

Synthesis of thiazole ring

(2-(Bis-(4-fluorophenyl)methyl)-4-hydroxythiazol-5-yl)acetic acid, lntermediate-1 (3.0 g, 13.1 mmol) was dissolved in pyridine (13 ml_). Mercaptosuccinic acid (2.4 g, 15.7 mmol) was added. The reaction mixture was heated at 100 ⁰C for 24 h. The mixture was concentrated and stripped with Et₂O (2 x 20 ml_). EtOH (50 mL) was added and the mixture was left over night to precipitate. The precipitate was filtered off and washed with Et₂O and then dried to give the product as a solid (1.5 g, 32%). LC/MS (an20p5): Rt = 2.1 min, m/z 362 [M+H]⁺. ¹H NMR (DMSO-Cf₆): δ 2.79 (m, 1 H), 3.00 (dd, 1 H), 4.31 (dd, 1 H), 7.17 (m, 8H), 10.54 (s, 1 H).

lntermediate-3 (prepared by Step 1.3)

Synthesis of triflate

(2-(Bis-(4-fluorophenyl)methyl)-4-trifluoromethanesulfonyloxythiazol-5-yl)acetic acid. lntermediate-2 (1.5 g, 4.2 mmol) was dissolved in dry DCM (70 mL) in a flame dried flask. Trifluoromethanesulfonic anhydride (2.2 mL, 12.5 mmol) was added very slow at 0 ⁰C under N₂. The reaction mixture was stirred at room temperature for 4 h, then poured into icewater (100 mL) and left for quenching over night. The mixture was extracted with DCM and the combined organic phase was dried (MgSO4) and concentrated to give the product as an oil (1.1 g, 54%). LC/MS (an20p5): Rt = 2.4 min, m/z 494 [M+H]⁺.

Example 1 - Compound A1 (prepared by Step 1.4) [2-[Bis-(4-fluoro-phenyl)methyl]-4-(2-methylpyridin-4-yl)thiazol-5-yl]acetic acid.

Suzuki coupling: lntermediate-3 (0.38 g, 0.77 mmol), 2-picoline-4-boronic acid (0.21 g, 1.5 mmol) and sat. Na₂CO₃ solution (1.2 ml.) was suspended in dry dioxane (3 ml_). The reaction mixture was flushed with N₂ for 15 min. PdCI₂(dppf) (10 mg, 0.038 mmol) was added under under N₂. The reaction mixture was stirred at 80 ⁰C over night. 1 N HCI was added and then the mixture was extracted with DCM. The organic phase was passed through a phase separation filter and concentrated. The residue was purified on a PEAX SPE column (equilibrated with 100% MeOH and then eluted with 10% AcOH in MeOH) and then on a SiO₂ column (0-5% MeOH in DCM) to give the product as a solid (89.7 mg, 27%). LC/MS (tfa20p5): Rt = 2.1 min, m/z 437 [M+Hf. ¹H NMR (DMSO-Cf₆): δ 2.52 (m, 3H), 4.00 (s, 2H), 6.06 (s, 1 H), 7.20 (t, 4H), 7.40 (m, 6H), 8.51 (d, 1 H).

lntermediate-4 (prepared by Step 1.4)

Suzuki coupling

[2-[Bis-(4-fluorophenyl)methyl]-4-(2-fluoropyridin-4-yl)thiazol-5-yl]acetic acid. lntermediate-3 (1.0 g, 2.0 mmol), 2-fluoropyridine-4-boronic acid (0.57 g, 4.1 mmol) and sat. Na₂CO₃ solution (2.0 mL) was suspended in dry dioxane (9 ml_). The reaction mixture was flushed with N₂ for 15 min. PdCI₂(dppf) (82 mg, 0.10 mmol) was added under under N₂. The reaction mixture was stirred at 90 °C for 2 h. 1 N HCI was added and then the mixture was extracted with DCM. The organic phase was passed through a phase-separation filter and concentrated. The residue was purified on a PEAX SPE column (equilibrated with 100% MeOH and then eluted with 10% AcOH in MeOH) to give the product (500 mg, 56%). LC/MS (an20p5): Rt = 2.9 min, m/z 441 [M+H]⁺.

General Synthetic Route 2

Example 2 - Compound A2 (prepared by Step 2.1) {4-(2-Aminopyridin-4-yl)-2-[bis-(4-fluorophenyl)methyl]thiazol-5-yl}acetic acid.

Nucleophilic aromatic substitution of fluorine: lntermediate-4 (0.5 g, 1.1 mmol) was dissolved in 28% ammonium hydroxide (15 mL). The reaction mixture was heated to 90 ⁰C for a week. 1 N HCI, H₂O and DCM were added. The product seemed to be a solid between the two layers and was collected by filtration. The solid was dried and purified on a PEAX SPE column (equilibrated with 100% MeOH and then eluted with 10% AcOH in MeOH) and then on a SiO₂ column (0:0:100 - 2:20:100 NH₃/MeOH/DCM) to give the product as a solid (79.6 mg, 16%). LC/MS (tfa20p5): Rt = 2.1 min, m/z 438 [M+H]⁺. ¹H NMR (DMSO-Cf₆): δ 3.92 (s, 2H), 6.02 (bs, 3H), 6.65(m, 1 H), 6.68 (s, 1 H), 7,19 (t, 4H), 7.38 (m, 4H), 7.94 (d, 1 H).

General Synthetic Route 3

lntermediate-5 (prepared by Step 3.1)

Synthesis of enamine

(Z, E)-4-Dimethylamino-3-(3-fluorobenzoyl)-but-3-enoic acid ethyl ester. To a solution of commercially available 4-(3-fluorophenyl)-4-oxobutyric acid ethyl ester (200 mg, 0.89 mmol) in Λ/,Λ/-dimethylformamide dimethyl acetal (1mL) was added catalytic amount of glacial acetic acid (1 drop). The reaction mixture was heated 3x30 min at 120 ⁰C in a microwave reactor. Solvent was removed in vacuo to give the crude product, which was used directly in the next step. LC/MS (an20p5): Rt 1.8 min, m/z 280 [M+H]⁺.

lntermediate-6 (prepared by Step 3.2)

Synthesis of amidine

2,2-Bis-(4-fluorophenyl)acetamidine. To a flame dried flask was added ammonium chloride (230 mg, 4.32 mmol) and toluene (2 mL). To the cooled mixture (0 ⁰C) was slowly added, under an argon atmosphere, a 2M solution of trimethylaluminium in toluene (2 ml, 4 mmol). After completion, the mixture was allowed to stir for 2 hours at room temperature upon which a solution of intermediate-1 (550 mg, 2.40 mmol) in toluene (20 mL) was added. The reaction mixture was heated to 80 ⁰C for 3 days. After cooling to 0 ⁰C₁ water (10 ml.) was slowly added, followed by the addition of EtOAc. The mixture was filtered through celite and the organic and aqueous phases were separated. The aqueous phase was concentrated in vacuo and the residue was taken up in DCM/MeOH (9/1). Solid ammonium chloride was filtered off and the filtrate was concentrated in vacuo to give the title compound (567 mg, 96%). ¹H NMR (DMSO- d_β): δ 5.48 (s, 1 H), 7.17 (m, 8H), 9.05 (s br, 3H).

lntermediate-7 (prepared by Step 3.3)

Synthesis of pyrimidine ring

p-JBis^-fluoro-phenylJ-methyll-^S-fluoro-phenylJ-pyrimidin-δ-yll-acetic acid ethyl ester

To a solution of intermediate-5 (200 mg, 0.72 mmol) and intermediate-6 (180 mg, 0.72 mmol) in absolute ethanol (2 ml_) was added a solution of sodium terf-butoxide (69 mg, 0.72 mmol) in absolute ethanol (2ml_). The reaction mixture was heated to 50 ⁰C for 2 days. After cooling, solvent was removed in vacuo. The residue was partitioned between EtOAc and brine. The phases were separated and the organic phase was dried over MgSO4 and concentrated in vacuo. The residue was purified on a SiO₂ column (EtOAc/Heptane: 1/4) to give the title , compound (67 mg, 20%): LC/MS (tfa20p5): Rt 2.8 min, m/z 463.1 [M+H]⁺. ¹H NMR (CDCI₃): δ 1.15 (t, 3H), 3.59 (s, 2H), 4.10 (q, 2H), 5.70 (s, 1 H), 6.85-7.45 (m, 12H), 8.68 (s, 1 H).

Example 3 - Compound A3 (prepared by Step 3.4) [2-[Bis-(4-fluoro-phenyl)-methyl]-4-(3-fluoro-phenyl)-pyrimidin-5-yl]acetic acid.

Hydrolysis of ester: To a solution of intermediate-7 (64 mg, 0.14 mmol) in THF (0.6ml_) was added a solution of lithium hydroxide H₂O (12 mg, 0.28 mmol) in water (0.6 ml_). The reaction mixture was stirred for 1 hour at room temperature. 1 N aq. HCI (up to pH ~1) and DCM were added. The phases were separated on a phase separation filter and the organic phase was concentrated in vacuo to give title compound (59 mg, 97%): LC/MS (tfa20p5.m): Rt 3.0 min, m/z 435.1 [M+H]⁺. ¹H NMR (CDCI₃): δ 3.65 (s, 2H), 5.70 (s, 1 H), 6.92 (m, 4H), 7.08-7.39 (m, 8H), 8.68 (s, 1 H).

Biological data:

Compounds were tested in the receptor binding assay and the functional antagonist assay described below, and their IC₅₀ values were assessed. The compounds are grouped in three classes:

A: IC₅₀ value lower than 0.5 μM

B: IC₅₀ value between 0.5 μM and 5 μM

C: IC₅₀ value higher than 5 μM

Table 1 gives the biological test results for the compounds synthesised above

Table 1

13

Biological Assays Materials and Methods

Generation/origin of the cDNA Constructs. The coding sequence of the human CRTH2 receptor (genbank accession no NM_004778) was amplified by PCR from a human hippocampus cDNA library and inserted into the pcDNA3.1(+) expression vector (invitrogen) via 5' Hind/// and 3' EcoR/. To generate a CRTH2-Renilla luciferase (CRTH2-Rluc) fusion protein, the CRTH2 coding sequence without a STOP codon and Rluc were amplified, fused in frame by PCR and subcloned into the pcDNA3.1(+)Zeo expression vector (invitrogen). Human β-arrestin2 (β-arr2) N-terminally tagged with GFP² (βarr2-GFP²) and Renilla luciferase were purchased from BioSignal Packard Inc, (Montreal, Canada). The sequence identity of the construct was verified by restriction endonuclease digests and sequencing in both directions on an ABI Prism (Applied Biosystems, Foster City, CA).

Cell Culture and Transfection. COS-7 cells were grown in Dulbecco's modified Eagle's medium (DMEM) 1885 supplemented with 10% fetal bovine serum, 100 units/ml penicillin, 1000 μg/ml streptomycin, and kept at 37⁰C in a 10% CO₂ atmosphere. HEK293 cells were maintained in Minimum Essential medium (MEM) supplemented with 10% (v/v) heat inactivated fetal calf serum (HIFCS), 2mM Glutamax™-!, 1 % non essential amino acids (NEAA), 1% sodium pyruvate and 10 μg/ml gentamicin. For binding experiments, COS7 cells were transiently transfected with the CRTH2 receptor using a calcium phosphate-DNA coprecipitation method with the addition of chloroquine (as described by Hoist et al., 2001*). To perform the functional Bioluminescence Resonance Energy Transfer (BRET) assays, a HEK293 cell clone stably expressing βarr2-GFP² and CRTH2-Rluc was generated (CRTH2- HEK293 cells).

Binding assay. 24h after transfection COS-7 cells were seeded into 96well plates at a density of 30.000 cells/well. Competition binding experiments on whole cells were then performed about 18-24 h later using 0.1 nM [³H]PGD2 (NEN, 172 Ci/mmol) in a binding buffer consisting of HBSS (GIBCO) and 10 mM HEPES. Competing ligands were diluted in DMSO which was kept constant at 1% (v/v) of the final incubation volume. Total and nonspecific binding were determined in the absence and presence of 10 μM PGD2. Binding reactions were routinely conducted for 3 h at 4°C and terminated by 2 washes (100 μl each) with ice cold binding buffer. Radioactivity was determined by liquid scintillation counting in a TOPCOUNTER (Packard) following over night incubation in Microscint 20. Stable HEK293 cells were seeded at a density of 30.000 cells/well 18-24 h prior to the binding assay which was performed essentially as described for COS7 cells above. Determinations were made in duplicates.

BRET assay. Functional BRET assays were performed on HEK293 cells stably expressing human CRTH2-Rluc and GFP²-β-arr2. Prior to their use in the BRET assay cells were detached and re-suspended in D-PBS with 1000 mg/L L-Glucose at a density of 2x10⁶ cells/mL DeepBlueC™ was diluted to 50 μM in D-PBS with 1000 mg/L L-Glucose (light sensitive). 100 μl_ of cell suspension was transferred to wells in a 96-well microplate (white OptiPlate) and placed in the Mithras LB 940 instrument (BERTHOLD TECHNOLOGIES, Bad Wildbad, Germany). 12 μL/well agonist was then injected by injector 1 and 10 μL/well DeepBlueC™ was injected simultaneously by injector 2. Five seconds after the injections the light output from the well was measured sequentially at 400 nm and 515 nm, and the BRET signal (mBRET ratio) was calculated by the ratio of the fluorescence emitted by GFP²-β-arr2 (515 nm) over the light emitted by the receptor-Rluc (400 nm). Antagonists were added before placing the microplates into the Mithras LB 940 and allowed to incubate for 15 minutes prior to the addition of agonist and DeepBlueC™. Compounds were dissolved in DMSO and the final DMSO concentration was kept constant at 1 % in the assay.

Claims

Claims:

1. A compound selected from [2-[bis-(4-fluoro-phenyl)methyl]-4-(2-methylpyridin-4- yl)thiazol-5-yl]acetic acid, {4-(2-aminopyridin-4-yl)-2-[bis-(4-fluorophenyl)methyl]thiazol-5- yl}acetic acid, [2-[bis-(4-fluoro-phenyl)-methyl]-4-(3-fluoro-phenyl)-pyrimidin-5-yl]acetic acid, and salts, hydrates and solvates thereof.

2. A pharmaceutical composition comprising a compound as claimed in claim 1 , together with a pharmaceutically acceptable carrier.

3. A compound as claimed in claim 1 for use in medicine.

4. The use of a compound as claimed in claim 1 in the manufacture of a medicament for treatment diseases responsive to modulation of CRTH2 receptor activity,

5. A method of treatment of a subject suffering from a disease responsive to modulation of CRTH2 receptor activity, which comprises administering to the subject an amount of a compound as claimed in claim 1 effective to ameliorate the disease.

6. The use as claimed in claim 4 or a method as claimed in claim 5 wherein the disease is asthma, rhinitis, allergic airway syndrome, allergic rhinobronchitis, bronchitis, chronic obstructive pulmonary disease (COPD), nasal polyposis, sarcoidosis, farmer^'s lung, fibroid lung, cystic fibrosis, chronic cough, conjunctivitis, atopic dermatitis, Alzheimer's disease, amyotrophic lateral sclerosis, AIDS dementia complex, Huntington's disease, frontotemporal dementia, Lewy body dementia, vascular dementia, Guillain-Barre syndrome, chronic demyelinating polyradiculoneurophathy, multifocal motor neuropathy, plexopathy, multiple sclerosis, encephalomyelitis, panencephalitis, cerebellar degeneration and encephalomyelitis, CNS trauma, migraine, stroke, rheumatoid arthritis, ankylosing spondylitis, Behςet's Disease, bursitis, carpal tunnel syndrome, inflammatory bowel disease, Crohn^'s disease, ulcerative colitis, dermatomyositis, Ehlers-Danlos Syndrome (EDS), fibromyalgia, myofascial pain, osteoarthritis (OA), osteonecrosis, psoriatic arthritis, Reiter's syndrome (reactive arthritis), sarcoidosis, scleroderma, Sjogren's Syndrome, soft tissue disease, Still's Disease, tendinitis, polyarteritis Nodossa, Wegener's Granulomatosis, myositis (polymyositis dermatomyositis), gout, atherosclerosis, lupus erythematosus, systemic lupus erythematosus (SLE), type I diabetes, nephritic syndrome, glomerulonephritis, acute and chronic renal failure, eosinophilia fascitis, hyper IgE syndrome, sepsis, septic shock, ischemic reperfusion injury in the heart, allograft rejection after transplantations, or graft versus host disease.

7. The use as claimed in claim 4 or a method as claimed in claim 5 wherein the disease is asthma, rhinitis, allergic airway syndrome, or allergic rhinobronchitis.