WO2005082884A2

WO2005082884A2 - 2-pyridin-2yl-pyrimidine derivatives useful in the treatment of gastro-esophagea l reflux disease

Info

Publication number: WO2005082884A2
Application number: PCT/US2005/004751
Authority: WO
Inventors: Martin Johansson; Jonas MALMSTRÖM; Alexander Minidis; Karolina Nilsson; David Wensbo; Andreas WÅLLBERG; Krister ÖSTERLUND
Original assignee: Astrazeneca Ab; Nps Pharmaceuticals, Inc.
Priority date: 2004-02-20
Filing date: 2005-02-15
Publication date: 2005-09-09
Also published as: WO2005082884A3; UY28762A1; AR047967A1; TW200538180A

Abstract

The present invention is directed to novel compounds, to a process for their preparation, their use in therapy and pharmaceutical compositions comprising the novel compounds.

Description

NEW COMPOUNDS

Field of the invention

The present invention is directed to novel compounds, to a process for their preparation, their use in therapy and pharmaceutical compositions comprising said novel compounds.

Background of the invention

The metabotropic glutamate receptors (mGluR) are G-protein coupled receptors that are involved in the regulation and activity of many synapses in the central nervous system (CNS). Eight metabotropic glutamate receptor subtypes have been identified and are subdivided into three groups based on sequence similarity. Group I consists of mGluRl and mGluR5. These receptors activate phospholipase C and increase neuronal excitability. Group II, consisting of mGluR2 and mGluR3 as well as group III, consisting of mGluR4, mGluR6, mGluR7 and mGluR8 are capable of inhibiting adenylyl cyclase activity and reduce synaptic transmission. Several of the receptors also exist in various isoforms, occurring by alternative splicing (Chen, C-Yet al, Journal of Physiology (2002), 538.3, pp. 773-786; Pin, J-P et al., European Journal of Pharmacology (1999), 375, pp. 277-294; Brauner-Oshorne, Het al. Journal of Medicinal Chemistry (2000), 43, pp. 2609-2645; Schoepp, D.D, Jane D.E. Monn J.A. Neuropharmacology (1999), 38, pp. 1431- 1476).

The lower esophageal sphincter (LES) is prone to relaxing intermittently. As a consequence, fluid from the stomach can pass into the esophagus since the mechanical barrier is temporarily lost at such times, an event hereinafter referred to as "reflux".

Gastro-esophageal reflux disease (GERD) is the most prevalent upper gastrointestinal tract disease. Current pharmacotherapy aims at reducing gastric acid secretion, or at neutralizing acid in the esophagus. The major mechanism behind reflux has been considered to depend on a hypotonic lower esophageal sphincter. However, e.g. Holloway & Dent (1990) Gastroenterol. Clin. N. Amer. 19, pp. 517-535, has shown that most reflux episodes occur during transient lower esophageal sphincter relaxations (TLESRs), i.e. relaxations not triggered by swallows. It has also been shown that gastric acid secretion usually is normal in patients with GERD. The problem underlying the present invention was to find new compounds useful in the treatment of GERD.

Outline of the invention

The present invention is directed to novel compounds according to the general formula I:

wherein

R¹, R², R³ and R⁴ are each and independently selected from H, Cι-C₄ alkyl, halogen, CN and

NO₂;

R⁵ and R⁶ are each and independently selected from H, halogen, CN and NO₂; Q is aryl or heteroaryl, optionally substituted by H, Cι-C₄ alkyl, C₂-C₄ alkenyl, halogen, alkoxy,

CH₂F, CHF₂, CF₃, NH₂, NHAc, OH, OAc or carboxylic esters and wherein one or more of the substituents may form part of a ring.

In one embodiment, Q is selected from

wherein X is selected from C, N, S and O; wherein R⁷, R⁸. R⁹, R¹⁰, R¹¹, R¹² ₅ R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ are each and independently selected from H, C1-C4 alkyl, C₂-C₄ alkenyl, halogen, alkoxy, CH₂F, CHF₂, CF₃, NH₂, NHAc,

OH, OAc and carboxylic esters and wherein one or more of R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴,

R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ may form part of a ring.

The general terms used in the definition of formula I have the following meanings:

Halogen is chloro, fluoro, bromo or iodo.

Cι-C₄ alkyl is a straight or branched alkyl group, each independently containing 1, 2, 3 or 4 carbon atoms, for example methyl, ethyl, n-propyl, isopropyl or n-butyl. The alkyl groups may contain one or more heteroatoms selected from O, N and S, i.e. one or more of the chain carbon atoms may be substituted by a heteroatom as just mentioned. Examples of such groups are methyl-ethylether, methyl-ethylamine and methyl-thiomethyl.

C₂-C₄ alkenyl is a straight or branched alkenyl group, each independently containing 2, 3 or 4 carbon atoms, for example vinyl, isopropenyl and 1-butenyl. The alkenyl groups may contain one or more heteroatoms selected from O, N and S, i.e. one or more of the chain carbon atoms may be substituted by a heteroatom as just mentioned. Examples of such groups are 3 -acrylic acid and 3-methylsulfanyl-propenyl.

The herein used term "aryl" means an aromatic ring having 6-14 carbon atoms including both single rings and polycyclic compounds, such as phenyl, benzyl or naphtyl.

The term "heteroaryl" as used herein means a heteroaromatic ring having 3-14 carbon atoms, in which one or more of the ring atoms is either oxygen, nitrogen or sulphur, including both single rings and polycyclic compounds, such as imidazopyridine, furanyl or thiophenyl.

Within the scope of the invention are also pharmaceutically acceptable salts of the compounds of formula I as well as isomers and isoforms thereof. It will be imderstood that certain compounds of the present invention may exist in solvated, for example hydrated, as well as unsolvated forms. It is to be understood that the present invention encompasses all such solvated forms. Pharmaceutically acceptable salts of the compound of formula I are also within the scope of the present invention. Such salts are for example salts formed with mineral acids such as hydrochloric acid; alkali metal salts such as sodium or potassium salts; or alkaline earth metal salts such as calcium or magnesium salts.

The novel compounds according to the present invention are useful in therapy. In one aspect of the invention said compounds are useful for the inhibition of transient lower esophageal sphincter relaxations (TLESRs) and thus for treatment or prevention of gastro-esophageal reflux disorder (GERD). In further embodiments, the compounds according to the present invention are useful for the prevention of reflux, treatment or prevention of regurgitation, treatment or prevention of asthma, treatment or prevention of laryngitis, treatment or prevention of lung disease and for the management of failure to thrive.

A further aspect of the invention is the use of a compound according to formula I, for the manufacture of a medicament for the inhibition of transient lower esophageal sphincter relaxations, for the treatment or prevention of GERD, for the prevention of reflux, for the treatment or prevention of regurgitation, treatment or prevention of asthma, treatment or prevention of laryngitis, treatment or prevention of lung disease and for the management of failure to thrive.

Still a further aspect of the invention is a method for the treatment of any one of the conditions mentioned above, whereby a pharmaceutically effective amount of a compound according to formula I above, is administered to a subject suffering from said conditions).

In one aspect of the invention, the compounds of formula I are useful for the treatment and/or prevention of acute and chronic neurological and psychiatric disorders, anxiety and chronic and acute pain disorders. In a further aspect, said compounds are useful for the prevention and or treatment of pain related to migraine, inflammatory pain, neuropathic pain disorders such as diabetic neuropathies, arthritis and rheumatoid diseases, low back pain, post-operative pain and pain associated with various conditions including cancer, angina, renal or billiary colic, menstruation, migraine and gout. A further aspect of the invention is the use of a compound according to formula I for the manufacture of a medicament for the treatment or prevention of functional gastrointestinal disorders, such as functional dyspepsia (FD). Yet another aspect of the invention is the use of a compound according to formula I for the manufacture of a medicament for the treatment or prevention of irritable bowel syndrome (IBS), such as constipation predominant IBS, diarrhea predominant IBS or alternating bowel movement predominant IBS.

The term "isomers" is herein defined as compounds of formula I, which differ by the position of their functional groups and/or orientation. By "orientation" is meant stereoisomers, diastereoisomers, regioisomers and enantiomers.

The term "isoforms" as used herein is defined as compounds of formula I which differ by their crystal lattice, such as crystalline compounds and amorphous compounds.

The wording "TLESR", transient lower esophageal sphincter relaxations, is herein defined in accordance with Mittal, R.K., Holloway, R.H., Penagini, R., Blackshaw, L.A., Dent, J, 1995; Transient lower esophageal sphincter relaxation. Gastroenterology 109, pp. 601-610.

The wording "reflux" is herein defined as fluid from the stomach being able to pass into the esophagus, since the mechanical barrier is temporarily lost at such times.

The wording "GERD", gastro-esophageal reflux disease, is herein defined in accordance with van Heerwarden, M.A., Smout A.J.P.M., 2000; Diagnosis of reflux disease. Bailliere's Gin. Gastroenterol. 14, pp. 759-774.

Methods of preparation

The compounds of formula I may be synthesized from the corresponding 4-Chloro-2-pyridin-2- yl-pyrimidine (A) in reaction with a thiol nucleophile in the presence or absence of a base, such as for example sodium hydride (Scheme 1).

(A) SCHEME 1

The 4-chloro-2-ρyridin-2-yl-pyrimidines (A) may be synthesized from the corresponding 2- pyridin-2-yl-3H-pyrimidin-4-ones (B) by boiling at elevated temperatures in the range of 35-140 °C in phosphorus oxychloride (Scheme 2) according to the procedure described by J. B. Medwid et. al. (J. Med. Chem. 1990, 33, 1230-1241).

SCHEME 2

The 2-pyridin-2-yl-3H-pyrimidin-4-ones (B) in turn may be synthesized from the corresponding pyridiαe-2-carboxamidines (C) in reaction with the sodium salt of ethyl 3-hydroxy-acrylate (D) by refluxing in ethanol (Scheme 3). The method has been described by J. S. Moffat (J. Chem. Soc. 1950, 1603) and the synthesis of compounds such as (D) by S. Gabriel (Ber. Dtsch. Chem. Ges. 1904, 37, 3638).

SCHEME 3 Compounds (C) containg an amidine functionality are commonly synthesized by conversion of a nitrile group. Several methods are available to the one skilled in the art, usually involving a transformation of the nitrile functionality to an iminoester or thioiminoester, followed by 5 conversion with ammonia in methanol/ethanol or other appropriate solvents, or an ammonia equivalent, e.g. ammonium chloride or ammonium acetate, as described e.g. by Medwid et al., J. Med. Chem. 1990, 33, pp 1230-1241 or Barber & Slack, J Am. Chem. Soc. 1944, p. 1607 or Wendt et al., J. Med. Chem. 2004, 47, pp. 303-324. Using basic conditions instead of acidic ones for the formation of the iminoester may be lo advantageous in terms of cleaner conversions and lesser byproducts when employed for example, but not limited, to compounds of formula (E) with R¹⁼Me or (E) with R²=F. This method may be extended using microwave technology to shorten reaction times, by first employing catalytic amounts of sodium alcoholate (for example, but not limited to methanolate, ethanolate) in a corresponding alcohol (for example, but not limited to methanol or ethanol, is respectively) in a sealed microwave vial at temperatures as high as 220°C and as short as 2-5 minutes, followed by addition of ammonium chloride and further reaction under microwave conditions at temperatures as high as 220°C and as short as 2-5 minutes.

SCHEME 4 20 Alternative methods of preparation Compounds of formula (I) may also be prepared from corresponding 2-hal-4-thio substituted pyrimidines of formula (F) (hal may be chloro, bromo or iodo) via transition metal catalyzed cross-coupling reactions with substituted or unsubstituted pyridines containing a suitable leaving 25 group in the 2-position (Scheme 5) using conditions as known to the one skilled in the art. For example, 2-bromo pyridines, can sequentially be treated with n-butyl lithium and a zinc halide and the resulting organozinc compound can then be coupled with (F) in the presence of a palladium catalyst (Negishi conditions) as described by S. L. Hargreaves et al {Jet Lett. 2000, 41, 1653-1656). Alternatively, a 2-stannyl pyridine can be coupled using Stille reaction 30 conditions (P. Gros and Y. Fort Synthesis 1999, 5, 754-756). Furthermore, a 2-stannyl pyridine may alternatively be prepared in situ from the corresponding 2-bromo pyridine using hexamethyldistannane and a typical palladium catalyst, such as Pd(PPh₃) . The coupling reaction

002.1318826.1 ⁷ can also be carried out with a Suzuki reaction using a 2-boronic acid - or boronic ester pyridine and a palladium catalyst, as described by K. Deshayes et al (J. Org. Chem. 1991, 56, 6787-6795) under thermal or microwave heating conditions.

Ar may be Aryl or Heteroaryl hal = CI, Br, I SCHEME 5

Compounds of formula (F) may be synthesized by reacting for example 2,4-dichloro pyrimidines of formula (G) with thiol nucleophiles to regioselectively give the 2-chloro-4-thio substituted pyrimidines (G. Luo et al 7et. lett. 2002, 43, 5739-5742 and G.A. Breault et al Bioorg. Med. Chem Lett. 2003, 13, 2961-2966) (Scheme 6), for instance using sodium hydride as base in a solvent such as DMF.

G Ar may be Aryl or Heteroaryl SCHEME 6

In scheme 1, 2, 3, 4, 5 and 6 above, R¹, R², R³, R⁴, R⁵, R⁶ and Q are defined as in formula I above.

Pharmaceutical formulations

For clinical use, the compounds of formula I are in accordance with the present invention suitably formulated into pharmaceutical formulations for oral administration. Also rectal, parenteral or any other route of administration may be contemplated to the skilled man in the art of formulations. Thus, the compounds of formula I are formulated with at least one pharmaceutically and pharmacologically acceptable carrier or adjuvant. The carrier may be in the form of a solid, semi-solid or liquid diluent. In the preparation of oral pharmaceutical formulations in accordance with the invention, the compound of formula I to be formulated is mixed with solid, powdered ingredients such as lactose, saccharose, sorbitol, mannitol, starch, amylopectin, cellulose derivatives, gelatin, or another suitable ingredient, as well as with disintegrating agents and lubricating agents such as magnesium stearate. calcium stearate, sodium stearyl fumarate and polyethylene glycol waxes. The mixture is then processed into granules or compressed into tablets.

Soft gelatine capsules may be prepared with capsules containing a mixture of the active compound or compounds of the invention, vegetable oil, fat, or other suitable vehicle for soft gelatine capsules. Hard gelatine capsules may contain the active compound in combination with solid powdered ingredients such as lactose, saccharose, sorbitol, mannitol, potato starch, corn starch, amylopectin, cellulose derivatives or gelatine.

Dosage units for rectal administration may be prepared (i) in the form of suppositories which contain the active substance(s) mixed with a neutral fat base; (ii) in the form of a gelatine rectal capsule which contains the active substance in a mixture with a vegetable oil, paraffin oil, or other suitable vehicle for gelatine rectal capsules; (iii) in the form of a ready-made micro enema; or (iv) in the form of a dry micro enema formulation to be reconstituted in a suitable solvent just prior to administration.

Liquid preparations for oral administration may be prepared in the form of syrups or suspensions, e.g. solutions or suspensions, containing the active compound and the remainder of the formulation consisting of sugar or sugar alcohols, and a mixture of ethanol, water, glycerol, propylene glycol and polyethylene glycol. If desired, such liquid preparations may contain colouring agents, flavouring agents, saccharine and carboxymethyl cellulose or other thickening agent. Liquid preparations for oral administration may also be prepared in the form of a dry powder to be reconstituted with a suitable solvent prior to use.

Solutions for parenteral administration may be prepared as a solution of a compound of the invention in a pharmaceutically acceptable solvent. These solutions may also contain stabilizing ingredients and/or buffering ingredients and are dispensed into unit doses in the form of ampoules or vials. Solutions for parenteral administration may also be prepared as a dry preparation to be reconstituted with a suitable solvent extemporaneously before use.

In one aspect of the present invention, the compounds of formula I may be administered once or twice daily, depending on the severity of the patient's condition.

A typical daily dose of the compounds of formula I is from 0.1 - 100 mg per kg body weight of the subject to be treated, but this will depend on various factors such as the route of administration, the age and weight of the patient as well as of severity of the patient's condition.

Examples

The invention will now be described in more detail by the following examples.

Preparation of intermediates 2-Pyridin-2-yl-3H-pyrimidin-4-one

Pyridine-2-carboxamidine hydrochloride (1.0 g, 6.5 mmol), sodium (lR)-3-ethoxy-3-oxoprop-l- en-1-olate (3.5 g, 25 mmol) and sodium ethoxide (0.45 g, 6.5 mmol) were added to ethanol (50 mL, 99.5 %) and the reaction mixture was refluxed under nitrogen atmosphere for 18 h, filtered hot and concentrated. The residue was dissolved in water (20 mL), neutralised with hydrochloric acid (1 M) and purified with reversed phase preparative HPLC This gave 0.68 g (60 %) of the title compound.

1HN R (400 MHz, dmso-d₆) δ 12.07 (br s, 1 H), 8.73 (m, 1 H), 8.29 (m, 1 H), 8.06-7.97 (m, 2 H), 7.63 (m, 1 H), 6.34 (d, J=6.8 Hz, 1 H). 4-Chloro-2-pyridin-2-yl-pyrimidine

2-Pyridin-2-yl-3H-ρyrirnidin-4-one, (0.945g, 5.45 mmol) was stirred in dichloromethane (25 mL) and phosphorous oxychloride (10 mL, 107 mmol) at 80°C for 1 h. The phosphorous oxychloride and dichloromethane was removed by vacuo. Crushed ice (50 mL) was added to the reaction mixture followed by K₂CO₃ (1 M, aq.) until pΗ reached 7. The resulting mixture was extracted with ethyl acetate (3x50 mL). The combined organic layers were extracted with brine (1x30 mL) and dried ( gSO₄). The solvent was evaporated to give the title compound (0.975 g, 93%).

^!Η MR (400 MHz, dmso-dβ) δ 7.6 (t, J=5.5 Hz, 1 H) 7.8 (d, J=5.1 Hz, 1 H) 8.0 (td, J=7.8, 1.2 Hz, 1 H) 8.4 (d, J=7.7 Hz, 1 H) 8.8 (m, 1 H) 8.9 (d, J=5.0 Hz, 1 H).

6-Methylpyridine-2-carboximidamide hvdrochlori.de

6-Methyl-2-cyanopyridine (252.7 mg, 2.13 mmol) and sodium methoxide (25.1 mg, 0.46 mmol) were dissolved in metb-anol (5 mL). The mixture was submitted to single wave continuous microwave irradiation at 2450 MHz for 625 sec at 100 °C. Ammonium chloride (115.0 mg, 2.14 mmol) was added, followed by microwave irradiation for 720 sec at 80 °C. The methanol is evaporated under reduced pressure. Ethanol (5 mL) was added, followed by brief heating to reflux, then cooling to room temperature, followed by filtration & evaporation under reduced pressure. The solid was taken up in water and washed with dichloromethane. The aqueous layer was freeze-dried to give the title compound (286.6 mg, 78%). 1H NMR (400 MHz, dmso-dβ) δ 9.22 (s br, 3 H), 8.07 (s, 1 H), 8.02 (t, 1 H), 2.59 (s, 3 H).

2-f6-Methylpyridin-2-yr)pyrimidin-4f3H)-one

6-Methylpyridine-2-carboximidamide hydrochloride (0.285 g, 1.66 mmol), sodium (l£)-3- ethoxy-3-oxoprop-l-en-l-olate (0.872 g, 6.31 mmol) and sodium ethoxide 0.114 g, 1.66 mmol) were added to EtOH (15 mL, 99.5 %) and the reaction mixture was refluxed under nitrogen atmosphere for 19 h. The solvent was evaporated and the residue dissolved in water, neutralized with hydrochloric acid (1M). The aqueous phase was extracted with EtOAc (3x). The combined organic layers were washed with brine, dried (MgSO₄), filtered and the solvent evaporated to afford 0.254 g (82 %) of the title compound, which was used in the next step without further purification.

LC-MS (API-ES) m/z 188 (M⁺+1).

4-Chloro-2-(6-methylpyridin-2-yl^')pyrimidine

Prepared according to procedure described in 4-Chloro-2-pyridin-2-yl-pyrimidine. Starting from 2-(6-methylpyridin-2-yl)pyrimidin-4(3H)-one (0.099 g, 0.53 mmol) in dichloroethane instead of dichloromethane, 0.095 g (87 %) of the title compound were obtained. LC-MS (API-ES) m/z 206 (MM).

2-Chloro-4-(3,4-dichloro-phenylsulfanylVpyrimidine

3,4-dichloro-thiophenol (3.0 g, 16.2 mmol) in DMF (60 ml) was added to a mixture of NaΗ (452 mg, 17.9 mmol) in DMF (60 ml) at -5°C under nitrogen. After 10 min 2,4-dichloropyrimidine

(2.66 g, 17.9 mmol) was added. After 30 min the reaction mixture was diluted with ethyl acetate.

The solution was washed with 1 M NaOΗ, water and brine, dried (Na₂SO₄) and concentrated.

Recrystallization from ethyl acetate/heptane gave 3.3 g (70%) of the title compound.

1H NMR (400 MHz, CDCl₃):δ 6.79 (d, 1 H) 7.45 (m, 1 H) 7.59 (d, 1 H) 7.72 (d, 1 H) 8.28 (d, 1 H) MS (API-ES) m/z 293 (M*^"+l). Preparation of final compounds

Method A 4-(3-Chloro-phenylsulfanylV2-pyridin-2-yl-pyrimidine

4-Chloro-2-pyridin-2-yl-pyrimidine (0.04g, 0.24mmol) and 3-chloro-benzenethiol (0.07g, 0.47mmol) were stirred in dimethylformamide (0.5 ml) at room temperature over night. The solvent was evaporated and the reaction mixture was purified by HPLC: Waters Fraction- Lynxsystem with UN, ELSD and MS; Column: Ace C8 5μ 100 mm x 21,2 mm id, to give the title compound (0.042g, yield 58%).

1H ΝMR (400 MHz, dmso-d₆) δ 7.0 (d, J=5.2 Hz, 1 H) 7.5-7.6 (m, 2 H) 7.7 (t, J=7.5 Hz, 2 H) 7.9 (t, J=2.0 Hz. 1 H) 8.0 (m, 1 H) 8.7 (d, J=4.0 Hz, 1 H) 8.7 (m, 2 H).

4-[(4-chlorophenyl thio1-2-pyridin-2-ylpyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.050g, 0.26mmol) and 4- chloro-benzenethiol (0.050g, 0.35mmol), 0.070g (yield 90%) of the title compound was isolated. 1H ΝMR (400 MHz, dmso-d₆) δ 8.71 (d, J=4.2 Hz, 1 H), 8.63 (d, J=5.4 Hz, 1 H), 8.19 (d, J=7.9 Hz, 1 H), 7.92 (dt, J=7.8, 1.6 Hz, 1 H), 7.74-7.60 ( , 4 H), 7.50 (m, 1 H), 6.92 (d, J=5.4 Hz, 1 H).

4-(3-Bromo-phenylsulfanyl^')-2-pyridin-2-yl-pyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.048g, 0.25mmol) and 3- bromo-benzenethiol (0.071g, 0.375mmol), 0.067g (yield 52%) of the title compound was isolated. Η NMR (500 MHz, dmso-dβ) δ 7.1 (d, J=5.5 Hz, 1 H) 7.5 (m, 2 H) 7.7 (d, J=7.7 Hz, 1 H) 7.8 (d, J=8.1 Hz, 1 H) 7.9 (t, J=7.7 Hz, 1 H) 8.0 (t, J=1.7 Hz, 1 H) 8.2 (d, J=7.9 Hz, 1 H) 8.7 (d, J=5.5 Hz, 1 H) 8.7 (d, J=4.9 Hz, 1 H).

2-Pyridin-2-yl-4- 3-trifluoromethyl-phenylsulfanylVpyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.048g, 0.25mmol) and 3- trifiuoromethyl-benzenethiol (0.067g, 0.375mmol), 0.061g (yield 49%) of the title compound was isolated, H NMR (500 MHz, dmso-de) δ 7.2 (d, J=5.5 Hz, 1 H) 7.5 (m, 1 H) 7.8 (t, J=7.8 Hz, 1 H) 7.9 (td, J=7.7, 1.8 Hz, 1 H) 8.0 (d, J=8.5 Hz, 1 H) 8.0 (d, J=7.8 Hz, 1 H) 8.2 (d, J=9.0 Hz, 2 H) 8.7 (d, J=5.4 Hz, 1 H) 8.7 (d, J=4.6 Hz, 1 H).

2-Pyridin-2-yl-4-(4-trifluoromethyl-phenylsulfanyl^')-pyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 4- trifluoromethyl-benzenethiol (0.032g, 0.209mmol), 0.024g (yield 68%) of the title compound was isolated.

1H NMR (400 MHz, dmso-de) δ 7.1 (d, J=5.3 Hz, 1 H) 7.5 (m, 1 H) 7.9 (m, 5 H) 8.2 (dt, J=7.9, 0.9 Hz, 1 H) 8.7 (d, J=5.4 Hz, 1 H) 8.7 (d, J=4.7 Hz, 1 H).

4-r3.4-Dichloro-ρhenylsulfanyl')-2-pyridin-2-yl-ρyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 3,4- dichloro-benzenethiol (0.045g, 0.25mmol), 0.019g (yield 48%) of the title compound was isolated. 1H NMR (400 MHz, dmso-d₆) δ 7.1 (d, J=5.4 Hz, 1 H) 7.5 (m, 1 H) 7.7 (dd, J=8.4, 2.1 Hz, 1 H) 7.8 (d, J=8.4 Hz, 1 H) 7.9 (dt, J=7.7, 1.8 Hz, 1 H) 8.1 (d, J=2.1 Hz, 1 H) 8.2 (d, J=7.8 Hz, 1 H) 8.7 (d, J=5.4 Hz, 1 H) 8.7 (m, 1 H).

4-(3-Methoxy-phenylsulfanylV2-pyridin-2-yl-pyrimidine

Using m A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.048g, 0.25mmol) and 3- methoxy-benzenethiol (0.053g, 0.375mmol), 0.048g (yield 43%) of the title compound was isolated, 1H NMR (500 MHz, dmso-d₆) δ 3.8 (s, 3 H) 6.9 (d, J=5.5 Hz, 1 H) 7.2 (ddd, J=8.3, 2.4, 0.6 Hz, 1 H) 7.3 (m, 2 H) 7.5 (m, 2 H) 8.0 (dt, J=7.8, 1.8 Hz, 1 H) 8.3 (d, J=7.9 Hz, 1 H) 8.6 (d, J=5.5 Hz, 1 H) 8.7 (m, 1 H).

2-Pyridin-2-yl-4-m-tolylsulfanyl-pyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.048g, 0.25mmol) and 3- methoxy -benzenethiol (0.047g, 0.375mmol), 0.043g (yield 41%) of the title compound was isolated.

1H NMR (500 MHz, dmso-dg) δ 2.4 (s, 3 H) 6.9 (d, J=5.5 Hz, 1 H) 7.4 (m, 1 H) 7.5 (m, 4 H) 8.0 (td, J=7.6, 1.7 Hz, 1 H) 8.3 (dt, J=7.9, 1.1 Hz, 1 H) 8.6 (d, J=5.4 Hz, 1 H) 8.7 (m, 1 H).

4-(4-Fluoro-phenylsulfanylV2-pyridin-2-yl-pyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 4- fluoro-benzenethiol (0.032g, 0.209mmol), 0.018g (yield 59%) of the title compound was isolated. 1H NMR (500 MHz, dmso-d₆) δ 6.9 (d, J=5.4 Hz, 1 H) 7.4 (m, 2 H) 7.5 (m, 1 H) 7.8 (m, 2 H) 8.0 (td, J=7.6. 1.8 Hz, 1 H) 8.2 (dt, J=7.9, 1.1 Hz, 1 H) 8.6 (d, J=5.5 Hz, 1 H) 8.7 (m, 1 H).

N-[4-(2-Pyridin-2-yl-pyrimidin-4-ylsulfanylVphenyl]-acetamide

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) andN- (4-mercapto-phenyl)-acetamide (0.034g, 0.203mmol), O.OlOg (yield 19%) of the title compound was isolated.

1H ΝMR (500 MHz, dmso-dg) δ 2.1 (m, 3 H) 6.8 (d, J=5.4 Hz, 1 H) 7.5 (m, 1 H) 7.6 (d, J=8.7 Hz, 2 H) 7.8 (d, J=8.5 Hz, 2 H) 8.0 (td, J=7.8, 1.7 Hz, 1 H) 8.3 (d, J=7.8 Hz, 1 H) 8.6 (d, J=5.5 Hz, 1 H) 8.7 (m, 1 H) 10.3 (m, 1 H).

4-(3,4-Dimethoxy-ρhenylsulfanylV2-pyridin-2-yl-pyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 3,4- dimethoxy-benzenethiol (0.039g, 0.23mmol), 0.018g (yield 34%) of the title compound was isolated. 1H NMR (500 MHz, dmso-d₆) δ 3.8 ( , 3 H) 3.9 (m, 3 H) 6.8 (d, J=5.5 Hz, 1 H) 7.2 (m, 1 H) 7.3 (m, 2 H) 7.5 (m, 1 H) 8.0 (td, J=7.8, 1.8 Hz, 1 H) 8.3 (dt, J=7.9, 1.0 Hz, 1 H) 8.6 (d, J=5.4 Hz, 1

H) 8.7 (m, 1 H). 4-Methyl-6-f2-ρyridin-2-yl-pyrimidin-4-ylsulfanylVchromen-2-one

usi g method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 6- mercapto-4-methyl-chromen-2-one (0.040g, 0.21mmol), 0.026g (yield 13%) of the title compound was isolated. ^lK NMR (500 MHz, dmso-d₆) δ 2.5 (s, overlapped by dmso-de, 3 H) 6.5 (d, J=1.2 Hz, 1 H) 7.1 (d, .7=5.5 Hz, 1 H) 7.5 (m, 1 H) 7.7 (m, 1 H) 7.8 (d, J=1.7 Hz, 1 H) 8.0 (m, 2 H) 8.3 (d, J=7.9 Hz, 1 H) 8.7 (d, J=5.4 Hz, 1 H) 8.7 (m, 1 H).

|^"4-(^"2-Pyridin-2-yl-pyrimidin-4-ylsulfanylVphenyn-acetic acid

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 4- mercapto-phenyl-acetic acid (0.038g, 0.22mmol), 0.033g (yield 78%) of the title compound was isolated. ^JH NMR (500 MHz, dmso-de) δ 3.7 (s, 3 H) 6.9 (d, J=5.4 Hz, 1 H) 7.5 (d, J=8.3 Hz, 2 H) 7.5 (m, 1 H) 7.7 (d, J=8.2 Hz, 2 H) 7.9 (td, J=7.7, 1.8 Hz, 1 H) 8.2 (d, J=7.9 Hz, 1 H) 8.6 (d, J=5.5 Hz, 1 H) 8.7 (dd, J=4.7, 0.9 Hz, 1 H).

2-Pyridin-2-yl-4-(pyridin-2-ylsulfanyl^')-pyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and 2- pyridinethiol (0.032g, 0.209mmol), 0.018g (yield 64%) of the title compound was isolated. 1H NMR (400 MHz, dmso-d₆) δ 7.3 (d, J=5.4 Hz, 1 H) 7.5 (m, 2 H) 7.9 (d, J=7.9 Hz, 1 H) 7.9 (tt, J=7.7, 2.0 Hz, 2 H) 8.2 (d, J=7.9 Hz, 1 H) 8.7 (dt, J=4.8, 0.9 Hz, 1 H) 8.7 (d, J=5.4 Hz, 1 H) 8.7 (m, 1 H). 2-Pyridin-2-yl-4-(thiazol-2-ylsulfanylVpyrimidine

Using method A starting from 4-chloro-2-pyridin-2-yl-pyrimidine (0.020g, 0.104mmol) and thiazole-2-thiol (0.032g, 0.209mmol), O.Olδg (yield 54%) of the title compound was isolated. 1H NMR (400 MHz, dmso-de) δ 7.3 (d, J=5.4 Hz, 1 H) 7.5 (ddd, J=7.5, 4.7, 1.1 Hz, 1 H) 8.0 (td, J=7.7, 1.8 Hz, 1 H) 8.1 (d, 3.4 Hz, 1 H) 8.1 (d, 3.4 Hz, 1 H) 8.3 (d, J=7.9 Hz, 1 H) 8.7 (ddd, J=4.8, 1.6, 0.9 Hz, 1 H) 8.8 (d, J=5.3 Hz, 1 H).

Method B

4- [(3.4-DifluorophenyDthiol -2-pyridin-2-ylpyrimidine

To a solution of 4-chloro-2-pyridin-2-yl-pyrimidine (0.054 g, 0.28 mmol) and 3,4- difluorothiophenol (32 mL, 0.28 mmol) in dry DMF was added at 0 °C NaH (95 %, 0.009 g, 0.28 mmol) and the reaction was stirred at 0 °C under a nitrogen atmosphere for 1 h 15 min. NaOH (1M) and EtOAc were added and the layers separated. The aqueous phase was extracted with EtOAc (3x). Combined organic phases were washed (water and brine), dried (MgSO₄), filtered and evaporated under reduced pressure, followed by preparative HPLC purification to give 0.045 g (53 %) of the title compound. ^lH NMR (400 MHz, DMSO-de) δ 7.06 (d, 1H), 7.53 (m, 1H), 7.64 (m, 2H), 7.95 (m, 2H), 8.21 (d, 1H), 8.66 (d, 1H), 8.73 (m, 1H); LC-MS (API-ES) m/z 302 (-vf+l).

4- [(3.4-Dichlorophenyr)thio] -2-(6-methylpyridin-2-vDpyrimidine

Prepared according to method B using 4-chloro-2-(6-methylpyridin-2-yl)pyrimidine (0.090 g, 0.44 mmol) and 3,4-dichlorobenzenethiol (53 μL, 0.42 mmol), yielding 0.059 g (39 %) of the title compound. 1H NMR (400 MHz, DMSO-d6) δ 2.56 (s, 3H), 7.16 (dd, 1H), 7.39 (d, 1H), 7.71 ( , 1H), 7.82 (m, 2H), 8.01 (d, 1H), 8.10 (d, 1H), 8.66 ( , 1H); LC-MS (API-ES) m/z 348 (M⁺+1).

s Method C 4-r3.4-Dichloro-phenylsulfanyl -2-(5-fluoro-pyridin-2-yl -pyrimidine

A solution of 2-bromo-5-fluoro-pyridine (352 mg, 2.0 mmol), hexamethyldistannane (760 mg,o 2.31 mmol) and tetrakistriphenylphosphine palladium (0) (92 mg, 0.08 mmol) in degassed toluene (19 ml) was heated at 80°C under nitrogen over night. 2-Cnloro-4-(3,4-dichloro- ρhenylsulfanyl)-pyrimidine (525 mg,1.8 mmol) followed by tetrakistriphenylphosphine palladium (0) (92 mg, 0.08 mmol) was added and the mixture was heated at 110°C for 3 h. The reaction mixture was cooled to room temperature and concentrated under reduced pressure. Flashs chromatography (100% heptane to 100% ethyl acetate) afforded 30 mg of the title compound. 1H NMR (400 MHz, CDCl₃):δ ppm 6.89 (d, 1 H) 7.48 - 7.52 (m, 1 H) 7.54 (m, 1 H) 7.60 (d, 1 H) 7.81 (d, 1 H) 8.35 (m, 1 H) 8.60 (d, 1 H) 8.66 (d, 1 H)

Experimental details0 Pyridine-2-carboxamidine is commercially available from Avocado (Avocado Research, Shore Road, Port of Heysham Industrial Park, Heysham, Lancashire LA3 2XY, United Kingdom). If not stated otherwise, the chemicals used are commercially available, well known and are used as such without further purification. Biological evaluation

Functional assessment ofmGluR5 antagonism in cell lines expressing mGluR5D

The properties of the compounds of the invention can be analyzed using standard assays for pharmacological activity. Examples of glutamate receptor assays are well known in the art as described in for example Aramori et al, Neuron 8:757 (1992), Tanabe et al., Neuron 8:169 (1992), Miller et al, J. Neuroscience 15: 6103 (1995), Balazs, et al, J. Neurochemistry 69:151 (1997). The methodology described in these publications is incorporated herein by reference. Conveniently, the compounds of the invention can be studied by means of an assay (FLIPR) that measures the mobilization of intracellular calcium, [Ca²⁺]i in cells expressing mGluR5 or another assay (IP3) that measures inositol phosphate turnover.

FLIPR Assay

Cells expressing human mGluR5d as described in WO97/05252 are seeded at a density of 100,000 cells per well on collagen coated clear bottom 96-well plates with black sides and experiments are done 24 h following seeding. All assays are done in a buffer containing 127 mM NaCl, 5 mM KC1, 2 mM MgCl₂, 0.7 mM NaH₂PO₄, 2 mM CaCl₂, 0.422 mg/ml NaHCO₃, 2.4 mg/ml HEPES, 1.8 mg/ml glucose and 1 mg/ml BSA Fraction IV (pH 7.4). Cell cultures in the 96-well plates are loaded for 60 minutes in the above mentioned buffer containing 4 μM of the acetoxymethyl ester form of the fluorescent calcium indicator fluo-3 (Molecular Probes, Eugene, Oregon) in 0.01% pluronic acid (a proprietary, non-ionic surfactant polyol - CAS Number 9003- 11-6). Following the loading period the fluo-3 buffer is removed and replaced with fresh assay buffer. FLIPR experiments are done using a laser setting of 0.800 W and a 0.4 second CCD camera shutter speed with excitation and emission wavelengths of 488 nm and 562 nm, respectively. Each experiment is initiated with 160 μl of buffer present in each well of the cell plate. A 40 μl addition from the antagonist plate was followed by a 50 μL addition from the agonist plate. A 90 second interval separates the antagonist and agonist additions. The fluorescence signal is sampled 50 times at 1 second intervals followed by 3 samples at 5 second intervals immediately after each of the two additions. Responses are measured as the difference between the peak height of the response to agonist, less the background fluorescence within the sample period. IC50 determinations are made using a linear least squares fitting program. IP 3 Assay

An additional functional assay for mGluR5d is described in WO97/05252 and is based on phosphatidylinositol turnover. Receptor activation stimulates phospholipase C activity and leads to increased formation of inositol l,4,5,triphosphate (IP₃). GHEK stably expressing the human mGluR5d are seeded onto 24 well poly-L-lysine coated plates at 40 x 10⁴ cells /well in media containing 1 μCi/well [3H] myo-inositol. Cells were incubated overnight (16 h), then washed three times and incubated for 1 h at 37°C in HEPES buffered saline (146 mM NaCl, 4.2 mM KC1, 0.5 mM MgCl₂, 0.1% glucose, 20 mM HEPES, pH 7.4) supplemented with 1 unit/ml glutamate pyruvate transaminase and 2 mM pyruvate. Cells are washed once in HEPES buffered saline and pre-incubated for 10 min in HEPES buffered saline containing 10 mM LiCl. Compounds are incubated in duplicate at 37°C for 15 min, then either glutamate (80 μM) or DHPG (30 μM) is added and incubated for an additional 30 min. The reaction is terminated by the addition of 0.5 ml perchloric acid (5%) on ice, with incubation at 4°C for at least 30 min. Samples are collected in 15 ml polyproplylene tubes and inositol phosphates are separated using ion-exchange resin (Dowex AG1-X8 formate form, 200-400 mesh, BIORAD) columns. Inositol phosphate separation was done by first eluting glycero phosphatidyl inositol with 8 ml 30 mM ammonium formate. Next, total inositol phosphates is eluted with 8 ml 700 mM ammonium formate / 100 mM formic acid and collected in scintillation vials. This eluate is then mixed with 8 ml of scintillant and [3H] inositol incorporation is determined by scintillation counting. The dpm counts from the duplicate samples are plotted and IC₅₀ determinations are generated using a linear least squares fitting program.

Abbreviations BSA Bovine Serum Albumin

CCD Charge Coupled Device

CRC Concentration Response Curve

DHPG 3,5-dihydroxyphenylglycine

DPM Disintegrations per Minute EDTA Ethylene Diamine Tetraacetic Acid

FLIPR Fluorometric Imaging Plate reader

GHEK GLAST-containing Human Embrionic Kidney

GLAST glutamate/aspartate transporter

HEPES 4-(2-hydroxyethyl)-l-piperazineethanesulfonic acid (buffer) IP₃ inositol triphosphate

Generally, the compounds were active in the assay above with IC₅₀ values less than 10 000 nM. In one aspect of the invention, the IC₅₀ value is less than 1 μM. In a further aspect of the invention, the ICs₀ value is less than 100 nM.

Screening for compounds active against TLESR

Adult Labrador retrievers of both genders, trained to stand in a Pavlov sling, are used. Mucosa- to-skin esophagostomies are formed and the dogs are allowed to recover completely before any experiments are done.

Motility measurement

In brief, after fasting for approximately 17 h with free supply of water, a multilumen sleeve sidehole assembly (Dentsleeve, Adelaide, South Australia) is introduced through the esophagostomy to measure gastric, lower esophageal sphincter (LES) and esophageal pressures. The assembly is perfused with water using a low-compliance manometric perfusion pump (Dentsleeve, Adelaide, South Australia). An air-perfused tube is passed in the oral direction to measure swallows, and an antimony electrode monitored pH, 3 cm above the LES. All signals are amplified and acquired on a personal computer at 10 Hz.

When a baseline measurement free from fasting gastric/LES phase III motor activity has been obtained, placebo (0.9% NaCl) or test compound is administered intravenously (i.v., 0.5 ml/kg) in a foreleg vein. Ten min after i.v. administration, a nutrient meal (10% peptone, 5% D-glucose, 5% Intralipid, pH 3.0) is infused into the stomach through the central lumen of the assembly at 100 ml min to a final volume of 30 ml/kg. The infusion of the nutrient meal is followed by air infusion at a rate of 500 ml/min until an intragastric pressure of 10+1 mmHg is obtained. The pressure is then maintained at this level throughout the experiment using the infusion pump for further air infusion or for venting air from the stomach. The experimental time from start of nutrient infusion to end of air insufflation is 45 min. The procedure has been validated as a reliable means of triggering TLESRs. TLESRs is defined as a decrease in lower esophageal sphincter pressure (with reference to intragastric pressure) at a rate of >1 mmHg/s. The relaxation should not be preceded by a pharyngeal signal <2s before its onset in which case the relaxation is classified as swallow- induced. The pressure difference between the LES and the stomach should be less than 2 mmHg, and the duration of the complete relaxation longer than 1 s.

Claims

1. A compound of formula I

wherein R¹, R², R³ and R⁴ are each and independently selected from H, C C₄ alkyl, halogen, CN and NO₂; R⁵ and R⁶ are each and independently selected from H, halogen, CN and NO₂; Q is aryl or heteroaryl, optionally substituted by H, Cι-C alkyl, C₂-C₄ alkenyl, halogen, alkoxy, CH₂F, CHF₂, CF₃, NH₂, NHAc, OH, OAc or carboxylic esters and wherein one or more of the substituents may form part of a ring; as well as pharmaceutically acceptable salts, hydrates, isoforms and/or optical isomers thereof.

2. A compound according to claim 1, wherein Q is selected from

wherein X is selected from C, N, S and O; wherein R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ are each and independently selected from H, Cι-C₄ alkyl, C₂-C₄ alkenyl, halogen, alkoxy, CH₂F, CHF₂, CF₃, NH₂, NHAc, OH, OAc and carboxylic esters and wherein one or more of R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ may form part of a ring.

3. A compound according to claim 1 or 2 selected from 4-(3-Chloro-phenylsulfanyl)-2- pyridin-2-yl-pyrimidine; 4-[(4-cWorophenyl)thio]-2-pyridin-2-ylpyrimidine; 4-(3-Bromo- phenylsulfanyl)-2-pyridin-2-yl-pyrimidine; 2-Pyridin-2-yl-4-(3-trifluoromethyl- phenylsulfanyl)-pyrimidine; 2-Pyridin-2-yl-4-(4-trifluoromethyl-phenylsulfanyl)- pyrimidine; 4-(3,4-Dichloro-phenylsulfanyl)-2-pyridin-2-yl-pyrimidine; 4-(3-Methoxy- phenylsulfanyl)-2-pyridin-2-yl-pyrimidine; 2-Pyridin-2-yl-4-m-tolylsulfanyl-pyrimidine; 4-(4-Fluoro-phenylsulfanyl)-2-pyridin-2-yl-pyrimidine; N-[4-(2-Pyridin-2-yl-pyrimidin- 4-ylsulfanyl)-phenyl]-acetamide; 4-(3,4-Dimethoxy-phenylsulfanyl)-2-pyridin-2-yl- pyrimidine; 4-Methyl-6-(2-pyridin-2-yl-pyrimidin-4-ylsulfanyl)-chromen-2-one; [4-(2- Pyridin-2-yl-pyrimidin-4-ylsulfanyl)-phenyl] -acetic acid; 2-Pyridin-2-yl-4-(pyridin-2- ylsulfanyl)-pyrimidine, 2-Pyridin-2-yl-4-(thiazol-2-ylsulfanyl)-pyrimidine, 4-[(3,4- Difluorophenyl)thio] -2-pyridin-2-ylpyrimidine, 4- [(3 ,4-Dichlorophenyl)thio] -2-(6- methylpyridin-2-yl)pyrimidine and 4-(3,4-Dichloro-phenylsulfanyl)-2-(5-fluoro-pyridin- 2-yl)-pyrimidine.

4. A compound according to any one of claims 1-3 for use in therapy.

5. A compound according to claim 4, wherein the therapy is treatment or prevention of gastroesophageal reflux disease.

6. Use of a compound according to any one of claims 1-3, or a pharmaceutically acceptable salt or an optical isomer thereof, for the manufacture of a medicament for the inhibition of transient lower esophageal sphincter relaxations.

7. Use of a compound according to any one of claims 1-3, or a pharmaceutically acceptable salt or an optical isomer thereof, for the manufacture of a medicament for treatment or prevention of gastroesophageal reflux disease.

8. A pharmaceutical composition comprising a compound according to any one of claims 1- 3 as an active ingredient, together with a pharmacologically and pharmaceutically acceptable carrier.

9. A process for the preparation of a compound of formula I, comprising the steps of a) synthesizing a 2-Pyridin-2-yl-3H-pyrimidin-4-one from the corresponding Pyridine-2-carboxamidine by reaction with the sodium salt of ethyl 3-hydroxy- acrylate; b) synthesizing a 4-Chloro-2-pyridin-2-yl-pyrimidine from said 2-Pyridin-2-yl-3H- pyrimidin-4-one by reflux in phosphorus oxychloride; and c) synthesising a compound of formula I from said 4-Chloro-2-pyridin-2-yl- pyrimidine by reaction with a thiol nucleophile.

10. A method for the inhibition of transient lower esophageal sphincter relaxations whereby an effective amount of a compound according to any one of claims 1-3 is administered to a subject in need of such inhibition.

11. A method for the treatment or prevention of gastroesophageal reflux disease, whereby an effective amount of a compound according to any one of claims 1-3 is administered to a subject in need of such treatment or prevention.