NOVEL CHROMONE OXIME DERIVATIVE AND ITS USE AS ALLOSTERIC MODULATOR OF METABOTROPIC GLUTAMATE RECEPTORS

Abstract

The present invention provides a novel chromone oxime derivative of formula (I), which is a modulator of nervous system receptors sensitive to glutamate and, furthermore, presents an advantageously high brain penetration upon oral administration. The invention also relates to a pharmaceutical composition containing this compound, and to its use for the treatment or prevention of conditions associated with altered glutamatergic signalling and/or functions, or conditions which can be affected by alteration of glutamate level or signalling, particularly acute and chronic neurological and/or psychiatric disorders.

##STR00001##

Claims

1. A compound of the following formula (I): ##STR00017## or a pharmaceutically acceptable salt, solvate or prodrug thereof.

2. The compound of claim 1, wherein said compound has the (E)-configuration at the oxime group comprised in formula (I).

3. The compound of claim 1 or 2, wherein the pharmaceutically acceptable salt is a hydrochloride salt.

4. The compound of any one of claims 1 to 3 for use as a medicament.

5. A pharmaceutical composition comprising the compound of any one of claims 1 to 3 and a pharmaceutically acceptable excipient.

6. The compound of any one of claims 1 to 3 or the pharmaceutical composition of claim 5 for use in the treatment or prevention of a condition associated with altered glutamatergic signalling and/or functions, or a condition which can be affected by alteration of glutamate level or signalling.

7. The compound or the pharmaceutical composition for use according to claim 6, wherein said condition associated with altered glutamatergic signalling and/or functions, or said condition which can be affected by alteration of glutamate level or signalling is selected from: dementias, parkinsonism and movement disorders, acute or chronic pain, anxiety disorders, schizophrenia, mood disorders, endocrine and metabolic diseases, diabetes, disorders of the endocrine glands, hypoglycaemia, or cancers.

8. The compound or the pharmaceutical composition for use according to claim 7, wherein said dementias are selected from: dementias of the Alzheimer's type (DAT); Alzheimer's disease; Pick's disease; vascular dementias; Lewy-body disease; dementias due to metabolic, toxic and deficiency diseases, including alcoholism, hypothyroidism, and vitamin B12 deficiency; AIDS-dementia complex; Creutzfeld-Jacob disease; or atypical subacute spongiform encephalopathy.

9. The compound or the pharmaceutical composition for use according to claim 7, wherein said parkinsonism and movement disorders are selected from: Parkinson's disease; multiple system atrophy; progressive supranuclear palsy; corticobasal degeneration; hepatolenticular degeneration; chorea, including Huntington's disease and hemiballismus; athetosis; dystonias, including spasmodic torticollis, occupational movement disorder, and Gilles de la Tourette syndrome; tardive or drug induced dyskinesias, including levodopa-induced dyskinesia; tremor; or myoclonus.

10. The compound or the pharmaceutical composition for use according to claim 7, wherein said anxiety disorders are selected from: panic disorders; phobias; obsessive-compulsive disorders; stress disorders, including post-traumatic stress disorder; or generalized anxiety disorders.

11. The compound or the pharmaceutical composition for use according to claim 7, wherein said mood disorders are selected from depressive disorders or bipolar disorders.

12. The compound of any one of claims 1 to 3 or the pharmaceutical composition of claim 5 for use in the treatment or prevention of Parkinson's disease.

13. The compound or the pharmaceutical composition for use according to any one of claims 6 to 12, wherein said compound or said pharmaceutical composition is to be administered orally.

14. Use of the compound of any one of claims 1 to 3 for the preparation of a medicament for the treatment or prevention of a condition associated with altered glutamatergic signalling and/or functions, or a condition which can be affected by alteration of glutamate level or signalling.

15. The use of claim 14, wherein said condition associated with altered glutamatergic signalling and/or functions, or said condition which can be affected by alteration of glutamate level or signalling is selected from: dementias, parkinsonism and movement disorders, acute or chronic pain, anxiety disorders, schizophrenia, mood disorders, endocrine and metabolic diseases, diabetes, disorders of the endocrine glands, hypoglycaemia, or cancers.

16. The use of claim 15, wherein said dementias are selected from: dementias of the Alzheimer's type (DAT); Alzheimer's disease; Pick's disease; vascular dementias; Lewy-body disease; dementias due to metabolic, toxic and deficiency diseases, including alcoholism, hypothyroidism, and vitamin B12 deficiency; AIDS-dementia complex; Creutzfeld-Jacob disease; or atypical subacute spongiform encephalopathy.

17. The use of claim 15, wherein said parkinsonism and movement disorders are selected from: Parkinson's disease; multiple system atrophy; progressive supranuclear palsy; corticobasal degeneration; hepatolenticular degeneration; chorea, including Huntington's disease and hemiballismus; athetosis; dystonias, including spasmodic torticollis, occupational movement disorder, and Gilles de la Tourette syndrome; tardive or drug induced dyskinesias, including levodopa-induced dyskinesia; tremor; or myoclonus.

18. The use of claim 15, wherein said anxiety disorders are selected from: panic disorders; phobias; obsessive-compulsive disorders; stress disorders, including post-traumatic stress disorder; or generalized anxiety disorders.

19. The use of claim 15, wherein said mood disorders are selected from depressive disorders or bipolar disorders.

20. Use of the compound of any one of claims 1 to 3 for the preparation of a medicament for the treatment or prevention of Parkinson's disease.

21. The use of any one of claims 14 to 20, wherein said medicament is to be administered orally.

22. A method of treating a condition associated with altered glutamatergic signalling and/or functions, or a condition which can be affected by alteration of glutamate level or signalling, the method comprising the administration of the compound of claim 1 to a subject in need thereof.

23. The method of claim 22, wherein said condition associated with altered glutamatergic signalling and/or functions, or said condition which can be affected by alteration of glutamate level or signalling is selected from the group consisting of: dementias, parkinsonism and movement disorders, acute or chronic pain, anxiety disorders, schizophrenia, mood disorders, endocrine and metabolic diseases, diabetes, disorders of the endocrine glands, hypoglycaemia, and cancers.

24. The method of claim 23, wherein said dementias are selected from the group consisting of: dementias of the Alzheimer's type (DAT); Alzheimer's disease; Pick's disease; vascular dementias; Lewy-body disease; dementias due to metabolic, toxic and deficiency diseases, including alcoholism, hypothyroidism, and vitamin B12 deficiency; AIDS-dementia complex; Creutzfeld-Jacob disease; and atypical subacute spongiform encephalopathy.

25. The method of claim 23, wherein said parkinsonism and movement disorders are selected from the group consisting of: Parkinson's disease; multiple system atrophy; progressive supranuclear palsy; corticobasal degeneration; hepatolenticular degeneration; chorea, including Huntington's disease and hemiballismus; athetosis; dystonias, including spasmodic torticollis, occupational movement disorder, and Gilles de la Tourette syndrome; tardive or drug induced dyskinesias, including levodopa-induced dyskinesia; tremor; and myoclonus.

26. The method of claim 23, wherein said anxiety disorders are selected from the group consisting of: panic disorders; phobias; obsessive-compulsive disorders; stress disorders, including post-traumatic stress disorder; and generalized anxiety disorders.

27. The method of claim 23, wherein said mood disorders are selected from the group consisting of depressive disorders and bipolar disorders.

28. The method of claim 22, wherein the method comprises orally administering said compound to said subject.

29. The method of claim 22, wherein said subject is a human.

30. A method of treating Parkinson's disease, the method comprising the administration of the compound of claim 1 to a subject in need thereof.

31. The method of claim 30, wherein the method comprises orally administering said compound to said subject.

32. The method of claim 30, wherein said subject is a human.

Description

[0066] The invention is also described by the following illustrative figures. The appended figures show:

[0067] FIG. 1: PXT002331 and PXT001858 brain exposure after oral administration in rats (10 mg/kg).

[0068] FIG. 2: PXT002331 and PXT001858 plasma concentration after oral administration in rats (10 mg/kg).

[0069] FIG. 3: PXT002331 and PXT001858 brain level after oral administration in rats (10 mg/kg).

[0070] FIG. 4: PXT002331 and PXT001858 brain/plasma ratio after oral administration in rats (10 mg/kg).

[0071] FIG. 5: Evaluation of the anti-parkinsonian efficacy of PXT002331 in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) macaque model of Parkinson's disease (see Example 3). (A) PXT002331 as a stand-alone treatment; oral administration twice a day during 4 days, assessment of parkinsonian scores at day 4; data are mean+s.e.m. over 2 hours observation (n=7 per group; 1 of the 8 monkeys initially used was excluded); “Veh”=vehicle; “LD opt”=L-dopa optimal dose”; *=P<0.05 vs Veh; ***=P<0.001 vs Veh; statistical analysis: Friedman followed by Dunn's. (B) Combined treatment using PXT002331 (25 mg/kg)+low dose of L-dopa (4-9 mg/kg)—parkinsonism time course; oral administration twice a day during 4 days, assessment at day #4; L-dopa optimal dose (“LDopt”): >20 mg/kg; L-dopa suboptimal dose (“LDso”): 4-9 mg/kg; combined administration of L-dopa (suboptimal dose) and PXT002331: twice a day/4 days. (C) Combined treatment using PXT002331+low dose of L-dopa—difference in parkinsonian score for monkeys treated with low dose of L-dopa and PXT002331 in comparison to low dose of L-dopa alone, and in comparison to optimal dose of L-dopa; assessment at day 4, between 1 and 2 h after L-dopa administration (i.e., 2 and 3 h after PXT002331 administration); all monkeys treated with PXT002331+L-dopa showed a significant improvement in parkinsonian score. (D) Combined treatment using PXT002331+low dose of L-dopa—dose-response evaluation for different doses of PXT002331; assessment of parkinsonian scores at day 4; “Veh”=vehicle; “low LD”=low dose of L-dopa; “LD opt”=optimal dose of L-dopa; *=P<0.05 vs low LD; statistical analysis: non-parametric one-way repeated, measures ANOVA (Friedman's test), followed by Dunn's multiple comparison; N=7. (E) Computerized locomotor activity in early-stage PD monkey model for PXT002331 in combination with L-dopa (low dose or optimal dose) upon oral administration; *=P<0.05 vs vehicle; **=P<0.01 vs vehicle; ***=P<0.001 vs vehicle; statistical analysis: Friedman followed by Dunnett's; N=5 (6 monkeys/1 excluded). (F) Combined treatment using PXT002331+optimal dose of L-dopa—disability score and dyskinesia score.

[0072] The present invention particularly relates to the following items: [0073] 1. A compound of the following formula (I):

##STR00005##  or a pharmaceutically acceptable salt, solvate or prodrug thereof. [0074] 2. The compound of item 1, wherein said compound has the (E)-configuration at the oxime group comprised in formula (I). [0075] 3. The compound of item 1 or 2, wherein the pharmaceutically acceptable salt is a hydrochloride salt. [0076] 4. The compound of any one of items 1 to 3 for use as a medicament. [0077] 5. A pharmaceutical composition comprising the compound of any one of items 1 to 3 and a pharmaceutically acceptable excipient. [0078] 6. The compound of any one of items 1 to 3 or the pharmaceutical composition of item 5 for use in the treatment or prevention of a condition associated with altered glutamatergic signalling and/or functions, or a condition which can be affected by alteration of glutamate level or signalling. [0079] 7. Use of the compound of any one of items 1 to 3 for the preparation of a medicament for the treatment or prevention of a condition associated with altered glutamatergic signalling and/or functions, or a condition which can be affected by alteration of glutamate level or signalling. [0080] 8. A method of treating or preventing a condition associated with altered glutamatergic signalling and/or functions, or a condition which can be affected by alteration of glutamate level or signalling, the method comprising the administration of the compound of any one of items 1 to 3 or the pharmaceutical composition of item 5 to a subject in need thereof. [0081] 9. The compound or the pharmaceutical composition for use according to item 6 or the use of item 7 or the method of item 8, wherein said condition associated with altered glutamatergic signalling and/or functions, or said condition which can be affected by alteration of glutamate level or signalling is selected from: dementias, parkinsonism and movement disorders, acute or chronic pain, anxiety disorders, schizophrenia, mood disorders, endocrine and metabolic diseases, diabetes, disorders of the endocrine glands, hypoglycaemia, or cancers. [0082] 10. The compound or the pharmaceutical composition for use according to item 9 or the use of item 9 or the method of item 9, wherein said dementias are selected from: dementias of the Alzheimer's type (DAT); Alzheimer's disease; Pick's disease; vascular dementias; Lewy-body disease; dementias due to metabolic, toxic and deficiency diseases, including alcoholism, hypothyroidism, and vitamin B12 deficiency; AIDS-dementia complex; Creutzfeld-Jacob disease; or atypical subacute spongiform encephalopathy. [0083] 11. The compound or the pharmaceutical composition for use according to item 9 or the use of item 9 or the method of item 9, wherein said parkinsonism and movement disorders are selected from: Parkinson's disease; multiple system atrophy; progressive supranuclear palsy; corticobasal degeneration; hepatolenticular degeneration; chorea, including Huntington's disease and hemiballismus; athetosis; dystonias, including spasmodic torticollis, occupational movement disorder, and Gilles de la Tourette syndrome; tardive or drug induced dyskinesias, including levodopa-induced dyskinesia; tremor; or myoclonus. [0084] 12. The compound or the pharmaceutical composition for use according to item 9 or the use of item 9 or the method of item 9, wherein said anxiety disorders are selected from: panic disorders; phobias; obsessive-compulsive disorders; stress disorders, including post-traumatic stress disorder; or generalized anxiety disorders. [0085] 13. The compound or the pharmaceutical composition for use according to item 9 or the use of item 9 or the method of item 9, wherein said mood disorders are selected from depressive disorders or bipolar disorders. [0086] 14. The compound of any one of items 1 to 3 or the pharmaceutical composition of item 5 for use in the treatment or prevention of Parkinson's disease. [0087] 15. Use of the compound of any one of items 1 to 3 for the preparation of a medicament for the treatment or prevention of Parkinson's disease. [0088] 16. A method of treating or preventing Parkinson's disease, the method comprising the administration of the compound of any one of items 1 to 3 or the pharmaceutical composition of item 5 to a subject in need thereof. [0089] 17. The compound or the pharmaceutical composition for use according to any one of items 6 or 9 to 14 or the use of any one of items 7, 9 to 13 or 15 or the method of any one of items 8 to 13 or 16, wherein said compound, said pharmaceutical composition or said medicament is to be administered orally. [0090] 18. The method of any one of items 8 to 14, 16 or 17, wherein said subject is a human.

[0091] The invention will now be described by reference to the following examples which are merely illustrative and are not to be construed as a limitation of the scope of the present invention.

EXAMPLES

Example 1: Preparation of the Compound of Formula (I)

[0092] 1) General Synthetic Route

[0093] The compound of formula (I) according to the invention (i.e., PXT002331) can be prepared from readily available starting materials by several synthetic approaches, using solution-phase or solid-phase chemistry protocols, or mixed solution and solid phase protocols. For example, the compound of formula (I) can be prepared using the synthetic schemes depicted below.

##STR00006##

[0094] The commercially available bromo acetophenone I is reacted with commercial thieno[3,2-c]pyridine methyl ester II in a solvent such as tetrahydrofuran (THF) and in the presence of a weak base like potassium tert-butoxide (tBuOK) to yield the intermediate diketone III. This procedure is known as Baker Venkataraman rearrangement (Baker, W., J. Chem. Soc, 1933, 1381).

[0095] The intermediate diketone III is then cyclized under acidic conditions in the presence of a strong dehydrating agent like sulfuric acid (H.sub.2SO.sub.4) in refluxing acetic acid (AcOH) to yield the chromone IV.

##STR00007##

[0096] Introduction of the oxime may be obtained by reacting the derivative IV with hydroxyl amine hydrochloride (HONH.sub.2, HCl) in pyridine or ethanol under microwave conditions to yield directly the chromone oxime advanced intermediate that would lead to PXT002331 in a couple of reaction steps. This advanced intermediate leading to PXT002331 can be also obtained by using a two-step procedure as depicted above using tert-butyl hydroxylamine hydrochloride (tBuONH.sub.2, HCl) in ethanol followed in a subsequent step by deprotection of the tert-butyl group under acidic conditions like hydrochloric acid (HCl) in a mixture of polar solvent such as THF and acetic acid.

##STR00008##

[0097] Introduction of the alkylene side chain is obtained by a palladium catalyzed cross-coupling reaction such as Negishi cross-coupling using a commercially available zinc reagent and appropriate ligand/palladium catalytic system. Subsequent functionalization followed by standard reductive amination using weak reducing agents such as triacetoxy borohydride yield advanced intermediate VII in good yields. Final deprotection of the oxime protecting group under acidic conditions lead to the compound of formula (I), i.e. PXT002331.

[0098] 2) Synthesis of the Compound of Formula (I)

[0099] The commercially available starting materials used in the following experimental description were purchased from Aldrich, Sigma, ACROS or ABCR unless otherwise reported.

[0100] The compounds described in the following have been named according to the standards used in the program AutoNom v1.0.1.1 (MDL Information Systems, Inc.).

[0101] .sup.1H NMR analyses were carried out using BRUKER NMR, model DPX-400 MHz FT-NMR. Residual signal of deuterated solvent was used as internal reference. Chemical shifts (δ) are reported in ppm in relative to the residual solvent signal (δ=2.50 for .sup.1H NMR in DMSO-d.sub.6, and 7.26 in CDCl.sub.3). s (singlet), d (doublet), t (triplet), q (quadruplet), br (broad). Some compounds in the experimental part exist as mixture of E/Z isomers in different ratios. E/Z isomer ratio was well determined for the final compound PXT002331.

[0102] The MS data provided herein below were obtained as followed: Mass spectrum: LC/MS Waters ZMD (ESI).

[0103] HPLC analyses were obtained as followed using a Waters X-bridge™ C8 50 mm×4.6 mm column at a flow of 2 mL/min; 8 min gradient H.sub.2O:CH.sub.3CN:TFA from 100:0:0.1% to 0:100:0.05% with UV detection (254 nm).

[0104] The mass directed preparative HPLC purifications were performed with a mass directed auto purification Fraction lynx from Waters equipped with a Sunfire Prep C18 OBD column 19×100 mm 5 μm, unless otherwise reported. All purifications were performed with a gradient of ACN/H.sub.2O or ACN/H.sub.2O/HCOOH (0.1%).

[0105] The compound of formula (I) was prepared as shown in the following reaction scheme:

##STR00009##

Steps 1 and 2: 6-Bromo-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one (3)

[0106] ##STR00010##

[0107] To a suspension of potassium tert-butoxide (156.0 g, 1.39 mol, 3.0 eq) in THF (500 mL) at 0° C. was added a solution of 5-bromo-2-hydroxyacetophenone (100.0 g, 0.47 mol, 1 eq) in THF (500 mL). The reaction mixture was stirred vigorously for 10 minutes. A solution of thienopyridine ester (98 g, 0.51 mol, 1.1 eq) in THF (1.0 L) was added to the reaction mixture. The resulting reddish suspension was refluxed for 1 h, at which time LC/MS analysis indicated completion of the reaction. The reaction mixture was cooled to room temperature (RT) to give a thick orange suspension and poured into ice water (5.0 L). The aqueous layer was neutralized by addition of an aqueous HCl solution (1.5 N) under vigorous stirring. The resulting yellow solid was collected by filtration, washed with water and dried under suction. The crude mass was again further dried overnight under pressure at 45° C. for 16 h, which yielded 156 g of a yellow solid.

[0108] The yellow solid (156 g) was then suspended at RT in glacial acetic acid (1.0 L) and concentrated H.sub.2SO.sub.4 (10 mL). This mixture was heated at 110° C. for 2 hours. The reaction mixture turned into a brown suspension. After confirming completion of the reaction (by LC/MS), the crude mass was suspended in ice water (2.0 L) and neutralized by addition of an aqueous NaOH solution (1 N). The precipitated beige solid obtained was collected by filtration, washed with water and dried under suction. The material was further dried one night at 50° C. under high vacuum to yield 140.0 g of the title compound as a beige solid.

[0109] Yield: 83%.

[0110] LC/MS: Mass found (m/z, M+1, 358.0), Area 94.78%.

[0111] .sup.1H NMR (DMSO-d.sub.6, 400 MHz) δ 9.32 (s, 1H), 9.06 (s, 1H), 8.15 (m, 2H), 8.06 (m, 1H), 7.84 (d, J 5.4 Hz, 1H), 7.77 (d, J 5.4 Hz, 1H), 7.32 (s, 1H).

Step 3: 6-Bromo-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one O-tert-butyl-oxime (4)

[0112] ##STR00011##

[0113] In a sealed tube, a suspension of 6-bromo-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one (20.0 g, 56 mmol, 1 eq) and O-tert-butyl hydroxylamine hydrochloride (14.0 g, 112 mmol, 2 eq) in anhydrous EtOH (300 mL) was heated at 115° C. for 20 hours. After confirming the reaction completion by TLC, the reaction mixture was filtered and the yellow solid washed twice with cold EtOH (50 mL) and dried under vacuum to yield 20 g of the title compound as a yellow solid.

[0114] Yield: 83%.

[0115] LC/MS: Mass found (m/z, M+1, 429.0), Area 97.83%.

[0116] .sup.1H NMR (DMSO-de, 400 MHz) δ 9.25 (s, 1H), 8.78 (s, 1H), 8.05 (m, 2H), 7.71 (m, 2H), 7.59 (s, 1H), 7.48 (s, 1H), 1.40 (s, 9H).

Step 4: 6-(2-[1,3]Dioxolan-2-yl-ethyl)-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one O-tert-butyl-oxime (5)

[0117] ##STR00012##

[0118] To a degassed solution of 6-bromo-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one O-tert-butyl-oxime (100.0 g, 233 mmol, 1 eq) and 2-di-tert-butylphosphino-2′,4′,6′-triisopropylbiphenyl (4.9 g, 11.6 mmol, 0.05 eq) in anhydrous THF (500 mL) was added palladium (II) acetate (2.6 g, 11.6 mmol, 0.05 eq) followed by 2-(1,3-dioxolan-2-yl)ethylzinc bromide solution (0.5 M in THF, 652 mL, 362 mmol, 1.5 eq). The reaction mixture was heated at 100° C. for 14 hours. After confirming completion of the reaction by LC/MS, the reaction mixture was quenched with water (20 mL) and concentrated under vacuum. The resulting crude yellow oil was purified by chromatography on silica gel using cyclohexane/ethyl acetate (80/20) as eluent to afford 85 g of the title compound as a yellow solid.

[0119] Yield: 82%

[0120] HPLC: 93.00% (254 nm), RT: 2.50 min.

[0121] LC/MS: Mass found (m/z, M+1, 451.0), Area 93.96%.

[0122] .sup.1H NMR (DMSO-de, 400 MHz) δ 9.27 (s, 1H), 8.77 (s, 1H), 8.05 (d, J 5.4 Hz, 1H), 7.78 (s, 1H), 7.73 (d, J 5.4 Hz, 1H), 7.62 (s, 1H), 7.43 (m, 2H), 4.85 (m, 1H), 3.93 (m, 2H), 3.80 (m, 2H), 2.75 (m, 2H), 1.90 (s, 2H), 1.39 (s, 9H).

Step 5: 3-(4-tert-Butoxyimino-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-6-yl)-propionaldehyde (6)

[0123] ##STR00013##

[0124] To a solution of 6-(2-[1,3]dioxolan-2-yl-ethyl)-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one O-tert-butyl-oxime (100.0 g, 222 mmol, 1 eq) in THF (1.0 L) was slowly added an aqueous solution of HCl (3 N, 1.0 L). The resulting yellow mixture was stirred at room temperature for 24 hours to give a thick yellow emulsion. After completion of the reaction (LC/MS), the reaction mixture was neutralized by addition of an aqueous saturated solution of NaHCO.sub.3 and extracted with CH.sub.2Cl.sub.2 (2×5.0 L). The combined organic extracts were washed with brine (2.0 L), dried over magnesium sulfate, filtered and concentrated under vacuum to yield 89 g of the title compound as a yellow solid. The resulting yellow solid was taken crude to the next step without further purification.

[0125] Yield: 92%

[0126] LC/MS: Mass found (m/z, M+1, 407.3), Area 91%.

[0127] .sup.1H NMR (CDCl.sub.3, 400 MHz) δ 9.79 (s, 1H), 9.09 (s, 1H), 8.39 (s, 1H), 7.82 (s, 1H), 7.67 (s, 1H), 7.52 (d, J 5.4 Hz, 1H), 7.43 (d, J 5.4 Hz, 1H), 7.17 (m, 2H), 2.93 (m, 2H), 2.77 (s, 2H), 1.37 (s, 9H).

Step 6: 6-(3-Morpholin-4-yl-propyl)-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one O-tert-butyl oxime (7)

[0128] ##STR00014##

[0129] To a mixture of 3-(4-tert-butoxyimino-(2-thieno[3,2-c]pyridin-6-yl)-4H-chromen-6-yl)-propionaldehyde (100.0 g, 246 mmol, 1 eq), morpholine (50 mL, 492 mmol, 2 eq) in CH.sub.2Cl.sub.2 (1.0 L) and Methanol (500 mL) was added sodium triacetoxyborohydride (104 g, 492 mmol, 2 eq) under N.sub.2 atmosphere. The reaction mixture was stirred at room temperature for 3 hours.

[0130] After completion of the reaction by LC/MS, the mixture was neutralized by addition of an aqueous saturated solution of NaHCO.sub.3 and extracted with CH.sub.2Cl.sub.2 (2×5.0 L). The combined organic extracts were washed with brine (2.0 L), dried over sodium sulfate, filtered and concentrated under vacuum to afford a thick brown solid. The resulting crude brown solid was purified by chromatography on silica gel to afford 73.0 g of the title compound as a yellow solid.

[0131] Yield: 63%.

[0132] HPLC: 95.97% (254 nm).

[0133] LC/MS: Mass found (m/z, M+1, 478.3), Area 96.62%.

[0134] .sup.1H NMR (DMSO-d.sub.6, 400 MHz) δ 9.24 (s, 1H), 8.74 (s, 1H), 8.03 (d, J 5.4 Hz, 1H), 7.76 (s, 1H), 7.70 (d, J 5.4 Hz, 1H), 7.59 (m, 1H), 7.39 (m, 2H), 3.56 (m, 4H), 2.65 (m, 2H), 2.28 (m, 6H), 1.73 (m, 2H), 1.36 (s, 9H).

Step 7: 6-(3-Morpholin-4-yl-propyl)-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one oxime

[0135] ##STR00015##

[0136] To a stirred solution of 6-(3-morpholin-4-yl-propyl)-2-(thieno[3,2-c]pyridin-6-yl)-4H-chromen-4-one O-tert-butyl oxime (10.0 g, 21 mmol, 1 eq) in acetic acid (100 mL) was added a solution of dioxane-HCl (4 M, 150 mL, 3 eq) at room temperature under inert atmosphere. The reaction mixture was heated at 80° C. for 14 hours (LC/MS monitoring indicated 100% conversion). The organic solvents were concentrated under vacuum where a solid mass started to precipitate. The yellow solid was filtered off, washed with dioxane (200 mL), Et.sub.2O (2×50 mL) to afford 8 g of a yellow solid as a HCl salt.

[0137] Yield: 90%

[0138] HPLC purity: 98.44% (254 nm). E/Z ratio=97.54%/1.75%.

[0139] LC/MS: Mass found (m/z, M+, 422.3), Area 97.3%.

[0140] .sup.1H NMR (DMSO, 400 MHz) δ 11.06 (brs, 1H), 10.72 (brs, 1H), 9.28 (s, 1H), 8.80 (s, 1H), 8.07 (d, J 5.4 Hz, 1H), 7.76-7.70 (m, 3H), 7.47-7.41 (m, 2H), 3.95 (m, 2H), 3.80 (m, 2H), 3.42, (m, 2H), 3.08 (m, 4H), 2.71 (m, 2H), 2.10 (m, 2H).

Example 2: Biological Evaluation of the Compound of Formula (I)

[0141] The compound of formula (I) according to the invention (i.e., PXT002331) was tested for its agonistic and/or positive allosteric modulator activity on human mGluR4 using the calcium assay described in Example 171 of WO 2011/051478. PXT002331 was found to have a potency of pEC.sub.50=7.12 (corresponding to an EC.sub.50 of about 0.076 μM), which is comparable to that of the compound of Example 127 of WO 2011/051478 (i.e., “PXT001858”) which has a pEC.sub.50 of 7.44 (corresponding to an EC.sub.50 of about 0.036 μM).

##STR00016##

[0142] The in vitro ADME profile of PXT002331 was also very similar with reference to phase I metabolic stability: CL (h/r): 55/101 μl/min/mg protein and intestinal absorption: CaCo-2 (A-B, pgp): 4.11 0.10-6 cm/s, no efflux.

[0143] In both cases, i.e. PXT002331 and PXT001858, plasma protein binding was high with less than 1% of free fraction and compounds do not suffer from a lack of solubility (s>10 mg/ml in water) as hydrochloride salt.

[0144] However, despite very similar physico-chemical properties and ADME profiles, PXT002331 was found to show an unexpected, highly advantageous oral in vivo PK profile when compared to PXT001858, as described in the following.

[0145] In Vivo Pharmacokinetics Evaluation:

[0146] PXT002331 and PXT001858 were administered per os (p.o.) at 10 mg/kg to male Sprague-Dawley rats. Volume of administration was 10 ml/kg. In parallel, PXT002331 was also administered intravenously (i.v.) at 1 mg/kg, with a volume of administration of 2 ml/kg. Blood samples (200 μl) were collected at time ranging from 15 minutes to 24 hours for the p.o. administration and from 5 minutes to 24 hours for the i.v. administration in ice-cold tubes containing 0.2% K.sub.2EDTA. Tubes were centrifuged at 10,000 rpm for 5 minutes at 4° C. The plasma (supernatant) was separated in another tube and stored at −80° C. until analysis. Two groups of 3 animals were used for each route of administration: in one group, blood samples were collected to determine the kinetics of plasma exposure over a 24-hour period, and in the second group, blood and brain were collected at one terminal time point (0.5, 1.0, 1.5, 2.0, 4.0 hours) to determine the kinetics of brain exposure and brain/plasma ratio.

[0147] Compound Analysis:

[0148] The respective parent compound (free base) was analysed in plasma samples and in brain homogenate using a LC-MS/MS method. Concentrations are expressed in ng/ml of plasma or in ng/g of brain tissue.

[0149] Results:

[0150] At 10 mg/kg, using the same vehicle (Tween-80/Ethanol/30% HPBCD (2/10/88)), PXT002331 showed a comparable plasma exposure than PXT001858 as reflected by its AUC (1.1-fold) and Cmax (0.7-fold). Oral bioavailability of PXT002331 in this experiment was 39%. Despite their similar oral absorption, PXT002331 has a higher brain/plasma ratio (6.5 versus 2.0 at T=1.5 h; see FIG. 4) leading to a 3-fold improvement in the brain AUC when compared to PXT001858. A posteriori, one potential hypothesis might rely on the difference of phase II conjugation in the intestine and liver during oral absorption. When both compounds were assayed in vitro in the presence of UGT (UDP-Glucuronosyl transferase), PXT002331 showed a much lower level of glucuronidation as compared to PXT001858 (see table below). Nonetheless, this difference observed in vitro cannot by itself explain the unexpected advantageous PK results obtained with PXT002331. The results obtained in these experiments are furthermore summarized in Tables 1 to 3 below and in FIGS. 1 to 4.

TABLE-US-00001 TABLE 1 PK parameters of PXT002331 and PXT001858 after oral administration in rats at 10 mg/kg. Brain/Plasma Cmax Oral PK ratio (Brain) Plasma AUC Brain AUC 10mpk (T = 1.5 h) (ng/G tissue) inf (h * ng/ml) inf (h * ng/g) PXT002331 6.5 818 432 2713 PXT001858 2.0 521 394 838

TABLE-US-00002 TABLE 2 PXT002331 and PXT001858 in vitro glucuronidation (peak area) in rat liver microsomes. Time (min) 0 5 15 30 60 PXT002331 0 0 0 0    0 PXT001858 0 164 353 798 2 556

TABLE-US-00003 TABLE 3 PXT002331 and PXT001858 in vitro glucuronidation (peak area) in rat intestinal microsomes. Time (min) 0 5 15 30 60 PXT002331 0  2 492  4 724  8 369  16 897 PXT001858 0 13 840 30 396 68 072 14 8307

[0151] These results demonstrate that the compound of formula (I) according to the present invention, i.e. PXT002331, has highly advantageous pharmacokinetic properties and shows a considerably improved brain exposure as compared to the compound of Example 127 of WO 2011/051478 (“PXT001858”). These properties render the compound of formula (I) particularly suitable as a therapeutic agent, e.g., for the treatment or prevention of neurological and/or psychiatric disorders.

Example 3: In Vivo Evaluation of the Compound of Formula (I) in an MPTP Monkey Model of Parkinson's Disease

[0152] The anti-parkinsonian efficacy of the compound of formula (I) according to the present invention (i.e., PXT002331) was evaluated in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) macaque model of Parkinson's disease (using macaques of the species Macaca fascicularis), which reproduces most of the clinical and pathological hallmarks of Parkinson's disease and is considered a “gold standard” (see Porras G et al., Cold Spring Harb Perspect Med., 2(3):a009308, 2012 and references cited therein for a general description of the MPTP model).

[0153] The results of these studies are summarized in FIGS. 5A to 5F. In particular, it was found that PXT002331 as a stand-alone treatment shows potent anti-parkinsonian activity in MPTP-treated macaques, with an optimal improvement of the parkinsonian score at administration doses of 2 to 25 mg/kg perorally (p.o.) twice a day (see FIG. 5A). In this experiment, PXT002331 was orally administered twice a day during a period of 4 days, and the parkinsonian score was assessed at day 4 over 2 hours of observation (data are mean values+standard error of the mean (s.e.m.); n=7 monkeys per group).

[0154] The anti-parkinsonian efficacy of PXT002331 (25 mg/kg) was further evaluated in combination with low (suboptimal) doses of L-dopa (levodopa; 4-9 mg/kg) (see FIGS. 5B and 5C). Doses were orally administered twice a day during 4 days, and assessment of parkinsonian scores took place at day 4 (between 1 and 2 h after L-dopa administration, i.e., between 2 and 3 h after PXT002331 administration). As also shown in FIG. 5B, it was found that the combined administration of PXT002331 and a suboptimal dose of L-dopa gave a considerable improvement in parkinsonian score as compared to the administration of L-dopa (suboptimal dose) alone. These data furthermore point to an increase of the “on”-time achieved by PXT002331 in combination with L-dopa, which is a clinically highly relevant advantage, as also reflected by the fact that “on”-time is an endpoint for the assessment of clinical efficacy in phase 3 in Parkinson's disease patients. Remarkably, all treated monkeys showed a significant improvement in parkinsonian score, which indicates a high robustness of the anti-parkinsonian effect of PXT002331 (see FIG. 5C). These results confirm that PXT002331 can advantageously be used as an add-on treatment together with L-dopa (levodopa).

[0155] The results of a dose-response evaluation of the combination of PXT002331 (at doses from 2 mg/kg to 100 mg/kg) with L-dopa (low dose) are shown in FIG. 5D (the assessment of parkinsonian scores took place at day 4). It was found that PXT002331 in combination with L-dopa provides a highly potent anti-parkinsonian effect upon oral administration over a range of different doses. The optimal anti-parkinsonian efficacy was achieved with administration doses of PXT002331 of 2 mg/kg to 25 mg/kg.

[0156] A significant improvement in locomotor activity could further be demonstrated for PXT002331 (25 mg/kg) administered orally in combination with either a low dose of L-dopa or an optimal dose of L-dopa, as also shown in FIG. 5E (early stage PD monkey model; N=5). In this experiment, each monkey was equipped with a detector of movements and signals were collected with 24 light beams and a video track recorder in order to descriminate all types of movements. The locomotor activity was measured during 1 hour.

[0157] As shown in FIG. 5F, it was furthermore found that increasing doses of PXT002331 in combination with L-dopa (optimal dose) provided an improvement in the disability score, without inducing dyskinesia. A particularly advantageous improvement in the disability score could be achieved using 25 mg/kg PXT002331 in combination with L-dopa (optimal dose). Moreover, none of the tested combinations of PXT002331 (at doses from 25 mg/kg to 100 mg/kg) with an optimal (high) dose of L-dopa resulted in any induction of dyskinesia, which is an undesirable adverse effect that typically occurs during treatment with L-dopa.

[0158] These findings confirm that PXT002331 is highly advantageous for use in the treatment or prevention of Parkinson's disease, both in monotherapy (without the concomitant use of further antiparkinson drugs) and in cotherapy using further antiparkinson drugs such as L-dopa (levodopa). In these experiments, doses of 2 mg/kg to 25 mg/kg of PXT002331, to be orally administered twice per day, were found to be particularly efficacious.