GB2352631A - Inverse agonist of GABA-A alpha-5 receptor subtype & spheron disruption inhibitor combination for treating neurodegenerative conditions eg Alzheimer's disease - Google Patents

Abstract

There is disclosed a combination of a spheron (or dense protein microsphere) disruption inhibitor and an inverse agonist of the GABA<SB>A</SB> a <SB>5</SB> receptor subtype, and the use of the combination in treating neurodegenerative conditions such as Alzheimer's Disease. These components act synergistically, thereby allowing for a lower overall dose of each to be administered, thus reducing side effects and decreasing any loss of effectiveness arising over a period of sustained use. GABA<SB>A</SB> a 5 inverse agonists include compounds of formula (I) or a pharmaceutically acceptable salt thereof (where the substituents are as defined in the specification): <EMI ID=1.1 HE=45 WI=62 LX=864 LY=1585 TI=CF> <PC>and <EMI ID=1.2 HE=42 WI=47 LX=935 LY=2079 TI=CF> A particularly favoured compound is 3-(5-methylisoxazol-3-yl)-6-(1-methyl-1,2,3-triazol-4-yl)methyloxy-1,2,4-triazolo[3,4-a]-phthalazine. Spheron disruption inhibitors include 1-(diphenylmethyl)-piperazines and diphenylmethyl ethers.

Description

2352631 THERAPEUTIC COMBINATION FOR TREATING ALZHEIMER'S DISEASE The

present invention relates to a combination of a spheron disruption inhibitor and an inverse agonist of the GABAA a5 receptor subtype, and the use of the combination in treating neurode generative conditions such as Alzheimer's Disease.

Alzheimer's Disease is a poorly understood neurodegenerative condition mainly affecting the elderly but also younger people who are generally genetically predispositioned to it.

The present invention provides a new and surprisingly effective synergistic combination of a spheron disruption inhibitor and an inverse agonist of the GABAA a5 receptor subtype.

The present invention provides a greater than expected improvement in the condition of subjects suffering from a neurode generative disorder with an associated cognitive deficit, such as Alzheimer's Disease or Parkinson's disease, or from a cognitive deficit which may arise from a normal process such as aging or from an abnormal process such as injury, than would be expected from administration of the active ingredients alone. Further, the combination allows for a lower overall dose of each of the active ingredients to be administered thus reducing side effects and decreasing any reduction in the effectiveness of each of the active ingredients over time.

Any inverse agonist of the GABAA a5 receptor subtype may be used which fulfills the criteria of WO-A-9625948. The inverse agonist may be either binding selective for the a5 subtype or functionally selective, or both. Thus the inverse agonist is preferably an antagonist, or has insignificant agonist or inverse agonist properties at the other GABAA a receptor subtypes when measured in oocytes as described in WO-A-9625948. Specific compounds are disclosed in WO-A-9804560, WO-A-9818792, WO-A-9850385, WO-A9962899 and WO-A-0012505.

A particularly favoured. compound for use in the present invention is 3(5methyllsoxazol-3-yl)-6-(l-methyl-1,2,3-triazol-4-yl)methyloxy-1,2,4-.

triazolo[3,4-a]-phthalazine.

A further class of GABAA cc5 inverse agonists which can be used the present invention includes a compound of formula (1) or a pharmaceutically acceptable salt thereof- 0 0 Ar N N H R N R 4 wherein:

R1 and R4 are independently chosen from hydrogen, halogen, Cj-r' alkyl, C2-6 alkenyl, C2-6 alkynyl, Cl-(3 haloalkyl, C2-6 haloalkenyl and C2-r' haloalkynyl:

R2 is hydrogen or Ci-6 alkyl; and Ar is phenyl, a 5-membered heterocyclic group containing 1, 2, 3 or 4 heteroatoms chosen from N, 0 and S, no more than one of which is 0 or S, or a 6-membered heterocyclic group containing one or two nitrogen atoms, each of which groups Ar is unsubstituted. or substituted by from one to three groups independently chosen from halogen, CI-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C3-7 cycloalkyl, C1-6 alkoxy, C2-6 alkenyloxy, C2-6 alkynyloxy, C3-7 cycloalkoxy, C1-6 haloalkyl, C2-6 haloalkenyl, C2-6 haloalkynyl, amino, Cl-r, alkylamino, di(Cl-6)alkylamino, hydroxy, hydroxy Ci-r, alkyl, cyano, nitro, amino Cl-r, alkyl, C1.6 alkylaminoCl-6 alkyl or di(CI-6 alkyl)aminoalkyl.

RI is preferably hydrogen, halogen or C1-6 alkyl and is particularly hydrogen.

R2 is preferably hydrogen or methyl especially hydrogen.

Ar is preferably phenyl or pyridine. When Ar is pyridine it may be 25 pyridine.

Ar is preferably unsubstituted or substituted with one or two groups independently selected from methyl, fluoro, chloro, methoxy, ethoxy, aminomethyl, aminoethyl or hydroxy, especially from methoxy, fluoro and aminoethyl.

Specific Examples of compounds of this class are:

4-oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid phenylamide; 4-oxo-4,5,6,7-tetrahydro-IH-indazole-3-carboxyhe acid-2, 5difluorophenylamide; 4-oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid pyridin-2- ylamide; 4-oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid 4methoxyphenylamide; and 4-oxo-4,5,6,7-tetrahydro-IH-indazole-3-carboxylic acid 4(2aminoethyl)phenylamide; and the pharmaceutically acceptable salts thereof The compounds may be prepared byreacting a compound of formula II with a compound of formula III:

0 0 i OH H2N- Ar R ----WN N wherein R1, R2, R4 and Ar are as defined above. The reaction is generally carried out in a mixture of DMF/DCM and in the presence of a coupling agent such as 1-(3-dimethylaminopropyl)-3-ethyI carbodlimide hydrochloride and dimethylaminopyridine. The reaction is generally carried out for about 36h.

If necessary any reactive portions of the moiety Ar are protected with a protecting group such as tert-butyloxycarbonyl. Such protecting groups can be removed after reaction of the compounds of formulae II and III to yield a compound of formula 1.

The compound of formula II can be made by hydrolyzing a compound of formula IV:

0 0 1 1 0----" N R1 N, N 4 R (IV) wherein R', R2 and R4 are as defined above, with a base such as NaOH generally by heating at reflux for about 3h in a solvent such as EtOH.

The compound of formula IV wherein R2 is other than hydrogen can be made by reaction of a compound of formula IV where R2 is hydrogen with a strong base such as Na H followed by alkylation for example with the appropriate alkyl iodide.

The compound of formula IV is made by reacting a compound of formula V with a compound of formula VI:

0 0 H(R2)NNH2.HCI R 0 0 R 4 M (VI) The compound of formula V is made by reacting a compound of formula VII with a compound of formula VIII:

0 CIC(O)C(O)OEt R 0 R 4 (Vil) (Vill) wherein RI and R4 are as defined above and the compound of formula VII is generally pre-reacted with trimethvlsilylchloride.

wherein R2 is as defined above, generally in a solvent such as DMF and 10 in the presence of a base such at Et3N at about 50'C for about 3 days.

Compounds of formulae III, V, VI, VII and VIII are commercially available or can be made from commercially available compounds by methods known in the art.

REFERENCE EXAMPLE 1 4-Oxo-4,5,6,7-tetrahydro-IH-indazole-3-carboxyhc acid phenylamide Step 1: 4-Oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboMlic acid ethyl ester A solution of 2-ethyloxalylcyclohexan-1,3-dione (6g, 28mmol) (Synthesis, 1976, 722) in DMF (30mL) was treated with hydrazine hydrochloride (1.9g, 28mmol) and triethylamine (3.9mL, 28mmol) and heated at 500C for 3 days. After evaporating to dryness the residue was partitioned between water and DCM and the organic layer separated. The aqueous phase was re-extracted with DCM (x 2) and the combined organic layers dried (MgS04) and evaporated. The residue was purified by column chromatography on silica gel, using MeOH:DCM (2:98) as the eluent, to give an orange solid. The solid was trituated with ether to give the title compound (640mg, 11%) as a yellow solid. IH NMR (250MHz, d6-DMSO) 8 1.28 (3H, t, J=7.lHz), 2.00-2.10 (2H, in), 2.41 (2H, t, J=6.8Hz), 2.87 (2H, t, J=6. 2Hz), 4.26 (2H, q, J=7.lHz), 13.62 (1H, br s). MS, (CI)+ 209 (M+H)+. Found: C, 57.39; H, 5.76; N, 13.37%. CjoH12N203 requires: C, 57.69; H, 5. 81; N, 13.45%.

Step 2: 4-Oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid A solution of the foregoing ethyl ester (450mg, 2.2mmol) in EtOH (3mL) and NaOH (4N, 15mL) was heated at reflux for 3h. The cooled solution was acidified (conc. HCI), and the resultant solid isolated by filtration and washed with water. The solid was dried at 450C in a vacuum oven to give the title compound (265mg, 67%) as a beige solid. 1H NMR (360MHz, d6- DMSO) 5 2.08-2.15 (2H, m), 2.60-2.64 (2H, in), 2.84-2.98 (2H, m), 14.03 (IH, br s). MS. (CI)+ 181 (M+H)+. Found: C, 52.33; H, 4.24; N, 15.00%. C8H8N2030.21420 requires: C, 52.29; H, 4.61; N, 15.24%.

Step 3: 4-Oxo-4,5,6,7-tetrah-vdro-lH-indazole-3-carboxylic acid Phenylamide A suspension of the foregoing carboxylic acid (100mg, 0.55mmol) in DMF (2mL) and DCM (5mL) was treated with 1-(3-dimethylaminopropyl)-3- ethyl carbodiimide.hydrochloride (160mg, 0.83mmol), 4dimethylaminopyridine (101mg, 0.83mmol) and aniline (77mg, 0.83mmol). The resultant solution was stirred for 36h then diluted with DCM (20mL) and washed with water (x1), 1N HC1 (x2), sat. NaHCO3 (xI) and water (x1). The organic layer was dried (MgS04) and evaporated. The residue was purified by column chromatography on silica gel, eluting with DCM:MeOH (97:3) to give the title compound (90mg, 64%) as a colourless solid. mp 244'C (dec. ). 1H NMR (50OMHz, d6-DMSO) 5 2.09-2.14 (2H, m), 2.63-2.67 (2H, m), 2.802. 95 (2H, m), 7.05-7.15 (1H, m) 7.30-7.40 (2H, m), 7.70-7.75 (2H, m) 12.24 (1H, br s), 13.68 and 14.20 (1H, 2 x br s) MS. (CI)+ 256 (M+H)+. Found: C, 64.22; H, 5.00; N, 15.97%. C14H13N302-0.3H20 requires: C, 64.51; H, 5.26; N, 16.12%.

REFERENCE EXAMPLE 2 4-Oxo-4,5,6,7-tetrahydro-IH-indazole-3-carboiylic acid-2,5 difluorophenylamide The title compound was obtained using the procedure described in Example 1, Step 3 using 2,5-difluoroanihne. The amide (15mg, 19%) was isolated as a colourless solid. 1H NMR (400 MHz, dc,-DMSO) 8 2.05-2.15 (2H, m), 2.60-2.68 (2H,m), 2.85-2.98 (2H, br s), 6.92-7.04 (IH, m), 7.30-7.40 (IH, in), 8.20-8.28 (1H, in), 12.43 (IH, br s), 13.83 and 14.35 (1H, 2 x br s). MS, (Cl)+ 292 (M+H)+.

REFERENCE EXAMPLE 3 4-Oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid pyridin-2-ylamide The title compound was obtained using the procedure described in Example 1, Step 3 using 2-aminopyridine. The amide (33mg, 46%) was isolated as a cream solid. -mp 250'C (dec.). IH NMR (40OMHz, d6-DMSO) 6 2.05-2.15 (2H, m), 2.62 (2H, t, J=6.2Hz), 2.85-2.95 (2H, br s). 7.10-7.20 (IH, in), 7.78-7.88 (IH, in), 8.24 (1H, d, J=8.3Hz), 8.35-8.41 (IH, m), 12.55 (1H, s), 13.78 and 14.26 (1H, 2 x br s). Found: C, 60.34; H, 4.34; N, 21.19%.

C13H12N402-0.05 CH202requires: C, 60.17; H, 4.68; N, 21.51%. MS (CI)+ 257 (M+H)+.

REFERENCE EXAMPLE 4 4-Oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid 4methoMhenylamide The title compound was obtained using the procedure described in Example 1, Step 3 using p-anisidine. The amide (15mg, 19%) was isolated as a beige solid. 1H NMR (40OMHz, d6-DMSO) 8 2.07-2.13 (2H, m), 2.63 (2H, t, J=6.3Hz), 2.82-2.94 (2H, in), 3.76 (3H, s), 6.95 (2H, d, J=8.9Hz), 7.63 (2H, dd, J=6.8 and 2. 1Hz), 12.14 (1H, br s), 13.65 and 14.20 (IH, 2 x br s). MS, (Cl)+:

286 (M+H)+.

REFERENCE KKAMPLE 5 4-Oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxylic acid 4-(2- aminoeth-vl)phenylamide Step 1: 2-(4-Aminophenyl)ethyl carbamic acid tert-butyl este A solution of 2-(4-aminophenyl)ethylamine (1g, 7.3mmol) in DCM (20mL) at room temperature was treated with triethylamine (0.82g, 7.7mmol). After 10 min the solution was cooled to -5'C. Di-tertbutyldicarbonate (1.68g, 7. 7mmol) was added portionwise over 10min and stirred for 30min before warming to room temperature. NaHC03 (sat. 2mL) was added followed by water (40mL). The organic layer was separated and aqueous re-extracted with DCM (x2-). The combined organic layers were dried (K2CO3) and evaporated. The residue was purified by column chromatography on silica gel, eluting with EtOAc:hexane (1:4) to obtain the title compound (1.4g, 80%) as a yellow solid. 1H NMR (360MHz, d6-DMSO) 8 1.37 (9H, s), 2.49-2.51 (2H, in), 2.99-3.06 (2H, m), 4.83 (2H, s), 6.49 (2H, d, J=8.3Hz), 6.77-6.80 (1H, m), 6.81 (2H, d, J=8.3Hz) MS (CI)+ 237 (M+H)+.

Step 2: [2-[4-(4-Oxo-4,5,6,7-tetrah-vdro-lH-indazole-315 carboLiyl)amino Jphen yl]ethyl carbamic acid tert-butyl ester The title compound was obtained using the procedure described in Example 1, Step 3 using the foregoing amine. The residue was purified by column chromatography on silica gel, eluting with DCM:MeOH (97:3) to give the amide (100mg, 45%) and was isolated as a colourless, low-melting solid.

H NMR (40OMHz, d6-DMSO) 1.37 (9H, s), 2.07-2.14 (2H, m), 2.63 (2H, t, J=6.4Hz), 2.69 (2H, t, J=7.lHz), 2.89 (2H, t, J=6.2Hz), 3.13-3.19 (2H, in), 6.52-6.65 (1H, in), 7.20 (2H, d, J=8.3Hz), 7.63 (2H, d, J=8.4Hz), 12.18 (IH, s), 14.00 (1H, br s).

Step 3: 4-Oxo-4,5,6,7-tetrahydro-lH-indazole-3-carboxyhc acid 442 aminoethvl)phenylamide A suspension of the foregoing carbamate (100mg, 0.25mmol) in DCM (5mL) was treated with trifluoroacetic acid (0.5mL) and stirred at room temperature for 5h. The mixture was evaporated and residue partitioned between water and MeOHJDCM (5:95) and neutralised with NaHC03 (sat.). 5 The organic layer was separated and the aqueous phase re-extracted with MeOH/DCM (5:95) (x2). The combined organic layers were dried (K2CO3) and evaporated. The residue was purified using column chromatography on silica gel, eluting MeOH:DCM (10:90) followed by DCM:MeOH:NH3 (80:20:1). The title compound (35mg, 47%) was isolated as a cream solid. mp 250'C (dec.).

1H NMR (360MHz, d6-DMSO) 8 2.06-2.14 (2H, m), 2.63 (2H, t, J=6.7Hz), 2.68 (2H, t, J=6.9Hz), 2.84 (2H, t, J=7.6Hz), 2.89 (2H, t, J=6.4Hz), 7.24 (2H, d, J=8.4Hz), 7.67 (2H, d, J=8.5Hz), 12.39 (1H, s). MS, (CI)+ 299 (M+H)+.

A further class of GABAA cc5 inverse agonists which can be used in the present invention includes a compound of the formula I:

N-N R T 'z N T 3 N 2 XT" L-Y-X wherein:

R1 is hydrogen, halogen or CN or a group CF3, OCF3, C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy or C2-4alkynyloxy, each of which groups is unsubstituted or substituted with one or two halogen atoms or with a pyridyl or phenyl ring each of which rings may be unsubstituted or independently substituted by one or two halogen atoms or nitro, cyano, amino, methyl or CF3 groups; R2 is hydrogen, halogen or CN or a group CF3, OCF3, C1.4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy or C2-4alkynyloxy each of which groups is unsubstituted or substituted with one or two halogen atoms; L is 0, S or NRn where Rn is H, C1.6alkyl or C3-6cycloalkyl; one of T', T2, T3 and T4 is nitrogen and the others are CH; X is a 5-membered heteroaromatic ring containing 1, 2, 3 or 4 heteroatoms independently chosen from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur, or a 6-membered heteroaromatic ring containing 1, 2 or 3 nitrogen atoms, the 5- or io 6-membered heteroaromatic ring being optionally fused to a benzene ring and the heteroaromatic ring being optionally substituted by Rx and/or Ry and/or RZ, where Rx is halogen, R3, OR3, OCOR3, NR4R5, NR4COR5, tri(CI-6alkyl)silylCI-6alkoxyCl-4alkyl, CN or R9, Ry is halogen, R3, OR3, OCOR3, NR4R5, NR4COR5 or CN and Rz is R3, OR-3 or OCOR3, where R3 is C1-6alkyl, C2-ralkenyl, C2-6alkynyl, C3-6cycloalkyl, hydroxyCl-6alkyl and R3 is optionally mono, di- or tri-fluorinated, R4 and R5 are each independently hydrogen, C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C3.6cycloalkyl or CF3 or R4 and R5, together with the nitrogen atom to which they are attached, form a 4-7 membered heteroaliphatic ring containing the nitrogen atom as the sole heteroatom, and R9 is benzyl or an aromatic ring containing either 6 atoms, 1, 2 or 3 of which are optionally nitrogen, or 5 atoms, 1, 2 or 3 of which are independently chosen from oxygen, nitrogen and sulphur, at most one of the atoms being oxygen or sulphur, and R9 is optionally substituted by one, two or three substituents independently chosen from halogen atoms and CI-4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy and C2-4alkynyloxy groups each of which groups is unsubstituted or substituted by one, two or three halogen atoms, and when X is a pyridine derivative, the pyridine derivative is optionally in the form of the N-oxide and providing that when X is a tetrazole derivative it is protected by a-Cl-4alkyl group; or X is phenyl optionally substituted by one, two or three groups independently selected from halogen, cyano, CI-6alkyl, C2-6alkenyl, C2-6alkynyl and C3-6cycloalkyl; Y is optionally branched C1-4alkylidene optionally substituted by an oxo group or Y is a group (CH2)jO wherein the oxygen atom is nearest the group X and j is 2, 3 or 4; Z is a 5-membered heteroaromatic ring containing 1, 2 or 3 heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur and providing that when one of the atoms is oxygen or sulphur then at least one nitrogen atom is present, or a 6-membered heteroaromatic ring containing 2 or 3 nitrogen atoms, Z being optionally substituted by Rv and/or Rw, where Rv is halogen, R6, NR7R8' NR7COR8' CN, furyl, thienyl, phenyl, benzyl, pyridyl or a 5-membered heteroaromatic ring containing at least one nitrogen atom and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur and Rw is R6 or CN; R6 is CI-6alkyl, C2-r ,alkenyl, C2.ralkynyl, C3-6cycloalkyl, hydroxyCI-6alkyl, Ci-,salkoxy, C2-6alkenyloxy, C2-6alkynyloxy, CI-6alkoxyCl-6alkyl, CH2F or CF3; and R7 and R8 are each independently hydrogen, C1-6alkyl, C2.6alkenyl, C2-6alkynyl, C3.6cycloalkyl or CF3 or R7 and R8, together with the nitrogen atom to which they are attached, form a 4-7 membered heteroaliphatic ring containing the nitrogen atom as the sole heteroatom; or a pharmaceutically acceptable salt thereof.

The compound is generally in the form of the free base.

RI may be hydrogen, halogen or CN or a group CI-4alkyl, C2.4alkenyl, C2-4alkynyl, C1.4alkoxy, C2-4alkenyloxy or C2-4alkynyloxy, each of which groups is unsubstituted or substituted with one or two halogen atoms or with a pyridyl or phenyl ring each of which rings may be unsubstituted or independently substituted by one or two halogen atoms or nitro, cyano, amino, methyl or CF3 groups. R1 is typically hydrogen, fluorine, chlorine, bromine or a group C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C24alkenyloxy or C2-4alkynyloxy, each of which groups is unsubstituted or substituted with one or two halogen atoms or by a pyridyl or phenyl ring each of which rings may be unsubstituted or substituted by one or two halogen atoms or nitro, cyano, amino, methyl or CF3 groups and is generally hydrogen, fluorine or pyridylmethoxy, typically hydrogen.

R2 may be hydrogen, halogen or CN or a group C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy or C2-4alkynyloxy each of which groups is unsubstituted or substituted with one or two halogen atoms. R2 is typically hydrogen, fluorine, chlorine or bromine, and is generally hydrogen or fluorine, typically hydrogen.

Preferably L is an oxygen atom. L may also be NRn in which Rn is preferably hydrogen or methyl. Rn may be hydrogen.

X is generally: pyridyl, pyrazinyl, pyridazinyl or pyrimidinyl optionally substituted by a halogen atom or a group R3, OR3, NR4R5 or a five membered heteroaromatic ring containing 1, 2 or 3 nitrogen atoms, and X is optionally fused to a benzene ring; a 5-membered heteroaromatic ring containing 2 or 3 heteroatoms chosen from oxygen, sulphur and nitrogen, at most one of the heteroatoms being oxygen or sulphur, which is unsubstituted or substituted by one, two or three groups independently chosen from halogen and R3, or which is substituted by a pyridyl, phenyl or benzyl ring which ring is optionally independently substituted by one, two or three halogen atoms or Ci-Galkyl or CF3 groups; or phenyl optionally substituted by one, two or three independently chosen halogen atoms. In particular X is pyridyl, pyrazinyl, pyridazinyl or pyrimidinyl which is unsubstituted or substituted by methyl, CF3, methoxy, bromine, chlorine, isopropoxy, dimethylamino or a 5 membered heterocyclic ring containing 1, 2 or 3 nitrogen atoms, and X is optionally fused to a benzene ring, or X is pyrazolyl, isothiazolyl, isoxazolyl, 1,2,4-triazolyl, thiazolyl, 1,2,3-triazolyl or imidazolyl. which is unsubstituted or substituted by one, two or three groups independently chosen from methyl, CF3 and chlorine or is substituted by a phenyl, benzyl or pyridyl ring which ring is unsubstituted or substituted by chlorine or CF3, or X is phenyl which is unsubstituted or substituted by chlorine. Specific values of X are 2- pyridyl, 6-methylpyridin-2-yl, 3-pyridyl, 4-pyridyl, 3,5-dimethylpyrazol-1-yl, 3 methoxypyridin-2-yl, 3-methylisoxazol-5-yl, pyrazol-1-yl, 6-chloropyridin- 2-yl, 6-bromopyridin-2-yl, 6-methoxypyridin-2-yl, 6-isopropoxypyridin-2-yl, 6NN dimethylpyridin-2-yl, 6-(imidazol-1-yl)pyridin-2-yl, 3-pyridazino, 4 pyrimidinyl, pyrazin-2-yl, 2-quinolinyl, 2-quinoxalyl, 2-(4 trifluoromethyl)pyridyloxy, 4-methylisothiazolyl, 2,6-dichlorophenyl, 4 methylthiazol-5-yl, 2-methylthiazol-4-yl, 2-[l-(3-trifluoromethyl)pyrid-6 yl]imidazolyl, 1-benzyllmidazol-2-yl, 1-(4-chlorophenyl)-1,2,3-triazol-4yl, 3 chloro-2-methyl-5-trifluoromethylpyrazol-4-yl, 1-methyl-1,2,4-triazol-3- yl, (5-trifluoromethyl)pyridyl-2-yl, (3-trifluoromethyl)pyrid-2-yl, (4 trifluoromethyl)pyrid-2-yl, 1-methylimidazol-2-yl, 2-{[2 (trimethylsllyl)ethoxy]methyll-1,2,4-triazol-3-yl, 3-methyhmidazol-4-yl, 1,2,4 triazol-3-yl, 1-isopropyl-1,2,4-triazol-3-yl, 4-methyl-1,2,4-triazol-3-yl, 1,2,3 triazol-4-yl, isothiazol-3-yl, 1 ethyl- 1, 2,4-triazol- 3 -yl, 2-methyl- 1,2,3-triazol-4 yl, 1-methyl-1,2,3-triazol-4-yl, 2-methyl-1,2,4-triazol-3-yl, 1- methyhmidazol 4-yl, 5-tert-butylpyridazin-3-yl and 1-methyl-1,2,3-triazol-5-yl. Still further particular values of X are 2-benzyl-1,2,4-triazol-3-yl, 1-benzyl-1,2,4- triazol-3 yl, 1-nbutyl-1,2,4-triazol-3-yl, 2-ethyl-1,2,4-triazol-3-yl, 2- methylpyrazol-3-yl, 1-methylpyrazol-3-yl, 1-npropyl-1,2,4-triazol-3-yl, 1-(2,2,2- trifluorethyl)-1,2,4 triazol-3-yl, 1 -ethyl- 1, 2,3-triazol-5-yl, 1-methyltetrazol-2-yl, imidazol-2-yl, 2 npropyl-1,2,4-triazol-3-yl, 1 -ethyl- 1, 2,3-triazol-4-yl, 2-ethyl-1,2,3- triazol-4-yl, 1-ethylimidazol-5-yl, 1-ethylimidazol-4-yl, 1-npropyl-1,2,4-triazol-3-yl and 1- ethyl1,2,3-triazol-5-yl. In particular X is pyrid-2-yl, 2-methyl-1,2,4triazol-3- yl, 1-methyl-1,2,4-triazol-3-yl, 1-methyl-1,2,3-triazol-4-yl, 3-methyl-1, 2,3 triazol-4-yl or 2 -ethyl- 1, 2,4-triazol- 3-yl.

When X is a substituted 6-membered heteroaromatic ring:

Rx is preferably halogen, R3, OR3, NR4R5 or a five-membered heteroaromatic ring containing 1, 2 or 3 nitrogen atoms and more preferably methyl, CF3, methoxy, bromine, chlorine, isopropoxy, dimethylamino or a five-membered heterocyclic ring containing 1, 2 or 3 nitrogen atoms; and RV and Rz are preferably absent. In particular X is optionally substituted pyridine. The optional substituents are generally halogen or C1-6alkyl, particularly methyl or ethyl, especially methyl. When X is pyridine it may be in the form of the N-oxide.

When X is a substituted 5-membered beteroaromatic ring:

Rx is preferably halogen, R3 or a pyridyl, phenyl or benzyl ring which ring is optionally independently substituted by one, two or three halogen atoms or Cl-,Galkyl or CF3 groups and more preferably Rx is methyl, CF3, chlorine or a phenyl, pyridyl or benzyl ring which ring is unsubstituted or substituted by chlorine or CF3; and RY and Rz are preferably halogen or R-3, and more preferably methyl, CF3 or chlorine. X is especially an optionally substituted triazole, either a 1,2,3- or 1,2,4-triazole, which is preferably substituted by methyl or ethyl, especially methyl.

Particularly aptly X is an unsubstituted six-membered heteroaromatic group containing one or two nitrogen atoms.

Apt values for Y include CH2, CH(CH3), CH2CH2 and CH2CH2CH2 optionally substituted by an oxo group, and CH2CH20 and CH2CH2CH20.

For example, Y can be CH2, CH2CH2, CH2CH2CH2, CH2CH20 or CH2CH2CH20Preferably Y is CH2 or CH2CH2 and most preferably CH2.

R,, is suitably chlorine, R6, thienyl, furyl, pyridyl or NR7R8, more particularly R6, thienyl, furyl, pyridyl or NR7R8, for example CI-6alkyl, C3-6CYCloalkyl, hydroxyCl-calkyl, pyridyl, thienyl or amino and more particularly methyl, ethyl, ethoxy, isopropyl, cyclopropyl, thienyl or pyridyl, and even more particularly methyl, ethyl, isopropyl, cyclopropyl, thienyl or pyridyl. A further example of Rv is chlorine.

Rw is suitably R6, for example C1-6alkyl, CH2F or hydroxyCl-6alkyl, more particularly methyl, CH2F or hydroxymethyl. Generally R- is absent.

Rx may be halogen, R3, OR3, OCOR3, NR4R5, NR4COR5, CN or R9.

Z is preferably a 5-membered heteroaromatic ring containing 1, 2 or 3 heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur and providing that io when two of the heteroatoms are nitrogen an oxygen or sulphur atom is also present and that when one of the atoms is oxygen or sulphur then at least one nitrogen atom is present, or a 6-membered heteroaromatic ring containing 2 or 3 nitrogen atoms, Z being optionally substituted by Rv and/or R-, where Rv is halogen, R6, NR7R8, NR7COR8, CN, furyl, thienyl, phenyl, benzyl, pyridyl or a 5-membered heteroaromatic ring containing at least one nitrogen atom and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur and Rw is R6 or CN.

Suitable values for Z include pyrimidinyl, pyrazinyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxachazolyl and thiadiazolyl groups which groups are optionally substituted by R6, thienyl, furyl, pyridyl or N- R7R8 groups.

Z is very aptly a 5-membered heteroaromatic ring containing one oxygen and one or two nitrogen ring atoms and is optionally substituted by a group R6. In such compounds R6 is favourably a methyl group.

Favoured values for Z include optionally substituted isoxazoles and oxadiazoles.

Z may be unsubstituted.

Z may very aptly be substituted by methyl.

Z is especially isoxazole which is unsubstituted or substituted by C1-6alkyl or Cl-ralkoxy, especially methyl or ethoxy.

Particular values of Z are 3-methyloxadiazol-5-yl, 3 cyclopropyloxadiazol-5-yl, 5-methylisoxazol-3-yl, 5-(3-pyridyl)-isoxazol-3-yl, 5 hydroxymethylisoxazol-3-yl, 4,5-dimethylisoxazol-3-yl, 5-ethylisoxazol-3- yl, 5 cyclopropyhsoxazol-3-yl, 5-isopropylisoxazol-3-yl, isoxazol-3-yl, 5 thienylisoxazol-3-yl, 5-fluoromethylisoxazol-3-yl, 4-methyhsoxazol-3-yl, 5 ethoxyisoxazol-3-yl, 4-methyl-5-chloroisoxazol-3-yl, 5- trifluoromethylisoxazol 3-yl, 5-(pyrid-2-yl)isoxazol-3-yl, 5-benzylisoxazol-3-yl, 5chloroisoxazol-3-yl, 3 cyclopropyloxadiazol-5-yl, 5-methoxyisoxazol-3-yl, 5- methoxymethylisoxazol 3-yl, 5-methyloxadiazol-3-yl, pyrazin-2-yl and 3-methylisoxazol-5-yl. In particular Z is 5-methyhsoxazol-3-yl, isoxazol-3-yl or 5-ethoxyisoxazol-3- yl.

R3 may be C1-6alkyl, C2.6alkenyl, C2-6alkynyl, C3-6cycloalkyl, hydroxyCi-Galkyl or CF3.

is Generally R3 is C1-6alkyl, C1-6alkoxy or CF3. In particular R3 is methyl, methoxy, ispropoxy or trifluoromethyl.

Generally R4 and R5 are independently hydrogen or Cl.calkyl, in particular hydrogen or methyl, for example both can be methyl.

R6 may be C1.6alkyl, C2-6alkenyl, C2-6alkynyl, C3-rcycloalkyl, hydroxyCl-6alkyl, Cl-ralkoxy, C2-6alkenyloxy, C2.6alkynyloxy, CH2F or CF3.

Generally R6 is CH2F, CF3, C1-6alkoxy, C3-6cycloalkoxy, C1-6alkyl or hydroxyCl-6alkyl, for example, CH2F, CFa, methyl, ethyl, isopropyl, cyclopropyl or hydroxymethyl, particularly methyl or cyclopropyl.

Alternatively R6 is C1-6alkyl or hydroxyCl-6alkyl, for example, methyl, ethyl, isipropyl, cyclopropyl or hydroxymethyl.

Generally R7 and R8 are independently hydrogen or Cl-C'alkyl, particularly hydrogen or methyl.

Generally R9 is pyrazolyl, imidazolyl, phenyl., benzyl or pyridyl.

optionally substituted by halogen, preferably chlorine, or CF3. In particular R9 can be imidazol-1-yl, 3-trifluoromethylpyrid-5-yl, benzyl and 4 chlorophenyl.

Generally RIO is Ci-,salkyl or CF3, in particular methyl or CF3, for example CF3.

In a preferred subclass of compounds of formula I:

R1 and R2 are hydrogen; L is 0; X is pyridine or triazole and is unsubstituted or substituted by C1-6alkyl; Y is CH2; and Z is isoxazole, which is unsubstituted or substituted by Ci.6alkyl or CI-6alkoxy.

Specific compounds within this class include:

3-(5-methylisoxazol-3-yl)-5-(2-pyridylmethyloxy)- 1,2,3a,4,6-pentaaza cyclopenta [a]naphthalene; 3-(5-methyllsoxazol-3-yl)-5-(2-pyridylmethyloxy)-1,2,3a,4,9-pentaazacyclopenta [a]naphthalene; 3-(5-methylisoxazol-3-yl)-5-(2-pyridylmethvloxy)-1,2,3a,4,7-pentaazacyclopenta [a]napthalene;3-(5-methylisoxazol-3-yl)-5(2-pyridylmethyloxy)-1,2,3a,4,8-pentaazacyclopenta [a] naphthalene; 3-(5-methylisoxazol-3-yl)-5-(2-methyl-1,2,4-triazol-3-ylmethyloxy)- 1, 2,3a, 4,6-pentaaza-cyclopenta [a] naphthalene; 3-(5-ethoxyisoxazol-3-yl)-5-(l-methyl-1,2,4-triazol-3-ylmethyloxy)- 1, 2,3a, 4,6-pentaaza-cyclopenta [a] naphthalene; 3-isoxazol-3-yl-5-(2-methyl-1,2,4-triazol-3-ylmethoxy)-1,2,3a,4,6pentaaza-cyclopenta [a] naphthalene; 3-isoxazol-3-yl-5-(l-methyl-1,2,4-triazol-3-ylmethoxy)-1,2,3a,4,6pentaaza-cyclopenta [a] naphthalene; 3-(5-methyhsoxazol-3-yl)-5-(l-methyl1, 2,4-triazol-3-ylmethoxy) 1, 2,3a, 4,6-pentaaza-cyclopenta [a] naphthalene; 3-(5-methylisoxazol-3-yl)-5-(l-methyl-1,2,3-triazol-4-ylmethoxy)- 1, 2,3a, 4,6-p entaaza-cyclopenta [a] naphthalene; 3-(5-methylisoxazol-3-yl)-5-(3-methyl-1,2,3-triazol-4-ylmethoxy)- 1, 2,3a, 4,6-pentaaza-cyclopenta[a] naphthalene; 3-(5-methylisolxazol-3-yl)-5-(2-ethyl-1,2,4-triazol-3-ylmethoxy)- 1, 2,3a,4,6-pentaaza-cyclopenta [a] naphthalene; 3-(5-ethoxyisoxazol-3-yl)-5-(l-methyl-1,2,3-triazol-4-ylmethoxy)- 1, 2,3 a, 4,6-p entaaza-cyclopenta [a] naphthalene; 3-(5-ethoxyisoxazol-3-yl)-5-(3-methyl-1,2,3-triazol-4-ylmethoxy)- 1, 2,3a, 4,6-pentaaza-cyclopenta[al naphthalene; 3-(5-ethoxylsoxazol-3-yl)-5-(2-ethyltriazol-1,2,4-3-ylmethoxy)- 1, 2,3a, 4,6-pentaaza-cyclopenta[a] naphthalene; and pharmaceutically acceptable salts thereof.

The compounds of this class may be prepared by a process which comprises reacting a compound of formula III with a compound of formula IV:

N-N R Zi T N B-Y-X TT N T4 R 2 G (111) (IV) wherein T, T2, T3, T4, R1, R2, X and Y are as defined above, G is a leaving group such as chlorine, OCH2CF3 or tosylate, B is LH where L is as defined above and Z' is a group Z as defined above or is a moiety which can be converted into a group Z by further reaction.

The reaction between compounds III and IV when L is 0 is conveniently effected by stirring the reactants in a suitable solvent, typically N,N-dimethylformamide, in the presence of a strong base such as sodium hydride or lithium bis(trimethylsilyl)amide, typically without heating. and under an inert atmosphere such as nitrogen. When L is NRn the reaction is conveniently effected in the presence of a strong base such as Et3N or NaH and a solvent such as DMF or DMSO generally for 15 to 60 hours with heating to 50-120'C.

The intermediates of formula III above may be prepared by reacting a compound of formula V, which constitutes a further feature of the present invention, with a compound of formula VI:

HNH2 R AT N R YTI N W- CO -Z' G M (Vi) wherein T', T2, T3, T4, R1, R2, G and Z' are as defined above, and W represents a suitable leaving group such asCl-6alkoxy, chlorine or hydroxy.

The reaction is advantageously conducted in an inert organic solvent, generally in the presence of an organic nitrogen base and preferably under an inert atmosphere such as nitrogen. Suitable solvents include xylene, dioxane, 20 tetrahydrofuran and lower aliphatic halogenated and aromatic hydrocarbons. Suitable organic nitrogen bases that may be employed include trialkylamines and pyridine. The reaction is generally conducted at a temperature range of from.-20'C to the reflux temperature of the reaction mixture, for a period of time that depends on the reactants employed and the temperature at which the reaction is carried out. The compound of formula VI may be activated by reacting with a compound such as bis (2-oxo-3-oxazolidinyl)phosphinic chloride or 1, I'-dicarbonylcliimidazole before reaction with the hydrazine.

When Z' is not a group Z, it is, for example, an allylformyloxime group which can be converted to a carboxaldehydeoxime using tetrakis(triphenylphosphine)palladium(O) generally under an inert atmosphere such as nitrogen in the presence of triethylammonium, formate, in a solvent such as ethanol for about 18 hours. The carboxaldehydeoxime lo can be converted to a carboxaldehydechloroxime by reacting with a chlorinating agent such as N-chlorosuccinimide in a solvent such as DMF.

The carboxaldehydechloroxime can be converted to the desired group Z by reacting with an unsaturated compound such a vinylidene chloride, methyl propargy]. ether, 3-phenyl-l-propyne, 2-pyridylacetylene, trifluoromethylacetylene or ethoxyacetylene generally in the presence of a base such a triethylamine, and a solvent such as dichloromethane.

Alternatively, the carboxaldehydechloroxime can be converted to a group Z by reacting with ammonium hydroxide generally in a solvent such as ethanol for about 30 minutes and then acetic anhydride generally with heating to reflux for about 16 hours.

Compounds of formula III in which G is OCH2CF3 can be prepared by reacting a compound of formula III in which G is chlorine with 2,2,2 trifluoroethanol in the presence of a base such as lithium bis(trimethylsilyl)amide generally in a solvent such as DMF, preferably with cooling to about -20'C-O'C for a period of about 30 minutes.

The compound of formula V is prepared by reaction of a compound of formula VII:

G R T T 2 N I I T 4 N R T G (VII) where T', T2, T3, T4, R1, R2 and G are as defined above, and G' is another suitable leaving group which may be the same as or different to G, with hydrazine, usually in the form of its monohydrate, generally in a solvent such as ethanol and generally by refluxing for a suitable period such as 15 minutes to 2 hours.

As the compound of formula VII is asymmetrical, the substitution pattern about the fused benzene ring is not symmetrical. Consequently the reaction between this compound and hydrazine will usually give rise to a mixture of isomeric products depending on whether group G or G' is displaced first. Thus in addition to the required product of formula V, the isomeric compound wherein the R1 and R2 Moieties are reversed or where the nitrogen atom in the fused pyridine ring is in its alternative location, will usually be obtained to some extent. For this reason it will generally be necessary to separate the resulting mixture of isomers by conventional methods such as chromatography.

The compound of formula VII can be used to prepare a compound of formula III in a single step by reacting with the appropriate hydrazoic acid, that is a compound of formula XIII:

H2NNHC(O)Z (XIII) wherein Z is as defined above. This is generally carried out in the presence of a base, such as triethylamine, in a solvent such as xylene, at reflux under an inert atmosphere such as.nitrogen.

The compound of formula VII can be prepared by reacting a compound 5 of formula X:

0 R T t2 NH I I T NH R 2 0 N where T', T2, T3, T4, RI and R2 are as defined above, with a suitable reagent for introducing leaving groups G and G, for example where G and GI are both chlorine POC13 can be used generally with heating to reflux for about 16 hours.

The compound of formula X can be prepared by reacting a compound of formula XI with hydrazine hydrate (H2NNH2.H20):

R 0 AT I 0 T'T R 2 0 (XI) where T', T2, T3, T4, R1 and R2 are as defined above. The reaction is generally carried out in a protic solvent, such as 40% aqueous acetic acid, and in the presence of a buffering agent such as sodium acetate, generally with heating to reflux for about 16 hours to about 4 days.

The compound of formula XI can be prepared by reaction of a compound of formula XII:

0 T' 4 0 0 (XII) wherein T', T2, T3 and T4 are as defined above with suitable reagents to introduce the substituents RI and R2 where necessary. For example, when R1 is phenyloxy or pyridyloxy or a derivative thereof, the corresponding hydroxy compound can be used as a reagent. The compounds of formula XII are commercially available.

Alternatively, when RI is the same as L-Y-X in the compound of formula I, it can be introduced by displacing another group RI which can act as a leaving group, such as fluorine, in the reaction between the compounds of formulae III and IV.

In another procedure, the compounds of this class wherein L is 0 may be prepared by a process which comprises reacting a compound of formula VIII with a compound of formula IX:

N-N 1 1 / -'z Ti N J-YX T I I /,T.,, N 2 T4 OH (IX) 20 wherein T', T2, T3, T4, R1, R2, X, Y and Z are as defined above and J represents a suitable leaving group such as a halogen atom, typically chlorine. The reaction between compounds VIII and IX is conveniently effected by stirring the reactants in a suitable solvent, typically N,N- dimethylformamide, in the presence of a strong base such as sodium hydride. 5 The intermediates of formula VIII above may be conveniently prepared by reacting a compound of formula III as defined above with an alkaline hydroxide, e.g. sodium hydroxide. The reaction is conveniently effected in an inert solvent such as 1,4-dioxane, ideally at the reflux temperature of the solvent. A compound of formula III in which G is para- sulphonyltoluene can io be made by reacting a compound of formula VIII with 4toluenesulphony1chloride. Where they are not commercially available, the starting materials of formula IV, VI, VIII and IX may be prepared by methods analogous to those described in the accompanying Examples, or by standard methods known from the art.

It will be understood that any compound of formula I initially obtained from the above process may, where appropriate, subsequently be elaborated into a further compound of formula I by techniques known from the art.

REFERENCE EXAMPLE 6 3-(5-Methyhsoxazol-3-yl)-5-(2-pyridylmethyloxy)-1,2,3a,4,6pentaazacyclopenta [a]naphthalene a) 6,7-Dihydro-pyrido[2,3-d]-pyridazine-5,8-dione Hydrazine hydrate (13.09g, 0.261mol) was added to a stirred solution of pyridine-2,3-dicarboxylic anhydride (30.0g, 0.201mol) and sodium acetate (21.45g, 0.261mol) in 40% acetic acid/water (400ml). The reaction was heated at reflux for 3 days under nitrogen. The yellow precipitate was filtered off and washed successively with water (4 x 200ml), hexane. (3 x 150ml) and diethyl ether (3 x 150ml) to give the title-compound (25.0g, 76%), 1H NMR (250MHz, d6-DMSO) 8 7.90 (1H,q, J=4.5Hz, Ar-H), 8.51 (1H, d, J=4.5Hz, Ar-H), 9.13 (1H, d, J=4.6Hz, Ar-H), 11.65 (2H, br s, 2 of NH); MS (ES+) m/e 164 [MIi]+.

b) 5,8-Dichloro-pyido[2,3-dlpvridazine The preceding compound (25.0g, 0.185mol) was dissolved in phosphorus oxychloride (260ml) and heated at reflux for 4h under nitrogen. The solvent was removed in vacuo, and the resulting brown solid was taken up in dichloromethane (300ml) and water (100ml) and sodium hydrogen carbonate added until the mixture was neutral. The mixture was filtered and the organic layer was separated. The aqueous layer was extracted with dichloromethane (2 x 200ml) and the combined organic layers were dried (MgS04) and evaporated in vacuo.

-The brick-red coloured solid was dissolved in hot dichloromethane, filtered and triturated with diethyl ether to give the title-compound (15.2g, 50%), IH NMR (250MHz, CDC13) 8 7.25 (1H, m, Ar-H), 7.87 (1H, q, J=4.6Hz, Ar-H), 8.03 (1H, d, J=4.6Hz, Ar-H).

C) 5-Methylisoxazole-3-carboxvlic acid hydrazide To a solution of ethyl 5-methylisoxazole-3-carboxylate (3.0g, 19mmol) in methanol (30ml) at OOC under nitrogen was added hydrazine hydrate (3.04g, 95mmol) over 0.3h. The reaction was stirred at OOC for 0.25h and at RT for 1h. The white precipitate was filtered off and washed with methanol to give the title-compoun (0.78g, 29%) as a white solid, 111 NMR (250MHz, CDC13) 8 2.41 (3H, d, J=0.8 Hz,CH3), 4.07 (2H, br s, NH2), 6.44 (1H, q, J=0.8 Hz, Ar-H), 7.99 (111, br s, N-H); MS (ES+) m/e 142 [MM+.

d) 5-Chloro-3-(5-met4vlisoxazol-3-yl)-1,2,3a,4,6-pentaaza-c-vclol)enta[a naphthalene and 5-Chloro-3-(5-meLhyl-isoxazol-3-yl)-1,2,3a,4,9pentgazacyclopentaral naphthalene To a solution of 5,8-dichloro-pyrido[2,3d]pyridazine (2.21g, 11mmol) 10 and 5-methylisoxazole-3-carboxylic acid hydrazide (1.57g, 11mmol) in xylene (70ml) was added triethylamine (1. 55ml, 11mmol). The reaction was heated at reflux under nitrogen for 16h. The solvent was evaporated in vacuo and the residue taken up in dichloromethane (150ml), washed with water (3 x 75ml), dried (MgSO4) and evaporated 15 in vacuo. The crude product was purified by chromatography on silica gel, eluting with 4% methanol/dichloromethane. The two isomers were separated by chromatography on alumina (Grade III), eluting with 0. 5% ethanol/dichloromethane to give: 5-chloro-3-(5-methyhsoxazol-3-yl)-1,2, 3a,4,9-pentaaza-cyclopenta[a] 20 naphthalene (more polar isomer)(0.25g, 8%): 1H NMR (360MHz, d6DMSO) 8 3.31 (3H, s, CH3), 7.01 (1H, d, J=0.8 Hz, Ar-H), 8.08 (1H, q, J=4.5Hz, Ar-H), 8.75 (1H, d, J=4.5Hz, Ar-H) 9.33 (1H, q, J= 4.7Hz, Ar-H). 5-chloro-3-(5-methylisoxazol-3-yl)-1,2,3a,4,6pentaaza-cyclopenta[aI 25 naphthalene Gess polar isomer) (0.4g, 13%): 111 NMR (360MHz, dGDMSO) 8 3.31 (3H, s, CH3), 7.01 (1H, d, J=0.7Hz, Ar-H), 8. 15 (111, q, J=4.6Hz, Ar-H), 9.04 (1H, dd, J=8.2Hz and 1.6Hz, Ar-H), 9.27 (1H, dd, J= 4.6Hz and 1.5Hz, Ar-H).

e) 3-(5-Met4vlisoxazol-3-vl)-5-(2-lpvridylmethylox-v)- 1,2,3a, 4,6pentaaza- cyclopenta faInaphthalene Sodium hydride (63mg of a 60% dispersion in oil, 1.57mmol) was added to a stirred solution of 2-pyridyl carbinol (87mg, 0.84mmol) in DMF (15ml) at room temperature under nitrogen and the mixture stirred for 0.25h. After this time the less polar chloride (225mg, 0.79mmol) was added and the mixture stirred for 2h. The solvent was evaporated in vacuo and the residue dissolved in dichloromethane, washed with water (x2), dried (MgS04) and evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 4% methanol/dichloromethane, gave the title-product (100mg, 35%), 1H NMR (360MHz, CDC13) 5 2.59 (3H, d, J=0.7Hz, CH3), 5.88 (2H, s, CH2), 6.81 (1H, s, Ar-H), 7.27 (1H, m, Ar-H), 7.71-7.77 (2H, in, 2 of Ar-H), 7.89 (1H, q, J=4.7Hz, Ar-H), 8.70 (1H, d, J=4.7Hz, Ar-H), 9.00 (1H, q, J=8.lHz, Ar-H), 9.18 (1H, q, J=4.5Hz, Ar-H); MS (ES+) m/e 360 [MH]+; Anal. Found. C, 59.36; H, 3.36; N, 26.80. C18 H13 N702. 0.1 (CH202) requires C, 59.10; H, 3.61; N, 26.65%.

REFERENCE EXAMPLE 7 3-(5-Methylisoxazol-3-yl)-5-(2-pyridylmethyloxy)-1,2,3a,4,91)entaazacyclopenta [aInaphthalene The title-compound was prepared from 5chloro-3-(5-methyhsoxazol-325 yl)- 1, 2,3a, 4,9-p entaaza-cyclopenta [a] naphthalene according to the procedure given in Example 6, part e. IH NMR (360MHz, CDC13) 8 2.59 (3H, s, Ar-H), 5.78 (2H, s, CHA 6.85 (1H, d, J=0. 8Hz, Ar-H), 7.29 (1H, in, Ar-H), 7.74-7.79 (3H, m, 3 of Ar-H), 8.62 (1H, d, J=8.OHz, Ar-H), 8.70 (1H, d, J=4.6Hz, Ar-H), 9.23 (1H, q, J=4.6Hz, Ar-H); MS (ES+) m/e 360 [MH]+. Anal. Found. C, 60.02; H, 3.31; N, 27.00. C18H13N702 requires C, 60.16; H, 3.65; N, 27.28%.

REFERENCE EXAMPLE 8 3-(5-Methvhsoxazol-3-yl)-5-(2-pyridylmeth-vlo2W)-1,2,3a,4,7-I)entaazaaclopentaLabaphthalene and 3-(5-Metbvlisoxazol-3-yl)-5(2 pyridylmeLhyloxy)-1,2,3a,4,8-1)entaaza-cyclopentarajna-phthalene The title-compounds were prepared as described in Example 6, parts a e, using pyridine-3,4 dicarboxylic anhydride instead of pyridine-2,3 dicarboxylic anhydride in part a. The isomers were separated in part e by HPLC:

3-(5-Methylisoxazol-3-yl)-5-(2-pyridylmethyloxy)-1,2,3a,4,7-pentaazacyclopenta [a]naphthalene: IH NMR (50OMHz, CDC13) 8 2.73 (3H, s, CH3), 5.94 (2H, s, CH2), 6.97 (1H, s, Ar-H), 7.47 (1H, t, J=6.OHz, Ar-H), 7.90-7.96 (2H, in, 2 of Ar-H), 8.62 (1H, d, J=5.3Hz, Ar-H), 8.82 (1H, d, J=4.6Hz, Ar-H), 9.27 (1H, d, J=5.3Hz, Ar-H), 9.75 (1H, s, Ar-H); MS (ES+) m/e 360 [MIII+.

3-(5-Methylisoxazol-3-yl)-5-(2-pyridylmethyloxy)-1,2,3a,4,8-pentaazacyclopenta [a]naphthalene: IH NMR (360MHz, CDC13) 6 2.60 (3H, d, J=0.7Hz, CH3), 5.78 (2H, s, CH2), 6.82 (1H, s, Ar-H), 7.31 (1H, m, 2 of Ar-H), 7.74-7.78 (2H, in, 2 of Ar-H), 8.08 (1H, d, J=4.5Hz, Ar-H), 8.70 (1H, d, J=4.5Hz, Ar-H), 9.08 (1H, d, J=5.3Hz), 10.03 (1H, s, Ar-H); MS (ES+) m/e 360 [MHI+.

REFERENCE EXAMPLE 10 3-(5-Methylisoxazol-3-yl)-5-(2-methyl-1,2,4-triazol-3-ylmethylox-Y)1, 2, 3a, 4,6-Pentgaza-cyclopenta [a] naphthalene A solution of 5-chloro-3-(5-methylisoxazol-3-yl)-1,2,3a,4,6-pentaazacyclopenta[a]naphthalene (100mg, 0.35mmol) in N,N-dimethyl formamide (7ml) was added to a solution of 2-methyl-1,2,4-triazole-3 methanol (43mg, 0.38mmol) (prepared using the conditions of Itoh and Okongi, EP-A-421210) under nitrogen, and the mixture cooled to -780C.

Lithium bis(trimethylsilyl)amide (0.42ml, LOM in tetrahydrofuran, 0.42mmol) was added, and the reaction stirred at -78'C for 2h, then allowed to warm to room temperature and stirred for 3h. The solvents were evaporated by azeotroping with xylene and the residue pre absorbed onto silica (1g) from methanol/dichloromethane. Flash chromatography on a silica bond elute cartridge (10g) eluting with a 0% - 5% methanol/dichloromethane gradient, followed by recrystallisation (dichloromethane/ethyl acetate) gave the title-product (52mg, 41%), mp 255-257'C; IH NMR (360MHz, CDC13) 8 9.16 (IH, dd, J=4.4Hz and 1.7Hz, Ar-H), 9.01 (IH, dd, J=8.2Hz and 1.7Hz, Ar-M, 7.92 (1H, m, Ar-H), 7.90 (1H, s, Ar-H), 6.93 (1H, s, Ar-H), 5.88 (2H, s, CH2), 4.12 (3H, s, CH3), 2.60 (3H, s, CH3); MS (ES+) m/e 364 [Mlfl+.

REFERENCE EXAMPLE 11 3-(5-Ethoxvisoxazol-3--vl)-5-(l-methyl-1,2,4-triazol-3-ylmeth-vloxy)- 1, 2,3a, 4,6-pentaaza-c-vclopentaral naphthalene a) 4-Chloro-l-hydrazino-2,3,5-azanaphthalene and 1-chloro-4-hydrazino2,3, 5-azanaphthalene To a solution of 5,8-dichloropyrido[2,3-d]pyridazine (21. 5g, 108mmol) 5 (prepared as described in example 6, part b) in ethanol (600ml) was added hydrazine hydrate (32.4g, 65mmol). The reaction was stirred at room temperature for 18h and the precipitate filtered off and washed with diethyl ether to give the title compounds as a brick red solid (21.0g, 100%), 1H NMR (250MHz, d6-DMSO) 5 9.16 (1H, in, Ar-H), 8.45 10 (1H, m, Ar-H), 8.03 (1H, in, Ar-H), 4.69 (2H, br s, NH2). The regioisomers were separated by chromatography. b) 5-Chloro-3dichloromethyl-1,2,3a,4,6-pentaaza-cyclopentafa] naphthalene To the preceding hydrazine (54g, 277mmol) in toluene (400ml) was added dichloroacetic acid (150ml) and the reagents heated under DeanStark conditions for 1.5h. On cooling, saturated potassium carbonate solution (aq) (200ml) was added. The emulsion formed was filtered 20 through celite, and the filtrate evaporated in vacuo. The residue was taken in dichloromethane and washed with water (x2). The organic phase was dried (MgSO4) and evaporated in vacuo. The required isomer was separated by chromatography on silica gel, eluting with 20% -> 100% ethyl acetatelhexane to give the title-compound (4.69g, 25 6%) (less polar isomer), 1H NMR (250MHz, CDC13) 8 7.32 (1H, s, C-H), 7.99 (1H, in, Ar-H), 9.05 (IH, dd, J=1.6Hz and 8.IHz, Ar-H) 9.26 (IH, dd, J=1.7Hz and 4.6Hz, Ar-H).

C) 3-Dichloromethyl-5-(2,2,2-trifluoroethyloxy)- 1, 2,3a, 4,6-PentaazacyclopentaFaInaplithalene A solution of the preceding chloride (4.69g, 16mmol) in N,N dimethylformamide (40ml) was added to a solution of 2,2,2 trifluoroethanol (1.3ml, 17.8mmol) in tetrahydrofuran (30ml), under nitrogen, and the mixture cooled to -780C. Lithium bis(trimethylsilyl)amide (19.5ml, LOM in tetrahydrofuran, 19.5mmol) was added, and the mixture stirred at -78'C for 0.5h, then at room temperature for 2h. The solvent was evaporated in vacuo by azeotroping with xylene, and the residue partitioned between dichloromethane and water. The aqueous phase was separated and extracted with dichloromethane (x3). The combined organic phases were dried (MgSO4) and the solvent in vacuo. Flash chromatography of the residue on silica gel, eluting with 1% --> 3% methanol/ dichloromethane gave the title-compound (2.5g, 44%), 1H NMR (250 MHz, CDC13) 5 9.24 (1H, dd, J=4.6Hz and 1.6Hz, Ar-H), 8.99 (IH, dd, J=8.2Hz and 1.7Hz, Ar-H) 7.95 (1H, m, Ar-H), 7.28 (IH, s, C-H) 5.08 (2H, q, J=8.OHz, CH2); MS (ES+) m/e 352 [MH]+.

d) 3-Carboxamidoxime-5-(2,2,2)-trifluoroethyloxy-1,2,3a,4,6-pentazacyclopenta[aInaphthalene To the preceding product (2.5g, 7mmol) in formic acid (213ml) and water (36ml), was added hydroxylamine hydrochloride (0.987g, 14mmol) and the reagents heated at 110"C for 20h. On cooling, the solvent was evaporated in vacuo and the residue triturated with water, filtered and washed successively with water and diethyl ether to give the title-product (1.1g, 50%), 1H NMR (250MHz, d6-DMSO) 8 12.51 and 8 12.30 (IH, 2 x s, C-H E and Z), 9.18 (1H, dd, J=4.5Hz and 1AHz, Ar- H), 8.93 (IH, dd, J=8.2Hz and 1.6Hz, Ar-H), 8.60 and 8.14 (1H, s, OH E and Z), 8.10 (1H, in, Ar-H), 5.29 (2H, q, J=8.8Hz, CH2); MS (ES+) m/e 313 [MHJI.

e) 3-Carboxamidochloroxime-5-(2,2,2)-trifluoroetkylou-1,2,3a,4,6pentaazagyclol)enta[alnqphthalene To the preceding product (1.1g, 35mmol) in N,Ndimethylformamide 10 (60ml) was added N-chlorosucciminide (0.471g, 35mmol) and the mixture heated briefly until the reagents were in solution. The mixture was allowed to cool, and poured into ice/water (100MI). The precipitate was filtered off, washed with water and ethanol and dried to give the title-compound (0.696g, 57%), IH NMR (250MHz, d6- DMSO) 15 8 13.33 (1H, s, OH), 9.22 (1H, dd, J=4.5Hz and 1.5Hz, Ar-H), 8. 98 (1H, dd, J=8.2Hz and 1.5 Hz, Ar-H), 8 8.11 (IH, in, Ar-M, 5.19 (2H, q, J=8.7Hz, CH2). f) 3-(5-EthoLcyisoxazol-3-yl)-5-(2,2,2-trifluoroethylo2;y)1,2,3a,4,620 pentaaza-ffclo-pentafalnaohthalene To the preceding product (692mg, 2mmol) in dichloromethane at room temperature under nitrogen was added ethoxyacetylene (40% solution in hexanes, 1.05g, 6mmol). A solution of triethylamine (0.28ml, 25 2mmol) in dichloromethane (30ml) was then added dropwise over 1h. The mixture was stirred for 1h, the solvent evaporated and the residue triturated with water and filtered. The solid was washed with water, hexane, and diethyl ether. Flash chromatography on silica gel, eluting with 2% --> 4% methanol/dichloxomethane (gradient elution), gave the title-compound (580mg, 76%), 1H NMR (250MHz, CDC13) 8 9.22 (1H, dd, J=4. 6Hz and 1.7Hz, Ar-H(9.02 (1H, dd, J=8.2Hz and 1.7Hz, Ar-H), 7.94 (1H, m, Ar-H),_ 6.06 (1H, s, Ar-H), 5.09 (2H, q, J=8.OHz, CH2), 4.41 (2H, q, J=7. 1Hz, C112), 1.55 (3H, t, J=7. 1Hz, CH3).

g) 3-(5-EthM-isoxazol-3-vl)-5-(l-methyl-1,2,4-triazol-3-ylmethyloxy)- 1, 2,3a, 4,6-pentaaza-cyclopenta Lal naphthalene The title-compound was prepared from the preceding product (145mg, 0.38mmol) and 1-methyl 1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) (47mg, 0.42mmol) following the procedure described in example 4 part b, 1H NMR (360MHz, CDC13) 8 9. 15 (1H, dd, J=4.5Hz and 1.7Hz, Ar-H), 8.99 (1H, dd, J=8.OHz and 1.7Hz, Ar- H), 8.04 (1H, s, Ar-H) 7.87 (1H, m, Ar-H), 6.25 (1H, s, Ar-H), 5.79 (2H, s, CHA 4.43 (2H, q, J=7. 1Hz, CH2), 3.94 (3H, s, CHA 1.54 (2H, t, J=7. 1Hz, CHO; MS (ES+) m/e 394 [MM+; Anal. Found. C, 51.34; H, 3.62; N, 31.91. C17H15N902- OJH20 requires C, 51.67; H, 3.88; N, 31.90%.

Spherons (also known as dense protein microspheres) are intracellular protein deposits believed to be present in all human brains from the age of one year. Spherons gradually enlarge throughout life until they reach a maximal size at which they burst and degenerate, and it is believed that the disrupted spheron becomes the principal lesion of Alzheimer's disease (see Averback, Drug News Perspect., 11(8), 1998 pp 469-479, and WO-A-9852898). It is also believed that the disruption of spherons proceeds via an autocatalytic mechanism whereby the disruption of a single spheron triggers or accelerates the disruption of one or more neighbouring spherons.

Spheron disruption inhibitors are compounds which are effective in vivo in the prevention, arresting, attenuation or retardation of the disruption of spherons, and/or effective in suppressi. Lng or attenuating deleterious effects arising from the disruption of spherons. Included within this definition are compounds which prevent or delay the disruption of spherons, compounds which reduce the volume of tissue occupied by redistributed, transformed protein material arising from disruption of a spheron and its associated injury focus, compounds which reduce the persistence or duration of injury and inflammation associated with the disrupted spheron and redistributed transformed spheron protein material, and compounds which promote the digestion and removal of spheron material through the reticuloendothelial system.

Suitable compounds, possessing one or more of the properties listed above, may be identified using the screening tests disclosed in WO-A-9852898. Examples of suitable compounds are also disclosed in WO-A-9852898, and include 1-(diphenylmethyl)-piperazines and diphenylmethyl ethers.

The present invention also provides a pharmaceutical composition comprising a spheron disruption inhibitor, an inverse agonist of the GABAA U5 receptor subtype and a pharmaceutically acceptable carrier.

There is also provided a kit of parts comprising a first pharmaceutical composition comprising a spheron disruption inhibitor and a first pharmaceutically acceptable carrier and a second pharmaceutical composition comprising an inverse agonist of the GABAA a,5 receptor subtype and a second pharmaceutically acceptable carier for simultaneous, sequential or separate administration.

There is further provided a combination of a spheron disruption inhibitor and an inverse agonist of the GABAA a5 receptor subtype for use in a method of treatment of the human body, particularly for the treatment of a neuro degenerative disorder with associated cognitive deficit such as Alzheimer's Disease or Parkinson's disease, or of a cognitive deficit arising from a normal process such as aging or of an abnormal process such as injury.

The combination is particularly beneficial in the treatment of Alzheimer's Disease.

There is also provided the use of a combination of a spheron disruption inhibitor and an inverse agonist of the GABAA (x,5 receptor subtype in the manufacture of a medicament for the treatment of a neurode generative disorder such as Alzheimer's Disease or Parkinsons disease, or of a cognitive deficit arising from a normal process such as aging or of an abnormal process such as injury. The treatment of Alzheimer's Disease is particularly preferred.

There is also disclosed a method of treatment of a subject suffering from a neurodegenerative disorder, such as Alzheimer's Disease or Parkinson's disease, or a cognitive deficit arising from a normal process such as aging or an abnormal process such as injury, which comprises administering to that subject a therapeutically effective amount of a combination of a spheron disruption inhibitor and an inverse agonist of the GABAA CC5 receptor subtype. The treatment of Alzheimer's Disease is particularly preferred.

The pharmaceutical compositions of the present invention are preferably in unit dosage forms such as tablets, pills, capsules, powders, granules, sterile parenteral solutions or suspensions, metered aerosol or liquid sprays, drops, ampoules, transdermal patches, auto-injector devices or suppositories; for oral, parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation. For preparing solid compositions such as tablets, the principal active ingredient is mixed with a pharmaceutical carrier, e.g. conventional tableting ingredients such as corn starch, lactose, sucrose, sorbitol, talc, stearic acid, magnesium stearate, dicalcium. phosphate or gums or surfactants such as sorbitan monooleate, polyethylene glycol, and other pharmaceutical diluents, e.g. water, to form a solid preformulation composition containing a homogeneous mixture of a compound of the present invention, or a pharmaceutically acceptable salt thereof. When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules. This solid preformulation composition is then subdivided into unit io dosage forms of the type described above containing from 0.1 to about 500 mg of each active ingredient of the present invention. Typical unit dosage forms contain from 1 to 100 mg, for example 1, 2, 5, 10, 25, 50 or 100 mg, of each active ingredient. The tablets or pills of the novel composition canbe coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former. The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers or coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, cetyl alcohol and cellulose acetate.

The liquid forms in which the novel compositions of the present invention may be incorporated for administration orally or by injection include aqueous solutions, suitably flavoured syrups, aqueous or oil suspensions, and flavoured emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil or peanut oil, as well as elixirs and similar pharmaceutical vehicles. Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethyleellulose, methylcellulose, polyvinyl-pyrrolidone or gelatin.

For the treatment of a ne urode generative condition, a suitable dosage level is about 0.01 to 250 mg/kg per day, preferably about 0.01 to 100 mg/kg per day, and especially about 0.01 to 5 mg/kg of body weight per day of each active ingredient. The compounds may be administered on a regimen of 1 to 4 times per day. In some cases, however, dosage outside these limits may be used.

The synergistic effect of the combination of the present invention can be shown, for example, by comparing the combined dosage of the combination with dosages of the same amount of each of the active ingredients separately on subjects using the Mini-Mental State Examination (MMSE) as described in Folstein and Folstein J. Psychiat. Res., 1975, 12, 189-198 or a variant thereof as discussed in Tombaugh and McIntyre, JAGS, 1992, 40, 922.

These formulations may be prepared with separate active ingredients or with a combination of active ingredients in one composition. In such combined preparations, the ratio of the GABAA a5 inverse agoni-st and the spheron disruption inhibitor will depend upon the choice of active ingredients.

FORMULATION EXAMPLE 1 Tablets containing 50-300ing of QARAA a5 inverse agonist and 20mg of spheron disrLiption inhibitor Amount in GABAA cc5 inverse agonist 50.0 100.0 300.0 Spheron disruption inhibitor 20.0 20.0 20.0 Microcrystalline cellulose 80.0 80.0 80.0 Modified food corn starch 80.0 80.0 80.0 Lactose 169.5 119.5 119.5 Magnesium Stearate 0.5 0.5 0.5 The active ingredients cellulose, lactose and a portion of the corn starch are mixed and granulated with 10% corn starch paste. The resulting granulation is sieved, dried and blended with the remainder of the corn starch and the magnesium stearate. The resulting granulation is then compressed into tablets containing 50mg, 100mg and 300mg of the GABAA a5 inverse agonist per tablet.

FORMULATION EXAMPLE 2 Parenteral ipjection Amount Active Ingredients 10 to 300mg Citric Acid Monohydrate 0.75mg Sodium Phosphate 4.5mg Sodium Chloride 9mg Water for injection to 10ml The sodium phqsphate, citric acid monchydrate and sodium chloride are dissolved in a portion of the water. The active ingredients are dissolved or suspended in the solution and made up to volume.

Claims (5)

1. A combination of a spheron disruption inhibitor and an inverse agonist of the GABAA (x5 receptor subtype for separate, simultaneous or simultaneous administration.

2. A kit of parts comprising a first pharmaceutical composition comprising a spheron disruption inhibitor and a first pharmaceutically acceptable carrier and a second pharmaceutical composition comprising an inverse agonist of the GABAA a5 subtype and a second pharmaceutically acceptable carrier for simultaneous, separate or sequential administration.

3. A combination of a spheron disruption inhibitor and an inverse agonist of the GABAA oc5 receptor subtype for use in a method of treatment of the human or animal body.

4. Use of a combination of a spheron disruption inhibitor and an inverse agonist of the GABAA a5 receptor subtype for the manufacture of a medicament for the treatment of a neurode generative disorder.

5. Use according to claim 4 wherein the neurode generative disorder is Alzheimer's Disease.