WO2014024125A1 - Pyrazolo[4,3-d]pyrimidin-7(6h)-one derivatives as pde9 inhibitors - Google Patents

Abstract

Pyrazolo[4,3-d]pyrimidin-7(6H)-one derivatives represented by the general formula (I), wherein R¹ represents hydrogen atom or methyl; when R¹ represents hydrogen atom, then R² represents cyclopentyl, tetrahydropyranyl, cyclohexyl, or cyclohexyl substituted with 1 or 2 halogen atoms; when R¹ represents methyl, then R² represents cyclopentyl; R³ is selected from the group consisting of phenyl unsubstituted or substituted with 1 to 3 substituents selected from F, CI, Br, I, and OCH₃; and 6- to 10-membered heteroaryl with 1 to 3 heteroatoms selected independently form O, N and S; and Q represents C1 -C3-alkylene group, which is unsubstituted or substituted with 1 to 3 C1 -C3-alkyl groups; and their salts. The compounds are PDE9A inhibitors useful as medicaments, in particular for treatment of cognitive function disorders and neurodegenerative diseases.

Description

PYRAZOLO[4,3-D]PYRIMIDIN-7(6H)-ONE DERIVATIVES AS PDE9 INHIBITORS

The present invention relates to novel heterocyclic pyrazolo[4,3-d]pyrimidin- 7(6H)-one compounds exhibiting the ability of phosphodiesterase 9A inhibition, pharmaceutical compositions containing them, and their use as medicaments. In particular, the compounds can find use in the treatment of cognitive functions disorders and neurodegenerative diseases, such as Alzheimer's disease.

Cognitive functions, i.e. mental processes involved in perception, reasoning and memory, can be disordered to a different extent due to the action of various factors and in many diseases. Disorders of cognitive functions are the feature of many diseases of central nervous system in a broad range of psychotic and neurodegenerative diseases.

Cyclic monophosphate cGMP is a common signaling molecule in all mammal cells, involved in the process of regulation of synapses functioning. cGMP is hydrolysed with high selectivity by the enzyme phosphodiesterase 9A (PDE9A) from the family of phosphodiesterases. It is expressed mainly in the brain, with high concentrations in the cerebellum, cerebral cortex, striatum, and hippocampus. It is believed that PDE9A inhibitors can potentiate cGMP signalling and synaptic transmission, enhancing neuronal communication in the brain involved in cognitive functions, including processes of learning and memorising, perception, reasoning and concentration.

Therefore, selective inhibition of PDE9A enzyme activity has become recently one of the targets in attempts to discover new medicaments for treating disorders of cognitive functions, including disorders of cognitive functions associated with pathologies of central nervous system, such as various types of neurodegenerative processes in the brain, such as for example Alzheimer's disease.

There are known in the art PDE9 inhibitors, including pyrazolo[4,3-d]pyrimidin- 7(61-1 )-one derivatives, of potential utility in the treatment of neurodegenerative diseases associated with disorders of memory, perception, concentration, learning, such as Alzheimer's disease. Known compounds have different substituents in the positions 3 and 5 of pyrazolopyrimidine moiety.

WO03/037432 discloses pyrazolo[4,3-d]pyrimidin-7(6H)-one derivatives among others substituted in the position 3 with alkyl, especially isopropyl, cycloalkyl or heteroaryl, and in the position 5 with alkyl, especially methyl, optionally substituted with cycloalkyl, heteroaryl or aryl. The compounds are described as capable of inhibition of PDE9 activity and useful in the treatment of diabetes. WO2004/09681 1 discloses pyrazolo[4,3-d]pyrimidin-7(6H)-one derivatives of the formula presented below, substituted in the position 3 among others with cycloalkyl, heterocycloalkyl or alkyl, and in the position 5 with cycloalkyl, heterocycloalkyl, aryl or heteroaryl linked via methylene bridge and substituted with a substituent comprising carboxy, amide, amine or sulphonamide moiety. The compounds are described as capable of inhibition of PDE9 activity and useful in the treatment of cardiovascular diseases and diabetes.

WO2010/084438 discloses pyrazolo[3,4-d]pyrimidin-4(5H)-one derivatives of the formula presented below, substituted in the position 6 with 1 -azetidinylmethyle- ne or 1 -pyrrolidinylmethylene group, and in the position 1 with cycloalkyl or heterocycloalkyl group as capable of inhibition of PDE9 activity, and useful in the treatment of neurodegenerative diseases.

WO2008/ 139293 discloses pyrazolo[3,4-d]pyrimidin-4(5H)-one derivatives of the formula presented below, substituted in the position 6 with substituted pyrrolidin-3-yl group, and in the position 1 with cycloalkyl or heterocycloalkyl group as capable of inhibition of PDE9 activity and useful in the treatment of neurodegenerative diseases. One of disclosed compounds, 6-[(3S,4S)-4-methyl-1 - (pyrimidin-2-ylmethyl)pyrrolidin-3-yl]- 1 -(tetrahydro-2H-pyran-4-yl)-1 ,5-dihydro- 4H-pyrazolo[3,4-d]pyrimidin-4-one, is known under code designation PF- 04447943 and is undergoing clinical trials as a potential medicament improving cognitive function.

WO2012/040230 discloses imidazo[5,1 -f][1 ,2,4]triazyn-4(3H)-one derivatives of the formula presented below, substituted in the position 6 with pyrrolidin-3-yl group, and in the position 7 with cycloalkyl or heterocycloalkyl group, as capable of inhibition of PDE9 activity and useful in the treatment of neurodegenerative diseases.

However, the need still exists of novel PDE9A inhibitors of potential utility in the treatment of diseases associated with cognitive functions disorders and neurodegenerative diseases that exhibit high selectivity and thus lowered potential to cause adverse effects, are highly effective and have good bioavailability.

The object of the invention are novel compounds represented by the general formula (I):

wherein

R¹ represents hydrogen atom or methyl;

when R¹ represents hydrogen atom, then R² represents cyclopentyl, tetrahydro- pyranyl, cyclohexyl, or cyclohexyl substituted with 1 or 2 halogen atoms;

when R¹ represents methyl, then R² represents cyclopentyl;

R³ is selected from the group consisting of:

- phenyl unsubstituted or substituted with 1 to 3 substituents selected from F, CI, Br, I, and OCH₃; and

- 6- to 10-membered heteroaryl with 1 to 3 heteroatoms selected independently from 0, N and S; and Q represents C1 -C3-alkylene group, which is unsubstituted or substituted with 1 to 3 C1 -C3-alkyl groups;

and their salts, including pharmaceutically acceptable salts, and including optically active diastereoisomers and their mixtures.

Substituent R¹ in the above formula (I) is attached to one of nitrogen atoms of the pyrazole ring in the pyrazolopyrimidine core of the molecule. Therefore, depending on the place of attachment of the substituent R¹, the compounds of the formula (I) can be presented by means of two structures, which are specific cases of the formula (I), that is by means of specific formula (IA), wherein substituent R¹ is attached in the position 1 of the pyrazolopyrimidine core, or by means of specific formula (IB), wherein substituent R¹ is attached in the position 2 of the pyrazolopyrimidine core

(IA) (IB) and remaining symbols R², R³ and Q in formulas (IA) and (IB) have the meanings such as defined above for formula (I).

It will be apparent for a skilled person that in the case when R¹ represents hydrogen atom, formulas (IA) and (IB) represent two tautomeric forms of the compound that can exist in equilibrium with each other.

The compounds of the invention can differ in configuration of substituents in the positions 3 and 4 of the pyrrolidinyl-3-yl substituent (cis or trans).

Preferably, the compounds of the above formulas (I), (IA) and (IB) have configuration trans of the substituents in the positions 3 and 4 of the pyrrolidinyl-3-yl substituent (3,4-trans).

The compounds of formulas (I), (IA) and (IB) possess chiral carbon atoms in the positions 3 and 4 of the pyrrolidinyl-3-yl substituent and can, therefore, exist in the form of two diastereoisomers. Each of the configurations cis and trans can exist in the form of two diastereoisomers.

Therefore, the invention encompasses the compounds of the formulas (I), (IA) and (B) in the form of single diastereoisomers and their mixtures, including racemic mixtures. The compounds in the configuration trans can exist in the form of diastereoisomers (3S,4S) and (3R,4R). Preferred are compounds of the formulas (I), (IA) and (B) in the form of single diastereoisomers. Preferably, the compounds have the configuration (3S,4S).

It has been found that novel compounds, pyrazolo[4,3-d]pyrimidin-7(6H)-one derivatives of the invention show high ability of PDE9A enzyme inhibition as well as activity in animal models that demonstrate their beneficial effect on cognition processes. Therefore they can found use as medicaments.

Accordingly, the present invention relates also to the compound of the general formula (I) as defined above for use as a medicament.

The present invention relates also to a pharmaceutical composition, comprising as an active ingredient a compound of the general formula (I) as defined above in combination with pharmaceutically acceptable excipients.

As PDE9A inhibitors, the compounds of the general formula (I) defined above can be useful in the treatment of cognitive functions disorders and neurodegenerative diseases of central nervous system, including dementia and Alzheimer's disease.

The present invention relates therefore to the use of a compound of the general formula (I) as defined above for the preparation of a medicament for treating cognitive function disorders and neurodegenerative diseases.

The present invention relates further to a method of treating of cognitive function disorders and neurodegenerative diseases in a mammal subject, including humans, comprising administering to the subject in need thereof a therapeutically effective amount of a compound of the general formula (I) as defined above or a pharmaceutical composition as defined above.

One group of the compounds of the invention is represented by the general formula (I), (IA) or (IB), wherein

R¹ represents hydrogen atom or methyl;

when R¹ represents hydrogen atom, then R² represents cyclopentyl or tetrahydropyranyl;

when R¹ represents methyl, then R² represents cyclopentyl;

R³ is selected from the group consisting of:

- phenyl unsubstituted or substituted with 1 to 3 substituents selected from F, CI, Br, I, and OCH₃; and - 6- to 10-membered heteroaryl with 1 to 3 heteroatoms selected independently form 0, N and S; and

Q represents C1 -C3-alkylene group, which is unsubstituted or substituted with 1 to 3 C1 -C3-alkyl groups;

and their salts, including pharmaceutically acceptable salts, and including optically active diastereoisomers and their mixtures.

In one of specific embodiments, the invention relates to the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom. In this embodiment of the compound represented by the above formula (I), (IA) or (IB), R² represents cyclopentyl, tetrahydropyranyl, cyclohexyl or cyclohexyl substituted with 1 or 2 halogen atoms.

In the above embodiment, preferably R¹ represents cyclohexyl substituted with 1 or 2 halogen atoms, preferably 2 halogen atoms, such as 2 F atoms, especially geminally substituted, such as 4,4-difluorocyclohexyl.

In another specific embodiment, the invention relates to the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents methyl. In this embodiment of the compound represented by the above formula (I), (IA) or (IB), R² represents cyclopentyl.

In another specific embodiment, the invention relates to the compound represented by the above formula (I), (IA) or (IB), wherein R³ is 6- to 10- membered heteroaryl with 1 to 3 ring heteroatoms selected independently from 0, N and S.

In particular, R³ can represent 10-membered heteroaryl with one nitrogen ring atom, such as quinolinyl, 8-quinolinyl, 7-quinolinyl, 6-quinolinyl, 5-quinolinyl, 3- quinolinyl and 2-quinolinyl, especially 8-quinolinyl. R³ can also represent isoquinolinyl.

In particular, R³ can also represent 10-membered heteroaryl with two nitrogen ring atoms, such as quinoxalinyl.

In particular, R³ can also represent 6-membered heteroaryl with one nitrogen ring atom, such as pyridyl, including 2-pyridyl, 3-pyridyl and 4-pyridyl.

In particular, R³ can also represent 6-membered heteroaryl with two nitrogen ring atoms (diazynyl), such as pyrimidinyl (1 ,3-diazynyl), including 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl and 6-pyrimidinyl, pirazynyl (1 ,4-diazynyl) or pyridazynyl (1 ,2-diazynyl). Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R³ is selected from the group consisting of phenyl and pyrimidinyl.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R³ is phenyl substituted with 1 to 3 substituents selected from F, CI, Br, I, and OCH₃, especially phenyl substituted with F atom.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein Q represents -CH₂-.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom, and Q represents -CH₂-.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom, R² represents tetrahydropyranyl, Q represents -CH₂-, and R³ represents phenyl.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom, R² represents tetrahydropyranyl, Q represents C1 -C3-alkylene group, especially -CH₂-, which can be optionally substituted with 1 to 3 C1 -C3-alkyls, and R³ represents phenyl substituted with F atom, especially 3-fluorophenyl.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom, R² represents tetrahydropyranyl, Q represents -CH₂-, and R³ represents pyrimidinyl.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom, R² represents cyclopentyl, Q represents -CH₂-, and R³ represents phenyl.

Another embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein R¹ represents hydrogen atom, R² represents cyclohexyl substituted with two F atoms, especially geminally substituted, Q represents -CH₂-, and R³ represents pyrimidinyl.

Further embodiment of the invention is the compound represented by the above formula (I), (IA) or (IB), wherein:

R¹ represents methyl;

R² represents cyclopentyl;

R³ is selected from the group consisting of phenyl and pyrimidinyl; and Q represents -CH₂-.

In the above formulas the term „-C1 -C3-alkyl" encompasses -CH₃ (methyl), -CH₂CH₃ (ethyl), -CH₂CH₂CH₃ (propyl), and -CH(CH₃)₂ (isopropyl).

The term „C1 -C3-alkylene" encompasses bivalent hydrocarbyl group with straight or branched chain and 1 to 3 carbon atoms, that is methylene (-CH₂-), ethylene (-CH₂-CH₂-), and propylene (-CH₂-CH₂-CH₂-) groups.

Specific embodiments of the invention are the compounds selected from the group consisting of:

5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 -methyl-1 H- pyrazolo[4,3-d]pyrimidin-7(6H)-one;

5-((3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl)-3-cyclopentyl-2-methyl-2H- pyrazolo[4,3-d]pyrimidin-7(6H)-one;

5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H-pyrazolo[4,3- d]pyrimidin-7(6H)-one;

(-)-5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H-pyrazolo- [4,3-d]pyrimidin-7(6H)-one;

(+)-5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H- pyrazolo[4,3-d]pyrimidin-7(6H)-one;

5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3-(tetrahydro- 2H-pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(-)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3- (tetrahydro-2H-pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(+)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylomethyl)pyrrolidin-3-yl]-3- (tetrahydro-2H-pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

3-cyclopentyl-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]- 1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)-1 H- pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(-)-5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)- 1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(+)-5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)- 1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one; 3-(4,4-DiTluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methylpyrrolidin-3- yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(-)-3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methyl- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(+)-3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methyl- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one; and

3-(4,4-DiTluorocyclohexyl)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

and their salts, especially pharmaceutically acceptable salts,

including optically active diastereoisomers thereof and their mixtures, such as racemic mixtures.

Salts of the compounds of formula (I) of the invention include salts with inorganic or organic acids. Preferred are salts that are pharmaceutically acceptable. Inorganic and organic acids that can form pharmaceutically acceptable salts with compounds having basic nitrogen atom are well known in the art. Salts with inorganic acids especially comprise those of hydrochloric, hydrobromic, sulphuric, and phosphoric acids. Salts with organic acids especially comprise those of methanesulfonic, ethanesulfonic, toluenesulfonic, benzene- sulfonic, naphthalenedisulfonic, acetic, propionic, lactic, tartaric, malic, citric, fumaric, maleic, and benzoic acids.

Salts of the compounds of formula (I) of the invention comprise also salts with inorganic or organic bases, especially pharmaceutically acceptable. Inorganic and organic that can form pharmaceutically acceptable salts are well known in the art. Salts with inorganic bases especially comprise those of alkaline metals (for example sodium and potassium salts), alkaline earth metals (for example calcium and magnesium salts), and ammonia derived ammonium salts. Salts with organic bases especially comprise those of organic amines having from 1 to 16 carbon atoms, such as (and advantageously) ethylamine, diethylamine, triethylamine, ethyldiisopropylamine, monoethanoloamine, diethanoloamine, triethanoloamine, dicyclohexylamine, dimethylaminoethanol, procaine, dibenzylamine, N-methylmorpholine, dehydroabiethylamine, arginine, lisine, ethylenediamine and methylpiperidine.

The compounds of the invention of the general formula (I) can be prepared by reacting corresponding aminoamidopyrazole of the general formula (II)

with corresponding pyrrolidine acid derivative of the general formula (III)

wherein R¹, R², R³ and Q have the meanings such as defined above for formula (I), and X represents chlorine atom or OR, wherein R represents methyl or ethyl.

The reaction of the compound of formula (II) with the compound of formula (III) wherein X represent OR (ester) is carried out in an aprotic solvent in the presence of a base at the solvent reflux point. Suitable solvents are ethanol or tetrahydrofuran. Suitable bases can be sodium hydride, sodium ethanolate sodium or potassium tert-butanolate. Preferably, the reaction is carried out in the presence of potassium tert-butanolate in tetrahydrofuran.

The reaction of the compound of formula (II) with the compound of formula (III), wherein X represents chlorine atom (acid chloride) is carried out in an inert solvent in the presence of a base. Solvents that do not undergo chemical transformation under reaction conditions are used. Suitable solvents are ethers, for example diethyl ether, dioxane, tetrahydrofuran, or diglyme, hydrocarbons such as toluene, amines such as pyridyne. Mixtures of the solvents mentioned above can be used. Especially advantageous are tetrahydrofuran, toluene or pyridyne. As bases, alkaline metal hydrides, cyclic amines, such as piperidine, pyridine, dimethylaminopyridine (DMAP), and aliphatic amines, for example triethylamine, can be used. Preferred bases are sodium hydride, pyridine and DMAP. The amount of a base is in the range from 1 to 4 molar equivalents per 1 mol of the compound of the general formula (II). Preferred amount is from 1.2 to 3 molar equivalents.

The compound of formula (II) can be prepared from the corresponding ketone of formula (IV)

R²-C(=0)-CH₃ (IV)

wherein R² has the meaning as defined above for formula (I), in the following steps. In the case when R² represents cyclopentyl, the compound of the above formula (IV), that is cyclopentylmethylketone, is reacted in the condensation reaction with diethyl oxalate to obtain intermediate compound of formula (V)

Condensation is carried out in an inert solvent such as ethanol, tetrahydrofuran, or toluene, preferably ethanol, in the temperature range 0-60 °C. Preferred temperature range is from 0°C to room temperature.

Then the compound of the above formula (V) is reacted with hydrazine of formula (VI)

R¹-NH-NH₂ (VI)

wherein R¹ has the meaning as defined above for formula (I), to obtain an ester of formula (VII)

The reaction of the compound of formula (V) with hydrazine of formula (VI) is carried out in a solvent in the temperature range 20° C - solvent reflux point, preferably at room temperature. Ethanol is the preferred solvent; acetic acid can also be used.

In the case when R¹ represents methyl, in the reaction of the compound of formula (V) with hydrazine of formula (VI) there is obtained a mixture of structural isomers of the compound of formula (VII) differing in place of substitution of methyl group at one of the two ring nitrogen atoms, that can be represented as formulae (VI IA) and (VI IB). The mixture can be separated into structural isomers by means of column chromatography, for example on silica gel.

B) Then the ester of the above formula (VII) or separated isomer of formula (VIIA) or (VI IB) is hydrolysed to form carboxylic acid of formula (VIII)

Hydrolysis to the carboxylic acid of formula (VIII) is carried out using a base such as sodium, potassium or lithium hydroxide. As a solvent, dioxane, methanol, ethanol, tetrahydrofuran or Ν,Ν-dimethylformamide can be used. Temperature ranges from room temperature to the solvent reflux point; reflux point is preferred.

Subsequently, carboxylic acid of formula (VIII) is reacted in the nitration reaction to form nitro compound of formula (IX)

In the nitration reaction conventional reagents, i.e. nitric acid and sulphuric acid can be used; the reaction takes place in the temperature range 20-100° C (preferred temperature is 60° C).

The compound of formula (IX), wherein R¹ represents methyl group, can be also obtained by methylation of the compound of formula (IX), wherein R¹ represents hydrogen atom. Methylation can be carried out in accordance with known procedures, for example with dimethyl sulphate, in a solvent, for example toluene.

Nitro compound of formula (IX) thus obtained is then converted to nitroamide of formula (X) by treatment with thionyl chloride, preferably at reflux temperature, and then treatment with ammonia

Ammonia gas or its aqueous or aqueous-acetone solution can be used. Preferrably, ammonia gas at 0°C is used. In the last step, nitroamide of the above formula (X) is reduced to form the compound of formula (II). Reducing agent can be hydrogen in the presence of a catalyst, for example Raney nickel, palladium on active carbon, sodium borohydride, dithionite sodium, potassium hydrogencarbonate, or tin chloride. Preferred solvents are alcohols such as methanol or ethanol. Temperature of the reaction is usually 20 to 50°C, preferably about 50°C.

In the case when R² represents tetrahydropyranyl, the compound of the above formula (IV), that is 1 -(tetrahydro-2H-pyran-4-yl)ethanone, is reacted in the condensation reaction with diethyl oxalate in basic conditions in a solvent to form intermediate compound of formula (XI).

Preferably, sodium ethanolate is used as the base and ethanol as the solvent.

The compound of formula (XI) is then reacted with sodium nitrite and aniline to form diazonium compound (XII).

The reaction is effected at 0°C.

Diazonium compound (XII) is then reacted with hydrazine in the presence of acetic acid at room temperature to obtain pyrazole ester (XIII).

Pyrazole ester (XIII) is then reduced to form aminoester (XIV).

(XIV)

Preferred reducing agent is tin(ll) chloride, with ethanol as a solvent; the reaction takes place at lowered temperature, preferably at 0°C. Aminoester (XIV) is converted to aminoamide (II) in the reaction with ammonia at raised temperature (above 100°C). Preferably, ammonia solution in water or in alcohol is used.

Starting compound of formula (III)

in the case when X represents group OR, wherein R is methyl or ethyl, and R³ represents phenyl, can be prepared from alpha, beta-unsaturated esters, i.e. methyl or ethyl crotonate, respectively, by reaction with commercially available N-(methoxymethyl)(phenyl)-N-[(trimethylsilyl)methyl]methanamine in a known manner (Hosomi et al., Chem. Lett. 13(7), 1117-1120, 1984). The reaction is catalyzed by acid.

In the case when R² represents cyclohexyl or cyclohexyl substituted with two halogen atoms, the compound of the above formula (II) is prepared analogously as described above for the compound of the above formula (II) wherein R² represents tetrahydropyranyl, starting from the corresponding compound of formula (IV), i.e. 1 -(optionally substituted cyclohexyl)ethanone.

Starting compound of formula (III), in the case when R represents methyl or ethyl, and R³ represents 6- to 10-membered heteroaryl with 1 to 3 heteroatoms independently selected from 0, N and S, can be obtained from the corresponding compound of formula (III), wherein R³ represents phenyl.

For this, the compound of formula (III), wherein R³ represents phenyl, is subjected to debenzylation reaction by reduction, to form aminoester of formula

(XV).

ph enyl ) (XV) (I I I , R³ = h eteroary l)

Preferred reducing agent is hydrogen, and the most suitable catalyst is palladium on active carbon. Preferred solvent is ethanol. The reaction takes place at room temperature, and can be also carried out at raised temperature (up to 50°C) and under hydrogen pressure (up to 25 atm).

Then aminoester of formula (XV) is alkylated with halogenide of formula (XVI), wherein R³ represents 6- do 10-membered heteroaryl with 1 to 3 heteroatoms independently selected from 0, N and S, in the presence of a base to form corresponding compound of formula (III). The most suitable solvents are aprotic polar solvents, for example acetonitrile. Potassium or cesium carbonate can be used as the base. Preferably, the reaction is carried out at room temperature.

Starting compound of formula (III)

wherein X represents chlorine atom, can be obtained from corresponding compound of formula (III), wherein X represents OR group, where R is methyl or ethyl, and R³ has the meaning as defined for formula (I), using methods known in the art, usually by hydrolysis to the corresponding acid in alkaline conditions and reaction with thionyl chloride.

Compounds of formula (I) are obtained in the form of a racemic mixture of trans isomers in the positions 3 and 4 of the pyrrolidine ring.

(l)-trans

Such isomers can be easily separated by means of high-performance liquid chromatography (HPLC) using chiral stationary phase. Exemplary conditions for such separation are illustrated in the Examples hereinbelow. The compounds of the invention of the formula (I) as defined above can find use as medicaments in the treatment of diseases associated with disorders of cognitive functions and neurodegenerative diseases.

The compounds of the invention can be used in particular for preventing, controlling or treating the following neurodegenerative diseases: Alexander disease, Alpers' disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS; Lou Gehrig's disease; motor neuron disease), ataxia-telangiectasia, Batten's disease (Spielmeyer-Vogt-Sjogren-Batten disease), Binswanger's dementia (subcortical arteriosclerotic encephalopathy), bipolar disorder, bovine spongiform encephalopathy (BSE), Canavan disease, chemotherapy-induced dementia, Cockayne syndrome, corticobasal degeneration, Creutzfeldt-Jakob disease, depression, Down syndrome, frontotemporal lobar degeneration (including progressive nonfluent aphasia), Gerstmann-Straussler-Scheinker disease, glaucoma, Huntington's disease, HIV-associated dementia, hyperkinesias, Kennedy's disease, Korsakokoff's syndrome, Krabbe's disease, Lewy body dementia, Machado- Joseph disease (spinocerebellar ataxia type 3), multiple sclerosis, multiple system atrophy, myasthenia gravis, Parkinson's disease, Pelizaeus-Merzbacher disease, Pick's disease, mild cognitive impairment, primary lateral sclerosis, primary progressive aphasia, radiation- induced dementia, Refsum's disease, Sandhoff disease, Schilder's disease, schizophrenia, senile dementia, Shy-Drager syndrome, spinocerebellar ataxias, spinal muscular atrophies, Steele-Richardson-Olszewski disease, tabes dorsalis, tardive dyskinesia, vascular amyloidosis, vascular dementia.

The compounds described in the present application can be especially useful for preventing, controlling or treating, including symptomatic treating, of Alzheimer's disease.

The compounds described in the present application can be useful in the treatment or convalescense of patients that experienced brain, medulla or peripheral nerves damage due to an accident or a pathological process.

The compounds of formula (I) can be administered in the treatment in the form of a pharmaceutical composition or preparation containing them.

The object of the invention is therefore also a pharmaceutical composition comprising as an active ingredient a compound or compounds of formula (I) as defined above in the mixture with pharmaceutically acceptable excipients.

The invention relates also to a method for treating of cognitive function disorders and neurodegenerative diseases in a mammal subject, including humans, which comprises administration to the subject in need thereof of a therapeutically effective amount of the compound of the above formula (I) or a pharmaceutical composition comprising said compound of the above formula (I) as an active ingredient.

In the treatment of diseases mentioned above the compounds of formula (I) of the invention can be administered as a chemical compound, but usually will be used in the form of pharmaceutical compositions comprising the compound of the invention or its pharmaceutically acceptable salt such as defined above as the active ingredient, in combination with pharmaceutically acceptable carriers and excipients.

In the treatment of diseases mentioned above the compositions of the invention will be administered by any route, preferably by oral route or parenteral route and will have the form of a preparation destined for use in medicine, depending on the intended route of administration.

Compositions for oral administration can have a form of solid or liquid preparations. Solid preparations can have the form of, for example, tablets or capsules produced in a conventional manner from pharmaceutically acceptable inactive excipients such as binders (for example, pregelatinised corn starch, polyvinylpyrrolidone or hydroxypropylomethylcellulose); fillers (for example lactose, saccharose or calcium hydrogenphosphate), lubricants (for example magnesium stearate, talc or silica), wetting agents (for example sodium laurylsulphate). Tablets can be coated with well known in the art simple coatings, delayed/controlled-release coatings or enteral coatings. Liquid preparations for oral administration can be in the form of, for example, solutions, syrups or suspensions, or can have the form of a dry solid product for reconstitution with water or other suitable vehiculum before use. Such liquid preparations can be prepared using conventional means from pharmaceutically acceptable excipients, such as suspending agents, for example sorbitol syrup, cellulose derivatives or hydrogenated edible oils, emulsifiers, for example lecithine or acacia gum, nonaqueous vehicles, for example mandelic oil, oil esters, ethyl alcohol or fractionated vegetable oils, and preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid. Preparations can also include suitable buffering agents, flavoring agents and sweeteners.

Preparations for oral administration can be formulated so as to obtain controlled release of the active compound using methods known for a person skilled in the art.

Parenteral route of administration includes administration by intramuscular and intravenous injections, as well as intravenous infusions. Compositions for parenteral administration can, for example, have the form of unit dosage form, such as ampoules, or multidosage containers, with the addition of a preservative. Compositions can have the form such as suspensions, solutions or emulsions in oily or aqueous vehiculum, and can include excipients such as suspending agents, stabilizers, and/or dispersing agents. Alternatively, the active ingredient can have the form of a powder for reconstitution before use in a suitable carrier, for example sterile, pyrogen-free water.

The method of treatment with the use of the compounds of the present invention will comprise administration of a therapeutically effective amount of the compound of the invention, preferably in the form of a pharmaceutical composition, to the subject in need of such treatment.

Proposed dosage of the compounds of the invention is from 0.1 to about 1000 mg per day, in a single dose or in divided doses. It will be apparent for a person skilled in the art that the selection of a dosage required for obtaining desirable biological effect will depend on many factors, for example specific compound, the indication, the manner of administration, the age and condition of a patient and that exact dosage will be ultimately determined by a responsible physician.

Examples

Intermediate and starting compounds

Intermediate P1. Cyclopentylmethylketone

The solution of cyclopentanecarboxylic acid (17.00 g, 147.45 mmol) in dry diethyl ether (250 ml) was cooled to -78°C, and then methyUithium solution (1.6M in diethyl ether, 202 ml, 324.39 mmol, 2.2 eq.) was added dropwise during 90 minutes while maintaining temperature of the reaction mixture below -55°C. When the addition of methyUithium was complete, the mixture was cooled for further 5 hours and then slowly warmed to room temperature. 100 ml of saturated ammonium chloride were added, and aqueous layer was extracted with diethyl ether (1 x 100 ml). Organic layers were combined and dried over sodium sulphate. Solvent was removed and the crude product was distilled under reduced pressure, collecting fraction boiling at 55-60°C/20 mm Hg. 11.000 g of the title product in the form of colorless liquid were obtained (yield 66,5%). ¹H NMR (300 MHz, CDCl₃): δ 2.95 - 2.79 (m, 1 H), 2.16 (t, J = 1.9 Hz, 3H), 1.91 - 1.48 (m, 8H).

Intermediate P2. Ethyl 3-cyclopentyl-1 H-pyrazole-5-carboxylate

To the solution of diethyl oxalate (7.970 g, 53.99 mmol) in ethanol (70 ml) at 0°C sodium ethanolate (21%, 15.747 g, 48.59 mmol) was added and the mixture was stirred for 15 minutes. Then, while still cooling, cyclopentylmethylketone (Intermediate P1 , 6.056 g, 53.99 mmol) was added and the mixture stirred overnight at room temperature. The mixture was heated for further 6 hours at 60°C. Then the whole mixture was again cooled to 0°C and 1 equivalent of glacial acetic acid (3.275 g, 53.99 mmol) was added. After addition of the acid stirring was continued at 0°C for 30 minutes and hydrazine hydrate was added (65%, 4.191 g, 53.99 mmol). After addition of hydrazine hydrate the mixture was slowly brought during about 2 hours to room temperature, and stirring was continued for further 18 hours. After addition of water (300 ml) and ethyl acetate (150 ml), the product was separated quantitatively by extraction with ethyl acetate (additional 3 portions of 30 ml). Organic layer was dried over sodium sulphate. Solvents were removed to obtain 9.590 g of the crude title product. The product was purified by chromatography on silica gel (heptane/ethyl acetate 9:1 ), to obtain 8.411 g of the title product as an orange oil (yield 74,8%). ¹H NMR (300 MHz, CDCl₃): δ 6.58 (s, 1 H), 4.35 (q, J = 7.1 Hz, 2H), 3.19 - 3.03 (m, 1 H), 2.16 - 1.97 (m, 2H), 1.85 - 1.52 (m, 6H), 1.34 (t, J = 7.1 Hz, 3H). ¹³C NMR (75 MHz, CDCl₃): δ 161.92, 152.26, 141.14, 104.89, 60.83, 37.05, 32.98, 25.04, 14.22.

Intermediate P3A: Ethyl 3-cyclopentyl-1 -methyl-1 H-pyrazole-5-carboxylate

Intermediate P3B: Ethyl 5-cyclopentyl-1 -methyl-1 H-pyrazole-3-carboxylate

Synthesis was performed in a manner analogous to that described for Intermediate P2. Starting from cyclopentylmethylketone (Intermediate P1 , 1.150 g, 10.25 mmol), diethyl oxalate (1.514 g, 10.25 mmol) and methylhydrazine (0.472 g, 10.25 mmol) 2 g of the crude title product as a mixture of two structural isomers P3A and P3B were obtained. The compounds were separated chromatographically on silica gel (heptane/ethyl acetate 4: 1 , compound P3A, R_f = 0.55; ethyl acetate, compound P3B, R_f = 0, 1 ). 0.480 g of the compound P3A in the form of a colorless oil and 0.320 g of the compound P3B in the form of a yellow oil were obtained (total yield 30.7%).

¹ H NMR (300 MHz, CDCl₃, compound P3A): δ 6.64 (s, 1 H), 4.39 - 4.25 (q, 2H), 4.12 (s, 3H), 3.06 (m, 1 H), 2.05 (m, 2H), 1 .83 - 1 .54 (m, 6H), 1 .37 (t, J = 7.1 Hz, 3H). ¹³C NMR (75 MHz, CDCl₃): δ 160.00, 155.83, 132.73, 108.06, 60.78, 39.10, 38.75, 33.37, 25.28, 14.24.

¹ H NMR (300 MHz, CDCl₃, compound P3B): δ 6.58 (s, 1 H), 4.39 (q, J = 7.1 Hz, 2H), 3.89 (s, 3H), 3.03 (dd, J = 15.9, 7.9 Hz, 1 H), 2.09 (m, 2H), 1 .88 - 1 .52 (m, 6H), 1 .44 - 1 .33 (t, 3H). ¹³C NMR (75 MHz, CDCl₃): δ 162.62, 149.21 , 141 .99, 105.31 , 60.73, 37.17, 36.15, 32.53, 25.07, 14.39.

Intermediate P4: 3-Cyclopentyl-1 H-pyrazole-5-carboxylic acid

To the solution of ethyl 3-cyclopentyl-1 H-pyrazole-5-carboxylate (Intermediate P2, 8.41 1 g, 40.39 mmol) in methanol (80 ml) 2.5 eq. of 10M sodium hydroxide solution were added and the whole was heated at reflux for 3 hours. Reaction mixture was concentrated to constant weight, then water was added and aqueous layer was washed with 3 x 20 ml of chloroform to remove organic impurities. Aqueous layer was cooled with ice and acidified with 6M hydrochloric acid to pH = 4. Light-yellow precipitate thus obtained was washed with water and dried. 6.470 g of the title product were obtained (yield 82.5%). ¹ H NMR (300 MHz, DMSO-de): δ 12.88 (s, broad 1 H), 6.48 (s, 1 H), 3.19 - 2.89 (m, 1 H), 2.60 - 2.45 (m, 2H), 2.22 - 1 .26 (m, 6H). ¹³C NMR (75 MHz, DMSO-d₆): δ 162.87, 104.62, 99.54, 99.52, 36.62, 32.74, 24.65.

Intermediate P5: 3-Cyclopentyl-4-nitro-1 H-pyrazole-5-carboxylic acid

The mixture of nitric acid (11.316 g, 8.2 ml, 113.14 mmol) and sulphuric acid (16.376 g, 8.9 ml, 163.62 mmol) was heated to 65°C and solid 3-cyclopentyl-1 H- pyrazole-5-carboxylic acid (Intermediate P4, 5.285 g 29.33 mmol) was added. Obtained mixture was heated at 65°C for 24 hours. The mixture was cooled to 0°C, 6M hydroxide sodium was added to pH = 2, and obtained yellow solid was washed with water and dried. 2.666 g of the title product were obtained (yield 40.4%). ¹H NMR (300 MHz, DMSO-d₆): δ 13.95 (s, 1 H), 3.50 (m, 1 H), 2.07 (m, 2H), 1.70 (m, 6H).

Intermediate P6: 3-Cyclopentyl-4-nitro-1 H-pyrazole-5-carboxamide

To the solid 3-cyclopentyl-4-nitro-1 H-pyrazole-5-carboxylic acid (Intermediate P5, 2.666 g, 11.84 mmol) 15 ml of thionyl chloride were added and the whole was heated at reflux for 4 hours to obtain clear solution. The residue obtained after removing the excess of thionyl chloride was dissolved in dry tetrahydrofuran (50 ml), cooled to 0°C and gaseous ammonia was bubbled through the obtained solution during 40 minutes. The mixture was left to warm to room temperature and stirring was continued for further 20 hours. After removing of the solvent water was added, and crude product was isolated by extraction with ethyl acetate (5 x 20 ml) and then with chloroform (3 x 20 ml). Organic layers were combined, dried over sodium sulphate and concentrated, to obtain 2.455 g of the title product (yield 92.1%). ¹H NMR (300 MHz, DMSO-d₆): δ 13.80 (s, 2H), 3.55 (p, J = 8.4 Hz, 1 H), 2.06 (m, 2H), 1.70 (m, 6H).

Intermediate P7: 4-Amino-3-cyclopentyl-1 H-pyrazole-5-carboxamide

The mixture of 3-cyclopentyl-4-nitro-1 H-pyrazole-5-carboxamide (Intermediate P6, 2.455 g, 10.95 mmol) and tin chloride hydrate (9.881 g, 43.80 mmol) in 150 ml of anhydrous ethanol was heated at reflux for 18 hours. To the mixture 200 ml of saturated ammonium carbonate solution were added, obtained abundant white solid was filtered off and washed with 400 ml of ethyl acetate with the addition of methanol (2%). Filtrate was extracted with the ethyl acetate- methanol mixture (98:2, 6 x 50 ml). Combined organic fractions were dried over sodium sulphate. Drying agent and solvents were removed to obtain 3.05 g of the crude product. The product was purified by chromatography on silica gel (chloroform/methanol, gradient 0-6%). 2.020 g of the title product were obtained (yield 95%). MS-ESI: (m/z) calculated for C₉H₁₅N₄0 [M+H]⁺: 195.12, found 195.1.

Intermediate P8: 3-Cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-5-carboxylic acid

To 3-cyclopentyl-4-nitro-1 H-pyrazole-5-carboxylic acid (Intermediate P5, 1.083 g, 4.81 mmol) in toluene (20 ml) dimethyl sulphate (0.607 g, 4.81 mmol) was added and the whole was heated at reflux for 4 hours. To the mixture 2.5 eq. of 10M sodium hydroxide solution 40 ml of methanol were added and the whole was heated at reflux for 3 hours. Product was isolated by extraction with toluene (2 x 15 ml), aqueous layer was acidified with 6M HCl to pH=3 and additionally extracted with ethyl acetate (6 x 15 ml). Organic layers were combined and dried over sodium sulphate. After removing of solvents and drying agents 1.257 g of the title product in the form of an orange, crystallizing oil were obtained (yield 76.0%).

¹H NMR (300 MHz, DMSO-d₆): δ 3.83 (s, 3H), 3.43 (m, 1 H), 2.08 - 1.87 (m, 2H), 1.64 (m, 6H). ¹³C NMR (75 MHz, DMSO-d₆): δ 172.03, 159.79, 150.30, 129.40, 38.38, 31.15, 24.99, 21.08.

Intermediate P9: 3-Cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-5-carboxamide

The compound was obtained by a method analogous to that described for Intermediate P6. Starting from 3-cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-5- carboxylic acid (Intermediate P8, 1.257 g, 5.25 mmol) 1.234 g of the title product were obtained (yield 89.7%).

¹H NMR (300 MHz, DMSO-d₆): δ 8.43 (s, 1 H), 8.25 (s, 1 H), 3.78 (s, 3H), 3.53 (m, 1 H), 2.01 - 1.99 (m, 2H), 1.75-1.63 (m, 6H). ¹³C NMR (75 MHz, DMSO-d₆): δ 159.58, 150.82, 138.73, 128.78, 37.88, 37.00, 31.08, 24.37.

MS-ESI: (m/z) calculated for Ci₀H₁₅N₄O₃ [M+H]⁺: 239.11 , found 239.1.

Intermediate P10: 4-Amino-3-cyclopentyl-1 -methyl-1 H-pyrazole-5-carboxamide

The compound was obtained by a method analogous to that described for Intermediate P7. Starting from 3-cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-5- carboxamide (Intermediate P9, 1.234 g, 4.71 mmol) and tin chloride hydrate (4.252 g, 18.85 mmol) 0.960 g of the title product were obtained (yield 78.2%).

¹H NMR (300 MHz, DMSO-d₆): δ 7.25 (s, 2H), 4.07 (s, 2H), 3.85 (s, 3H), 3.07 (m, 1 H), 2.01 - 1.91 (m, 2H), 1.75-1.57 (m, 6H). ¹³C NMR (75 MHz, DMSO-d₆): δ 162.00, 144.32, 128.60, 124.37, 38.97, 35.44, 31.47, 24.37.

Intermediate P11 : 5-Cyclopentyl-1 -methyl-1 H-pyrazole-3-carboxylic acid

The compound was obtained by a method analogous to that described for Intermediate P4. Starting from ethyl 5-cyclopentyl-1 -methyl-1 H-pyrazole-3- carboxylate (Intermediate P3B, 0.810 g, 3.64 mmol) 0.600 g of the title product were obtained (yield 84.8%).

¹H NMR (300 MHz, DMSO-d₆): δ 12.48 (s, broad, 1 H), 6.47 (s, 1 H), 3.82 (s, 3H), 3.22 - 3.01 (m, 1 H), 2.15 - 1.92 (m, 2H), 1.84 - 1.39 (m, 6H). ¹³C NMR (75 MHz, DMSO-de): δ 163.32, 148.70, 141.64, 104.85, 36.95, 35.38, 32.14, 24.70.

Intermediate P12: 5-Cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-3-carboxylic acid

The compound was obtained by a method analogous to that described for Intermediate P5. Starting from 5-cyclopentyl-1 -methyl-1 H-pyrazole-3-carboxylic acid (Intermediate P11 , 0.600 g, 3.09 mmol) 0.418 g of the title product were obtained (yield 56.6%).

¹H NMR (300 MHz, DMSO-d₆): δ 3.88 (s, 3H), 3.50 - 3.36 (m, 1 H), 2.06 - 1.90 (m, 2H), 1.79 - 1.53 (m, 6H). ¹³C NMR (75 MHz, DMSO-d₆): δ 159.44, 150.40, 134.95, 130.15, 38.68, 36.62, 31.16, 24.97. Intermediate P13: 5-Cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-3-carboxamide

The compound was obtained by a method analogous to that described for Intermediate P6. Starting from 5-cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-3- carboxylic acid (Intermediate P12, 0.418 g, 1.75 mmol) 0.500 g of the title product were obtained (yield 96.1%). ¹H NMR (300 MHz, DMSO-d₆): δ 7.92 (s, 1 H), 7.65 (s, 1 H), 3.90 (s, 3H), 3.51 (m, 1 H), 2.12 - 1.91 (m, 2H), 1.91 - 1.56 (m, 6H).

Intermediate P14: 4-Amino-5-cyclopentyl-1 -methyl-1 H-pyrazole-3-carboxamide

The compound was obtained by a method analogous to that described for Intermediate P7. Starting from 5-cyclopentyl-1 -methyl-4-nitro-1 H-pyrazole-3- carboxamide (Intermediate P13, 0.500 g, 1.68 mmol) 0.470 g of the title product were obtained (yield 99.5%).

¹H NMR (300 MHz, DMSO-d₆): δ 7.02 (d, 2H), 4.31 (s, broad, 2H), 3.73 (s, 3H), 3.05 (m, 1 H), 1.95-1.67 (m, 8H).

Intermediate P15: N-Benzyl-1 -(trimethylsilyl)methanamine

The mixture of benzylamine (59.516 g, 549.84 mmol) and (chloromethyl)- trimethylsilane (23.410 g, 187.02 mmol) was heated at 120°C for 4 hours, and then stirred at room temperature for 20 hours. To the mixture 78.328 g of potassium carbonate in 200 ml of water were added and the whole was extracted with diethyl ether (2 x 30 ml). Organic layer was dried over sodium sulphate. Solvent and drying agent were removed to obtain colorless liquid. The excess of benzylamine was distilled off (38-45°C/0.36 mm Hg) using Vigreux column. 35.500 g of the title product in the form of a colorless liquid were obtained (yield 93.3%). ¹H NMR (300 MHz, CDCl₃): δ 7.32 - 7.24 (m, 5H), 3.76 (s, 2H), 2.06 (s, 2H), 0.07 (s, 9H).

Intermediate P16: N-Benzyl-1 -methoxy-N-[(trimethylsilyl)methyl]methanamine

To the solution of formaldehyde (37%, 16.816 g, 207.19 mmol) at 0°C N-benzylo- 1 -(trimethylsilyl)methanamine (Intermediate P15, 28.588 g, 144.89 mmol) was added dropwise. To the mixture solid potassium carbonate (16.182 g, 115.91 mmol) was added and the whole was stirred at room temperature for 2 hours. Water (50 ml) was added and the mixture was extracted with diethyl ether (2 x 50 ml). Organic layer was washed with brine and dried over sodium sulphate. Solvent and drying agent were removed to obtain 33.551 g of the title product in the form of a yellow oil (yield 97.5%). ¹H NMR (300 MHz, CDCl₃): δ 7.35 - 7.18 (m, 5H), 3.99 (s, 2H), 3.75 (s, 2H), 3.22 (s, 3H), 2.18 (s, 2H), 0.13 (s, 9H).

Intermediate P17: Methyl (3,4-trans)-1 -benzyl-4-methylpyrrolidine-3-carboxylate

The mixture of N-benzyl-1 -methoxy-N-[(trimethylsilyl)methyl]methanamine (Intermediate P16, 33.500 g, 126.99 mmol), methyl crotonate (11.677 g, 114.29 mmol) and trifluoroacetic acid (13.299 g, 114.29 mmol) in toluene (280 ml) was heated at 50°C for 20 hours. The reaction mixture was concentrated, saturated aqueous solution of sodium carbonate was added to pH=7, and aqueous layer was extracted with dichloromethane (3 x 50 ml). Organic layer was washed with brine and dried over sodium sulphate. After concentration, the product was purified by chromatography on silica gel (heptane/ethyl acetate, gradient 4: 1 to 7:3). 11.285 g of the title product in the form of a colorless oil were obtained (yield 38.1%). ¹H NMR (300 MHz, CDCl₃): δ 7.35 - 7.13 (m, 5H), 3.64 (s, 3H), 3.57 (m, 2H), 2.80 (m, 2H), 2.50 (m, 1 H), 2.19 (m, 1 H), 1.10 (d, J = 6.6 Hz, 3H). ¹³C NMR (75 MHz, CDCl₃): δ 175.08, 138.84, 128.71 , 128.22, 126.85, 61.55, 60.04, 56.60, 51.72, 50.42, 36.72, 19.73.

Intermediate P18: (3,4-trans)-1 -Benzyl-4-methylpyrrolidine-3-carboxylic acid

To (3,4-trans)-1 -benzyl-4-methylpyrrolidine-3-carboxylate (Intermediate P17, 10.000 g, 38.57 mmol) lithium hydroxide monohydrate (4.955 g, 115.73 mmol) was added and the whole was stirred for 5 hours at room temperature. The mixture was acidified with 6N hydrochloric acid to pH =2 and extracted with ethyl acetate/chloroform (2:1 , 2 x 15 ml). Aqueous layer was concentrated and additionally washed with ethyl acetate/methanol (2: 1 , 3 x 50 ml). Organic layers were combined, dried over sodium sulphate and concentrated, to obtain 8.332 g of the title product as a solid (yield 88.6%). MS-ESI: (m/z) calculated for Ci₃H₁₈N0₂ [M+H]⁺: 220.13, found 220.2.

Intermediate P19: (3,4-trans)-1 -Benzyl-4-methylpyrrolidine-3-carboxylic acid chloride

To (3,4-trans)-1 -benzyl-4-methylpyrrolidine-3-carboxylic acid (Intermediate P18, 1.000 g, 3.91 mmol) thionyl chloride (9.969 g, 82.115 mmol) was added and the whole was stirred for 2 hours at room temperature. The mixture was concentrated to constant weight and 18 ml of dry tetrahydrofuran were added. The solution of the title product was obtained, which was used for the preparation of the compounds of the invention (Examples 1 , 2, and 3).

Intermediate P20: 1 -(Tetrahydro-2H-pyran-4-yl)ethanone

The mixture of methyl acetylacetate (24.770 g, 211.18 mmol), bis(2-chloroethyl) ether (30.506 g, 211.18 mmol), potassium carbonate (64.861 g, 464.59 mmol) and sodium iodide (31.974 g, 211.18 mmol) in N,N-dimethylformamide (1065 ml) was heated at 80°C for 18 hours. The mixture was cooled to room temperature, further portions of potassium carbonate (29.430 g, 210.80 mmol) and sodium iodide (31.974 g, 211.18 mmol) were added and the whole was heated at 80°C for further 2 hours. The reaction mixture was filtered over celite, washed with ethyl acetate (500 ml), then organic layer was washed with water (300 ml), brine (150 ml) and dried over sodium sulphate. Drying agent and solvent were removed to obtain 26.600 g of the intermediate compound methyl 4-acetyl- tetrahydro-2H-pyran-4-carboxylate. To the obtained compound (26.600 g, 112.47 mmol) isopropanol (125 ml), water (125 ml) and concentrated sulphuric acid (55.151 g, 562.37 mmol) were added and the whole was heated at reflux for 48 hours. The mixture was alkalized with sodium hydroxide solution (45.5 g NaOH in 500 ml of water). Aqueous layer was extracted with chloroform (3 x 100 ml). Extracts were dried over sodium sulphate. Crude product obtained after removing drying agent and solvent in the form of a brown liquid was distilled under reduced pressure using Vigreux column and collecting fraction boiling at 75-83°C/20 mm Hg. 10.874 g of the title product were obtained (yield 36.4%) in the form of a colorless liquid. ¹H NMR (300 MHz, CDCl₃): δ 4.03-3.97 (m, 2H), 3.47-3.38 (m, 2H), 2.54 (m, 1 H), 2.16 (s, 3H), 1.78-1.69 (m, 4H). ¹³C NMR (75 MHz, CDCl₃): δ 209.86, 67.13, 48.03, 28.00, 27.48.

Intermediate P21 : Ethyl 2,4-dioxo-4-(tetrahydro-2H-pyran-4-yl)butanoate

To the mixture of sodium ethanolate (21% solution in ethanol, 9.898 ml, 26.52 mmol) in ethanol (20 ml) at 0°C 1 -(tetrahydro-2H-pyran-4-yl)ethanone (Intermediate P20, 2.000 g, 15.60 mmol) and diethyl oxalate (3.916 g, 26.52 mmol) were added consecutively. The whole was stirred for 1 hours at 0°C, then for 2 hours at room temperature. The mixture was added with 30 ml of water and acidified with 6M hydrochloric acid to pH = 3. Aqueous layer was extracted with ethyl acetate ( 3 x 50 ml). Organic layer was dried over sodium sulphate. Solvent and drying agent were removed to obtain 5.056 g of the title product, which was used without purification for further reactions.

MS-ESI (m/z) calculated for CnHi₆0₄Na [M+Na]⁺: 251.09, determined 251.1

Intermediate P22: Ethyl (E)-2,4-dioxo-3-(phenyldiazenyl)-4-(tetrahydro-2H- pyran-4-yl)butanoate

To the mixture of aniline (1.599 g, 17.16 mmol) and 6M hydrochloric acid (13.005 ml, 78.03 mmol) at 0°C sodium nitrite solution (1.292 g, 18.73 mmol) in 20 ml of water were added dropwise during 30 minutes. Resulted solution of diazonium salt was added dropwise at 0°C to the mixture of ethyl 2,4-dioxo-4- (tetrahydro-2H-pyran-4-yl)butanoate (Intermediate P21 , 3.562 g, 15.60 mmol) and sodium acetate (4.245 g, 31.21 mmol) in the mixture water - ethanol (1 : 1 , 30 ml). After addition of diazonium salt the whole was stirred for 18 hours at 0°C. After removing ethanol, the reaction mixture (pH =1 ) was extracted with chloroform (3 x 50 ml), then aqueous layer was neutralized with sodium hydroxide and extracted additionally with chloroform (3 x 50 ml). Combined organic extracts were dried over sodium sulphate. Solvent and drying agent were removed to obtain 6 g of the title product, which was used without purification for further reactions. MS-ESI (m/z) calculated for Ci₇Hi₉N₂05Na [M+Na]⁺: 354.33, found 355.1 Intermediate P23: Ethyl 4-(phenyldiazenyl)-3-(tetrahydro-2H-pyran-4-yl)-1 H- pyrazole-5-carboxylate

To the solution of ethyl (E)-2,4-dioxo-3-(phenyldiazenyl)-4-(tetrahydro-2H-pyran- 4-yl)butanoate (Intermediate P22, 5.000 g, 15.04 mmol) in glacial acetic acid (150 ml) at room temperature hydrazine monohydrate (65%, 1.390 g, 18.05 mmol) was added and the whole was stirred for 18 hours. The excess of acetic acid was removed under reduced pressure, and the residue was brought to pH = 9 with saturated aqueous solution of sodium hydrogencarbonate. Crude prodcut was isolated by extraction with chloroform/isopropanol (95:5). After removing solvents and drying agent the product was purified by chromatography on silica gel (heptane/aceton, gradient 0-20%) 0.830 g of the title product in the form of a crystallizing oil were obtained (yield 16.8%). MS-ESI (m/z) calculated for C17H21 N4O3 [M+H]⁺: 329.16, found 329.1

Intermediate P24: Ethyl 4-amino-3-(tetrahydro-2H-pyran-4-yl)-1 H-pyrazole-5- carboxylate

To the mixture of tin chloride dihydrate (3.467 g, 9.99 mmol) in 1M hydrochloric acid (6 ml) at 0°C the solution of ethyl 4-(phenyldiazenyl)-3-(tetrahydro-2H- pyran-4-yl)-1 H-pyrazole-5-carboxylate (Intermediate P23, 0.820 g, 2.49 mmol) in 5 ml of ethanol was added. The reaction was carried out for 2 hours at 0°C. To the mixture 20 ml of saturated sodium carbonate solution with the addition of 3 ml of 25% aqueous ammonia solution, and then 50 ml of ethyl acetate were added. Reaction solution was filtered through celite and concentrated with toluene to remove water. The product was purified by chromatography on silica gel (chloroform/isopropanol, gradient 0-10%). 0.342 g of the title product in the form of a yellow, crystallizing oil were obtained (yield 57.2%).

MS-ESI (m/z) calculated for CnH₁₈N₃0₃ [M+H]⁺: 240.13, found 240.1 Intermediate P25: 4-Amino-3-(tetrahydro-2H-pyran-4-yl)-1 H-pyrazole-5- carboxamide

To ethyl 4-amino-3-(tetrahydro-2H-pyran-4-yl)-1 H-pyrazole-5-carboxylate (Intermediate P24, 0.342 g, 1.43 mmol) 25% aqueous ammonia solution (35 ml) was added and the whole was heated at 110°C in a closed tube for 19 hours. The mixture was extracted consecutively with ethyl acetate/isopropanol (9: 1 , 3 x 15 ml) and chloroform /isopropanol (9:1 , 7 x 15 ml). Combined organic fractions were dried over sodium sulphate. Solvents and drying agents were removed and the product was purified by chromatography on silica gel (chloroform- isopropanol, gradient 0-60%). 57 mg of the title product as a solid were obtained (yield 19.0%).

MS-ESI (m/z) calculated for C₉H₁₃N₄0₂Na [M+Na]⁺: 232.21 , found 233.1

Intermediate P26: Methyl (3,4-trans)-4-methylpyrrolidine-3-carboxylate

Methyl (3,4-trans)-1 -benzyl-4-methylpyrrolidine-3-carboxylate (Intermediate P17, 16.220 g, 69.52 mmol) was dissolved in anhydrous ethanol (70 ml). To the solution palladium on active carbon (10%, 1.637 g, 1.67 mmol) was added, the mixture was placed in autoclave and hydrogen was introduced into under pressure of 13 atm. The reaction was carried out for 18 hours at room temperature, while monitoring the progress of the reaction by TLC. Hydrogen pressure was raised to 25 atm, and autoclave was heated at 50°C for additional 6 hours. The mixture was filtered through celite, washed with ethanol and concentrated. The product was purified by chromatography on silica gel (chloroform-methanol, gradient 0-5%). 7.000 g of the title product in the form of an oil were obtained (yield 63.3%). MS-ESI (m/z) calculated for C₇Hi₄N0₂ [M+H]⁺: 144.10, found 144.2

Intermediate P27: Methyl (3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)- pyrrolidine-3-carboxylate

The mixture of methyl (3,4-trans)-4-methylpyrrolidine-3-carboxylate (Intermediate P26, 0.939 g, 6.55 mmol), 2-(chloromethyl)pyrimidine (0.843 g, 6.55 mmol), and potassium carbonate (0.924 g, 6.55 mmol) in acetonitrile (20 ml) was stirred at room temperature for 16 hours. The mixture was filtered through celite and concentrated. The product was purified by chromatography on silica gel (chloroform /isopropanol, gradient 0-7%). 1.447 g of the title product in the form of an oil were obtained (yield 84.4%).

MS-ESI (m/z) calculated for Ci₂H₁₈N₃0₂ [M+H]⁺: 236.13, found 236.1

Intermediate P28: Methyl (3,4-trans)-1 -(3-fluorobenzyl)-4-methylpyrrolidine-3- carboxylate

The mixture of methyl (3,4-trans)-4-methylpyrrolidine-3-carboxylate (Intermediate P26, 1.210 g, 8.42 mmol), 3-fluorobenzyl bromide (1.450 g, 7.57 mmol), and potassium carbonate (1.410 g, 10.10 mmol) in acetonitrile (25 ml) was stirred at reflux for 1 hour. Inorganic salts were filtered off on Schott's funnel and the filtrate concentrated. 1.970 g of the product in the form of a yellow oil were obtained (yield 93.2%).

MS-ESI (m/z) calculated for Ci₄H₁₈FN0₂ [M+H]⁺: 252.12, found 252.1

Intermediate P29: 1 -(4,4-Difluorocyclohexyl)ethanone

Synthesis was performed in a manner analogous to that described for Intermediate P1. Starting from 4,4-difluorocyclohexanecarboxylic acid (23.7 g, 141.0 mmol) 23.2 g of the title product were obtained as an oil (yield 85.8%). ¹H NMR (500 MHz, CDCl₃): δ 2.43 (m, 1 H), 2.18 (s, 3H), 2.12 (m, 2H), 1.96 (m, 2H), 1.80 (m, 2H), 1.73 (m, 2H). ¹³C NMR (125 MHz, DMSO-d₆): δ 209.85, 124.59, 122.67, 120.75, 47.68, 33.77, 32.63, 27.93, 27.06, 24.49, 23.72.

Intermediate P30: 4-(4,4-Difluorocyclohexyl)-2,4-dioxobutanoic acid ethyl ester

Synthesis was performed in a manner analogous to that described for Intermediate P21. Starting from 1 -(4,4-difluorocyclohexyl)ethanone (Intermediate P29, 23.9 g, 125.0 mmol) and diethyl oxalate (31.1 g, 213.0 mmol) 13.1 g of the title product were obtained as an amorphous solid (yield 40.1 %).

¹H NMR (500 MHz, CDCl₃): δ 6.42 (s, 2H), 4.36 (q, 2H), 2.47 (m, 1 H), 2.18 (m, 2H), 1.99 (m, 2H), 1.80 (m, 4H), 1 ,37 (t, 3H).

MS-ESI (m/z) calculated for Ci₂H₁₆F₂0₄Na [M+H]⁺: 285.23, found 285.1

Intermediate P31 : 4-(4,4-Difluorocyclohexyl)-2,4-dioxo-3-[(E)-phenyldiazenyl]- butanoic acid ethyl ester

Synthesis was performed in a manner analogous to that described for Intermediate P22. Starting from 4-(4,4-difluorocyclohexyl)-2,4-dioxobutanoic acid ethyl ester (Intermediate P30, 13.1 g, 50.0 mmol) and aniline (5.12 g, 54.9 mmol) 16.2 g of the title product were obtained as a brown solid (yield 88.5%). MS-ESI (m/z) calculated for Ci₈H₁₉F₂N₂0₄ [M-H]^": 365.36, found 365.1

Intermediate P32: Ethyl 3-(4,4-difluorocyclohexyl)-4-[(E)-phenyldiazenyl]-1 H- pyrazole-5-carboxylate

Synthesis was performed in a manner analogous to that described for Intermediate P23. Starting from 4-(4,4-difluorocyclohexyl)-2,4-dioxo-3-[(E)- phenyldiazenyl]butanoic acid ethyl ester (Intermediate P31 , 16.2 g, 44.2 mmol) and hydrazine (3.41 g, 44.2 mmol) 7.48 g of the title product were obtained as an orange solid (yield 46.7 %).

MS-ESI (m/z) calculated for Ci₈H₂oF₂N₄02Na [M+Na]⁺: 385.36, found 385.1

Intermediate P33: 3-(4,4-Difluorocyclohexyl)-4-[(E)-phenyldiazenyl]-1 H-pyrazole- 5-carboxylic acid

To the solution of ethyl 3-(4,4-difluorocyclohexyl)-4-[(E)-phenyldiazenyl]-1 H- pyrazole-5-carboxylate (Intermediate P32, 7.48 g, 19.6 mmol) in methanol (40 ml) 75 ml of water and lithium hydroxide monohydrate (8.23 g, 196.0 mmol) were added successively. The reaction was carried out at room temperature for 18 hours. The reaction mixture was diluted with water (50 ml) and extracted with chloroform (5 x 30 ml) to remove organic impurities. Aqueous phase was acidified with 6N hydrochloric acid to pH = 4. Formed precipitate was collected on Schott funnel, washed with water and dried under reduced pressure; 5.23 g of the title product were obtained as a yellow solid (yield 79.8 %).

MS-ESI (m/z) calculated for C^^Oi [M-Na]^": 333.32, found 333.1

Intermediate P34: 3-(4,4-Difluorocyclohexyl)-4-[(E)-phenyldiazenyl]-1 H-pyrazole- 5-carboxamide

To a suspension of 3-(4,4-di luorocyclohexyl)-4-[(E)-phenyldiazenyl]-1 H-pyrazole- 5-carboxylic acid (Intermediate P33, 5.23 g, 15.6 mmol) in dry dichloromethane (100 ml, containing 0.1 ml of dry Ν,Ν-dimethylformamide) oxalyl chloride (3.18 ml, 37.5 mmol) was added dropwise at room temperature during 10 minutes. After the addition of oxalyl chloride the whole was stirred vigorously at room temperature for 2 hours. The reaction mixture was then concentrated under reduced pressure, keeping bath temperature below 30°C. The obtained solid residue was suspended in dry tetrahydrofuran (100 ml) and cooled to 0°C. Gaseous ammonia was passed through the reaction mixture during 30 minutes with vigorous stirring. The reaction mixture was left at 0°C, stirred overnight and slowly brought to room temperature, and then concentrated. 7.11 g of the crude product as a yellow solid containing inorganic salts were obtained (yield 136%). The product was used in the next step without further purification.

MS-ESI (m/z) calculated for Ci6Hi₆F₂N₅0 [M-H]^": 332.34, found 332.1

Intermediate P35: 4-Amino-3-(4,4-difluorocyclohexyl)-1 H-pyrazole-5- carboxamide

3-(4,4-Difluorocyclohexyl)-4-[(E)-phenyldiazenyl]-1 H-pyrazole-5-carboxamide (Intermediate P34, 6.98 g, 20.9 mmol) was placed in an autoclave. Absolute ethanol (100 ml) and palladium(O) on activated charcoal (1.11 g, 1.05 mmol) were added. The whole was hydrogenated (pressure 45 atm) during 60 hours at room temperature, with vigorous stirring. The reaction mixture was filtered through celite, washed with ethanol and concentrated. 7.73 g of a brown, oily solid were obtained. The crude product was purified by chromatography on silica gel (mobile phase chloroform/methanol 99:1 ). 3.00 g of the title product as a light-pink solid were obtained (yield 58.7%).

¹H NMR (500 MHz, CDCl₃): δ 12.38 (s, 1 H), 7.14 (s, 1 H), 6.92 (s, 1 H), 4.60 (s, 1 H), 4.39 (s, 1 H), 2.77 (m, 1 H), 2.08 (m, 2H), 1.87-1.66 (m, 6H).

MS-ESI (m/z) calculated for CioH₁₄F₂N₄0Na [M+Na]⁺: 267.23, found 267.1

Compounds of the invention

Example 1. 5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 - methyl-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The mixture of 4-amino-3-cyclopentyl-1 -methyl-1 H-pyrazole-5-carboxamide (Intermediate P10, 0.361 g, 1.73 mmol), (3,4-trans)-1 -benzyl-4-methylpyrrolidi- ne-3-carboxylic acid chloride (Intermediate P19, 0.182M solution in tetrahydro- furan, 0.712 g, 2.59 mmol) and triethylamine (1.227 g, 12.12 mmol) were heated at 60°C for 19 hours, and then for next 2 hours at reflux. The reaction mixture was concentrated, tert-butanol (15 ml) and potassium tert-butanolate (1.943 g, 17.32 mmol) were added and the whole was heated at reflux for 18 hours. The product was isolated by the addition of water (50 ml) and extraction with ethyl acetate (5 x 30 ml). Organic layers were combined and dried over sodium sulphate. After removing drying agent and solvents, the crude product was purified by chromatography on silica gel (chloroform/isopropanol, gradient od 0 to 5%), to obtain 0.415 g of the title product in the form of a racemic mixture (yield 61.2%).

¹H NMR (300 MHz, CDCl₃, racemate): δ 11.23 (s, br,1 H), 7.38-7.27 (m, 5H), 4.22 (s, 3H), 3.75-3.65 (dd, 2H), 3.40-3.32 (m, 2H), 3.00-2.83 (m, 2H), 2.55-2.49 (m, 1 H), 2.42-2.33 (m, 1 H), 2.11 -2.05 (m, 1 H), 1.93-1.79 (m, 6H), 1.73-1.66 (m, 2H), 1.20 (d, 3H). ¹³C NMR (75 MHz, CDCl₃, racemate): δ 157.05, 154.75, 148.98, 137.69, 137.56, 128.69, 128.63, 127.49, 125.08, 61.14, 59.42, 56.89, 50.63, 38.92, 36.91 , 32.73, 32.60, 25.39, 20.39.

(-)-5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 -methyl-1 H- pyrazolo[4,3-d]pyrimidin-7(6H)-one and (+)-5-[(3,4-trans)-1 -benzyl-4-methyl- pyrrolidin-3-yl]-3-cyclopentyl-1 -methyl-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

Racemate (63.77 mg) was separated into diasteroisomers by HPLC (Chiralpak IB column, 250 x 20 mm, bed 5 μιτι, mobile phase heptane/ethanol 90: 10, flow 15 ml/min.). 14.6 mg of enantiomer A (R_t = 8,2 min. ) and 16.3 mg of enantiomer B (R_t = 8,8 min.) were obtained.

Example 2. 5-[(3,4-trans)-1 -Benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-2- methyl-2H-pyrazolo[4,3-d]pyrimidin-7(6H)-one (racemate)

The compound was obtained by a method analogous to that described in Example 1. Starting from 4-amino-5-cyclopentyl-1 -methyl-1 H-pyrazole-3-carbox- amide (Intermediate P14, 0.470 g, 2.26 mmol) and (3R,4R)-1 -benzyl-4-methyl- pyrrolidine-3-carboxylic acid chloride (Intermediate P19, 0.182M solution in tetrahydrofuran, 2.925 g, 11 .28 mmol) 0.150 g of the title product in the form of a racemic mixture were obtained (yield 35.8%). ¹H NMR (300 MHz, CDCl₃, racemate): δ 10.77 (s, br, 1 H), 7.41 -7.22 (m, 5H), 4.03 (s, 3H), 3.34-3.22 (m, 2H), 3.00 (d, 1 H), 2.79-2.75 (m, 1 H), 2.68-2.65 (m, 2H), 2.51 -2.47 (m, 2H), 2.42- 2.36 (m, 1 H), 2.15-1.97 (m, 6H), 1.72-1.68 (m, 2H), 1.18 (d, 3H). ¹³C NMR (75 MHz, CDCI3, racemate): δ 158.71 , 152.59, 128.82, 128.60, 128.29, 128.01 , 127.39, 126.76, 61.38, 59.59, 56.95, 51.08, 38.79, 38.66, 36.57, 31.52, 31.37, 25.69, 20.31.

Example 3. 5-[(3,4-trans)-1 -Benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H- pyrazolo[4,3-d]pyrimidin-7(6H)-one

The compound was obtained by a method analogous to that described in Example 1. Starting from 4-amino-3-cyclopentyl-1 H-pyrazole-5-carboxamide (Intermediate P7, 1.750 g, 9.01 mmol) and (3R,4R)-1 -benzyl-4-methylpyrroli- dine-3-carboxylic acid chloride (Intermediate P19, 0.182M solution in tetrahydrofuran, 3.706 g, 13.51 mmol) 1.399 g of the title product in the form of a racemic mixture were obtained (yield 41.1 %). ¹H NMR (300 MHz, CDCI3, racemate): δ 11.35 (s, br, 1 H), 7.43-7.24 (m, 5H), 3.82 (d, 1 H), 3.63 (d, 1 H), 3.52-3.37 (m, 2H), 2.96-2.88 (m, 2H), 2.58 (m, 1 H), 2.47 (m, 1 H), 2.14 (m, 1 H), 2.01 -1.83 (m, 6H), 1.72-1.67 (m, 2H), 1.21 (d, 3H). ¹³C NMR (75 MHz, CDCl₃, racemate): δ 157.04, 155.12, 149.87, 137.57, 128.78, 128.66, 127.49, 127.02, 61.19, 59.40, 56.85, 50.67, 38.95, 36.89, 32.58, 32.44, 25.39, 20.29.

(-)-5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H-pyrazolo- [4,3-d]pyrimidin-7(6H)-one, and

(+)-5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H- pyrazolo[4,3-d]pyrimidin-7(6H)-one

Racemate (103.66 mg) was separated into diastereoisomers by HPLC (Chiralpak IB column, 250 x 20 mm, bed 5 μιτι, mobile phase heptane/ethanol 85: 15, flow 15 ml/min. ). 53.3 mg of enantiomer A (R_t = 12.2 min. ) and 57.6 mg of enantiomer B (R_t = 15,8 min.) were obtained. Example 4. 5-[(3,4-trans)-4-Methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3- (tetrahydro-2H-pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

To the mixture of 4-amino-3-(tetrahydro-2H-pyran-4-yl)-1 H-pyrazole-5-carbox- amide (Intermediate P25, 0.220 g, 1.05 mmol) and methyl (3,4-trans)-4-methyl- 1 -(pyrimidin-2-ylmethyl)pyrrolidino-3-carboxylate (Intermediate P27, 1.230 g, 5.23 mmol) in anhydrous tetrahydrofuran (25 ml) potassium tert-butanolate (0.605 g, 5.23 mmol) was added and the whole was heated at reflux for 24 hours. Then water (20 ml) and the mixture chloroform/isopropanol (9: 1 , 20 ml) were added. After intense stirring and separation of layers, aqueous layer was extracted with chloroform/isopropanol (9: 1 , 9 x 15 ml). Organic layer was dried over sodium sulphate and concentrated. The product was purified by chromatography on silica gel (dichloromethane/ methanol, gradient 0-15%). 44 mg of the title product in the form of a racemic mixture were obtained (yield 10.6%). ¹H NMR (300 MHz, DMSO-d₆, racemate): δ 13.67 (s, 1 H), 11.94 (s, br, 1 H), 8.80 (d, 2H), 7.42 (t, 3H), 3.99-3.92 (m, 3H), 3.85 (d, 1 H), 3.51 (m, 1 H), 3.22 (m, 1 H), 3.12 (t, 1 H), 2.98 (m, 2H), 2.88 (m, 1 H), 2.62 (m, 1 H), 2.39 (m, 1 H), 1.94 (m, 4H), 1.08 (d, 3H).

MS-ESI (m/z) calculated for C20H26N7O2 [M+H]⁺: 396.21 , found 396.2

(-)-5-[(3,4-trans)-4-Methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3-(tetra- hydro-2H-pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one, and

(+)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3-(tetra- hydro-2H-pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The racemic mixture obtained above (44 mg) was separated into diasteroisomers by HPLC (Chiralpak IA column, 250 x 20 mm, bed 5 μιτι, mobile phase heptane/2- propanol (with the addition of 0.2% triethylamine) 50:50, flow 5 ml/min.). 18.59 mg of enantiomer A (R_t = 48.6 min.) and 21.18 mg of enantiomer B (R_t = 59,7 min.) were obtained.

Example 5. 3-Cyclopentyl-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The compound was obtained by a method analogous to that described in Example 4. Starting from 4-amino-3-cyclopentyl-1 H-pyrazole-5-carboxamide (Intermediate P7, 0.320 g, 1.64 mmol) and methyl (3,4-trans)-4-methyl-1 - (pyrimidin-2-ylmethyl)pyrrolidine-3-carboxylate (Intermediate P27, 0.862 g, 3.29 mmol) 59 mg of the title product in the form of a racemic mixture were obtained (yield 7.5%). ¹H NMR (300 MHz, CDCl₃, racemate): δ 12.28 (s, broad, 1 H), 11.26 (s, 1 H), 10.79 (s, 1 H), 8.93 (s, 2H), 7.59 (s, 1 H), 4.99-4.80 (m, 2H), 4.19-3.87 (m, 2H), 3.81 -3.67 (m, 1 H), 3.58-3.42 (m, 2H), 3.18 (s, 1 H), 1.98-1.73 (m, 6H), 1.69-1.61 (m, 2H), 1.16 (d, 3H).

MS-ESI (m/z) calculated for C₂oH₂6N₇0 [M+H]⁺: 380.22, found 380.2

Example 6. 5-[1 -(3-Fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H- pyran-4-yl)-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The compound was obtained by a method analogous to that described in Example 4. Starting from 4-amino-3-(tetrahydro-2H-pyran-4-yl)-1 H-pyrazole-5- carboxamide (Intermediate P25, 0.50 g, 2.38 mmol) and methyl (3,4-trans)-1 -(3- fluorobenzyl)-4-methylpyrrolidine-3-carboxylate (Intermediate P28, 1.20 g, 4.76 mmol) 0.224 g of the title product in the form of racemic mixture were obtained (yield 22.9%).

¹H NMR (300 MHz, CDCl₃, racemate): δ 12.15 (s, br, 1 H), 7.39-7.36 (q, 1 H), 7.26- 7.24 (d, 2H), 7.09-7.08 (d, 1 H), 6.99-6.95 (t, 1 H), 4.11 -4.08 (m, 2H), 3.84-3.82 (d, 1 H), 3.66-3.59 (m, 3H), 3.41 -3.35 (m, 2H), 3.04-3.03 (d, 1 H), 2.96 (m, 1 H), 2.62 (m, 1 H), 2.47-2.45 (m, 1 H), 2.18-2.13 (m, 1 H), 2.01 -1.97 (m, 3H), 1.22 (d, 3H). ¹³C NMR (75 MHz, CDCl₃, racemate): δ 163.66, 162.03, 156.95, 154.92, 149.15, 137.49, 130.37, 130.31 , 126.81 , 124.40, 115.75, 115.61 , 114.51 , 114.37, 67.98, 61.17, 58.97, 56.99, 50.68, 38.97, 33.17, 31.65, 31.54, 20.18.

MS-ESI (m/z) calculated for C₂₂H₂₆FN₅0₂ [M+H]⁺: 412.48, found 412.4 (-)-5-[1 -(3-Fluorobenzyl)-4-methylpyrrolidin -yl]^-(tetrahydro-2H-pyran-4-yl)- 1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one, and

(+)-5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)- 1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The racemic mixture obtained above (200 mg) was separated into diastero- isomers by HPLC (Chiralpak IA column, 250 x 20 mm, bed 5 μιτι, mobile phase heptane/ethanol 90: 10, flow 15 ml/min.). 49 mg of enantiomer A (R_t = 25.5 min. ) and 41 mg of enantiomer B (R_t = 35.5 min.) were obtained.

Example 7. 3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4- methylpyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The compound was obtained by a method analogous to that described in Example 4. Starting from 4-amino-3-(4,4-difluorocyclohexyl)-1 H-pyrazole-5- carboxamide (Intermediate P35, 0.895 g, 3.66 mmol) and methyl (3,4-trans)-1 - (3-fluorobenzyl)-4-methylpyrrolidine-3-carboxylate (Intermediate P28, 1.840 g, 7.33 mmol) 0.592 g of the title product in the form of a racemic mixture were obtained (yield 36.3%).

¹H NMR (500 MHz, DMSO-d₆, racemate): δ 13.68 (s, 1 H), 11.93 (s, br, 1 H), 7.36 (m, 1 H), 7.16 (t, 2H), 7.06 (m, 1 H), 3.66 (m, 2H), 2.98 (m, 1 H), 2.88 (m, 2H), 2.77 (m, 1 H), 2.69 (m, 1 H), 2.31 (m, 1 H), 2.05 (m, 9H), 1.08 (s, 3H).

MS-ESI (m/z) calculated for CzsHzeFsNsONa [M+Na]⁺: 468.47, found 468.2.

(-)-3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methyl- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one, and

(+)-3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methyl- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The racemic mixture obtained above (375 mg) was separated into diasteroisomers by HPLC (Chiralpak IA column, 250 x 20 mm, bed 5 μιτι, mobile phase heptane/2-propanol (with the addition of 0.2% triethylamine) 50:50, flow 5 ml/min.). 160.37 mg of enantiomer A (R_t = 19.8 min. ) and 170.25 mg of enantiomer B (R_t = 26.6 min.) were obtained. Example 8. 3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-4-methyl-1 -(pyi ylmethyl)pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one

The compound was obtained by a method analogous to that described in Example 4. Starting from 4-amino-3-(4,4-difluorocyclohexyl)-1 H-pyrazole-5- carboxamide (Intermediate P35, 0.738 g, 3.02 mmol) and methyl (3,4-trans)-4- methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidine-3-carboxylate (Intermediate P27, 1.422 g, 6.04 mmol) 0.087 g of the title product in the form of a racemic mixture were obtained (yield 6.71%).

MS-ESI (m/z) calculated for C21 H25F2N7O [M+H]⁺: 430.46, found 430.2.

Biological activity of the compounds of the invention

Assay of phosphodiesterase 9 inhibitory activity in vitro

Activity of compounds of the invention was analyzed in vitro in phosphodiesterase 9 inhibitory activity assay as described below.

Recombinant phosphodiesterase 9A (PDE9A, Fisher et al., J.Biol. Chem, 1998, 273 (25): 15559-15564) was purified to homogeneity from Sf9 cells over- expressing PDE9A gene (GenBank/EMBL accession number: NM_001001567).

Inhibitory activity of chemical compounds towards PDE9 was tested using PDE- Glo (Promega Corporation, Madison, USA) luminescent method. Tested compounds were dissolved in 100% DMSO and resulted solutions were diluted 5x in concentrated PDE-Glo Reaction Buffer to the final concentration of test compound in the complete reaction mixture 10 μΜ. 5 μΐ of thus obtained solutions were applied into the wells of a 96-well plate. Then, 7.5 μΐ of solution containing PDE9A enzyme diluted in 1x concentrated PDE-Glo Reaction Buffer was added into the wells to obtain the final amount of 60-100 ng (depending on the activity of enzyme batch used in the test). In order to facilitate interaction between chemical compounds and the enzyme, plates were incubated for 5 minutes at room temperature. Reaction was initiated by addition of 12.5 μΐ of 20 μΜ cGMP solution into the wells and subsequently plate was incubated at room temperature. After 60 minutes reaction was stopped by addition of 12 μΐ of PDE- Glo Termination Buffer. Plate content was stirred with orbital shaker at 500 RPM and 12.5 μΐ of freshly prepared PDE-Glo Detection Solution was added into the wells in the next step. Plate was incubated for 20 minutes at room temperature before 50 μΐ of Kinase Glo reagent (Promega Corporation, Madison, USA) was applied into the wells and incubation at room temperature was continued for the next 10 minutes. After the incubation, luminescence intensity in wells was measured with Victor Light (Perkin Elmer Inc. ) luminometer.

Percent of PDE9 inhibition by test compounds was determined on the basis of luminescence intensity measurements in wells containing tested compounds and in control wells. Negative control wells contained all abovementioned reagents except test compounds and positive control wells contained all abovementioned reagents except test compounds and PDE9A enzyme. Each chemical compound was assayed in at least 6 runs (6 wells) on 2 separate 96-well plates with at least 3 wells of each of controls.

Averaged results of phosphodiesterase 9 inhibitory activity of selected representative chemical compounds of the invention are presented below:

Test of social recognition in vivo

Effects of chemical compounds on cognitive performance were evaluated in the social recognition test that allows assessment of capability of laboratory animals to discriminate between known and unknown individuals of the same species. During subsequent meetings within the same pair, the animal (object of the study) should display reduced interest in other individual (the animal that is used as a social stimulus) what is manifested as the reduction of time spent on social behavior. Therefore, social recognition test is an appropriate assay to analyze the effects of chemical compounds on learning and memory.

Male laboratory Wistar rats (4-5 months old) as objects and male Wistar rats (4-5 weeks old) as social stimuli were used in the test. 30 minutes before the beginning of experiment tested animals (objects) were moved to separate cages. Next, each tested animal was placed in the experimental cage (dimensions 60x38x20 cm) with elevation (20 cm) made of gray, matt PVC. After next 4 minutes, a juvenile rat (social stimulus) was placed in the same cage for the period of 4 minutes (Trial #1 ). During this time, juvenile rat-oriented social behavior of object rats was scored. In particular, approaches towards a partner, following a partner, partner's body exploration, "nose-to-nose" contact, grooming of a partner, walking under or climbing on a partner, head orientation towards a partner, focusing attention on a partner and remaining in close contact were scored as social behaviors.

After 24 hours Trial #2 was conducted with the same pair of animals, according to the identical protocol and with identical behaviors scored.

Animal behavior during the study was recorded into digital video files with the camera installed on the ceiling of the cage and the 45 degrees slant mirror placed on the side of the cage that enabled simultaneous side view observation of the animals. Recordings were analyzed by two independent observers. Analysis was performed with BehaView software. In comparison to Trial #1 , reduction of time spent by rat-object on interaction with partner was observed in Trial #2, what demonstrated remembering social stimulus by the object. Percent reduction of time spent by the object on interaction with partner (% RSI) was calculated using the equation:

% RSI = ^{tTrial #1" tTrial #2} x 100% ,

tTriai #1

% RSI - percent reduction of time spent by object on interaction with partner during Trial #2 in comparison to Trial #1

tTriai #₁ - time spent by object on interaction with partner during Trial #1

tTriai #₂ - time spent by object on interaction with partner during Trial #2

Test compounds were administered to animals (objects) immediately after Trial #1 , p.o., in a dose of 3 mg/kg body weight. Solutions of chemical compounds were prepared in a vehicle containing 75% H₂0, 10% solutol, and 5% ethanol. Experimental groups consisted of at least 8 adult rats. Animals from the control group received the vehicle solution (no test compounds were administered). ANOVA with LSD post-test was used for analysis of statistical significance of obtained results.

Results obtained for selected chemical compounds of invention that were evaluated in the social recognition test were expressed as percent reduction of time spent by object on interaction with partner (%RSI) and are presented below:

Example No. % RIS

Control (vehiculum) 4

3, racemate 33

4, racemate 28

5, racemate 24

Claims

Claims

1. A compound represented by the general formula (I)

wherein

R¹ represents hydrogen atom or methyl;

when R¹ represents hydrogen atom, then R² represents cyclopentyl, tetrahydro- pyranyl, cyclohexyl, or cyclohexyl substituted with 1 or 2 halogen atoms;

when R¹ represents methyl, then R² represents cyclopentyl;

R³ is selected from the group consisting of:

- phenyl unsubstituted or substituted with 1 to 3 substituents selected from F, CI, Br, I, and OCH₃; and

- 6- to 10-membered heteroaryl with 1 to 3 heteroatoms selected independently form 0, N and S; and

Q represents C1 -C3-alkylene group, which is unsubstituted or substituted with 1 to 3 C1 -C3-alkyl groups;

and its salts;

including optically active diastereoisomers and their mixtures.

2. The compound according to claim 1 represented by the general formula (I)

wherein

R¹ represents hydrogen atom or methyl; when R¹ represents hydrogen atom, then R² represents cyclopentyl or tetrahydropyranyl;

when R¹ represents methyl, then R² represents cyclopentyl;

R³ is selected from the group consisting of:

- phenyl unsubstituted or substituted with 1 to 3 substituents selected from F, CI, Br, I, and OCH₃; and

- 6- to 10-membered heteroaryl with 1 to 3 heteroatoms selected independently form 0, N and S; and

Q represents C1 -C3-alkylene group, which is unsubstituted or substituted with 1 to 3 C1 -C3-alkyl groups;

and its salts;

including optically active diastereoisomers and their mixtures.

3. The compound according to claim 1 or 2, represented by the general formula (IA) or (IB)

(IA) (IB)

4. The compound according to any one of claims 1 to 3, wherein R¹ represents hydrogen atom and R² represents cyclopentyl or tetrahydropyranyl.

5. The compound according to any one of claims 1 to 3, wherein R¹ represents hydrogen atom and R² represents cyclohexyl substituted with 1 or 2 halogen atoms.

6. The compound according to claim 5, wherein R² represents cyclohexyl substituted with 2 F atoms.

7. The compound according to any one of claims 1 to 6, wherein Q represents -CH₂-.

8. The compound according to any one of claims 1 to 7, wherein R³ represents phenyl.

9. The compound according to any one of claims 1 to 7, wherein R³ represents phenyl substituted with F atom.

10. The compound according to any one of claims 1 to 7, wherein R³ represents 6- or 10-membered heteroaryl with one or two nitrogen ring atoms.

1 1 . The compound according to claim 10, wherein R³ represents pyrimidinyl.

12. The compound according to claim 1 , selected from the group consisting of the following:

5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 -methyl-1 H- pyrazol[4, 3-d]pyrimidin-7(6H)-one;

5-((3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl)-3-cyclopentyl-2-methyl-2H- pyrazol[4,3-d]pyrimidin-7(6H)-one;

5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H-pyrazol[4,3- d]pyrimidin-7(6H)-one;

(-)-5-[(3,4-trans)-1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H-pyrazol- [4,3-d]pyrimidin-7(6H)-one;

(+)-5-[(3,4-trans)- 1 -benzyl-4-methylpyrrolidin-3-yl]-3-cyclopentyl-1 H-pyrazol- [4,3-d]pyrimidin-7(6H)-one;

5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3-(tetrahydro- 2H-pyran-4-yl)-1 H-pyrazol[4,3-d]pyrimidin-7(6H)-one;

(-)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethylo)pyrrolidin-3-yl]-3-(tetra- hydro-2H-pyran-4-yl)-1 H-pyrazol[4,3-d]pyrimidin-7(6H)-one;

(+)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3-(tetra- hydro-2H-pyran-4-yl)-1 H-pyrazol[4,3-d]pyrimidin-7(6H)-one; and

3-cyclopentyl-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]- 1 H-pyrazol[4,3-d]pyrimidin-7(6H)-one;

and their salts;

including optically active diastereoisomers and their mixtures.

13. The compound according to claim 1 , selected from the group consisting of the following:

5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)-1 H- pyrazol[4, 3-d]pyrimidin-7(6H)-one;

(-)-5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)- 1 H-pyrazol[4, 3-d]pyrimidin-7(6H)-one; and (+)-5-[1 -(3-fluorobenzyl)-4-methylpyrrolidin-3-yl]-3-(tetrahydro-2H-pyran-4-yl)- 1 H-pyrazol[4,3-d]pyrimidin-7(6H)-one;

and their salts;

including optically active diastereoisomers and their mixtures.

14. The compound according to claim 1 , selected from the group consisting of the following:

3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methylpyrrolidin-3- yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(-)-3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methyl- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

(+)-3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-1 -(3-fluorobenzyl)-4-methyl- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one; and

3-(4,4-Difluorocyclohexyl)-5-[(3,4-trans)-4-methyl-1 -(pyrimidin-2-ylmethyl)- pyrrolidin-3-yl]-1 H-pyrazolo[4,3-d]pyrimidin-7(6H)-one;

and their salts;

including optically active diastereoisomers and their mixtures.

15. A pharmaceutical composition, comprising as an active ingredient a compound of the general formula (I) as defined in any one of claims 1 to 14, in combination with pharmaceutically acceptable excipients.

16. A compound of the general formula (I) as defined in any one of claims 1 to 14 for use as a medicament.

17. A use of a compound of the general formula (I) as defined in any one of claims 1 to 14 for the preparation of a medicament for treating cognitive function disorders and neurodegenerative diseases.

18. A compound of the general formula (I) as defined in any one of claims 1 to 14 for use in a method of treatment of cognitive function disorders and neurodegenerative diseases of central nervous system.

19. A method of treating of cognitive function disorders and neurodegenerative diseases of central nervous system in a mammal subject, including humans, comprising administering to the subject in need thereof a therapeutically effective amount of a compound of the general formula (I) as defined in any one of claims 1 to 14 or a pharmaceutical composition as defined in claim 15.