HK1057036A1 - Adamantane derivatives for the treatment of inflammatory, immune and cardiovascular diseases - Google Patents

Description

The present invention relates to adamantane derivatives, a process for their preparation, pharmaceutical compositions containing them, a process for preparing the pharmaceutical compositions, and their use in therapy.

The P2X₇ receptor (previously known as P2Z receptor), which is a ligand-gated ion channel, is present on a variety of cell types, largely those known to be involved in the inflammatory/immune process, specifically, macrophages, mast cells and lymphocytes (T and B). Activation of the P2X₇ receptor by extracellular nucleotides, in particular adenosine triphosphate, leads to the release of interleukin-1β (IL-1β) and giant cell formation (macrophages/microglial cells), degranulation (mast cells) and L-selectin shedding (lymphocytes). P2X₇ receptors are also located on antigen-presenting cells (APC), keratinocytes, salivary acinar cells (parotid cells), hepatocytes, erythrocytes, erythroleukaemic cells, monocytes, fibroblasts, bone marrow cells, neurones and renal mesangial cells. WO99/29660 and WO99/29661 relate to adamantane derivatives that demonstrate P2X₇ receptor antagonist activity.

It would be desirable to make compounds effective as P2X₇ receptor antagonists for use in the treatment of inflammatory, immune or cardiovascular diseases, in the aetiologies of which the P2X₇ receptor may play a role.

In accordance with the present invention, there is therefore provided a compound of general formula wherein D represents CH₂ or CH₂CH₂, preferably CH₂; E represents NHC(O); R¹ and R² each independently represent hydrogen, halogen (e.g. fluorine, chlorine, bromine or iodine), amino (NH₂), nitro (NO₂), C₁-C₆ alkyl or trifluoromethyl, but R¹ and R² may not both simultaneously represent hydrogen; R³ represents a group of formula R⁴ represents a C₁-C₆ alkyl group; X represents a group NR¹³; R⁵ represents hydrogen; and R¹³ represents hydrogen; or a pharmaceutically acceptable salt or solvate thereof.

In the context of the present specification, unless otherwise indicated, an alkyl substituent or alkyl moiety in a substituent group may be linear or branched. In the present invention, an alkyl group or moiety may contain up to 6 carbon atoms, examples of which include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl and n-hexyl. A C₂-C₆ alkenyl group may be linear or branched In a di-C₁-C₆-alkylamino group, the alkyl moieties may be the same or different.

Preferably, R¹ and R² each independently represent a hydrogen or halogen atom, or an amino, nitro, C₁-C₄ alkyl or trifluoromethyl group (but R¹ and R² may not both simultaneously represent a hydrogen atom).

More preferably, R¹ and R² each independently represent a hydrogen, chlorine or bromine atom, or an amino, nitro, C₁-C₃ alkyl or trifluoromethyl group (but R¹ and R² may not both simultaneously represent a hydrogen atom).

Most preferably, R¹ and R² each independently represent a hydrogen or chlorine atom (but R¹ and R² may not both simultaneously represent a hydrogen atom).

R⁴ represents a C₁-C₆ alkyl group, for example a linear C₁-C₆ alkyl group such as CH₂, (CH₂)₂, (CH₂)₃ or (CH₂)₄.

Preferred compounds of the invention include:

• 5-(2-Aminoethyl)-2-chlom-N-(tricyclo[3.3.1.13,7]dec-1-ylmethyl)benzamide,

and pharmaceutically acceptable salts and solvates thereof.

The present invention further provides a process for the preparation of a compound of formula (I) as defined above which comprises:

1. (a) when X represents an oxygen or sulphur atom or a group NR¹³, reacting a compound of general formula wherein L¹ represents a leaving group (e.g. a halogen atom or trifluoromethanesulphonate group) and D, E, R¹, R² and R⁴ are as defined in formula (I), with a compound of general formula wherein X' represents an oxygen or sulphur atom or a group NR¹³, and R⁵ is as defined in formula (I), optionally in the presence of a suitable silver salt (e.g. silver trifluoromethanesulphonate); or
2. (b) when X represents a group NR¹³ , reacting a compound of general formula

wherein R²⁰ represents a bond or C₁-C₅ alkyl group and D, E, R¹ and R² are as defined in formula (I), with a compound of general formula wherein R⁵ and R¹³ are as defined in formula (I), in the presence of a reducing agent (e.g. sodium triacetoxyborohydride); and optionally after (a) or (b) converting the compound of formula (I) obtained to a pharmaceutically acceptable salt or solvate thereof.

The processes of the invention may conveniently be carried out in a solvent, e.g. an organic solvent such as dichloromethane, 1, 2-dichloroethane or tetrahydrofuran, at a temperature, e.g. in the range from 0 to 200 °C, preferably in the range from 0 to 150 °C.

Compounds of formula (V) in which R²⁰ represents a bond may be prepared by reacting a compound of general formula wherein Hal represents a halogen atom such as bromine and D, E, R¹ and R ² are as defined in formula (I), with a base such as t-butyllithium and then with a formylating agent such as dimethylformamide.

Compounds of formula (VII) may conveniently be prepared by reacting a compound of general formula wherein R²⁵ represents NH₂ or CO₂H and D is as defined in formula (I), with a compound of general formula wherein R³⁰ represents CO₂H or NH₂, and R¹, R² and Hal are as defined in formula (VII) above.

Compounds of formula (V) in which R²⁰ represents a C₁-C₅ alkyl group may be prepared, for example, by reacting a corresponding compound of formula (V) in which R²⁰ represents a bond with (methoxymethyl)diphenylphosphineoxide in the presence of a base, or, with a compound of general formula in which n is 0, 1, 2 or 3 and R and R' independently represent C₁-C₆ alkyl groups, followed by hydrogenation.

Alternatively, compounds of formula (V) in which R²⁰ represents a C₂-C₅ alkyl group may be prepared by reacting a compound of formula (VII) with an alkenol (e.g. 2-propen-1-ol (allyl alcohol), but-3-enol, pent-4-enol or hex-5-enol) in the presence of a palladium catalyst, optionally followed by a hydrogenation reaction and an oxidation reaction using, for example, Dess-Martin periodinane reagent (these last two steps are not required when the alkenol is allyl alcohol),

As a further alternative, compounds of formula (V) in which R²⁰ represents a C₂-C₅ alkyl group may be prepared by reacting a compound of formula (VII) with an alkenoate ester (e.g. methyl acrylate or ethyl acrylate) in the presence of a palladium catalyst such as palladium acetate, followed by reduction of the ester group to a hydroxyl group and then oxidation to the aldehyde with an oxidising agent (e.g. Dess-Martin periodinane reagent).

Compounds of formula (I) wherein E represents a group NHC(O) may be prepared from a compound of general formula wherein R¹, R² and R³ are as defined in formula (I) and X represents NR¹³, by reaction with adamantylmethylamine or adamantylethylamine, in the presence of a coupling agent such as 1,1'-carbonyldiimidazole.

Compounds of formula (XI) can be prepared from a compound of general formula wherein L² represents a leaving group (such as a halogen atom or trifluoromethanesulphonate group) and R¹, R² and R⁴ are as defined in formula (I), with a compound of formula (IV) as defined above, optionally in the presence of a silver salt such as silver trifluoromethanesulphonate.

Compounds of formula (III), (IV), (VI), (VIII), (IX), (X), (XIII) and (XIV) as well as compounds HO-R⁷Z, HS-R⁷Z and H₂N-R⁷Z are either commercially available, are well known in the literature or may be prepared easily using known techniques.

It will be appreciated by those skilled in the an that in the processes of the present invention certain functional groups such as hydroxyl, carboxyl, aldehyde, carbonyl or amino groups in the starting reagents or intermediate compounds may need to be protected by protecting groups. Thus, the preparation of the compounds of formula (I) may involve at a certain stage the removal of one or more protecting groups.

The protection and deprotection of functional groups is described in 'Protective Groups in Organic Chemistry', edited by J.W.F. McOmie, Plenum Press (1973) and 'Protective Groups in Organic Synthesis', 2nd edition, T.W. Greene and P.G.M. Wuts, Wiley-Interscience (1991).

The compounds of formula (I) above may be converted to a pharmaceutically acceptable salt or solvate thereof, preferably an acid addition salt such as a hydrochloride, hydrobromide, phosphate, acetate, fumarate, maleate, tartrate, citrate, oxalate, methanesulphonate orp-toluenesulphonate, or an alkali metal salt such as a sodium or potassium salt.

Certain compounds of formula (I) are capable of existing in stereoisomeric forms. It will be understood that the invention encompasses all geometric and optical isomers of the compounds of formula (I) and mixtures thereof including racemates. Tautomers and mixtures thereof also form an aspect of the present invention.

The compounds of the present invention are advantageous in that they possess pharmacological activity and have utility as modulators of P2X₇ receptor activity. They are therefore indicated as pharmaceuticals for use in the treatment or prevention of rheumatoid arthritis, osteoarthritis, psoriasis, allergic dermatitis, asthma, hyperresponsiveness of the airway, chronic obstructive pulmonary disease (COPD), bronchitis, septic shock, glomerulonephritis, irritable bowel disease, Crohn's disease, ulcerative colitis, atherosclerosis, growth and metastases of malignant cells, myoblastic leukaemia, diabetes, neurodegenerative disease, Alzheimer's disease, meningitis, osteoporosis, burn injury, ischaemic heart disease, stroke, peripheral vascular disease and varicose veins.

Accordingly, the present invention provides a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as hereinbefore defined for use in therapy.

In another aspect, the invention provides the use of a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as hereinbefore defined in the manufacture of a medicament for use in therapy.

In the context of the present specification, the term "therapy" also includes "prophylaxis" unless there are specific indications to the contrary. The terms "therapeutic" and "therapeutically" should be construed accordingly.

Prophylaxis is expected to be particularly relevant to the treatment of persons who have suffered a previous episode of, or are otherwise considered to be at increased risk of, the disease or condition in question. Persons at risk of developing a particular disease or condition generally include those having a family history of the disease or condition, or those who have been identified by genetic testing or screening to be particularly susceptible to developing the disease or condition.

The compounds of the invention may be used in a method of effecting immunosuppression (e.g. in the treatment of rheumatoid arthritis, irritable bowel disease, atherosclerosis, psoriasis, pulmonary disease, e.g. COPD or bronchitis, or diseases of the central nervous system, e.g. Alzheimer's disease or stroke) which comprises administering a therapeutically effective amount of a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as hereinbefore defined to a patient.

For the above-mentioned therapeutic uses the dosage administered will, of course, vary with the compound employed, the mode of administration, the treatment desired and the disease or condition indicated. For effecting immunosuppression, the daily dosage of the compound of formula (I) will typically be in the range from 0.001 mg/kg to 30 mg/kg.

The compounds of formula (I) and pharmaceutically acceptable salts and solvates thereof may be used on their own but will generally be administered in the form of a pharmaceutical composition in which the formula (I) compound/salt/solvate (active ingredient) is in association with a pharmaceutically acceptable adjuvant, diluent or carrier. Depending on the mode of administration, the pharmaceutical composition will preferably comprise from 0.05 to 99 %w (per cent by weight), more preferably from 0.10 to 70 %w, of active ingredient, and, from 1 to 99.95 %w, more preferably from 30 to 99.90 %w, of a pharmaceutically acceptable adjuvant, diluent or carrier, all percentages by weight being based on total composition.

Thus, the present invention also provides a pharmaceutical composition comprising a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as hereinbefore defined in association with a pharmaceutically acceptable adjuvant, diluent or carrier.

The invention further provides a process for the preparation of a pharmaceutical composition of the invention which comprises mixing a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as hereinbefore defined with a pharmaceutically acceptable adjuvant, diluent or carrier.

The pharmaceutical composition of the invention may be administered topically (e.g-to the lung and/or airways or to the skin) in the form of solutions, suspensions, heptafluoroalkane aerosols and dry powder formulations; or systemically, e-g. by oral administration in the form of tablets, capsules, syrups, powders or granules, or by parenteral administration in the form of solutions or suspensions, or by subcutaneous administration or by rectal administration in the form of suppositories or transdermally.

The present invention will now be further explained by reference to the following illustrative examples.

Example 1 5-(2-Aminoethyl)-2-chloro-N-(tricyclo[3.3.1.1^3,7]dec-1-ylmethyl)benzamide

• a) 5-(Bromomethyl)-2-chloro-N-(2-tricyclo[3.3.1.13,7]dec-1-ylmethyl)-benzamide To a solution of 2-chloro-5-(bromomethyl)-benzoic acid (1.0 g) in dichloromethane (25ml) at 0°C was added dimethylformamide (0.05ml) followed by oxalyl chloride (0.52 ml). The reaction was allowed to warm to room temperature and stirred for 30min. The volatiles were removed under vacuum and the residue dried under high vacuum. The residue was dissolved in dichloromethane (20 ml) and added to a solution of 2-adamantanemethylamine hydrochloride salt (0.95g) in dichloromethane (20ml) and diisopropylethylamine (2 ml) at 0°C. The reaction was allowed to warm to room temperature and stirred for 2h. The organics were washed with water (20ml) then saturated aqueous ammonium chloride solution and the organic layer dried over magnesium sulfate then filtered. The filtrate was concentrated under reduced pressure to a solid. The crude material was recrystallised from dichloromethane/hexane to afford the subtitled compound as a white solid (1.3 g).
• b) 2-Chloro-5-(cyanomethyl)-N-(tricyclo[3.3.1.13,7]dec-1-ylmethyl)benzamide Potassium cyanide (525mg) and 18-crown-6 (150mg) were added to a solution of 5-(bromomethyJ)-2.chloro-N-(2-tricyclo[3.3.1. 13,7]dec-1-ylmethyl)-benzamide (Example la, 1.8g) in ethanol (50ml) and the mixture heated under reflux for 24h. On cooling the reaction mixture was evaporated to dryness and the residue partitioned between ethyl acetate and saturated sodium hydrogencarbonate solution. The organics were separated, washed with brine, dried over magnesium sulfate, filtered and evaporated. Purification by chromatography on silica (eluting with a gradient of iso-hexane/ethyl acetate /4:1 to 6:4) gave the subtitled product as a pink solid (1.0g). MS (APCI +ve) 343/345 (M+H)+1H NMR (DMSO-d6) δ 8.38 (1H, t); 7.52 (1H, d); 7.43-7.38 (2H, m); 4.08 (2H, s); 2.94 (2H, d); 1.92 (3H, s); 1.63 (6H, q); 1.52 (6H, s).
• c) [2-[4-Chloro-3-([(tricyclo[3.3.1.13,7]dec-1-ylmethyl)amino]carbonyl]phenyl]-ethyl]carbamic acid, 1,1-dimethylethyl ester Sodium borohydride (1.6g) was added portionwise to a cooled solution of 2-chloro-5-(cyanomethyl)-N-(tricyclo[3.3.1.13,7]dec-1-ylmethyl)benzamide (Example 1b, 2.1g), (1,1-dimethylethoxy)carbonyl carbonic acid, 1,1-dimethylethyl ester (2.67g) and cobalt(II)chloride (1.6g) in methanol (100ml). After 1.5h the solvent was evaporated and the residue slurried between ethyl acetate and saturated sodium hydrogencarbonate solution and the insoluble cobalt salts filtered. The organic phase was separated and washed with brine, dried over sodium sulfate, filtered and evaporated to give the subtitled product as a foam (2.2g). MS (APCI +ve) 447/449 (M+H)+1H NMR (CDCl3) δ 7.54 (1H, d); 7.34 (1H, d); 7.19 (1H, dd); 6.28 (1H, s, br); 4.54 (1H, s, br); 3.39 (2H, q); 3.18 (2H, d); 2.80 (2H. t); 2.04 (3H, s); 1.70 (6H, q); 1.64 (6H. s); 1.42 (9H, s).
• d) 5-(2-Aminoethyl)-2-chloro-N-(tricyclo[3.3.1.13,7]dec-1-ylmethyl)benzamide, hydrochloride salt Hydrochloric acid (4M in 1,4-dioxane, 3.0ml) was added to a solution of [2-[4-chloro-3-[[(tricyclo[3.3. 1.13,7]dec-1-ylmethyl)amino]carbonyl]phenyl]ethyl]carbamic acid, 1,1-dimethylethyl ester (2.2g, Example 1c) in methanol/dichloromethane (1:1) (50ml). After 24h the solvent was evaporated to leave the title compound as a foam (1.85g). MS (APCI +ve) 347/349 (M+H)+1H NMR (DMSO-d6) δ 8.31 (1H, t); 8.15 (3H, s, br); 7.43 (1H, d); 7.31 (2H, m); 3.05-2.98 (2H, m); 2.95-2.85 (4H, m); 1.94 (3H, s); 1.63 (6H, q); 1.52 (6H, s).

Pharmacological Analysis

Certain compounds such as benzoylbenzoyl adenosine triphosphate (bbATP) are known to be agonists of the P2X₇ receptor, effecting the formation of pores in the plasma membrane (Drug Development Research (1996), 37(3), p. 126). Consequently, when the receptor is activated using bbATP in the presence of ethidium bromide (a fluorescent DNA probe), an increase in the fluorescence of intracellular DNA-bound ethidium bromide is observed. The increase in fluorescence can be used as a measure of P2X₇ receptor activation and therefore to quantify the effect of a compound on the P2X₇ receptor.

In this manner, each of the title compounds of the Examples was tested for antagonist activity at the P2X₇ receptor. Thus, the test was performed in 96-well flat bottomed microtitre plates, the wells being filled with 250 µl of test solution comprising 200 µl of a suspension of THP-1 cells (2.5 x 10⁶ cells/ml) containing 10^-4M ethidium bromide, 25 µl of a high potassium buffer solution containing 10^-5 M bbATP, and 25 µl of the high potassium buffer solution containing 3 x 10^-5M test compound. The plate was covered with a plastics sheet and incubated at 37 °C for one hour. The plate was then read in a Perkin-Elmer fluorescent plate reader, excitation 520 nm, emission 595 nm, slit widths: Ex 15 nm, Em 20 nm. For the purposes of comparison, bbATP (a P2X₇ receptor agonist) and pyridoxal 5-phosphate (a P2X₇ receptor antagonist) were used separately in the test as controls. From the readings obtained, a pIC₅₀ figure was calculated for each test compound, this figure being the negative logarithm of the concentration of test compound necessary to reduce the bbATP agonist activity by 50%. Each of the compounds of the Examples demonstrated antagonist activity, having a pIC₅₀ figure > 5.0.

Claims (15)

1. A compound of general formula wherein D represents CH₂, or CH₂CH₂; E represents NHC(O); R¹ and R² each independently represent hydrogen, halogen, amino, nitro, C₁-C₆ alkyl or trifluoromethyl, but R¹ and R² may not both simultaneously represent hydrogen; R³ represents a group of formula R⁴ represents a C₁-C₆ alkyl group; X represents a group NR¹³; R⁵ represents hydrogen; and R¹³ represents hydrogen: or a pharmaceutically acceptable salt or solvate thereof.
2. A compound according to claim 1, wherein D represents CH₂.
3. A compound according to any one of claims 1 to 2, wherein R¹ and R² each independently represent a hydrogen, chlorine or bromine atom, or an amino, nitro. C₁-C₃ alkyl or trifluoromethyl group.
4. A compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, according to claim 1, which is 5-(2-Aminoethyl)-2-chloro-N-(tricyclo[3.3.1.1^3,7]dec-1-ylmethyl)benzamide.
5. A process for the preparation of a compound of formula (I) as defined in claim 1 which comprises:

   (a) reacting a compound of general formula wherein L¹ represents a leaving group and D, E, R¹, R² and R⁴ are as defined in formula (I), with a compound of general formula wherein R⁵ and R¹³ are as defined in formula (I), optionally in the presence of a suitable silver salt; or

   (b) reacting a compound of general formula

   wherein R²⁰ represents a bond or C₁-C₅ alkyl group and D, E, R¹ and R² are as defined in formula (I), with a compound of general formula (VI) as defined in (a) above, in the presence of a reducing agent; and optionally after (a) or (b) converting the compound of formula (I) obtained to a pharmaceutically acceptable salt or solvate thereof.
6. A pharmaceutical composition comprising a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 in association with a pharmaceutically acceptable adjuvant, diluent or carrier.
7. A process for the preparation of a pharmaceutical composition as claimed in claim 5 which comprises mixing a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as defined in any one of claims 1 to 6 with a pharmaceutically acceptable adjuvant, diluent or carrier.
8. A compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 for use in therapy.
9. A compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 for use in the treatment of rheumatoid arthritis.
10. A compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 for use in the treatment of chronic obstructive pulmonary disease.
11. A compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 for use in the treatment of osteoarthritis.
12. Use of a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 in the manufacture of a medicament for use in therapy.
13. Use of a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 in the manufacture of a medicament for use in treating rheumatoid arthritis.
14. Use of a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 in the manufacture of a medicament for use in treating chronic obstructive pulmonary disease.
15. Use of a compound of formula (I), or a pharmaceutically acceptable salt or solvate thereof, as claimed in any one of claims 1 to 4 in the manufacture of a medicament for use in treating osteoarthritis.