WO1996041803A1

WO1996041803A1 - Piperidineacetic acid derivatives as inhibitors of fibrinogen-dependent blood platelet aggregation

Info

Publication number: WO1996041803A1
Application number: PCT/EP1996/002536
Authority: WO
Inventors: Brian David Judkins
Original assignee: Glaxo Group Limited
Priority date: 1995-06-13
Filing date: 1996-06-10
Publication date: 1996-12-27
Also published as: ZA964968B; AU6302596A; GB9511989D0

Abstract

The invention relates to compounds of formula (I) and salts, solvates and esters thereof, and salts and solvates of such esters and pharmaceutically acceptable derivatives of compounds of formula (I), in which: X represents either CH2-CH2 or CH=CH, to processes for their preparation, to pharmaceutical compositions containing such compounds and to their use in medicine, particularly in the treatment of thrombotic disorders.

Description

P1per1d1neacet1c add derivatives as Inhibitors of fibrinogen-dependent blood platelet aggregation

This invention relates to acetic acid derivatives, to processes for their preparation, to pharmaceutical compositions containing such compounds and to their use in medicine.

It is widely accepted that the glycoprotein complex Gp I lb/11 la is the fibrinogen binding site on platelets that mediates the adhesive function required for platelet aggregation and thrombus formation. We have now found a group of non- peptidic compounds which inhibit fibrinogen-dependent platelet aggregation by blocking the binding of fibrinogen to the putative fibrinogen receptor Gp llb/llla complex.

The invention thus provides a compound of formula (I)

or a salt, solvate or ester thereof, or a salt or solvate of such ester, in which: X represents either CH₂-CH₂ or CH=CH.

The invention further provides a compound of formula (I)

or a pharmaceutically acceptable derivative thereof, in which: X represents either CH₂-CH₂ or CH=CH.

By pharmaceutically acceptable derivative is meant any pharmaceutically acceptable salt, solvate or ester, or salt or solvate of such ester, of the compounds of formula (I), or any other compound which upon administration to the recipient is capable of providing (directly or indirectly) a compound of formula (I) or an active metabolite or residue thereof.

It will be appreciated that, for pharmaceutical use, the salts referred to above will be the physiologically acceptable salts, but other salts may find use, for example in the preparation of compounds of formula (I) and the physiologically acceptable salts thereof.

Suitable physiologically acceptable salts of the compounds of formula (I) include acid addition salts formed with inorganic or organic acids (for example hydrochlorides, hydrobromides, sulphates, phosphates, benzoates, naphthoates, hydroxynaphthoates, p-toluenesulphonates, methanesulphonates, sulphamates, ascorbates, tartrates, salicylates, succinates, lactates, glutarates, glutaconates, acetates, tricarballylates, citrates, fumarates and maleates) and inorganic base salts such as alkali metal salts (for example sodium salts).

Other salts of the compounds of formula (I) include salts formed with trifluoro- acetic acid.

It will be appreciated by those skilled in the art that the compounds of formula (I) may be modified to provide pharmaceutically acceptable derivatives thereof at any of the functional groups in the compounds. Of particular interest as such derivatives are compounds modified at the carboxyl function.

Thus compounds of interest include carboxylic acid esters of the compounds of formula (I). Examples of such esters include Cι_6alkyl esters.

It will be appreciated by those skilled in the art that the pharmaceutically acceptable derivatives of the compounds of formula (I) may be derivatised at more than one position.

It will be further appreciated by those skilled in the art that carboxylic acid ester derivatives of formula (I) may be useful as intermediates in the preparation of compounds of formula (I), or as pharmaceutically acceptable derivatives of formula (I), or both. The term 'alkyl' as a group or part of a group means a straight or branched chain alkyl group, for example a methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl or t-butyl group.

It is to be understood that the present invention encompasses all isomers of the compounds of formula (I) and their pharmaceutically acceptable derivatives, including all geometric, tautomeric and optical forms, and mixtures thereof (e.g. racemic mixtures).

In the alternative, the present invention provides a compound selected from:

{4-[5-(2-piperidin-4-yl-(E)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid; {4-[5-(2-piperidin-4-yl-(Z)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid;

{4-[5-(2-piperidin-4-yl-ethyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid; and pharmaceutically acceptable derivatives thereof.

A preferred compound of the invention is:

{4-[5-(2-piperidin-4-yl-(E)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid or a pharmaceutically acceptable derivative thereof.

Compounds of formula (I) inhibit blood platelet aggregation as demonstrated by studies performed on human whole blood and human washed and resuspended platelets (HRP) using a Born-type optical aggregometer (Born, G.V., 1962, Nature, 194- 927-929).

In view of their fibrinogen antagonist activity, the compounds of the present invention are of interest for use in human and veterinary medicine, particularly in the treatment of thrombotic disorders. Particular examples of thrombotic disorders are known in the art and include occlusive vascular diseases such as myocardial infarction, cardiac fatalities, angina, transient ischaemic attacks and thrombotic stroke, arteriosclerosis, vessel wall disease, peripheral vascular disease, nephropathy, retinopathy, postoperative thrombosis, pulmonary embolism, deep vein thrombosis and retinal vein thrombosis. The compounds of the invention are also of interest for use in the prophylactic treatment of peri- and postoperative complications following organ transplantation (particularly cardiac and renal), coronary artery bypass, peripheral artery bypass, angioplasty, thrombolysis and endarterectomy. The compounds of the invention may also be useful for the treatment of other conditions in which the glycoprotein complex Gp llb/llla or other integrin receptors are implicated. Thus, for example, the compounds of the invention may potentiate wound healing and be useful in the treatment of bone conditions caused or mediated by increased bone resorption. Particular examples of bone diseases are known in the art and include osteoporosis, hypercalcaemia of malignancy, osteopenia due to bone metastases, periodontal disease, hyperparathyroidism, periarticular erosions in rheumatoid arthritis, Paget's disease, immobilization-induced osteopenia and glucocorticoid treatment.

The compounds of the invention may also be useful for the treatment of certain cancerous diseases. For example, compounds of the invention may be of use to prevent or delay metastasis in cancer.

According to a further aspect of the invention, we provide a compound of formula (I) or a pharmaceutically acceptable derivative thereof for use in human or veterinary medicine, particularly for use in the treatment of thrombotic disorders.

According to another aspect of the invention, we provide a compound of formula (I) or a pharmaceutically acceptable derivative thereof for use in the treatment of a condition which is mediated through the Glycoprotein complex Gpllb/llla or other integrin receptor.

According to a further aspect of the invention, we provide a method of treating a human or animal subject suffering from a condition which is mediated through the Glycoprotein complex Gpllb/llla or other integrin receptor which comprises administering to said subject an effective amount of a compound of formula (I) or a pharmaceutically acceptable derivative.

According to another aspect of the invention, we provide the use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof for the manufacture of a therapeutic agent for the treatment of thrombotic disorders.

According to a further aspect of the invention, we provide a method of treating a human or animal subject suffering from a thrombotic disorder, which method comprises administering to said subject an effective amount of a compound of formula (I) or a pharmaceutically acceptable derivative thereof.

It is to be understood that reference to treatment includes both treatment of established symptoms and prophylactic treatment, unless explicitly stated otherwise.

It will be appreciated that the compounds of the invention may advantageously be used in conjunction with one or more other therapeutic agents. Examples of suitable agents for adjunctive therapy include thrombolytic agents or any other compound stimulating thrombolysis or fibrinolysis and cytotoxic drugs. It is to be understood that the present invention covers the use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof in combination with one or more other therapeutic agents.

The compounds of formula (I) and their pharmaceutically acceptable derivatives are conveniently administered in the form of pharmaceutical compositions. Thus, in another aspect of the invention, we provide a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable derivative thereof adapted for use in human or veterinary medicine. Such compositions may conveniently be presented for use in conventional manner in admixture with one or more physiologically acceptable carriers or excipients.

The compounds according to the invention may be formulated for administration in any suitable manner. The compounds may, for example, be formulated for topical administration or administration by inhalation or, more preferably, for oral, transdermal or parenteral administration.

For oral administration, the pharmaceutical composition may take the form of, for example, tablets, capsules, powders, solutions, syrups or suspensions prepared by conventional means with acceptable excipients.

For transdermal administration, the pharmaceutical composition may be given in the form of a transdermal patch, such as a transdermal iontophoretic patch. For parenteral administration, the pharmaceutical composition may be given as an injection or a continuous infusion (e.g. intravenously, intravascularly or subcutaneously). The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. For administration by injection these may take the form of a unit dose presentation or as a multidose presentation preferably with an added preservative.

Alternatively for parenteral administration the active ingredient may be in powder form for reconstitution with a suitable vehicle.

The compounds of the invention may also be formulated as a depot preparation.

Such long acting formulations may be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the compounds of the invention may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

As stated above, the compounds of the invention may also be used in combination with other therapeutic agents. The invention thus provides, in a further aspect, a combination comprising a compound of formula (I) or a pharmaceutically acceptable derivative thereof together with a further therapeutic agent, in particular a thrombolytic agent.

The combinations referred to above may conveniently be presented for use in the form of a pharmaceutical formulation and thus pharmaceutical formulations comprising a combination as defined above together with a pharmaceutically acceptable carrier or excipient comprise a further aspect of the invention. The individual components of such combinations may be administered either sequentially or simultaneously in separate or combined pharmaceutical formulations.

When a compound of formula (I) or a pharmaceutically acceptable derivative thereof is used in combination with a second therapeutic agent active against the same disease state the dose of each compound may differ from that when the compound is used alone. Appropriate doses will be readily appreciated by those skilled in the art.

A proposed daily dosage of a compound of formula (I) for the treatment of man is 0.01 mg/kg to 30 mg/kg, which may be conveniently administered in 1 to 4 doses. The precise dose employed will depend on the age and condition of the patient and on the route of administration. Thus, for example, a daily dose of 0.1 mg/kg to 10mg/kg may be suitable for systemic administration.

Compounds of formula (I) and salts, solvates, and esters thereof, salts and solvates of such esters and pharmaceutically acceptable derivatives of compounds of formula (I) may be prepared by any method known in the art for the preparation of compounds of analogous structure.

Suitable methods for the preparation of compounds of the invention are described below.

In the formulae that follow X is defined as in formula (I) above unless otherwise stated and R represents a chlorine, bromine or iodine atom, or a -OSO₂CF₃ group.

Thus, according to a first process (A), compounds of formula (I) may be prepared by reacting a compound of formula (II)

or a protected derivative thereof with the compound of formula (III)

_H ^~ \-J ⁽"ID

or a protected derivative thereof, in the presence of a transition metal catalyst and at elevated temperature. Suitable transition metal catalysts include palladium catalysts, such as a palladium triarylphosphine catalyst. Suitable temperatures are from about 50 to about 200°C, such as 80 to 120°C, or the reflux temperature of the solvent.

Conveniently the reaction is effected in the presence of a base, such as a tertiary amine; a palladium catalyst, for example a palladium triarylphosphine catalyst; a solvent, such as a polar solvent, for example Λ/./V-dimethylfoimamide; and at elevated temperature, for example from about 50 to 200°C, such as at 80 to 120°C, or the reflux temperature of the solvent reflux.

According to another process (B) compounds of formula (I) may be prepared by interconversion, utilising other compounds of formula (I) as precursors.

For example, compounds of formula (I) in which X represents CH₂-CH₂ may be prepared from the corresponding compounds of formula (I) in which X represents CH=CH by hydrogenation. The hydrogenation may be effected in the presence of a transition metal catalyst, such as Raney Nickel, or a palladium, platinum or rhodium catalyst. Conveniently the reaction is effected in a solvent, such as an alcohol (e.g. ethanol).

Alternatively, hydrogenation may be effected using diimide. Conveniently the diimide is generated in situ from a suitable salt, such as diazenedicarboxylic acid, dipotassium salt, and the reaction is effected in the presence of an acid, such as acetic acid, and a solvent, such as an alcohol (e.g. methanol).

As will be appreciated by those skilled in the art it may be necessary or desirable at any stage in the above described processes to protect one or more sensitive groups in the molecule to prevent undesirable side reactions.

Another process (C) for preparing compounds of formula (I) thus comprises deprotecting protected derivatives of compounds of formula (I). In a particular embodiment of this process compounds of formula (I) may be prepared from protected carboxyl derivatives of compounds of formula (I). In a further embodiment of this process, compounds of formula (I) may be prepared from protected amino derivatives of compounds of formula (I).

The protecting groups used in the preparation of compounds of formula (I) may be used in conventional manner. See, for example, those described in 'Protective Groups in Organic Synthesis' by Theodora W. Green, second edition, (John Wiley and Sons, 1991), which also describes methods for the removal of such groups.

Particular carboxyl protecting groups include, for example, carboxylic acid ester groups such as carboxylic acid alkyl or aralkyl esters, for example where the alkyl or aralkyl portion of the ester function is methyl, ethyl, tert-butyl, methoxymethyl, benzyl, diphenylmethyl, triphenylmethyl or p-nitrobenzyl. When the ester is an unbranched alkyl (e.g. methyl) ester deprotection may be effected under conditions of either basic hydrolysis, for example using lithium hydroxide, or acidic hydrolysis, for example using hydrochloric acid. Tert-butyl and triphenylmethyl ester groups may be removed under conditions of acid hydrolysis, for example using formic or trifluoroacetic acid at room temperature or using hydrochloric acid in acetic acid. Benzyl, diphenylmethyl and nitrobenzyl ester groups may be removed by hydrogenolysis in the presence of a metal catalyst (e.g. palladium).

Particular amino protecting groups include, for example, aralkyl groups such as benzyl, diphenylmethyl or triphenylmethyl groups; and acyl groups such as N- benzyloxycarbonyl, t-butoxycarbonyl or trifluoroacetyl groups.

When a particular isomeric form of a compound of formula (I) is desired the required isomer may conveniently be separated using preparative high performance liquid chromatography (h.p.l.c.) applied to the final title compounds of processes (A) to (C) above or applied prior to any final deprotection step in said processes.

Compounds of formula (II) and (III), or protected derivatives thereof, may be prepared using conventional chemistry.

Certain intermediates described above are novel compounds, and it is to be understood that all novel intermediates herein form further aspects of the present invention. Compounds of formula (II), for example, [4-(5-bromo-indazol- 1-yl)-piperidin-1-yl]-acetic acid, tert-butyl ester, are key intermediates and represent a particular aspect of the present invention. The intermediates formed by coupling a protected derivative of a compound of formula (II) with a protected derivative of formula (III) are also an important aspect of the present invention and include 4-{2-[1-(1-tert-butoxycarbonylmethyl-piperidin-4-yl)-1H- indazol-5-yl]-(E)-vinyl}-piperidine-1 -carboxylic acid, tert-butyl ester.

Conveniently, compounds of the invention are isolated following work-up as acid addition salts, e.g. trifluoroacetate or hydrochloride salts. Pharmaceutically acceptable acid addition salts of the compounds of the invention may be prepared from the corresponding trifluoroacetate salts by exchange of ion using conventional means, for example by neutralisation of the trifluoroacetate salt using a base such as aqueous sodium hydroxide, followed by addition of a suitable organic or inorganic acid, for example, hydrochloric acid. Alternatively, pharmaceutically acceptable acid addition salts may be prepared directly by effecting deprotection with the appropriate organic or inorganic acid, for example, hydrochloric acid. Inorganic base salts of the compounds of the invention may also be prepared from the corresponding trifluoroacetate salts by addition of a suitable strong base such as sodium hydroxide.

Solvates (e.g. hydrates) of a compound of the invention may be formed during the work-up procedure of one of the aforementioned process steps.

The following Examples illustrate the invention but do not limit the invention in any way. All temperatures are in °C. Thin layer chromatography (T.l.c.) was carried out on silica plates. Preparative high performance liquid chromatography (h.p.l.c.) was carried out using a Dynamax 60A C18 8μM 25cm x 41.4mm i.d. column eluted with a mixture of solvents consisting of (i) 0.1% trifluoroacetic acid in water and (ii) acetonitrile, the eluant being expressed as the percentage of (ii) present in the solvent mixture, at a flow rate of 45ml per minute. Analytical h.p.l.c. was carried out using a Dynamax 60A C18 8μM 25 cm x 4.6mm i.d. column eluted with a mixture of solvents consisting of (i) and (iii), 0.05% trifluoroacetic acid in acetonitrile, the eluant being expressed as the percentage of (iii) present in the solvent mixture, at a flow rate of 1ml per minute. The following abbreviations are used: Me = methyl; Et = ethyl; and

DMF = Λ/,Λ/-dimethylformamide. Example 1

Synthesis of (4-f5-(2-piperidin-4-yl-(E)-vinyl)-indazol-1 -yll-piperidin-l -vIV-acetic acid

(i) 4-(5-Bromo-indazol-1-yl)-piperidine-1 -carboxylic acid, tert-butyl ester

Sodium hydride (60% dispersion in oil, 440mg) was added portionwise to a solution of 5-bromo-1 H-indazole¹ (2.13g) in DMF (120ml), at 21° under nitrogen. After 0.25h, a solution of 4-methanesulphonyloxy-pipehdine-1 -carboxylic acid tert-butyl ester² (3.42g) in DMF (15ml) was added dropwise and the mixture heated at 95-100° for 3 days. Water (3ml) was added and solvents removed in vacuo. The residue was partitioned between water (125ml) and ethyl acetate (125ml) and the organic phase dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography over silica (200g) with cyclohexane-ether (2:1-1:1 ) eluant to give the title compound (1.42g). T.l.c. Si0₂ (Et₂0) Rf = 0.5.

¹ REF: This may be prepared as described in C. Dell' Erba et al, Tetrahedron.

1994, 50, 3529

² REF: This may be prepared as described in EP-A-0 560268 A1

Alternatively, 5-bromo-1 H indazole may be prepared as follows:

A solution of sodium nitrite (37.1g) in water (80ml) was added dropwise to a stirred suspension of 4-bromo-2-methylaniline (100g) in fluoroboric acid (175ml, 48%w/w solution in water) at 0-5°C. The resulting suspension was stirred at ambient temperature for 1.0 h, and the solid isolated by filtration, washed with diethyl ether (3 x 200ml) and dried under vacuum at 40-45°C to constant weight (153g) to yield the tetrafluoroborate diazonium salt of 4-bromo-2-methylaniline. (NB Not shock sensitive but decomposes above 90°C).

A stirred suspension of the tetrafluoroborate diazonium salt of 4-bromo-2- methylaniline (65g), potassium acetate (44.8g) and 18-crown-6 (3.01 g) in chloroform (2.6I) was stirred at ambient temperature for 2.0 h. The suspension was filtered to remove inorganic residues, and the filtrate was washed with chloroform (2 x 250ml); the combined organic layers were washed with 2N aqueous sodium hydroxide (200ml), dried over magnesium sulphate, filtered and evaporated in vacuo to give 5-bromoindazole as a pale brown solid (41.3g).

(ii) 5-Bromo-1-piperidin-4-yl-1 H-indazole 4-(5-Bromo-indazol-1-yl)-piperidine-1 -carboxylic acid tert-butyl ester was dissolved in trifluoroacetic acid (16ml) - water (1ml) and allowed to stand for 2h. The solvent was removed in vacuo and the residue slowly treated with 2M sodium hydroxide (15ml) and the solution extracted with dichloromethane (7x50ml). The extracts were combined, dried (Na₂S0₄) and evaporated in vacuo to afford the title compound as a colourless solid (0.84g).

T.l.c. Si0₂ (CH₂CI₂ - MeOH - aq. NH₃89:10:1 ) Rf = 0.3.

(iii) f4-(5-Bromo-indazol-1-yl)-piperidin-1-vn-acetic acid. tert-butyl ester 5-Bromo-1-piperidin-4-yl-1 H-indazole (0.78g) in DMF (15ml) was treated with sodium hydrogen carbonate (0.43g) and tert-butyl bromoacetate (0.43ml) and the mixture was stirred at 22° for 16h. The solvent was removed in vacuo and the residue partitioned between ethyl acetate (50ml) and water (25ml). The organic phase was dried (Na₂S0 ) and evaporated in vacuo to give the title compound (1.11α). T.l.c. Si0₂ (CH₂CI₂-MeOH-aq. NH₃ 89:10:1) Rf = 0.8

(iv) 4-(2-Hvdroxy-ethyl)-piperidine-1 -carboxylic acid tert-butyl ester

A mixture of 4-(2-hydroxy-ethyl)piperidine (53.2g, 0.412mol; Acros Chimica NV),

1,4-dioxan (250ml) and 2N aqueous sodium hydroxide (200ml) was treated portionwise, over 15min, with di-tert-butyl dicarbonate (95.4g, 0.437mol) at 25°.

The mixture was stirred at 25° for 20h and evaporated in vacuo. The aqueous residue was diluted with water (1000ml) and extracted with diethyl ether' (3x600ml). The combined, dried (MgS0₄) organic extracts were evaporated in vacuo to give the title compound as a pale-yellow oil (94.5g 0.412mol, 100%). T.l.c. Si0₂ cyclohexane: diethyl ether (5:1 ) Rf = 0.1

(v) 4-(2-Bromo-ethyl)-piperidine-1 -carboxylic acid tert-butyl ester A mixture of 4-(2-hydroxy-ethyl)-piperidine-1 -carboxylic acid tert-butyl ester (94.0g 0.41 mol), carbon tetrabromide (198.7g 0.6mol) and dichloromethane (1500ml) at 0° under nitrogen was treated portionwise, over 45min, with triphenylphosphine (135.2g 0.515mol). The mixture was stirred for 1h at 10° and 1 h at 25° and then evaporated in vacuo. The residue was purified by flash column chromatography on silica gel (Merck 9385), eluant cyclohexane: ethyl acetate (15:1, gradient to 10:1) to give the title compound as a clear liquid (81.8g, 0.28mol, 68%).

T.l.c. Si0₂ cyclohexane: diethyl ether (5:1 ) Rf = 0.4

(vi) 4-Vinyl-piperidine-1 -carboxylic acid tert-butyl ester

A solution of 4-(2-bromo-ethyl)-piperidine-1 -carboxylic acid tert-butyl ester (81.5g 0.279mol) in dry tetrahydrofuran (1000ml) under nitrogen at 20° was treated portionwise, over 30min, with potassium tert-butoxide (63.2g 0.563mol). The mixture was stirred at 25° for 3h and partitioned between saturated aqueous ammonium chloride (1000ml) and diethyl ether (500ml). The aqueous phase was extracted with diethyl ether (4x500ml) and the combined, dried (MgS0₄) extracts were evaporated in vacuo. The residue was purified by flash column chromatography on silica gel (Merck 9385) eluant cyclohexane: diethyl ether (19:1) to give the title compound as an orange oil (37.1g, 0.176mol, 63%). Mass spectrum m/z = 212 [MH⁺] T.l.c. Si0₂ cyclohexane: diethyl ether (10:1) Rf = 0.3

(vii) 4-1241 -(1 -Tert-butoxycarbonylmethyl-piperidin-4-vD-1 H-indazol-5-ylHE)- vinyl>-piperidine-1 -carboxylic acid, tert-butyl ester

A mixture of [4-(5-bromo-indazol-1-yl)-piperidin-1-yl]-acetic acid, tert-butyl ester (1.11g), 4-vinyl-piperidine-1 -carboxylic acid tert butyl ester (0.60g), palladium (II) acetate (47mg), tri-o-tolyl phosphine (113mg), triethylamine (1.15ml) and

DMF (60ml) was heated at 130° for 20h under nitrogen. The DMF was removed in vacuo and the residue taken into dichloromethane (150ml) and washed with 8% sodium bicarbonate (50ml). The organic phase was dried (Na₂SO₄) and evaporated in vacuo and the residue purified by flash chromatography over silica (150g) with cyclohexane-ether (2:1) eluant to afford the title compound

(980mg).

H.p.l.c. Rt= 22.3 min. T.l.c. Si0₂ (Cyclohexane - ether 2:1 ) R_f = 0.4 (viia) Alternative synthesis of 4424141 -tert-butoxy∞rbonylmethyl-piperidin-4- yl)-1H-indazol-5-vn-(E)-vinyl -piperidine-1 -carboxylic acid tert-butyl ester A stirred suspension of [4-(5-bromo-indazol-1-yl)-piperidin-1-yl]-acetic acid tert- butyl ester (52.5g), palladium diacetate (2.99g), tri-o-tolylphosphine (8.1g), 4- vinylpiperidine-1 -carboxylic acid tert-butyl ester (29.6g), Haborlite (Trademark) filter aid (26g) and triethylamine (55.6ml) in Λ/,Λ/-dimethylformamide (1.051) was heated at 110°C for 8 h. The mixture was cooled to ambient temperature, filtered through Hyflo (Trademark) and evaporated in vacuo to give a brown oil. Purification by column chromatography on silica gel, eluting with ethyl acetate : cyclohexane, 1:1, gave the product as a pale yellow solid (56.3g).

A stirred, cloudy solution of the crude product (29g) in ethyl acetate (174ml) was heated to 78430°C and then clarified by filtration through a 1μm filter. The filtrate was concentrated to ca 30ml, diluted with isohexane (290ml) and the resulting suspension stirred at ambient temperature for 1 h. The solid was isolated by filtration, washed with ethyl acetate (2 x 60ml) and dried under vacuum at 40-45°C to constant weight (21.7g).

(viii) f44542-Piperidin-4-yl4E)-vinvO-indazol-1-yl1-piperidin-1-yl)-acetic acid. trifluoroacetate A solution of 44241 1 -tert-butoxvcarbonylmethvl-piperidin-4-vl)-1 H-indazol-5- yl]-(E)-vinyl}-pipeπdine-1 -carboxylic acid, tert-butyl ester (975mg) in trifluoroacetic acid - water (9:1, 20ml) was allowed to stand for 4h at 22°, then the solvent removed in vacuo. The residue was purified by preparative h.p.l.c.

(10-20% (ii) over 10 min, then 20% (ii) for 8 min, Rt 15.4 min.) to give the titje compound (580mg).

Analytical h.p.l.c. (gradient profile 10-90% (ii) in 25 min) R_t = 9.4 min.

Analysis Found: C, 46.9; H, 4.8; N, 8.5.

C₂₁H₂₈N₄0₂. 2.7CF₃CO₂H Requires: C, 46.9; H, 4.6; N, 8.3%

Example 2

Synthesis of (44542-piperidin-4-yl-ethyl)-indazol-1 -yll-piperidin-l -vIVacetic acid bis(trifluoroacetate)

(0 44241 1 -tert-Butoxycarbonylmethyl-piperidin-4-yl)-1 H-indazol-5-yπ- ethyl)piperidine-1 -carboxylic acid, tert-butyl ester A solution of 44.2-[1(1-tert-butoxycarbonylmethyl-piperidin-4-yl)-1H-indazol-5- yl]-E-vinyl}piperidine-1 -carboxylic acid, tert-butyl ester, (0.50g) in ethanol (15ml) was added to a prehydrogenated mixture of 10% palladium/carbon (100mg) in ethanol (10ml). The mixture was allowed to stir under a hydrogen atmosphere for 16h. The catalyst was removed by filtration and the filtrate was evaporated in vacuo to give the title compound as a colourless oil (0.5g). Tic Si0₂ Triethylamine deactivated plates (Diethyl Ether) Rf: 0.37.

(ii) (44542-Piperidin-4-yl-ethyl)-indazol-1 -yll-piperidin-l -yl acetic acid bis(trifluoroacetate)

44.2-[1 -(1 -tert-Butoxycarbonylmethyl-piperidin-4-yl)-1 H-indazol-5-yl]-ethyl}- piperidine-1 -carboxylic acid, tert-butyl ester (0.50g) in trifluoracetic acid (9ml)/water (1ml) was allowed to stand at 22°C for 2h. The solvent was removed in vacuo and the residue was purified by preparative HPLC. Gradient profile 10-25% (ii) over 10 min and isochratic 25% (ii) over 8 min, R_τ 14.5min.

The solvent from the collected eluant was removed in vacuo and the residue was triturated with diethylether to give the title compound as a white solid (0.157g). m/z 371 (MH⁺) C₂ιH3oN₄0₂.2.5CF₃C0₂H Requires C.47.64; H.5.00; N.8.55 Found C.47.93; H.4.93; N.8.74

Example 3

!44542-Piperidin-4-yl4Z)-vinyl)-indazol-1 -yll-piperidin-l -yl)-acetic acid trifluoroacetate salt {4-[5-(2-Piperidin-4-yl-(E)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid hydrochloride (80mg, 0.176mmol) was dissolved in water (5ml) and the solution allowed to stand at 22° for 24h. The sample was diluted to 400ml with water, and allowed to stand under irradiation from a 150W tungsten lamp for 96h at 22°. The solvent was evaporated in vacuo, and the residue purified by preparative hplc (gradient profile 10-35% (ii) in 15 min, Rt 14 min) to give the title compound (19mg).

Assay Found: C.46.2; H, 4.65, N, 8.2.

C21 H28N4O2.2.8CF3COOH requires: C, 46.5; H, 4.5; N, 8.15. Example 4

(44542-Piperidin-4-yl4E)-vinyl)-indazol-1 -yll-piperidin-l -yl> -acetic acid dihvdrochloride

A stirred suspension of 44.2-[1-(1-tert-butoxycarbonylmethyl-piperidin-4-yl)-1H- indazol-5-yl]-(E)-vinyl}-piperidine-1 -carboxylic acid tert-butyl ester (21 g) in 5N hydrochloric acid (105ml) was stirred in the dark at ambient temperature for 18h. The resulting solid was isolated by filtration, washed with acetone (3 x 60ml) and dried under vacuum at 40-45°C to constant weight (14.3g).

Analysis Found: C.55.0; H, 7.15; N, 12.3%

C21H28N O2.2HCI .1.2H₂0 requires: C, 54.6; H, 7.05; N, 12.3%

¹H NMR (D₂0) δ: 1.74 (2H) m; 2.10 (2H) m; 2.27 (2H) m; 2.4-2.6 (3H) m; 3.14 (2H) dt,J=2.7Hz, 12.7Hz; 3.39 and 3.6 (2H) m; 3.56 (2H) dt, J= 12.8Hz, 3.2Hz; 3.88 (2H) m; 4.10 (2H) s; 4.93 (1H) m; 6.31 (1H) dd, J=6.6Hz, 16.1 Hz; 6.63 (1H) d, J=16.1Hz; 7.59 (1H) d, J= 8.8Hz; 7.66 (1H) dd, J= 8.8Hz, 1.2Hz; 7.73 (1H) s; 8.10 (1H) s.

Biological Data

1. Human Washed Platelets Assay

Inhibition of platelet aggregation by compounds of the invention was determined according to the following procedure. Citrated whole blood (1 part 3.8% w/v trisodium citrate; 9 parts blood) was obtained from human volunteers, free of medication for at least 10 days prior to donation. The blood was treated with aspirin (0.1 mM) and prostacyclin (0.06μM) prior to centrifugation (1400g, 4 minutes, 20°C). The supernatant platelet-rich plasma (PRP) was isolated and further centrifuged (1400g, 10 minutes, 20°C) to sediment the platelets. The supernatant was discarded and the platelet pellet resuspended into a physiological salt solution (HEPES 5mM, NaHCO₃ 12mM, NaCI 140mM, KH₂P0₄ 0.74mM, D-Glucose 5.6mM and KCI 2.82mM) adjusted to pH 6.4. This platelet suspension was centrifuged (1400g, 8 minutes, 20°C) and the resultant platelet pellet was resuspended into the physiological salt solution adjusted to pH 7.4. The resultant washed-platelet preparation was diluted to give a final platelet count of 3x10⁸/l. Purified human fibrinogen (Knight, L.C. et al., 1981 Thromb. Haemostasis, 46, (3), 593-596), Ca²⁺ and Mg²⁺ were added back to the washed platelet preparation to give final concentrations of O.δmg/ml, 1mM and 0.5mM respectively. Platelet aggregation was quantified using a turbidometric method. Test compounds were incubated with the washed platelets (37°C) for 5 minutes prior to the addition of 1μM of the platelet aggregatory agonist U-46619 (a stable thromboxane A₂-mimetic). The inhibitory potency of the test compounds was expressed as an IC₅0 value, which is defined as the concentration of the compound required to inhibit platelet aggregation by 50%.

The compounds of Examples 1, 2 and 3, when tested in this screen, had IC5₀ values of 46, 27 and 370nM respectively.

2. Human Whole Blood Assay

Human citrated whole blood (1 part 3.8% w/v trisodium citrate: 9 parts blood) was obtained from human volunteers who had been free of medication for at least 10 days prior to donation. The blood was incubated with test compound for 5 minutes at 37°C in a shaking waterbath. A single platelet count was obtained using a Sysmex K-1000 haematological analyser and then platelet aggregation was induced by the addition of 1μM U-46619 (a stable thromboxane A2 mimetic). After a further 5 minute incubation in a shaking waterbath (37°C), another single platelet count was taken. The degree of platelet aggregation was assessed from the fall in single platelet count and the ability of the test compounds to inhibit this was determined. The ICso value was then calculated.

The compound of Example 4, when tested in this screen, had an IC5₀ value of 87nm.

Claims

A compound of formula (I)

or a salt, solvate or ester thereof, or a salt or solvate of such ester, in which: X represents either CH -CH₂ or CH=CH.

A compound of formula (I)

3. A compound according to claim 1 or 2 selected from:

{4-[5-(2-piperidin-4-yl-(E)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid; {4-[5-(2-piperidin-4-yl-(Z)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid; {4-[5-(2-piperidin-4-yl-ethyl)-indazol-1 -yl]-pipehdin-1 -yl}-acetic acid; and pharmaceutically acceptable derivatives thereof.

4. {4-[5-(2-Piperidin-4-yl-(E)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid, trifluoroacetate salt or a pharmaceutically acceptable derivative thereof.

5. {4-[5-(2-Piperidin-4-yl-(E)-vinyl)-indazol-1 -yl]-piperidin-1 -yl}-acetic acid hydrochloride salt or a pharmaceutically acceptable derivative thereof

6. A pharmaceutically composition comprising a compound of formula (I) or a pharmaceutically acceptable derivative thereof according to any one of claims 2 to 5 in admixture with one or more physiologically acceptable carriers or excipients.

7. A compound of formula (I) or a pharmaceutically acceptable derivative thereof according to any one of claims 2 to 5 for use in human or veterinary medicine.

8. Use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof according to any one of claims 2 to 5 in the manufacture of a therapeutic agent for the treatment of thrombotic disorders.

9. A method of treating a human or animal subject suffering from a condition which is mediated through the Glycoprotein complex Gpllb/llla or other integrin receptor which comprises administering to said subject an effective amount of a compound of formula (I) or a pharmaceutically acceptable derivative thereof according to any one of claims 2 to 5.

10. A method according to claim 9 wherein the condition is a thrombotic disorder.

11. A process for the preparation of a compound as defined in any one of claims 1 to 5, which comprises:

(A) reaction of a compound of formula (II)

or a protected derivative thereof with the compound of formula (III)

or a protected derivative thereof, and optionally

(B) interconversion to another compound of formula (I) or a protected derivative thereof, and/or

(C) deprotection of protected derivatives of a compound of formula (I), and/or optionally converting the resultant compound of formula (I) into a pharmaceutically acceptable derivative thereof.

12. A compound of formula (II)

or a protected derivative thereof, wherein R represents a chlorine, bromine or iodine atom, or a -OS0₂CF₃ group.