HRP931512A2 - Azole derivatives - Google Patents

Description

This invention relates to new azole derivatives, more precisely to new 2-heteroaryl-triazolo [1,5-a][1,3,5]triazines as well as to their pharmaceutically acceptable salts, which have useful pharmacological properties (and especially antagonistic action adenosine, such as vasodilation). The invention also includes pharmaceutical preparations containing new azole derivatives and used for the treatment of certain diseases and disorders in mammals in the cardiac, peripheral and/or cerebral vascular system. The production and formulation procedures of new azole derivatives are also included.

The compound theophylline (1,3~dimethylxanthin) has been used clinically (usually as the ethylene diamine salt, which is also known as aminophylline) as a respiratory stimulant, a centrally acting stimulant, a bronchodilator, a cardiac stimulant and as a diuretic. This breadth of clinical uses is an indication of the range of pharmacological actions attributed to theophylline. These include phosphodiesterase inhibition, prescription adenosine antagonism, intracellular calcium mobilization, and catecholamine release. Recently, theophylline has also been found to be useful in the treatment of ischemia (Maseri et al., The Lancet. 1989, 683-686), skeletal muscle ischemia (Picano et al., Angiology. 1989, 40, 1035-1039), and cerebral ischemia ( Skinhoj et al., Acta. Neurol. Scand., 1970, 46, 129-140). Theophylline's beneficial effects in these ischemic disorders are thought to be attributable to the reduction or prevention of a phenomenon known as "vascular escape" by the compound's ability to antagonize the action of adenosine by blocking adenosine receptors involved in

vasodilatation associated with metabolism.

The phenomenon of "vascular escape" can occur when a major artery, which supplies a certain vascular area, is partially or completely occluded, causing ischemia. In this case, the involved vascular area is dilated and the blood flow is maintained either by increasing the flow through the narrowed blood vessels or by increasing the flow through the collateral blood vessels. Of course, increased metabolic activity in adjacent vascular areas results in the release of mediators such as adenosine causing dilation resulting in restricted blood flow in certain vascular areas from which it is "stolen". Loss of blood from specific areas to a normally supplied area by the phenomenon of "vascular leakage" further reduces blood flow in a particular vascular area.

The variety of pharmacological properties of theophylline makes it difficult to use it regularly in the treatment or prevention of occlusive diseases and conditions of a vascular nature. Thus, its action as a phosphodiesterase inhibitor results in cardiac stimulation, which is suitable for patients with myocardial ischemia. Furthermore, the relatively low potency of theophylline means that dose levels that are therapeutically active are close to those that can cause serious central side effects.

European patent application number EP-A1-459702 describes certain 2-heteroaryl-triazolo[1,2,4]triazolo[1,5-a] [1,3,5]-triazines and pyrazolo[2,3-a ][1,3,5]triazines, which are effective antagonists of the action of adenosine, especially its vasodilator effects.

A compound 2-heteroaryl-triazolo[1,2,4]triazolo-[1,5-a][1,3,5]triazine has now been found which has particularly desirable pharmacological properties.

Accordingly, the invention provides the compound 2-(2-furyl)-5-[2-(morpholino)-ethylamino][1,2,4]triazolo [1,5-a] [1,3,5]triazine-7 -amine, and its pharmaceutically acceptable salts.

The compound according to the invention can be represented by formula I, which is shown later together with other formulas from the text that are marked with Roman numerals. Said compound will be referred to hereafter as a compound of formula I.

A compound of formula I has been found to be a selective adenosine antagonist at the adenosine A2a receptor, the receptor that mediates the vasodilating effect of adenosine. It was also found to have particularly good solubility in water and to be unexpectedly effective in vivo when administered orally or parenterally. This combination of properties is unexpected and particularly desirable.

Particularly acceptable pharmaceutical salts of the compound of formula I include, for example, salts with acids having physiologically acceptable anions, for example, salts with acids such as hydrochloric, hydrobromic, sulfuric, phosphoric, methanesulphonic, trifluoroacetic, oxalic, citric and maleic acids.

According to the next aspect, the invention provides a process for the preparation of the compound of formula I, or its pharmaceutically acceptable salt, which includes:

(a) reacting a compound of formula II wherein Z is a corresponding leaving group, for example hydrocarbylsulphonyl such as (1-6C)-alkylsulphonyl (such as methylsulphonyl or ethylsulphonyl), aryloxy such as phenoxy, or halogen (such as chloro or bromo), with N -(2-aminoethyl)morpholine or its salt.

The reaction is usually carried out at a temperature range of from 0 to 120°C, for example from 10 to 80°C. Suitable solvents include nitriles such as acetonitrile; alcohols such as ethanol or propanol; ethers such as tetrahydrofuran, 1,2-dimethoxyethane or t-butyl methyl ether; and amides such as N,N-dimethylformamide.

Examples of salts of N-(2-aminoethyl)morpholine include salts of alkali metals such as lithium, sodium and potassium salts.

Starting materials of formula II can be obtained by the methods described in EP-A1-459702. Thus, for example, those compounds of formula II in which Z is alkylsulphonyl can be obtained by oxidizing the corresponding alkylthio derivatives of formula III in which R1 is (1-6C)-alkylthio, using effective oxidants such as per acids, for example, peracetic, perbenzoic or of chloroperbenzoic acid, usually at a temperature range of, for example, 0 to 40°C and in a suitable solvent or diluent such as dichloromethane or chloroform. Similarly, those compounds of formula II in which Z is chloro or bromo can be obtained, for example, by reacting alkylthio derivatives of formula III (especially those in which R1 is methylthio or ethylthio) with chlorine or bromine in the presence of hydrogen chloride or hydrogen bromide, generally at temperature range, for example, from -20 to 15°C and in a generally inert polar solvent such as ethanol or 2-propanol.

Alkylthio starting materials of formula III may be prepared, for example, by reacting a compound of formula IV with the corresponding dialkyl N-cyanodithioiminocarbonate of formula V at an elevated temperature in the range, for example, 60 to 200°C, usually at the melting point without solvent or diluent.

The starting compounds of the formula IV can be obtained, for example, by the reaction of the corresponding iminoether of the formula Q.C(OR)=NH in which Q is 2-furyl and R is (1-4C)alkyl such as methyl or ethyl (formed from the corresponding nitrile of the formula Q.CN and an alcohol of the formula R.OH in the presence of an anhydride such as hydrogen chloride) with an aminoguanidine salt (especially a nitrate) in the presence of a suitable base, such as pyridine or 2,6-lutidine which may also be used as a reaction solvent, at a temperature range of, for example, 60 up to 120°C.

Compounds of formula II in which Z is a phenoxy group can be conventionally prepared by reacting 5,7-diphenoxy-[1,2,4]triazolo-[1,5-a][1,3,5]triazine with ammonia. The process is usually carried out at a temperature in the range, for example, from 0 to 100°C. Suitable solvents for the process include alcohols such as ethanol and ethers such as tetrahydrofuran. It is particularly convenient to use a solution of ammonia in alcohol, such as ethanol, at room temperature.

The starting materials 5,7-diphenoxy-[1,2,4]triazoli[1,5-a]-[1,3,5]triazines can be readily obtained by dehydrating a compound of formula VI in which Z is a phenoxy group. Suitable dehydrating agents include, for example, polyphosphoric acid silyl esters such as polyphosphoric acid trimethylsilyl ester; phosphorus pentoxide and sulphonyl chlorides such as p-toluenesulphonylchloride. Dehydration is usually carried out at a temperature ranging from 60 to 180°C. When polyphosphoric acid silyl ester or phosphorus pentoxide is used, common solvents include aromatic hydrocarbons such as xylene or toluene. When sulphonyl chloride is used, common solvents include tertiary amines such as pyridine.

Compounds of formula VI can be obtained by reacting a compound of formula VII in which Z is a phenoxy group with a compound OCOHal where Hal is a halogen atom such as a chlorine atom. The reaction is usually carried out at a temperature ranging from -10 to 40°C. Suitable solvents for the reaction include halogenated hydrocarbons such as dichloromethane.

Compounds of formula VII can be obtained by reacting a compound of formula VIII where each Z is a phenoxy group with hydrazine.

Alternatively, compounds of formula VI may be obtained by reacting a compound of formula VIII wherein each Z is a phenoxy group with a compound of formula QCONHNH 2 .

According to the next aspect, the invention provides another method for the preparation of the compound of formula I or its pharmaceutically acceptable salt, which comprises

(b) reacting a compound of formula IX wherein Z 1 is a suitable leaving group, for example hydrocarbylsulphonyloxy (such as p-toluene-sulphonyloxy) or halogeno (such as chloro or bromo), with a morpholine.

The process is usually carried out at a temperature range of, for example, 10 to 120°C, more simply in the range of 30 to 80°C. Suitable reaction solvents include, for example, alcohols such as ethanol, nitriles such as acetonitrile, amides such as N,N-dimethylformamide, and ethers such as tetrahydrofuran, 1,2-dimethoxy-ethane, and t-butyl methyl ether.

Starting materials of formula IX can be obtained by conventional procedures well known in the art, from the corresponding compound of formula IX where Z 1 is a hydroxy group. This compound can be prepared by reacting the compound of formula II with 2-aminoethanol according to process (a).

According to the next aspect, the invention provides another method for the preparation of the compound of formula I or its pharmaceutically acceptable salt, which comprises

(c) reacting a compound of formula X, wherein Z is a suitable leaving group, not for example aryloxy (such as phenoxy), alkylthio (such as methylthio) or halogeno (such as chloro or bromo) with ammonia.

The reaction is usually carried out at a temperature ranging, for example, from 0 to 100°C. Suitable solvents for the process include water, alcohols such as ethanol and ethers such as tetrahydrofuran.

Starting materials of formula X can be obtained by dehydrating a compound of formula XI. Suitable dehydrating agents include, for example, phosphorus pentoxide, a polyphosphoric acid silyl ester such as polyphosphoric acid trimethylsilyl ester or a sulphonyl chloride such as p-toluenesulphonyl chloride. Dehydration is usually carried out at a temperature ranging from 60 to 180°C. When phosphorus pentoxide is used, common solvents include aromatic hydrocarbons such as xylene or toluene. When sulphonyl chloride is used, common solvents include tertiary amines such as pyridine.

Compounds of formula XI can be obtained by reacting a compound of formula VI with N-(2-aminoethyl)morpholine.

According to the next aspect, the invention provides another method for the preparation of the compound of formula I or its pharmaceutically acceptable salt, which comprises

(d) dehydrating the compound of formula XII

Suitable dehydrating agents include, for example, polyphosphoric acid silyl esters such as polyphosphoric acid trimethylsilyl ester; phosphorus pentoxide and sulphonyl chlorides such as p-toluenesulphonylchloride. Dehydration is usually carried out at a temperature ranging from 60 to 180°C. When polyphosphoric acid silyl ester or phosphorus pentoxide is used, common solvents include aromatic hydrocarbons such as xylene or toluene. When sulphonyl chloride is used, common solvents include tertiary amines such as pyridine.

Starting materials of formula XII may be prepared from the compound of formula VIII by reaction, in any conventional manner, with ammonia, N-(2-aminoethyl)morpholine and 2-furoic acid hydrazine.

Later, when a pharmaceutically acceptable salt is required, it can be obtained, for example, by reacting a compound of formula I with an appropriate acid or base which gives the appropriate physiologically acceptable ion or by some other conventional method.

As previously mentioned, the compounds of this invention possess the property of antagonizing one or more physiological effects of adenosine and are valuable in the treatment of diseases and medical conditions manifested in mammals in cardiac diseases, diseases of the peripheral and/or cerebral vascular system such as cardiac ischemia (angina). , peripheral vascular disorder (claudication) and cerebral ischemia. The compounds may also be useful in the treatment of migraine.

The effects of the compounds of formula I as adenosine receptor antagonists can be demonstrated using one or more of the following in vitro and/or in vivo tests.

(a) A2a adenosine receptor affinity assay

This assay involves the ability of a tested adenosine antagonist to replace the known adenosine agent [3H]-N-ethylcarbox-amidoadenosine, (NECA) at binding sites on membrane preparations of PO 12 rat phaeochromocytoma cells (available from the Beatson Institute, Glasgow). The basic procedure is described by Williams et al. (J. Neurochemistry, 1987, 48(2), 498-502).

The membrane preparation was obtained in the following way:

Frozen pellets of PC 12 cells are washed twice with ice-cold buffered saline and cells are recovered by centrifugation (1500 G) at 30°C. The separated cells are then suspended in a hypotonic solution (distilled water) and allowed to stand on ice for 30 minutes and then carefully homogenized using a standard high-speed homogenizer, with periodic ice cooling, to obtain a fine suspension. The homogenate is centrifuged (48,000 G) and the pellet is resuspended in 50 mM Tris-HCl buffer, pH 7-4, containing adenosine deaminase (5 units/ml, Type VII from calf intestinal mucosa, obtained from Sigma Chemical Corporation, code no. A1280). The mixture is then incubated at 37°C. After 20 minutes, the reaction is terminated by dilution with ice-cold buffer and transferred to ice. The resulting material contains cell membranes obtained by centrifugation and washing by resuspension in a buffer and by centrifugation again. The resulting beads are then resuspended in ice-cold buffer using a manual homogenizer. The resulting membrane suspension is frozen and stored under liquid nitrogen until use.

The binding study is carried out in microtitre vessels, the tested mixture buffered in 50 mM tris-HCl, pH 7.4 at room temperature. The test compound is dissolved in dimethyl sulfoxide (DMSO) and then diluted with test buffer to obtain a test solution. [The final concentration of DMSO should not exceed 1% of the volume, thereby not allowing the binding of the radioligand to the membrane receptor J. Incubation is carried out at 30°C for 90 minutes in a total volume of 150 μl containing the test solution or buffer (50 μl), NECA (50 μl) and membrane suspension (50 μl). After incubation, samples are rapidly filtered through glass filters and these are then washed to remove radioligands that do not bind to the receptor. Radioligands that bind to the receptor and remain captured on the filter are then determined by liquid scintillation counting. Filtration and washing is carried out using the usual vacuum filtration cell equipment.

Specific binding (defined as the difference between total binding and non-specific binding) in the presence of an individual test compound was determined and compared to a control value. Results are usually expressed as the negative logarithm of the concentration required to cause 50% replacement of the control specific binder (pIC50).

The compound from Example 1 shows a pIC50 of 7.6. Using the same test procedure, the known compound 1,3-dimethylxanthine usually shows a pIC50 of about 5.

(b) Atrial bradycardia test in guinea pigs

Collis et al. (British J. Pharmacology, 1989, 97, 1274-1278) also described this test involving the ability of a test compound to antagonize the bradycardic effect of adenosine, 2-chloroadenosine, on a pulsatile guinea pig atrial preparation, an effect in which an adenosine receptor known to participate as A1.

The preparation of the atrial parts can be carried out in the following way:

Atrial sections were obtained from guinea pigs (Dunkin Hartley strain, 250-400 g, male) and placed in organic baths containing oxygenated Krebs buffer solution (95% O2; 5% CO2) at 37°C. Spontaneously pulsating parts are then placed under a constant load of 1 g and an equilibration period of 50 minutes is allowed with constant flow. The flow was then stopped and adenosine deaminase (1 unit/ml) was added to prevent accumulation of endogenously produced adenosine. After equilibration for 15 minutes, a cumulative dose response curve for adenosine, 2-chloroadenosine (10-8 M to 10-4 M) was applied to cause a maximal reduction in atrial velocity. After a 30-minute test, adenosine deaminase is applied again and allowed to equilibrate for 15 minutes. Then a 10-5 M solution of the tested compound in DMSO is added to the bath and the bath is left to incubate for 30 minutes. Any effect on pulse rate due to the action of the test compound is noted before repeating the dose-response curve for 2-chloroadenosine. Compounds that are adenosine antagonists attenuate the 2-chloroadenosine response.

The test compounds were examined by comparing the dose response curves for 2-chloroadenosine with the curves obtained in the presence of the test compound. Competitive adenosine antagonists produce a parallel curve shift in relation to the dose-response curve for 2-chloroadenosine. The dose ratio (DR) is calculated from the ratio of the concentration of 2-chloroadenosine required to produce a 50% reduction in atrial velocity (ED50) in the presence of the test compound divided by the ED50 concentration of 2-chloroadenosine in the absence of the test compound, for each atrial pair. pA2 is then calculated using a standard technique. The compound from Example 1 has a pA2 of 5.5. The well-known compound 1,3-dimethylxanthin, usually shows a pA2 of about 5.

If the pA2 value obtained for the compound from Example 1 of this test is compared with the pIC50 obtained for the same compound in test (a), it is evident that the compound is more than a hundred times more selective for the A2a receptor than for the A1 receptor. This is particularly desirable because antagonism of adenosine at the A1 receptor is associated with effects on the kidneys, obesity, heart, and central nervous system.

(c) Anesthetized dog test

This test involves examining the effect of a test compound on antagonizing the effect of adenosine in reducing heart rate and reducing vasodilation (as measured by hind leg pressure).

Brakirci dogs (12-18 kg) are anesthetized with sodium pentobarbitone (50 mg/kg, i.v.). The following blood vessels were catheterized:

right jugular vein (for anesthetic infusion approximately 112 mg per hour as a 3 mg/ml solution in isoronic saline solution), right brachial vein (for administration of drugs and tested compounds), right brachial artery (for measurement of systemic blood pressure and pulse rate), and the left carotid artery (for administration of adenosine in the left ventricle). Both vagus, right femoral and femoral nerves were collected and cut. Before perfusion of the right hind limb, a bolus injection of 1250 U of heparin was administered with constant blood flow from the iliac artery. The right leg was cut just below the ankle. Xamoterol (1 mg/kg) is then administered to the animal to stabilize the heart rhythm, and nitrobenzylthioinosine (NBTI, 0.5 mg/kg) to inhibit adenosine. The animal is sensitized to adenosine during the equilibration period after NBTI administration by recording a dose response curve (DRO). During this time, any disturbance in blood gas balance or pH value is corrected. The DRO control for adenosine was made with up to three DRO nalon cumulative applications of the test compound applied in a mixture of 50% v/v polyethylene glycol (PGE) 400 and 0.1 M sodium hydroxide. Each DRC is recorded 15 minutes after the application of the tested compound and the return of the measured parameters of heart rhythm and perfusion pressure in the right limb to a stable level. Likewise, blood gases and pH values were maintained within physiological limits during the study.

The amount of adenosine required to cause a 50% drop in the measured parameter (ED50), i.e. heart rate and perfusion pressure, was calculated for each dose of the tested compound and a Schild curve was constructed. From this curve, the KB value for the antagonism of the heart rhythm response and vasodilation response to adenosine was determined. The compound from Example 1 was found to have a KB in the range of 0.01 - 0.24 mg/kg for antagonism of the vasodilator response to adenosine without indication of toxicity or other unwanted properties at doses that are several times higher than the minimum effective doses.

(d) Blood pressure testing of a conscious cat

This test examines the ability of a test compound to antagonize the fall in diastolic blood pressure caused by the administration of adenosine.

Male cats (2-4.5 kg) were selected and trained to sit quietly and calmly in a box open at the front. Appropriate animals are then prepared for chronic catheterization. Anesthesia is induced with alphaloxone/alphadolone (18 mg, iv) and continued with halothane (1.5-3%) with oxygen. Dorsal and neutral regions on the neck are clamped and wiped with an alcohol/chlorhexidine/water mixture (70/20/10% v/v). The right carotid artery (for measuring systemic atrial blood pressure) and the right jugular vein (for administration of adenosine or test substance) are catheterized and made to be external. Both catheters are sutured and the openings closed with sutures. The cats are allowed to regain consciousness before being transferred to the animal room where they are housed individually. Allow at least one week post-surgical recovery time before animals are used for testing.

All surgical procedures are performed using an aseptic procedure, all instruments are pre-autoclaved. Catheters are immersed in an alcohol/chlorhexidine solution for at least one hour before implantation, the catheters are then flushed with sterile saline to avoid tissue necrosis caused by the alcohol/chlorhexidine solution.

The cats are placed individually in boxes open from the front. After a short period of acclimatization, 0.6 mg/kg of adenosine is administered to test the cat's sensitivity to adenosine. Three bolus injections of 0.6, 1.0 or 1 mg/kg adenosine are given one after the other and the drop in diastolic blood pressure is measured. Cats are then given the test compound either as a solid or as a solution in polyethylene glycol (PEG) 400, p.o. or in a solution for intravenous administration.

Administration of adenosine is repeated after 15 minutes and after 24 hours after administration of the test compound. The activity of the test compound is expressed as a percentage of inhibition of the diastolic blood pressure response. The compound of Example 1 was found to have significant activity as an adenosine antagonist at a dose of 0.3-1 mg/kg without any sign of toxicity at multiples of the minimum effective dose.

The compounds according to the invention are generally best administered to warm-blooded animals for therapeutic or prophylactic reasons for the treatment or prevention of cardiovascular diseases and similar conditions in the form of a pharmaceutical composition containing said compound of formula I or a pharmaceutically acceptable salt thereof, together with or in admixture with a pharmaceutically acceptable diluent or base. Such preparations constitute a further form of this invention.

In general, it is contemplated that a compound of formula I should be administered orally, intravenously, or by some other medically acceptable means (such as inhalation, insufflation, sublingually, or transdermally) at a dose generally ranging, for example, from 0.001 mg to 10 (and more specifically, for example from 0.05 up to 5 mg/kg) mg/kg of body weight. Of course, it is understood that the exact dose to be administered will vary depending on the nature and severity of the disease or condition to be treated as well as the age and gender of the patient.

The preparation according to the invention can be in different dosage forms.

For example, it can be in the form of tablets, capsules, solutions or suspensions for oral administration; in the form of suppositories for rectal administration; in the form of a sterile solution or suspension for intravenous or intramuscular injection; in the form of an aerosol or nebulizer solution or suspension for use by inhalation; in powder form, together with a pharmaceutically acceptable solid diluent such as lactose for administration by insufflation; or in the form of a patch for transdermal application. The preparations may typically be in unit doses of 5-200 mg of a compound of formula I or an equivalent amount of a pharmaceutically acceptable salt thereof.

The percentage by weight of the compound of formula I in the preparation according to the invention varies depending on the route of administration. For example, the preparation may contain from 0.1 to 99.5% by weight of the compound of formula I or its pharmaceutically acceptable salt.

The compositions may be prepared in conventional manner using pharmaceutically acceptable diluents and carriers well known in the art. Tablets and capsules for oral administration may be conventionally formulated with enteric coatings (such as those based on cellulose acetate phthalate) to reduce contact of the active ingredient with gastric acids.

The compositions according to the invention may also contain one or more agents useful for cardiovascular diseases or conditions to be treated. Thus, they may contain, in addition to the compound of formula I, for example: a known inhibitor of blood cell aggregation, a prostanoid constrictor antagonist or a synthase inhibitor (thromboxane A2 antagonist or aintase inhibitor), a cyclooxygenase inhibitor, a hypolipidemic agent, an inotropic agent or a thrombolytic agent.

In addition to their use in therapeutic medicine, compounds of formula I are also a useful pharmacological tool in the development and standardization of test systems for evaluating new cardiovascular agents in laboratory animals such as cats, dogs, rabbits, monkeys, rats and mice.

The invention will now be illustrated by the following non-limiting examples in which, unless otherwise indicated, it is believed that:

(I) evaporation is carried out by rotary evaporation in vacuo;

(II) operations are carried out at room temperature, which is in the range of 18 - 26°C;

(III) column light chromatography or medium pressure liquid chromatography (MPLC). are performed on silico gel (or Fluka Kieselgel 60 (Catalog No. 60738) obtained from Fluka AG, Buchs, Switzerland, or Merck Kieselgel Art. 9385, obtained from Merck, Darmstadt, Germany);

(IV) the yields are given for illustration and are not the maximum that can be obtained by developing the process;

(V) proton NMR is usually determined at 200 MHz in deuterated dimethyl sulphoxide as solvent using tetramethyl-silane (TMS) as an inert standard, and is expressed as chemical shifts (delta values) in parts per million relative to TMS using the usual abbreviations to describe of main peaks: s, singular; m, multiplet; t, triplet; no, wide; d, double; q, quadruple; and

(VI) all end products are characterized by microanalysis, NMR and/or mass spectroscopy.

Example 1

N-(2-aminoethyl)morpholine (2.60 g) was added to a stirred suspension of 7-amino-2-(2-furyl)-5-methylsulphonyl-[1,2,4]triazolo-[1,5-a][ 1,3,5]triazine (3.36 g) in acetonitrile (200 ml) and stirring was continued for 2 hours. The solvent was evaporated and the residue was purified by chromatography on silica (200 g) eluting with methanol containing dichloromethane (10% v/v). 4.0 g of the obtained solid was crystallized from ethanol to give 2-(2-furyl)-5[2-(morpholino)ethylamino][1,2,4]triazolo[1,5-a][1,3,5]triazine- 7-amine (3.03 g), m.p. 242-4°C; microanalysis found: C, 50.7; H, 5.40; N, 33.7; C14H18N8O2 and calculated C, 50.9; H, 5.5; N, 33.9; NMR: 2.47 (br, 6H, CH2N(CH2)2), 3.43 (q, 2H, CH2NH), 3.61 (m, 4H, CH OCH ), 6.68 (d from d, 1H, furyl-4H), 7.06 (d , 1H, furyl-3H), 7.27 (br, 1H, NH), 7-86 (d, 1H, furyl-5H) and 8.15 (br, 2H, NH2); m/e 331 (M+H)+.

The necessary starting material was prepared in the following way:

(1) Gaseous hydrogen chloride (20.0 g) is introduced into an ice-cold mixture of 2-furonitrile (4-6.5 g) and absolute ethanol (23.0 g). After the gas is added, the solid crystallizes from the mixture. The crystalline solid is collected by filtration and heated in 300 ml of pyridine with 56.0 g of aminoguanidine nitrate under reflux for 4 hours. The mixture was cooled, the solid material was removed by filtration and the filtrate was evaporated to give crude 3-amino-5-(2-furyl)-1,2,4-triazole. This is purified by treatment with nitric acid (400 ml, 50% v/v). The crystalline salt that forms is collected by filtration, washed alternately with water (100 ml) and ethanol (50 ml) and air dried to give 3-amino-5-(2-furyl)-1,2,4-triazole nitrate (45.0 g), m.p. 130-133°C (decomposition). 184 g of this salt is suspended in hot water (400 ml) and then 46.0 g of sodium carbonate is added in portions. The resulting alkaline solution was allowed to cool to give 3-amino-5-(2-furyl)-1,2,4-triazole (82.0 g) as colorless prisms, m.p. 204-206°C; NMR 6.05 (s, 2H, NH2), 6.6 (s, 1H, furyl-4H), 6.7 (s, 1H, furyl-3H), 7-7 (s, 1H, furyl-5H), 12.05 (br s, 1H, NH).

(2) A well-stirred mixture of 3-amino-5-(2-furyl)-1,2,4-triazole (33.0 g) and dimethyl N-cyanodithioiminocarbonate (33.0 g) is heated at 170°C for one hour with a gentle flow argon. After cooling, the resulting solid was purified by silica column chromatography (600 g) eluting with increasing amounts of ethyl acetate in dichloromethane (5-10% v/v) to give 7-amino-2-(2-furyl)-5-methylthio- [1,2,4]triazolo[1,5-a][1,3,5]triazine as a colorless solid (11.1 g), completely pure by TLC, which can be used without further purification. A small amount of the previous solid is recrystallized from ethanol to give crystals, m.p. 238-240°C; microanalysis found: C, 44.0; H, 3.3; N, 33.7; C9H8N6SO. 0.05C2H5OH, and calculated C, 43.6; H, 3.3; N, 33.6; NMR 1.05 and 3.4 (t+q, ethanol of crystallization), 2.5 (s, 3H, CH3S-), 6.7 (dd, 1H, furyl-4H), 7-2 (d, 1H, furyl-3H), 7.7 (d, 1H, furyl-5H), 8.7 - 9.0 (br d, 2H, NH2); m/e 248 (M+).

(3) A solution of 3-chloroperoxybenzoic acid (50% strength, 45.0 g) in dichloromethane (300 ml) was added to a stirred, ice-cold suspension of 7-amino-2-(2-furyl)-5-methylthio-[1 ,2,4]-triazolo[1,5-a]1,3,5]triazine (8.0 g) in dichloromethane (300 ml). The remaining aqueous layer is drained. The resulting suspension was warmed to room temperature and stirred for 16 hours. The solvent is evaporated and 150 ml of ethanol is added to the residue. The thus obtained suspension is left to stand for 30 minutes with occasional stirring. The solid was then collected by filtration, washed with ethanol and dried to give 7-amino-2-(2-furyl)-5-methylsulphonyl-[1,2,4]-triazolo[1,5-a][1,3,5 ]triazine (6.6 g) as a colorless solid, NMR: 3.3 (s, 3H, CH3SO2), 6.7 (q, 1H, furyl-4H), 7.3 (q, 1H, furyl-3H), 7.9 (q, 1H, furyl -5H), 9.4-9.8 (d, 2H, NH2), which was further used without further purification.

Example 2

A mixture of 7-amino-2-(2-furyl)-5-phenoxy-[1,2,4]triazolo[1,5-a]-[1,3,5]triazine (1.47 g) and N-(2 -aminoethyl)morpholine (0.78 g) in propanol (75 ml) is heated under reflux for 48 hours, until thin-wall chromatography shows that the reaction is complete. The solvent was removed and the residue was purified by chromatography on silica eluting with methylene chloride methanol 10% v/v. The resulting solid (1.1 g) was crystallized from ethanol to give 2-(2-furyl)-5-[2-(morpholino)ethylamino][1,2,4]triazolo[1,5-a][1,3,5 ]-triazin-7-amine (0.69 g) m.p. 243-6°C, which is in all respects identical to the product obtained in example 1.

The necessary starting material can be prepared in the following way:

3.0 moles of hexamethyldisiloxane are placed in a mixture of phosphorus pentoxide (1.5 moles, measured as P4O10) in xylene. The mixture is then heated to 90°C for 1.5 hours and then stirred for one hour at 90°C during which time all solids dissolve. N-2-(4,6-diphenoxy)-[1,3,5]triazinyl-N'-(2-furoyl)hydrazine (1.0 mol) was then added to the solution and the temperature was raised to the reflux temperature. The solid dissolves, but during cyclization another solid precipitates. The cyclization is normally completed in 2.5 hours when the mixture is cooled to 25°C and left to stand overnight just in case. Then acetonitrile is added and the temperature is lowered to 15°C. Then water is added. The mixture is cooled again to 15°C and 0.91 ammonia solution is added while keeping the temperature below 25°C. Once the addition is complete the temperature is raised to 40°C for one hour. The reaction mixture is then cooled to 25°C, the solid is removed by filtration and washed with a large amount of water. The yield is approximately 85%.

N-2-(4,6-diphenoxy)-[1,3,5]triazinyl-N'-(2-furoyl)hydrazine was prepared as follows:

A solution of 2,4,6-triphenoxy-1,3,5-triazine (7.2 g) and 2-furoic acid hydrazide (2.5 g) in xylene (60 ml) was heated under reflux for 3 hours. The solvent is then removed by evaporation and the residue is purified by chromatography on silica gel (400 g) eluting with a mixture of methylene chloride/methanol (2-3% v/v). A solid was obtained which crystallized from isopropanol to give N-2-(4,6-diphenoxy)-[1,3,5]triazinyl-N'-(2-furoyl)hydrazine as colorless prisms; d.p. 182-4°C; microanalysis; found C, 61.4; H, 3.8; N, 17.7%; C20H15N5O4 calculated 0.61.7; H, 3.9; N, 18.0%; NMR 6.63 (d of d, 1H, 4-furyl H), 7.05-7.5 (complex, 1H, 3-furyl H and phenyl H), 7.87 (s, 1H, 5-furyl H), 9.96 (s, 1H, NH), and 10.34 (s, 1H, NH); m/e 390 (M+H)+.

Example 3

2-(2-furyl)-5-[2-(morpholino)ethylamino][1,2,4]triazolo[1,5-a]-[1,3,5]triazin-7-amine (14.2 g) is dissolved in hot methanol (1,400 ml) and acidified to pH 3 with 7 N hydrogen chloride in dioxane. The mixture is left at pH 3 for 30 minutes. The solvent is evaporated and replenished with fresh methanol, which is then evaporated. This procedure is repeated two more times.

The residue was recrystallized from methanol (80 ml) to give, after drying at 80°C/vacuum/16 hours, 2-(2-furyl)-5-[2-(morpholino)-ethylamino][1,2,4]triazolo[1 ,5-a][1,3,5]triazin-7-amine, bis hydrochloride (15.6 g) m.p. 313-15 (disintegration), microanalysis; found: C, 39.6; H, 5.4; N, 26.6; Cl, 15.9; H2O, 5.1%, C14H18N8O2 - 2HCl-1.2 H2O - 0.05 CH3OH calculated: C, 39.57; H, 5.34; N, 26.27; Cl, 16.63; H2O, 5.06% MS 331 (M+H)+. NMR: at room temperature the spectrum is hindered by the presence of roramer. At 373°K δ 3.3 (m, 6H, 3 x CH2N); 3.75 (t, 2H, CH2NH); 3.9 (t, 4H, CH2OCH2); 6.65 (m, 1H, furyl-4H); 7.09 (d, 1H, furyl-3H); 7.5 (brs, 1H, NHCH2); 7-8 (d, 1H, furyl-5H); 8.0 (brs, 2H, NH2); also δ 3.2 (s, methanol from crystallization).

Example 4

The following examples illustrate common dosage forms containing a compound of formula I or a pharmaceutically acceptable salt thereof (hereinafter referred to as "compound x") for therapeutic or prophylactic use in humans:

(And)

[image]

(b)

[image]

The foregoing formulations may be obtained by conventional procedures well known in pharmacy. Tablets can be coated with different coatings, for example to provide a coating of cellulose acetate phthalate.

Chemical formulas

[image]

[image]

[image]

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Claims (7)

1. A compound characterized in that it is 2-(2-furyl)-5-[2-(morpholino)ethylamino] [1,2,4]triazolo[1,5-a][1,3,5]triazine -7-amine and its pharmaceutically acceptable salts. 2. The salt according to claim 1, characterized in that it is chosen from salts formed with hydrochloric, hydrobromic, sulfuric, phosphoric, methanesulfonic, trifluoroacetic, oxalic, limmnic or maleic acid. 3. The compound according to claim 1, characterized in that it is selected from 2-(2-furyl)-5-[2-(morpholino)ethylamino] (1,2,4)-triazolo[1,5-a][1 ,3,5]triazin-7-anine and 2-(2-furyl)-5-[2-(morpholino)ethylamino][1,2,4]triazolo[1,5-a][1,3,5 ]triazin-7-amine, bis hydrochloride. 4. The compound according to claim 1, characterized by the fact that 2-(2-furyl)-5- [2-(morpholino)ethylamino] [1,2,4]triazolo [1,5-a]-[1,3 ,5] triazin-7-amine. 5. Method of preparation of 2-(2-furyl)-5-[2-(morpholino)ethylamino]-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-amine , or its pharmaceutically acceptable salts, characterized in that it comprises (a) reaction of the compound of formula II [image] where Z is the corresponding leaving group, with N-(2-aminoethyl)-morpholine or a salt thereof; (b) reaction of a compound of formula IX [image] where Z 1 is the corresponding leaving group, with morpholine; (c) reaction of a compound of formula X [image] where Z 2 is the corresponding leaving group, with ammonia; or (d) dehydrating the compound of formula XII [image] and later, if a pharmaceutically acceptable salt is desired, salt formation. 6. Pharmaceutical preparation, characterized in that it contains 2-(2-furyl)-5-[2-(morpholino)ethylamino][1,2,4]triazolo-[1,5-a][1,3,53triazine -7-amine or a pharmaceutically acceptable salt thereof in admixture or together with a pharmaceutically acceptable diluent or carrier. 7. Use of 2-(2-furyl)-5-[2-(morpholino)ethylamino][1,2,4]-triazolo[1,5-a][1,3,5]triazin-7-amine or its pharmaceutically acceptable salts, indicated to serve in the production of drugs for the treatment of ischemic heart disease, peripheral vascular disease or cerebral ischemia.