4-Phenylphthalazine derivatives

Abstract: 4-Phenylphthalazine derivatives of the formula: wherein R¹ is an alkyl or hydroxyalkyl group of 1-5 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R², when taken together, may represent an alkylene group of 2-6 carbon atoms, said group optionally containing one or more oxygen atoms; R³ and R⁴ are independently a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, or when two of R³ are adjacently positioned, (R³) ℓ may represent a -O-(CH₂) p -O- group and/or when two of R⁴ are adjacently positioned, (R⁴) m may represent a -O-(CH₂) p -O- group; R⁵ is a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, a trifluoromethyl group or a hydroxy group, or when two of R⁵ are adjacently positioned, (R⁵) n may represent a -O-(CH₂) p -O- group; p is an integer of 1-3; ℓ and m are independently an integer of 1-2; and n is an integer of 1-3, and optical isomers and pharmaceutically acceptable acid addition salts thereof.

Description: The present invention relates to aminophthalazine derivatives having platelet aggregation inhibitory activity and thus being useful as prophylactic or therapeutic agents for cerebrovascular diseases such as cerebral thrombosis, cerebral embolus or the like, ischemic heart diseases such as cardiac infarction or the like, and circulatory disorders such as peripheral circular disease. More particularly, this invention is directed to 1-α-substitutedbenzylamino-4-phenylphthalazine derivatives or their pharmaceutically acceptable acid addition salts. Ischemic heart diseases such as cardiac infarction, angina pectoris or the like, cerebrovascular diseases such as cerebral thrombosis, cerebral embolus or the like and circulatory disorders such as peripheral circulatory disease are often attributable to generation of intravascular thrombosis which blocks the vessel. This phenomenon is mainly based on the platelet aggregation which takes place at the preliminary stage of thrombosis formation. Many 4-phenylphthalazine derivatives have heretofore been known as having platelet aggregation-inhibitory activity. For example, Japanese Patent Publication (Kokai) Nos. 53659/1981, 53660/1981 and 48972/1982 disclose 1-anilino-4-phenylphthalazine derivatives, and Japanese Patent Publication (Kokai) Nos. 218377/1985 and 243074/1985 disclose that the following two compounds show potent platelet aggregation-inhibitory activity in vitro . However, some of these known compounds hardly show the activity when orally administrated, and others have only insufficient platelet aggregation-inhibitory activity in vivo . On the other hand, 1-amino-4-phenylphthalazine derivatives of the following formula (IV) are disclosed in British Patent No. 1,303,061, J. Med. Chem., 12 , 555 (1969) and the like. However, only a few compounds are specifically disclosed in the above literatures, and as for the pharmacological activity, only antiinflammatory activity and antirheumatic activity are described therein. In GB-A-2 063 249, JP-A-56 53659 and JP-A-56 53660 compounds are disclosed represented by the following formula In said formula R represents wherein X represents -NH-, -O-, -S- or CH₂CO. These prior art compounds are useful as agents for supressing coagulation of blood platelets. As the result of investigations on the 4-phenylphthalazine derivatives to find out compounds having excellent platelet aggregation inhibitory activity in vivo and also having an activity directly inhibiting the undesirable affecting change in the affected region such as shrinkage of cardiac infarction nest or the like, the present inventors have discovered that the 4-phenylphthalazines having special α-substitutedbenzylamino group at the 1-position suffice the above requirements. Accordingly, the present invention provides 4-phenylphthalazine derivatives of the following formula (I): wherein R¹ is an alkyl or hydroxyalkyl group of 1-5 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R², when taken together, may represent an alkylene group of 2-6 carbon atoms, said group optionally containing one or more oxygen atoms; R³ and R⁴ are independently a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, or when two of R³ are adjacently positioned, (R³) ℓ may represent a -O-(CH₂) p -O- group and/or when two of R⁴ are adjacently positioned, (R⁴) m may represent a -O-(CH₂) p -O- group; R⁵ is a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, a trifluoromethyl group or a hydroxy group, or when two of R⁵ are adjacently positioned, (R⁵) n may represent a -O-(CH₂) p -O- group; p is an integer of 1-3; ℓ and m are independently an integer of 1-2; and n is an integer of 1-3, and optical isomers and pharmaceutically acceptable acid addition salts thereof. The present invention will be explained below in detail. In the compounds of the present invention represented by the general formula (I), R¹ is an alkyl group of 1 to 5 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, or 1-ethylpropyl group or a hydroxyalkyl group of 1-5 carbon atoms such as hydroxymethyl group, 2-hydroxyethyl group, 1-hydroxyethyl group, 3-hydroxypropyl group, 1-methyl-2-hydroxyethyl group, 4-hydroxybutyl group, 1,1-dimethyl-2-hydroxyethyl group, 2-methyl-3-hydroxypropyl group, 5-hydroxylpentyl group, or 2,2-dimethyl-3-hydroxypropyl group. R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, or 1-ethylpropyl group. However, R¹ and R² may combine together and represent an alkylene group of 2-6 carbon atoms optionally containing one or more oxygen atoms, such as ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, -CH₂OCH₂-group or -CH₂CH₂OCH₂CH₂-group. R³ and R⁴ are independently hydrogen atom; halogen atom such as fluorine atom, chlorine atom or bromine atom; alkyl group of 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group or tert-butyl group; or alkoxy group of 1 to 4 carbon atoms such as methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group or i-butoxy group. R⁵ is hydrogen atom; halogen atom such as fluorine atom, chlorine atom or bromine atom; alkyl group of 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group or tert-butyl group; or alkoxy group of 1 to 4 carbon atoms such as methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group or i-butoxy group; trifluoromethyl group or hydroxy group. However, two of R³, R⁴ or R⁵, when adjacently positioned, may form methylenedioxy group, ethylenedioxy group or trimethylenedioxy group. Finally, ℓ and m are independently an integer of 1 or 2, and n is an integer of 1 to 3. Preferred compounds of the present invention are those of the formula (I) wherein: (i) R¹ is an alkyl group of 1-5 carbon atoms or a hydroxyalkyl of 1-3 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R³, taken together, represent an alkylene group of 4-6 carbon atoms; (ii) R³ and R⁴ are independently a hydrogen or halogen atom, or an alkyl or alkoxy group of 1-4 carbon atoms; and/or (iii) R⁵ is a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, or a trifluoromethyl group; or two of R⁵ adjacently positioned represent -O-(CH₂) p -O- group. More preferred compounds (I) of the present invention are those wherein: (iv) R¹ is an alkyl group of 1-5 carbon atoms, R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms, or R¹ and R², taken together, represent an alkylene group of 4-6 carbon atoms; (v) R³ and R⁴ are independently a hydrogen, fluorine, or chlorine atom, or an alkyl or alkoxy group of 1-3 carbon atoms; and/or (vi) R⁵ is a hydrogen or halogen atom, or an alkyl or alkoxyl group of 1-4 carbon atoms. Preferred compounds are also those derivatives wherein R³ is a hydrogen or chlorine atom or an alkyl group of 1 to 3 carbon atoms, R⁴ is a hydrogen atom and ℓ and m are an integer of 1. Most preferred compounds (I) are those in which ℓ, m, and n are 1. The following Table 1 shows illustrative examples of the compounds in the present invention, but their respective isomers as well as their mixture are included in the present invention. Production of the compounds of the present invention will be explained below. The compounds of the present invention can be prepared by any one of conventional methods. For example, the following synthetic process is illustrated. (wherein R¹, R², R³, R⁴, R⁵, ℓ , m and n have the same significance as defined above) The above process consists of reacting the starting material (V) with the compound (VI) in the presence or absence of a base catalyst with or without a solvent. The starting material (V) can be synthesized according to the process as described in Yakugaku Zasshi, 86 576 (1966). The reaction is generally carried out at temperature from 0 to 250°C, preferably from 20 to 200°C over a period of 10 minutes to 24 hours. Examples of the solvents, when used, are ethers such as tetrahydrofuran or dioxane, halogenohydrocarbons such as chloroform or methylene chloride, aromatic hydrocarbons such as benzene, toluene, xylene or chlorobenzene, amides such as dimethylformamide, dimethylacetamide or N-methylpyrrolidone, or dimethyl sulfoxide. The amount of the solvent may range from 0.1 to 100 parts by weight with respect to the compound (V). Examples of the catalysts, when used, are organic bases such as triethylamine, diisopropylamine, N,N-dimethylaniline or pyridine or inorganic bases such as sodium hydride, sodium hydrogen carbonate, sodium carbonate, potassium carbonate, sodium hydroxide or potassium hydroxide. The amount of the catalyst to be used may range between 0.5 and 5 mol, preferably 1 and 3 mol with respect to the compound (V). Appropriate amount of the compound (VI) to be used in the reaction is generally 0.5 to 30 mol, preferably 1 to 10 mol, with respect to the compound (V). After completion of the reaction, and after removal of the solvent if necessary, the reaction mixture may be poured into an excessive amount of water or dissolved in a solvent such as dichloromethane. Then it may be neutralized with an aqueous alkali solution and the product may be purified in a conventional manner such as recrystallization or chromatography. Physiologically acceptable salts of the compounds (I) are preferable as their salts. For example, there are exemplified an inorganic acid salt such as hydrochloride, hydroiodide, sulfate or phosphate, and an organic acid salt such as methanesulfonate, p-toluenesulfonate, benzenesulfonate, camphor sulfonate, acetate, benzoate, malate, lactate, glycolate, glucuronate, maleate, fumarate, succinate, ascorbate, citrate, salicylate, nicotinate or tartarate. Since the compounds (I) and their salts may exists in the form of hydrate or solvated product, these hydrate and solvated product may be included in the compounds of the present invention. When the compound of the present invention is applied clinically as a circulatory improving agent, appropriate single dosage for adult is 1 to 100 mg for oral administration, and it is given 1 to 3 times per day. For intravenous administration, 0.01 to 10 mg is an appropriate single dosage and it is given 2 to 5 times per day for adult. For rectal administration, 1 to 100 mg is preferred single dosage and it is applied 1 to 3 times per day for adult. Preferably, said dosage may be appropriately increased or reduced, depending upon age, pathology and symptoms of particular patient. Pharmaceutical formulation can be prepared by admixing at least one of the compounds (I) or pharmaceutically acceptable salts thereof with customarily usable pharmaceutical carriers, lubricants and other additives. The carrier may be solid or liquid. The solid carrier illustratively includes lactose, kaolin, sucrose, crystalline cellulose, corn starch, talc, agar, pectin, acacia, stearic acid, magnesium stearate, lecithin or sodium chloride. The liquid carrier illustratively includes syrup, glycerin, peanut oil, polyvinylpyrrolidone, olive oil, ethanol, benzyl alcohol, propylene glycol or water. The pharmaceutical formulation may take various types. When the solid carrier is used, tablets, powders, granules, hard gelatin capsules, suppositories, or troches may be formulated. Appropriate amount of the solid carrier may vary broadly, but it is preferably about 1 mg to about 1 g per single dosage. Syrups, emulsions, soft gelatin capsules, sterilized injections, or aqueous or non-aqueous suspensions may be prepared using liquid carrier. The following detailed examples are presented by way of illustration of certain specific embodiments of the invention. Example 1 Preparation of D-1-α-methylbenzylamino-4-phenylphthalazine (D-form of Compound No. 1 in Table 1): To 5 ml of N-methylpyrrolidone were added 5.0 g of 1-chloro-4-phenylphthalazine (Compound V) and 5.0 g of D-α-methylbenzylamine, and the resultant mixture was stirred with heating at 130 to 140°C for 3 hours. After finishing the reaction, the mixture was cooled, mixed with 20 ml of 5% aqueous sodium hydroxide and extracted with chloroform. The organic layer was separated and dried over magnesium sulfate, concentrated and purified on a silica gel column (eluent: ethyl acetate-n-hexane-chloroform). The product was recrystallized from ethyl acetate-n-hexane to give 3.31 g of D-1-α-methylbenzylamino-4-phenylphthalazine as colorless crystals. M.P. 184 to 185.5°C. Example 2 to 38 The compounds listed in the following Table 2 were prepared in the same manner as in Example 1. Example 39 Preparation of 1-α,α-dimethylbenzylamino-4-phenylphthalazine (Compound No. 119 in Table 1) To 4 ml of N-methylpyrrolidone were added 1.5 g of 1-chloro-4-phenylphthalazine and 2.1 g of α,α-dimethylbenzylamine, and the mixture was heated at 160°C for 6 hours with stirring. After completion of the reaction, the reaction mixture was cooled, and extracted with chloroform with addition of 5% NaOH aqueous solution. The organic layer was separated, dried over MgSO₄, concentrated, and purified by silica gel chromatography. The resultant product was recrystallized using chloroform and ether to obtain 1-α,α-dimethylbenzylamino-4-phenylphthalazine as colorless crystals. M.P. 234-235°C Examples 40-42 The compounds listed in the following Table 3 were prepared in the same manner as in Example 39. Experiment 1 Platelet aggregation-inhibitory activity in vitro : Rat arterial blood was centrifuged to obtain platelet rich plasma. To 250 µl of said platelet rich plasma was added 5 µl of a solution of the test compound, and the mixture was incubated for 2 minutes, mixed with 3 µl of collagen (Hormon-Chemie) as a platelet aggregation-inducer, and the change of platelet aggregation was observed and recorded for 10 minutes with 2 channels aggregometer (Sienco DP 247E). Platelet aggregation inhibitory ratio was calculated by the following formula: Tc: Aggregation degree where only a solvent was added. Ts: Aggregation degree where a solution of the test compound was added. Table 4 shows the inhibitory ratio of the compounds tested at each of the mol concentrations indicated. Experiment 2 Platelet aggregation inhibitory activity in vivo (by oral administration): A group of 8 male Wistar ST rats each weighing about 250 grams were used. To the test animal was orally administered 4 ml/kg of a solution made by suspending a test compound in 1% aqueous tragacanth solution, and one hour later blood was collected from common carotid artery with a cannula. The blood was put in a plastic test tube in which 3.8% aqueous sodium citrate (1/10 volume) had been charged, and the mixture was stirred by overturning the tube, centrifuged by 200 x g for 15 minutes, and the supernatant was recovered as platelet rich plasma (PRP). The residue was further centrifuged by 2000 x g for 15 minutes and the supernatant was recovered as poor platelet plasma (PPP). The plasma samples were used for assaying the platelet aggregating ability. For assaying platelet aggregating ability, 2 channels aggregometer (Sienco DP 247E) was used, and the data were recorded on two pens recorder. As an aggregation inducer, 7 to 10 µg/ml of collagen (Hormon-Chemie) was used. Platelet Aggregation-inhibitory ratio was calculated by the following formula: A: Aggregating ratio of the group (control) in which only 1% aqueous tragacanth solution was administered. B: Aggregating ratio of the group in which a solution of the test compound in tragacanth solution was administered. Table 4 shows the test results. Experiment 3 Activity of the compounds (I) to rat left coronary artery ligation-induced cardiac infarction: A group of 8 male SD rats weighing 200 to 250 g were used. The rats were fixed at the dosal position under light ether paralysis, subjected to longitudinal incission in about 1.5 cm along the sternal left line to make thoractonomy under breaking the heart sac and exposing the heart. After ligating the left main coronary artery at 1 to 2 mm from the origin with black blade silk suture (Hama Ika Kogyo, 4-0), the heart was returned at the original position and the breast was closed immediately. The bilateral breast was pressed to exclude the air in the thoracic cavity to resume respiration. Electrocardiography (Nippon Koden, ECG-6601) showed ST elevation of II induction. Twenty-four hours after ligation, the blood was collected from the ventral vena cava, and the rat was killed by complete bleeding. The heart was taken out, and the cross circular slice (about 2 mm) at the central part of the heart was incubated at 37°C in the dark for 20 minutes in 20 ml of 1% solution of TTC (tryphenyl tetrazolium chloride, Wako Junyaku) in 0.09 M phosphate buffer (pH 8.6). The slice was photographed under a stereoscopic microscope, and the colored slides were prepared therefrom. The slides were projected on the wall, and the sections, the infarction parts (TTC non-dyed part) and non-infarction parts (TTC dyed part), were traced. So, the area of the infarction part in the total section area was calculated. A solution made by suspending the test compound in 1% aqueous tragacanth solution was orally administered 60 minutes prior to the coronary artery ligation. A: Infarction ratio where only 1% tragacanth solution was administered for control. B: Infarction ratio where the tragacanth solution containing the test compound was administered. Table 5 shows the test results. Since the compounds of the present invention inhibit remarkably platelet aggregation not only in vitro but in vivo by oral administration, these compounds are useful as a prophylactic or therapeutic agent for various circulatory disorders. Further, these compounds can reduce the cardiac infarction nest by direct action without being based on platelet aggregation inhibitory activity. Accordingly, the compounds are highly useful for treating ischemic heart diseases.

Claims: 4-Phenylphthalazine derivatives of the formula (I): wherein R¹ is an alkyl or hydroxyalkyl group of 1-5 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R², when taken together, may represent an alkylene group of 2-6 carbon atoms, said group optionally containing one or more oxygen atoms; R³ and R⁴ are independently a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, or when two of R³ are adjacently positioned, (R³) ℓ may represent a -O-(CH₂) p -O- group and/or when two of R⁴ are adjacently positioned, (R⁴) m may represent a -O-(CH₂) p -O- group; R⁵ is a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, a trifluoromethyl group or a hydroxy group, or when two of R⁵ are adjacently positioned, (R⁵) n may represent a -O-(CH₂) p -O- group; p is an integer of 1-3; ℓ and m are independently an integer of 1-2; and n is an integer of 1-3, and optical isomers and pharmaceutically acceptable acid addition salts thereof. The derivatives according to Claim 1 wherein R³ and R⁴ are independently a hydrogen or halogen atom, or an alkyl or alkoxy group of 1-4 carbon atoms. The derivatives according to Claim 2 wherein R³ and R⁴ are independently a hydrogen, fluorine, or chlorine atom, or an alkyl or alkoxy group of 1-3 carbon atoms. The derivatives according to Claim 3 wherein ℓ and m are an integer of 1. The derivatives according to Claim 4 wherein R³ and R⁴ are independently a hydrogen or chlorine atom, or an alkyl group of 1-3 carbon atoms. The derivatives according to Claim 5 wherein R³ is a hydrogen or chlorine atom or an alkyl group of 1-3 carbon atoms; and R⁴ is a hydrogen atom. The derivatives according to Claim 6 wherein R¹ is an alkyl group of 1-5 carbon atoms or a hydroxyalkyl group of 1-3 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R², taken together, represent an alkylene group of 4-6 carbon atoms. The derivatives according to Claim 7, wherein R¹ is an alkyl group of 1-5 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R², taken together, represent an alkylene group of 4-6 carbon atoms. The derivatives according to Claim 8 wherein R⁵ is a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, or a trifluoromethyl group; or when two of R⁵ are adjacently positioned, (R⁵) n may represent a -O-(CH₂) p -O- group. The derivatives according to Claim 9 wherein R⁵ is a hydrogen or halogen atom, or an alkyl or alkoxy group of 1-4 carbon atoms. The derivatives according to Claim 10 wherein n is an integer of 1. A pharmaceutical composition which comprises one of the derivatives according to Claim 1 together with a pharmaceutically acceptable carrier therefor. A pharmaceutical composition according to Claim 12 which is useful as a platelet aggregation inhibitory agent. A process for preparing the 4-phenylphthalazine derivative as defined in Claim 1, or an optical isomer or pharmaceutically acceptable acid addition salt thereof, which process is characterized in that a compound of the formula (V): wherein R³ and R⁴ are independently a hydrogen or halogen atom, or an alkyl or alkoxy group of 1-4 carbon atoms, or when two of R³ are adjacently positioned, (R³) ℓ may represent a -O-(CH₂) p -O- group and/or when two of R⁴ are adjacently positioned, (R⁴) m may represent a -O-(CH₂) p -O-group; p is an integer of 1-3; ℓ and m are independently an integer of 1-2, is allowed to react with 0.5-30 mole amount of a compound of the formula (VI): wherein R¹ is an alkyl or hydroxyalkyl group of 1-5 carbon atoms; R² is a hydrogen atom or an alkyl group of 1-5 carbon atoms; or R¹ and R², when taken together, may represent an alkylene group of 2-6 carbon atoms, said group optionally containing one or more oxygen atoms; R⁵ is a hydrogen or halogen atom, an alkyl or alkoxy group of 1-4 carbon atoms, a trifluoromethyl group or a hydroxy group, or when two of R⁵ are adjacently positioned, (R⁵) n may represent a -O-(CH₂) p -O- group; n is an integer of 1-3; p is as defined above, at temperature of 0-250°C for a period of time between 10 minutes and 24 hours in the presence or absence of a solvent and a basic catalyst. The use of 4-phenylphthalazine derivatives according to claim 1 for the preparation of a pharmaceutical composition. The use according to claim 15 wherein the pharmaceutical composition is useful as a platelet aggregation inhibitory agent.

Inventors: IWASE NORIMICHI, KANAYAMA TOSHIJI, MORINAKA YASUHIRO, TAMAO YOSHIKUNI, IWASE, NORIMICHI, KANAYAMA, TOSHIJI, MORINAKA, YASUHIRO, TAMAO, YOSHIKUNI
Applicants: MITSUBISHI CHEM IND, MITSUBISHI KASEI CORPORATION
Application year: 1991
Main classification: C07D237
IPC codes: C07D237