OXINDOL COMPOUNDS, COMPOSITIONS CONTAINING SAME AND PROCESSES FOR PREPARING SAME

Abstract: An oxindol compound of the formula (I) wherein A represents a lower alkylene group; R represents a hydrogen atom, a lower alkyl group, a phenyl-lower alkyl group, a phenoxy-lower alkyl group, a benzoyl-lower alkyl group, a lower alkoxycarbonyl group, a lower alkanoyl group, a benzoyl group which may be sub­ stituted with 1 to 3 of a lower alkyl group, a lower alkoxy group and a halogen atom on the benzene ring thereof, or a benzoyl group which is substituted with a lower alkylene-­ dioxy group on the benzene ring thereof; and m and n, which may be the same or different, each rep­ resents an integer of 0 or 1, with proviso that n is an integer of 1, then m is an integer of 1, when A is an ethylene group and m is an integer of 1, then R should not be 3,4,5-trimethoxybenzoyl group, and when A is a group of the formula: -C(R¹) (R²) - (where R¹ and R² are, the same or different, a hydrogen atom or a lower alkyl group) and m is an integer of 1, then R should not be a hydrogen atom; or its pharmaceutically acceptable salt, composition containing the compound and processes for preparing the same are disclosed. The compound is useful as a cardiotonic agent.

Description: This invention relates to certain oxindol compounds and to pharmaceutically acceptable salts thereof which are useful as cardiotonic agents, processes for preparing the same, and pharmaceutical compositions containing the oxindol compounds or salt thereof. Various oxindol compounds are known which have hypotensive, blood platelet coagulation inhibitory, anti-inflammatory or anti-ischemic activity as described in Japanese Patent Publication (examined) No. 40539/1983, U. S. Patent No. 3462450, Austrian Patent Application No. 10443/72 and Swiss Patent Application No. 8483/77. However, the oxindol compounds of this invention are structurally different from the conventional oxindol compounds. One object of this invention is to provide oxindol compounds having a cardiotonic activity. Another object of this invention is to provide a pharmaceutical composition containing the oxindol compound in a cardiotonically effective amount. A further object of this invention is to provide a process for preparing the oxindol compound and its pharmaceutically acceptable salts thereof. As a result of extensive research this invention has been accomplished which, in one aspect, provides an oxindol compound of the formula (I): or its pharmaceutically acceptable salt, wherein A represents a C₁-C₆ alkylene group; R represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group, a benzoyl-C₁-C₆ alkyl group, a C₁-C₆ alkoxycarbonyl group, a benzoyl group which may be substituted wish 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof; and m and n, which may be the same or different, each represents 0 or 1, with proviso that when A is an ethylene group and m is 1, then R should not be 3,4,5 trimethoxybenzoyl group, when n is 0, and m is 0, then R should not be a benzoyl group which is substituted with a C₁-C₆ alkyl group, and when n is 1 and m is 1, then R should not be a benzoyl group which is substituted with a C₁-C₆ alkoxy group. In another aspect, this invention provides a cardiotonic composition containing a compound of the formula (I) or a pharmaceutically acceptable salt thereof in a cardiotonically effective amount. In a further aspect, this invention provides processes for preparing the compounds of the formula (I) and pharmaceutically acceptable salts thereof. The compounds of the formula (I) above and pharmaceutically acceptable salts thereof have heart muscle contraction stimulating effect or positive inotropic effect and coronary blood flow increasing activity, and are useful as a cardiotonic agent for treating heart diseases such as congestive heart failure and the like. They are advantageous in that they do not or only slightly, if any, increase heart beats. As to the object compound of the formula (I), the following point is to be noted. That is, the "oxindol" moiety in the object compound of the formula (I) can be alternatively represented by its tautomer i.e. "2-hydroxyindole", and both of said moieties are in the state of tautomeric equilibrium as represented by the following scheme. This tautomerism has been well known in the arts, and it is obvious to a person skilled in the arts that both of the tautomeric isomers are equilibrated and lie in the reciprocally convertible state. In the present specification, however, the object compound of the invention including the group of such tautomeric isomers is represented by one of the expressions, i.e. "oxindol" and the formula: only for the convenient sake. The term "C₁-C₆"-alkylene" as used herein refers to a straight or branched chain alkylene group having 1 to 6 carbon atoms such as a methylene group, an ethylene group, a propylene group, a trimethylene group, a 2-methyltrimethylene group, a 2,2-dimethyltrimethylene group, a 1-methyltrimethylene group, a methylmethylene group, an ethylmethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group and the like. The term "C₁-C₆-alkyl" as used herein refers to a straight or branched chain alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tertbutyl group, a pentyl group and a hexyl group. The term "phenoxy-C₁-C₆- alkyl" as used herein refers to a phenoxy-lower alkyl group having a straight or branched chain alkyl group having 1 to 6 carbon atoms in the alkyl moiety such as a phenoxymethyl group, a 1-phenoxyethyl group, a 2-phenoxyethyl group, a 1-phenoxypropyl group, a 2-phenoxypropyl group, a 3-phenoxypropyl group, a 2-methyl-3-phenoxypropyl group, a 4-phenoxybutyl group, a 5-phenoxypentyl group, a 6-phenoxyhexyl group and the like. The term "benzoyl-C₁-C₆ alkyl" as used herein refers to a benzoyl-C₁-C₆ alkyl group having a straight or branched chain alkyl group having 1 to 6 carbon atoms in the alkyl moiety such as a benzoylmethyl group, a 1-benzolylethyl group, a 2-benzoylethyl group, a 1-benzoylpropyl group, a 3-benzoylpropyl group, a 4-benzoylbutyl group, a 5-benzoylpentyl group, a 6-benzoylhexyl group, a 1,1-dimethylbenzoylethyl group, a 2-methylbenzoylpropyl group and the like. The term "C₁-C₆ alkoxycarbonyl" as used herein refers to a straight or branched chain alkoxycarbonyl group having 1 to 6 carbon atoms in the alkoxy moiety such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a butoxycarbonyl group, a tert-butoxycarbonyl group, a pentyloxycarbonyl group, a hexyloxycarbonyl group and the like. The term "benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof" as used herein refers to a benzoyl group which may be substituted with 1 to 3 of a straight or branched chain alkyl group having 1 to 6 carbon atoms, a straight or branched chain alkoxy group havin 1 to 6 carbon atoms such as a benzoyl group, a 2-methylbenzoyl group, a 3-methylbenzoyl group, a 4-methylbenzoyl group, a 2-ethylbenzoyl group, a 3-ethylbenzoyl group, a 4-ethylbenzoyl group, a 3-isopropylbenzoyl group, a 4-hexylbenzoyl group, a 3,4-dimethylbenzoyl group, a 2,5-dimethylbenzoyl group, a 3,4,5-trimethylbenzoyl group, a 2-methoxybenzoyl group, a 3-methoxybenzoyl group, a 4-methoxybenzoyl group, a 2-ethoxybenzoyl group, a 3-ethoxybenzoyl group, a 4-ethoxybenzoyl group, a 4-isopropoxybenzoyl group, a 4-hexyloxybenzoyl group, a 3,4-dimethoxybenzoyl group, a 3,4-diethoxybenzoyl group, a 3,4,5-trimethoxybenzoyl group and a 2,5-dimethoxybenzoyl group. The compounds of this invention of the formula (I) can be prepared by various alternative procedures. A preferred example thereof is a process according to Reaction Scheme-1 below. Reaction Scheme-1 In the above formulae, X represents a halogen, atom, a C₁-C₆ alkanesulfonyloxy group, an arylsulfonyloxy group, an aralkylsulfonyloxy group or a hydroxy group; and R, A, m and n have the same meanings as defined above. In the formula (III), examples of the halogen atom represented by X include chlorine, fluorine, bromine and iodine; examples of the C₁-C₆ alkanesulfonyloxy group represented by X include a methanesulfonyloxy group, an ethanesulfonyloxy group, an isopropanesulfonyloxy group, a propanesulfonyloxy group, a butanesulfonyloxy group, a tert-butanesulfonyloxy group, a pentanesulfonyloxy group and a hexanesulfonyloxy group; examples of the arylsulfonyloxy group represented by X include a substituted or unsubstiuted arylsulfonyloxy group such as a phenylsulfonyloxy group, a 4-methylphenylsulfonyloxy group, a 2-methylphenylsulfonyloxy group, a 4-nitro phenylsulfonyloxy group, a 4-methoxyphenylsulfonyloxy group, a 3-chlorophenylsulfonyloxy group and a 1-naphthylsulfonyloxy group; and examples of the aralkylsulfonyloxy group represented by X include a substituted or unsubstituted aralkylsufonyloxy group such as a benzylsulfonyloxy group, a 2-phenylethylsulfonyloxy group, a 4-phenylbutylsulfonyloxy group, a 4-methylbenzylsulfonyloxy group, a 2-methylbenzylsulfonyloxy group, a 2-nitrobenzylsulfonyloxy group, a 4-methoxybenzylsulfonyloxy group, a 3-chlorobenzylsulfonyloxy group and a 1-naphthylmethylsulfonyloxy group. In the case where, of the compounds of the formula (III), those in which X represents a halogen atom, a C₁-C₆ alkanesulfonyloxy group, an arylsulfonyloxy group, or an aralkylsulfonyloxy group are used as a starting material, the reaction between the known compound of the formula (II) and the known compound of the formula (III) can be carried out generally in a suitable inert solvent in the presence or absence of a basic condensing agent. Examples of the suitable inert solvent which can be used include aromatic hydrocarbons such as benzene, toluene, xylene and the like, lower alcohols such as methanol, ethanol, isopropyl alcohol, butanol and the like, acetic acid, ethyl acetate, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoric triamide and the like. Examples of the basic condensing agent include carbonates such as sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate and the like, metal hydroxides such as sodium hydroxide, potassium hydroxide and the like, metal alcoholates such as sodium methylate, sodium ethylate and the like, tertiary amines such as pyridine, triethylamine and the like. In the above reaction, the proportion of the compound of the formula (III) to the compound of the formula (II) is not particularly limited, and can be varied broadly. Usually the reaction is carried out using at least an equimolar amount, and preferably from 1 to 5 mols, of the compound of the formula (III) per mol of the compound of the formula (II). The reaction can be carried out usually at about 40 to 120°C, preferably 50 to 100°C, and completed generally in about 5 to 30 hours. On the other hand, in the case where, of the compounds of the formula (III), that in which x represents a hydroxy group is used as a starting material, the reaction between the compound of the formula (II) and the compound of the formula (III) can be carried out in the presence of a dehydrating-condensing agent without solvents or in a suitable solvent. Examples of the dehydrating-condensing agent include condensed phosphoric acids such as polyphosphoric acid and the like, phosphoric acids such as orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid and the like, phosphorus acids such as orthophosphorus acid and the like, phosphoric anhydrides such as phosphorus pentoxide and the like, inorganic acids such as hydrochloric acid, sulfuric acid, boric acid and the like, metal phosphates such as sodium phosphate, boron phosphate, ferric phosphate, aluminum phosphate and the like, activated alumina, sodium hydrogensulfate, Raney nickel and the like. As for the solvent, high boiling point solvents such as dimethylformamide, tetralin and the like can be used. In the above reaction, the proportion of the compound of the formula (III) to the compound of the formula (II) is not particularly limited, and can be varied broadly. Usually, the reaction is carried out using at least an equimolar amount, and preferably 1 to 2 mols, of the compound of the formula (III) per mol of the compound of the formula (II). The amount of the dehydrating-condensing agent is not particularly limited, and can be varied broadly. Usually, at least a catalytic amount, preferably 0.5 to 5 mols, of the dehydrating-condensing agent per mol of the compound of the formula (II) is used. Preferably, the above reaction is carried out in a stream of an inert gas such as carbon dioxide, nitrogen in order to prevent oxidation reaction which is undesirable. The reaction can be carried out either at atmospheric pressure or under pressure. Preferably, the reaction is carried out at atmospheric pressure. The reaction can proceed advantageously usually at about 100 to 350°C, preferably 125 to 255°C and completed generally in about 3 to 10 hours. It should be noted that the compound of the formula (III) can be used in form of its salt. Of the compound of the formula (I), those in which R represents a C₁-C₆ alkoxycarbonyl group, a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof; and A, m and n have the same meanings as defined above, can be prepared according to the Reaction Schema-2 below. Reaction Scheme-2 In the above formulae, R' represents a C₁-C₆ alkoxycarbonyl group, a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or alkoxygroup on the benzene ring thereof. X¹ represents a hydroxy group; and A, m and n have the same meanings as defined above. The process shown in Reaction Scheme-2 above is a reaction between an oxindol derivative of the formula (Ia) and a carboxylic acid of the formula (IV) using a conventional amido formation reaction. The process can readily be achieved with applying conditions for known amido formation reaction. Representative examples of the processes include: (a) Mixed Acid Anhydride Process The compound of the formula (IV) is reacted with an alkyl haloformate to form mixed acid anhydride thereof which is then reacted with an amine of the formula (Ia). (b) Activated Ester Process The carboxylic acid compound of the formula (IV) is converted into a reactive ester such as a p-nitrophenyl ester, an N-hydroxy-succinimide ester or a 1-hydroxybenzotriazole ester, which is then reacted with an amine of the formula (Ia). (c) Carbodiimide Process The carboxylic acid compound of the formula (IV) and an amine of the formula (Ia) are condensed in the presence of an activating agent such as dicyclohexylcarbodiimide or carbonyldiimidazole. (d) Other Process The carboxylic acid compound of the formula (IV) is converted into an acid anhydride using a dehydrating agent such as acetic anhydride, followed by reacting the product with an amine of the formula (Ia); process in which the lower alcohol ester of the carboxylic acid compound of the formula (IV) is reacted with an amine of the formula (Ia) at a high temperature under pressurized conditions; the carboxylic acid compound of the formula (IV) is converted into an acid halide using a halogenating agent followed by reacting the product with an amine of the formula (Ia); or the carboxylic acid compound of the formula (IV) is converted into its activated form using phosphorus compounds such as triphenylphosphine, diethylchlorophosphate and the like followed by reacting the product with an amine of the formula (Ia). In the mixed acid anhydride process, the mixed acid anhydrides can be prepared in accordance with conventional Schötten-Baumann reaction and subjected further to reaction with the amine of the formula (Ia) without isolation to give the compound of the formula (Ib). The Schötten-Baumann reaction can be carried out in the presence of a basic compound. As for the basic compound, any conventional basic compound conventionally used in Schötten-Baumann reaction can be used. Examples of suitable basic compounds include organic bases such as triethylamine, trimethylamine, pyridine, N,N-dimethylaniline, N-methylmorpholine, 4-dimethylaminopyridine, 1,5-diazabicyclo [4,3,0] nonene-5 (DBN), 1,8-diazabicyclo[5,4,0]undcene-7 (DBU), 1,4-diazabicyclo-[2,2,2]octane (DABCO) and the like, inorganic bases such a potassium carbonate, sodium carbonate, potassium hydrogencarbonate, sodium hydrogencarbonate and the like. The reaction can proceed at about -20 to 100°C, preferably 0 to 50°C and continued for about 5 minutes to 10 hours, preferably 5 minutes to 2 hours. The reaction between the mixed acid anhydride and the amine of the formula (Ia) can proceed at about -20 to 150°C, preferably 10 to 50°C for about 5 minutes to 10 hours, preferably 5 minutes to 5 hours. The mixed acid anhydride process can proceed in the absence or presence of a solvent. As for the solvent any solvent used conventionally in the mixed acid anhydride processes can be used. Examples of suitable solvents include halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane and the like, aromatic hydrocarbons such as benzene, toluene or xylene, ethers such as diethyl ether, tetrahydrofuran or dimethoxyethane and the like, esters such as methyl acetate or ethyl acetate, and aprotic polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide or hexamethylphosphoric triamide. Examples of suitable alkyl haloformate which can be used in the mixed acid anhydride process include methyl chloroformate, methyl bromoformate, ethyl chloroformate, ethyl bromoformate and isobutyl chloroformate. In the above reaction, the alkyl haloformate and the carboxylic acid compound of the formula (IV) is used usually, at least about 1 mol, preferably 1 to 2 mols, relative to the amine of the formula (Ia). The activated ester process (b), when using N-hydroxysuccinimide ester for example, is carried out in a suitable solvent which does not influence the reaction. Examples of suitable solvents include halogenated hydrocarbons such as methylene chloride, chloroform and dichloroethane, aromatic hydrocarbons such as benzene, toluene, and xylene, ethers such as diethyl ether, tetrahydrofuran and dimethoxyethane, esters such as methyl acetate and ethyl acetate, aprotic polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide and hexamethylphosphoric triamide. The reaction is completed at temperatures of 0 to 150°C, preferably 10 to 100°C, in 5 to 30 hours. The N-hydroxysuccinimide ester is used at least 1 mol preferably 1 to 2 mols per mol of the amine of the formula (Ia). On the other hand, the reaction between the carboxylic acid halide and the amine of the formula (Ia) can be carried out in an appropriate solvent in the presence of a dehydrohalogenation agent. As for the dehydrohalogenation agent various known basic compounds can be used. For example, sodium hydroxide, potassium hydroxide, sodium hydride and potassium hydride, in addition to the basic compounds used in the above Schötten-Baumann reaction can be used. Examples of suitable solvents include, in addition to those used in the above Schötten-Baumann reaction, alcohols such as methanol, ethanol, propanol, butanol, 3-methoxy-1-butanol, ethyl cellosolve, methyl cellosolve and the like, pyridine, acetone, and acetonitrile. Proportion of the carboxylic acid halide to the amine of the formula (Ia) is not limited but can be varied widely. Usually, at least 1 mol, preferably 1 to 5 mols, of the carboxylic acid halide per mol of the amine of the formula (Ia) is used. The reaction can proceed usually at -30 to 180°C, preferably 0 to 150°C and completed generally in 5 minutes to 30 hours. The process in which a carboxylic acid of the formula (IV) activated with a phosphorus compound such as triphenylphosphine and diethylchlorophosphate is reacted with an amine of the formula (Ia) is carried out in a suitable solvent. Any solvent which does not influence the reaction can be used. Examples of suitable solvents include halogenated hydrocarbons such as methylene chloride, chloroform and dichloroethane, aromatic hydrocarbons such as benzene, toluene, and xylene, ethers such as diethyl ether, tetrahydrofuran, and dimethoxyethane, esters such as methyl acetate and ethyl acetate, and aprotic polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoric triamide. The reaction is preferably carried out in the presence of a base, for example, organic bases such as triethylamine, pyridine, dimethylaniline, N-methylmorpholine, DBN, DBU and DABCO, and inorgaic baes such as potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate. The reaction proceeds at temperatures from about 0 to 150°C, preferably from 0 to 100°C, for about 1 to 30 hours. The phosphorus compound is used usually at least one mol, preferably 1 to 3 mols per mol of the carboxylic acid of the formula (IV). Of the compounds of the formula (I), those in which R represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group or a benzoyl-C₁-C₆ alkyl group, and A, m and n have the same meanings as defined above, can be prepared according to Reaction Scheme-3 below. Reaction Scheme-3 In the above formulae, R" represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group or a benzoyl-C₁-C₆ alkyl group; X² represents a halogen atom, a lower alkanesulfonyloxy group, an arylsufonyloxy group or aralkylsulfonyloxy group; and A, m and n have the same meanings as defined above. The reaction between the compound of the formula (Ia) and the compound of the formula (V) can be carried out under conditions similar to those used in the reaction between the compound of the formula (Ia) and the carboxylic acid halide above. Of the compounds of the formula (I), those in which m is an integer of 1, n is an integer of 0, and R has the same meaning as defined above, can be prepared according to Reaction Scheme-4 below. Reaction Scheme-4 In the above formulae, R has the same meaning as defined above. The reaction between the compound of the formula (VI) and the compound of the formula (VII) can be carried out under conditions similar to those used in the reaction between the compound of the formula (Ia) and the carboxylic acid of the formula (IV) above. Of the compounds of the formula (I), those in which both of m and n are an integer of 1, and R and A have the same meanings as defined above, can be prepared according to Reaction Scheme-5 below. ` Reaction Scheme-5 In the above formulae, X³ represents a halogen atom; and R and A have the same meanings as defined above. The reaction between the compound of the formula (VIII) and the compound of the formula (VII) can be carried out under conditions similar to those used in the reaction between the compound of the formula (Ia) and the carboxylic acid halide above. The compound of the formula (VI) used in the preparation of a compound of the formula (Id) in the Reaction Scheme-4 detailed above is useful as an intermediate and has a cardiotonic activity per se and can be prepared, for example, by the processes shown in the following Reaction Scheme-6 or 7: Reaction Scheme-6 In the above formulae, X³ has the same meaning as defined above and R³ represents an aromatic amine group. A compound of the formula (XI) is obtained by the reaction of a compound of the formula (IX) and an aromatic amine (X) in the absence or presence of a suitable solvent. As for the solvent, any solvent that exerts no influence on the reaction can be used here. Examples of the suitable solvent include halogenated hydrocarbons such as methylene chloride and chloroform, dichloroethane, ethers such as diethyl ether, tetrahydrofuran and dimethoxyethane, esteres such as methyl acetate, and ethyl acetate, aprotic polar solvents such as N,N-dimethylformamide, dimethylsulfoxide and hexamethylphosphoric triamide. Examples of the aromatic amine include pyridine and quinoline. The aromatic amine is used at least equimolar, preferably in a great excess amount to the amount of the compound of the formula (IX). The reaction can proceed usually at about 50 to 200°C, preferably 70 to 150°C, and the reaction is completed generally in 1 to 10 hours. The hydrolysis of the compound of the formula (XI) obtained above can be carried out in water or an alcohol such as methanol, ethanol and the like, in the presence of an inorganic base such as sodium hydroxide, potassium hydroxide and the like or an acid such as hydrochloric acid, hydrobromic acid and the like, at room temperature to 150°C and the reaction is completed generally in 10 minutes to 10 hours. Reaction Scheme-7 In the above formulae, X³ has the same meaning as defined above. The reaction of a compound of the formula (XII) and a halogen is usually carried out in a solvent. Examples of the solvent include ethers such as tetrahydrofuran and dioxan carboxylic acids such as acetic acid and propionic acid aromatic hydrocarbons such as benzene, xylene, and toluene, dimethylformamide, dimethyl sulfoxide and the like. In the reaction, a deacidifying agent such as calcium carbonate may be added to remove the hydrogen halide produced as by-product. The proportion of a compound of the formula (XII) to the halogen is not particularly limited and can be varied broadly. Usually the reaction is carried out using 2 to 5 mols, preferably 2 to 3 mols, of the halogen per mol of the compound of the formula (XII). The reaction can be carried out usually at 0 to 50°C, and completed in several to 24 hours. The hydrolysis of the compound of the formula (XIII) into the compound of the formula (VI) is carried out preferably in water in the presence of a basic compound. Known basic compounds in wide range can be used. They are, for example, alkali metal hydroxides such as sodium hydroxide, and potassium hydroxide or alkaline earth metal hydroxides such as calcium hydroxide and the like. The amount of the basic compound to be used is not particularly limited and can be varied broadly. Preferably, from two mols to a great excess amount of the basic compound per mol of the compound of the formula (XIII) is used. The hydrolysis can be carried out usually at 50 to 150°C, preferably at 70 to 120°C, and completed generally in about 1 to 12 hours. The compound of the formula (VIII) used for the preparation of a compound of the formula (Ie) in the Reaction Scheme-5 includes partly novel compounds, and is prepared, for example, according to the process shown in the following Reaction Scheme-8. Reaction Scheme-8 In the above formulae, A and X³ have the same meanings as defined above. -` ` The reaction of oxindol of the formula (XIV) and a compound of the formula (XV) is generally called "Friedel-Crafts reaction", and usually carried out in a solvent in the presence of a Lewis acid. As for the solvent, any solvent to be commonly used in this reaction, for example, carbon bisulfide, nitrobenzene, chlorobenzene, dichloromethane, dichloroethane, trichloroethane and tetrachloroethane can be used. Any Lewis acid conventionally used can be used favarably; for example, aluminum chloride, zinc chloride, iron chloride, tin chloride, boron tribromide and concentrated sulfuric acid. The amount of the Lewis acid to be used is not particularly limited, and can be varied broadly. Usually, 2 to 6 mols, preferably 2 to 4 mols of the Lewis acid per mol of the oxindol of the formula (XIV) is used. The compound of the formula (XV) is usually used at least 1 mol, preferably 1 to 2 mols per mol of the oxindol of the formula (XIV). The reaction temperature can be selected appropriately, but usually 0 to 120°C, preferably 0 to 70°C is used. The reaction time cannot be absolutely mentioned being dependent on the raw materials, catalyst and reaction temperature but usually the reaction is completed in 0.5 to 6 hours. A compound used in the invention of which R is a hydrogen atom can be obtained from a compound of which R is a phenyl-lower alkyl group or a lower alkanoyl group by dephenyl(lower)alkylation or de(lower)alkanoylation, respectively. The dephenyl(lower)alkylation can be carried out under the conditions of ordinary de-N-phenyl(lower)alkylation reaction. The reaction can be carried out in a suitable solvent in the presence of a reduction catalyst such as palladium-carbon, and palladium black, at 0°C to room temperature, in about 0.5 to 3 hours. The solvent to be used is, for example, water, lower alcohols such as methanol, ethanol, isopropanol and the like, ethers such as dioxane and tetrahydrofuran acetic acid and the like. The de(lower)alkanoylation reaction is carried out in a similar manner to the ordinary hydrolysis, for example, in water or an alcohol such as methanol and ethanol in the presence of an inorganic base such as sodium hydroxide and potassium hydroxide or an acid such as hydrochloric acid, and hydrobromic acid. The dephenyl(lower)alkylation can be also carried out under similar conditions to those of the de(lower)alkanoylation mentioned above. The invention comprises as intermediate products an oxindol compound of the formula: or its pharmaceutically acceptable salt; wherein A represents a C₁-C₆ alkylene group; B represents a hydroxy group or a halogen atom; and n represents 0 or 1; provided that when n is 1 and A represents a group of the formula: Wherein R¹ and R² are the some or different, each represent hydrogen atom or C₁-C₂ alkyl group, B should not be halogen atom. The compounds of this invention represented by the formula (I) prepared as described above can form pharmaceutically acceptable salts with acids and this invention also includes within its scope such pharmaceutically acceptable salts. The pharmaceutically acceptable acids which can be used for the salt formation can be various inorganic acids, for example, hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, organic acids such as oxalic acid, maleic acid, fumaric acid, malic acid, tartaric acid, citric acid and benzoic acid, The compounds of the formula (VI) can be converted into a pharmaceutically acceptable base addition salt by reacting the acid group with a pharmaceutically acceptable basic compound. Examples of the basic compounds are inorganic basic compounds such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate and potassium hydrogencarbonate. The compounds of the formula (I) and the salts thereof obtained as described above can be isolated from the respective reaction mixtures upon completion of the reaction and purified by conventional procedures, for example, solvent extraction, dilution method, precipitation, recrystallization, column chromatography and preparative thin layer chromatography. As is apparent to those skilled in the art, the compounds of the formula (I) can exist in optically active forms and this invention includes such optical isomers within its scope. In using the compounds of this invention of the formula (I) and the salts thereof as therapeutic agents, these compounds can be formulated into pharmaceutical compositions together with ordinary pharmaceutically acceptable carriers. Suitable carriers which can be used are, for example, solvents, wetting agents, disintegrants, surface active agents and lubricants which are usually employed to prepare such drugs depending on the type of dosage form. Various dosage forms of the therapeutic agents as a cardiotonic agent can be selected according to the purpose of the therapy. Typical dosage forms which can be used are tablets, pills, powders, liquid preparations, suspensions, emulsions, granules, capsules, suppositories, and injectable preparations (solutions, suspensions and the like). In molding a pharmaceutical composition containing the compounds of the formula (I) or the pharmaceutically acceptable salt thereof as an active ingredient into a tablet form, a wide range of carriers known in the art can be used. Examples of suitable carriers include excipients such as lactose, white sugar, sodium chloride, glucose solution, urea, starch, calcium carbonate, kaolin, crystalline cellulose and silicic acid, binders such as water, ethanol, propanol, simple syrup, glucose, starch solution, gelatin solution, carboxymethyl cellulose, shellac, methyl cellulose, potassium phosphate and polyvinyl pyrrolidone, disintegrants such as dired starch, sodium alginate, agar powder, laminaria powder, sodium hydrogencarbonate, calcium carbonate, Tween, sodium laurylsulfate, stearic acid monoglyceride, starch, and lactose, disintegration inhibitors such as white sugar, stearic acid glyceryl ester, cacao butter and hydrogenated oils, adsorption promotors such as quaternary ammonium bases and sodium laurylsulfate, humectants such as glycerol and starch, adsorbents such as starch, lactose, kaolin, bentonite and colloidal silicic acid, and lubricants such as purified talc, stearic acid salts, boric acid powder, Macrogol (trade name for a polyethylene glycol produced by Shinetsu Chemical Industry Co., Ltd.) and solid polyethylene glycol. The tablets, if desired, can be coated, and made into sugar-coated tablets, gelatin-coated tablets, enteric-coated tablets, film-coated tablets, or tablets comprising two or more layers. In molding the pharmaceutical composition into pills, a wide variety of conventional carriers known in the art can be used. Examples of suitable carriers are excipients such as glucose, lactose, starch, cacao butter, hardened vegetable oils, kaolin and talc, binders such as gum arabic powder, tragacanth powder, gelatin, and ethanol, and disintegrants such as laminaria and agar. In molding the pharmaceutical composition into a suppository form, a wide variety of carriers known in the art can be used. Examples of suitable carriers include polyethylene glycol, cacao butter, higher alcohols, esters of higher alcohols, gelatin, and semisynthetic glycerides. When the pharmaceutical composition is formulated into an injectable preparation, the resulting solution and suspension are preferably sterilized, and are isotonic with respect to the blood. In formulating the pharmaceutical composition into the form of a solution or suspension, all diluents customarily used in the art can be used. Examples of suitable diluents are water, ethyl alcohol, propylene glycol, ethoxylated isostearyl alcohol, polyoxyethylene sorbitol, and sorbitan esters. Sodium chloride, glucose or glycerol may be incorporated into a cardiotonic agent, in an amount sufficient to prepare isotonic solutions. The cardiotonic agent may further contain ordinary dissolving aids, buffers, painalleviating agents, and preservatives, and optionally coloring agents, perfumes, flavors, sweeteners, and other drugs. The amount of the compound of the formula (I) and the pharmaceutically acceptable salts thereof of this invention as an active ingredient to be incorporated into a pharmaceutical composition useful as a cardiotonic agent is not particularly limited, and can vary over a wide range. A suitable therapeutically effective amount of the compound of the general formula (I) and the pharmaceutically acceptable salts thereof of this invention is usually about 1 to about 70% by weight, preferably 1 to 30% by weight, based on the entire composition. The administration method of the cardiotonic agent according to the invention is not particularly limited and can be adequately selected according to the form of the preparation, age and sex of the patient, and symptom of disease. For example, the tablets, pills, liquid preparations, suspensions, emulsions, granules, and capsules are orally administered. The injectable preparations are intravenously adminstered either alone or together with ordinary auxiliary agents such as glucose and amino acids. Furthermore, as required, the cardiotonic agent can be singly adminstered intramuscularly, intracutaneously, subcutaneously, or intraperitoneally. The suppository is administered intrarectally. The dosage of the cardiotonic agent is suitably selected according to the purpose of use, the symptoms and the like. Usually, a preferred dosage of the compound of this invention is about 0.1 to 10 mg/kg weight per day. It is advantageous that the active ingredient is contained in a single unit dose form in an amount of 1 to 200 mg. Hereinafter, this invention will be described in greater detail with reference to Reference Examples, Examples and Preparation Examples. Reference Example 1 5-Chloroacetyloxindol (45g) was added to 180ml of pyridine and the mixture was stirred at 80°C for an hour. After completion of reaction, the mixture was allowed to cool and crystals which precipitated were collected by filtration and washed with acetone. The crystals were then recrystallized from methanol to give 5-α-pyridinumacetyloxindolchloride. The compound was added to 600 ml of water containing 12.7 g of sodium hydroxide and stirred at 70-80°C for 30 minutes. After completion of reaction, the resultant solution was allowed to cool down and acidified with concentrated hydrochloric acid. Crystals which precipitated were collected by filtration and washed with water. The crystals were then recrystallized from a mixture of dimethylformamide (DMF) and water to give 28 g of 5-carboxyoxindol. m.p.: >300°C Colorless powdery crystal Elemental analyses for C₉H₇O₃N Reference Example 2 α-Chloroacetyl chloride (47.4g) and 80.0g of finely-ground anhydrous aluminum chloride were suspended in 100 ml of carbon bisulfide under ice-cooling. Oxindol (26.6g) was added thereto with vigorous stirring and the mixture was refluxed for about 3 hours. Then the solvent was removed under reduced pressure, and the residue was poured into 1ℓ of ice-water and allowed to cool for a while. Crystals which precipitated were collected by filtration, washed successively with water, methanol, and diethyl ether , and dried to give 15g of 5-(α-chloroacetyl)oxindol. m.p.: 246.5-247.0°C Example 1 A mixture of 5-aminooxindol (14g), 29g of bis(ß-bromoethyl)amine·hydrobromide in 250 ml of ethanol was stirred under reflux for 8 hours and allowed to stand overnight at room temperature. To the mixture was added sodium carbonate (10.1g) and the mixture was stirred further for 8 hours under reflux. After cooling to room temperature, crystals which precipitated were collected by filtration and recrystallized from a mixture of water and ethanol to give 16g of 5-(1-piperazinyl)oxindol·hydrobromide. (Not claimed) Pale yellow powdery crystal NMR (200MHz, DMSO-d₆) δ : 3.30 (8H, s), 3.47 (2H, s), 6.78 (1N, d, J=8 . 5Hz), 6.90 (1N, dd, J=8 . 5Hz, 2Hz), 7.04 (1N, d, J=2Hz), 8.88 (2H, brs), 10.27 (1N, s) Mass. M + : 217 In an analogous manner as Example 1, the compounds shown in Table 1 were prepared using appropriate starting materials. Example 6 5-(1-Piperazinyl)oxindol·hydrobromide (2.0g) was suspended in 30 ml of N,N-dimethylformamide (DMF), and 2.3 ml of triethylamine was added thereto subsequently. The mixture was cooled to 0 to 5°C. To the mixture was added dropwise 5 ml of DMF solution containing 1.5g of 3,4-dimethoxybenzoyl chloride at the same temperature as above with stirring. After completion of addition, the mixture was stirred at room temperature for one hour. The reaction mixture was poured into a large amount of water and extracted with chloroform. After washing with water, the extract was dried over anhydrous sodium sulfate and chloroform was removed by distillation. The residue was purified by silica-gel column chromatography (eluent: chloroform: methanol = 100:1) and recrystallized from methanol to give 1.5g of 5-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]oxindol. m.p.: 197-199°C Yellow powdery crystal Example 7 In an analogous manner as Example 6, the same compounds as those obtained in Examples 3 to 5 were prepared using appropriate starting materials. Example 8 A mixture of 5-aminooxindol·hydrobromide (3.8g), 5.9g of N,N(di-2-hydroxyethyl)-3,4-dimethoxybenzamide and 8.6g of 85% phosphoric acid was stirred at 165 to 175°C for 4.5 hours and allowed to cool to room temperature. To the reaction mixture was added 50 ml of water. The resultant mixture was neutralized with 48% aqueous sodium hydroxide solution and extracted with chloroform. After drying over potassium carbonate, chloroform was evaporated. The residue was recrystallized from methanol to give 4.1g of 5-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]oxindol. m.p.: 197-199°C Yellow powdery crystal. Example 9 In an analogous manner as Example 8, the same compounds as those obtained in Examples 2 and 3 to 5 above were prepared using appropriate starting materials. Example 10 3,4-Dimethoxybenzoic acid (2.6g) and 1.65g of 1,8-diazabicyclo[5,4,0]undecene-7 were added to 100 ml of DMF and to the mixture was added dropwise 1.5 ml of isobutyl chloroformate with ice-cooling externally with stirring. After completion of addition, the mixture was stirred for 30 minutes. To the mixture was added 40 ml of DMF solution containing 2.16g of 5-(1-piperazinyl)oxindol and the mixture was stirred at room temperature for 5 hours. After completion of reaction, the solvent was removed by distillation. The residue was extracted with 300 ml of chloroform and the extract was washed with a diluted aqueous solution of sodium hydrogencarbonate, water, diluted hydrochloric acid and water, successively. Chloroform was removed by distillation and the residue was recrystallized from methanol to give 1.6g of 5-[4(3,4-dimethoxybenzoyl)-1-piperazinyl]oxindol. m.p.: 197-199°C Yellow powdery crystal Example 11 In an analogous manner as Example 10, the same compounds as those obtained in Examples 3 to 5 were prepared using appropriate starting materials. Example 12 To a solution of 0.88g of 5-carboxyoxindol in 10 ml of DMF was added under ice-cooling 0.82 ml of triethylamine, and 0.77 ml of isobutyl chloroformate was added thereto subsequently. The mixture was stirred at the same temperature for 1 hour. Then, 1.1g of 1-benzylpiperazine was added thereto, and the mixture was stirred at room temperature overnight. After the reaction was completed, DMF was removed under reduced pressure, and to the residue was added an aqueous sodium hydrogencarbonate solution and extracted with chloroform. After washing with water and drying over magnesium sulfate, chloroform was distilled off under reduced pressure. The resultant residue was purified by silica-gel column chromatography (eluent: methylene chloride: methanol = 50:1) and recrystallized from isopropyl alcohol to give 0.7g of 5-(4-benzyl-1-piperazinylcarbonyl)oxindol. (Not claimed) m.p.: 151-153°C Colorless prisms In an analogous manner as Example 12, the compounds shown in Table 2 were prepared using appropriate starting materials. Example 18 A mixture of 0.8g of ß-chloropropiophenone, 1.0g of sodium iodide and 20 ml of acetone was refluxed for 1 hour. After the solvent was distilled off, to the residue were added 10 ml of DMF, 10g of 5-(1-piperazinylcarbonyl)oxindol hydrochloride, and 1.5 ml of triethylamine, and the mixture was reacted at room temperature for 3 hours. After completion of reaction, DMF was distilled off under reduced pressure, and the residue was washed with water. The resultant residue was purified by silica-gel column chromatography (eluent: dichloromethane: methanol = 100:5). By recrystallization from a mixture of methanol and dichloromethane, 0.4g of 5-[4-(2-benzoylethyl)-1-piperazinylcarbonyl]oxindol was obtained. m.p.: 208-210°C Colorless prisms Example 19 5-(1-Piperazinylcarbonyl)oxindol hydrochloride (1.0g), 1.2g of DBU, and 0.73g of isobutyl bromide were suspended in 15 ml of acetonitrile and the suspension was reflexed for 6 hours. To the mixture were then added 0.6 ml of triethylamine and 0.73g of isobutyl bromide and the mixture was further reflexed for 8 hours. The reaction mixture was poured into a saturated aqueous solution of sodium hydrogencarbonate and extracted with chloroform. The chloroform layer was washed with a saturated saline solution and dried over sodium sulfate. The residue obtained after the solvent was distilled off was purified by silica-gel column chromatography (eluent: dichloromethane: methanol = 20:1). The product was converted into the hydrochloride with acetone and hydrochloricacid, and recrystallized from a mixture of ethanol and methanol to give 0.39g of 5-(4-isobutyl-1-piperazinylcarbonyl)oxindol hydrochloride. m.p.: 285-289°C (decomposed) Colorless needles Example 20 In an analogous manner as Examples 18 or 19, the same compounds as those obtained in Examples 15 and 17 were prepared using appropriate starting materials. Example 21 5-(α-Chloroacetyl)oxindol (1.0g), 1.2g of 3,4-dimethoxybenzoyl-1-piperazine, and 0.8 ml of triethylamine were suspended in 10 ml of acetonitrile, and the suspension was stirred at room temperature ford 17 hours. Insoluble matters were filtered off. The filtrate was concentrated, added to a saturated aqueous solution of sodium hydrogencarbonate, and extracted with chloroform. The chloroform layer was washed with water and saturated saline solution, in turn, dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified by silica-gel column chromatography (eluent: chloroform: methanol = 20:1). It was converted into the hydrochloride with methanol and conc. hydrochloric acid. Recrystallization from a mixture of ethanol and methanol gave 0.34g of 5-[2-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]acetyl]-oxindol hydrochloride. m.p.: 218-221°C (decomposed) Pale yellow needles In an analogous manner as Example 21, the compound shown in Table 3 was prepared using appropriate starting material. Example 23 To a suspension comprising 1.0g of dihydrochloric acid salt of 5-[2-(1-piperazinyl)acetyl]oxindol, 0.63g of potassium carbonate, 5 ml of water and 10 ml of acetone was added dropwise a solution of 0.63g of m-chlorobenzoyl chloride in 2 ml of acetone under ice-cooling with stirring, and the mixture was stirred for 1.5 hours at the same temperature. After completion of reaction, the reaction mixture was poured into ice-water and extracted with chloroform. The chloroform layer was washed, in turn, with water and a saturated saline solution, and dried over sodium sulfate. The solvent was then distilled off under reduced pressure. The resultant residue was purified by silica-gel column chromatography (eluent: chloroform: methanol = 20:1) and recrystallized from a mixture of ethanol and chloroform to give 0.34g of 5-[2-[4-(3-chlorobenzoyl)-1-piperazinyl]acetyl]oxindol. (Not claimed) m.p.: 215-218°C (decomposed) Pale yellow prisms Example 24 In an analogous manner as Example 23, the same compounds as those obtained in Examples 21 and 22 were prepared using appropriate starting materials. Example 25 5-[2-(4-Benzyl-1-piperazinyl)acetyl]oxindol (11g) and 1g of 10% Pd-C were suspended in a mixed solvent of 100 ml ethanol and 5 ml water and the suspension was subjected to hydrogenolysis under atmospheric pressure at room temperature. After completion of reaction, the catalyst was filtered off and the filtrate was concentrated. The resultant residue was converted into its hydrochloride according to a conventional manner and recrystallized from a mixture of methanol and water to give 4.0g of 5-[2-(1-piperazinyl)acetyl]-oxindol dihydrochloride. Colorless prisms m.p.: 232-235°C Example 26 To a solution of 3.2g of benzoic acid and 4 ml of triethylamine in 50 ml of DMF was added dropwise a solution of 3.87g of isobutyl chloroformate in 2 ml of DMF. After stirring the mixture for 30 minutes at room temperature, a solution of 8.8g of 5-(1-piperazinylcarbonyl)oxindol in 3 ml of DMF was added dropwise thereto, and the mixture was stirred for 30 minutes at room temperature and then for 1 hour at 50 to 60°C. The reaction mixture was poured into a large amount of a saturated saline solution, extracted with chloroform, washed with water and dried. The solvent was distilled off, and the residue was recrystallized from methanol to give 1.9g of 5-(4-benzoyl-1-piperazinylcarbonyl)oxindol. m.p. 268-270°C Colorless prisms In an analogous manner as Example 26, the same compounds as those obtained in Examples 13, 21, 22 and 23 were prepared using appropriate starting materials. Example 27 To 100 ml of ethanol were added 1.36g of ethyl benzoate, 0.5g of sodium ethylate and 2.6g of 5-(piperazinylcarbonyl)oxindol hydrochloride and the mixture was reacted in an autocrave at 140 to 150°C under 110 atm for 6 hours. After cooling, the reaction mixture was concentrated under reduced pressure and the residue was dissolved in 200 ml of chloroform. After washing, in turn, with 1% aqueous potassium carbonate solution, dilute hydrochloric acid, and water, the chloroform solution was dried over anhydrous sodium sulfate and the solvent was distilled off. The resultant residue was purified by silica-gel column chromatography [silica-gel: WAKO C-200, eluent: chloroform: methanol (V/V) = 20:1], and the crude crystal was recrystallized from methanol to give 215 mg of 5-(4-benzoyl-1-piperazinylcarbonyl)oxindol. m.p.: 268-270°C Colorless prisms In an analogous manner as Example 27, the same compounds as those obtained in Examples 13, 21, 22 and 23 were prepared using appropriate starting materials. Example 28 To a mixed solvent of 20 ml of dioxane and 20 ml of methylene chloride were added 1.2g of benzoic acid and 3.0g of 5-(1-piperazinylcarbonyl)oxindol hydrochloride. To this mixture, a solution of 2.1g of N,N-dicyclohexylcarbodiimide dissolved in 5 ml of methylene chloride was added dropwise at 10 to 20°C under ice-cooling externally with stirring. Then, the mixture was stirred for 3.5 hours at the same temperature. Crystals which precipitated were filtered off, and the filtrate was concentrated to dryness under reduced pressure. The resultant residue was dissolved in 100 ml of methylene chloride, and the organic layer was washed, in turn, with 5% aqueous hydrochloric acid solution, 5% aqueous sodium hydrogen carbonate solution, and water, and dried over anhydrous sodium sulfate. Under reduced pressure, the solvent was distilled off and the residue was recrystallized from methanol to give 0.79g of 5-(4-benzoyl-1-piperazinylcarbonyl)oxindol. m.p.: 268-270°C Colorless prisms In an analogous manner as Example 28, the same compounds as those obtained in Examples 13, 21, 22 and 23 were prepared using appropriate starting materials. Pharmacological Tests Pharmacological activity of the compounds of this invention was determined as described below. Isolated Blood-Perfused Papillary Muscle Preparations Experiments were carried out on adult mongrel dogs of either sex. The papillary muscle preparations were obtained from dogs weighing 8-13 kg, anesthetized with pentobarbital sodium (30 mg/kg i.v.), given heparin sodium (1000 U/kg i.v.) and exsanguinated. The preparation was essentially the anterior papillary muscle excised together with the ventricular septum and was set up in cold Tyrode's solution. The preparation was placed in a glass water jacket maintained at about 38°C and cross-circulated through the cannulated anterior septal artery with blood from a donor dog at a constant pressure of 0,133bar (100 mmHg). Dogs used as donors were 18-27 kg in body weight and were anesthetized with pentobarbital sodium (30 mg/kg i.v.). Heparin sodium was given at a dose of 1000 U/kg i.v. The papillary muscle was driven with rectangular pulse about 1.5 times the threshold voltage (0.5-3 V) and 5 msec duration at a fixed rate of 120 beats/min. through bipolar pacing electrodes. Tension developed by the papillary muscle was measured with a strain-guage transducer. The muscle was loaded with a weight of about 1.5 g. Blood flow through the anterior septal artery was measured by an electromagnetic flow meter. Recording of developed tension and blood flow was made on charts with an ink-writing rectigraph. Details of the preparation have been described by Endoh and Hashimoto (Am. J. Physiol. 218, 1459-1463, 1970). The compounds in volumes of 10-30 µl were injected intraarterially in 4 sec. The inotropic effects of the compounds are expressed as a percentage of the developed tension before the injection of the compounds. The effects of the compounds on blood flow are expressed as difference (ml/min.) between the values before and after the injection of the compounds. The results obtained are shown in Table 4 below. Test compounds 1. 5-(4-(3,4-Dimethoxybenzoyl)-1-piperazinyl]oxindol 2. 5-[4-(4-Ethoxybenzoyl)-1-piperazinyl]oxindol 3. 5-(4-Ethoxycarbonyl-1-piperazinyl)oxindol 4. 5-(4-Isobutyl-1-piprazinylcarbonyl)oxindol hydrochloride 5. 5-[4-(2-Phenoxyethyl)-1-piperazinylcarbonyl]oxindol 6. 5-[2[4-(4-Methylbenzoyl)-1-piperazinyl]acetyl]-oxindol 1/4 hydrate Tablets each having the above composition were prepared in a conventional manner. Tablets each having the above composition were prepared in a conventional manner. The above parabens, sodium metabisulfite and sodium chloride were dissolved in the distilled water at 80°C while stirring. The resulting solution was cooled to 40°C and the compound of the invention, polyethylene glycol and polyoxyethylene sorbitan monooleate were dissolved therein. Then, distilled water for injection was added to adjust the volume to final one. The mixture was filtered using a suitable filter paper to sterilize and then filled in an ampoule of 1 ml, thus forming preparation for injection. Tablets each having the above composition were prepared in a conventional manner. Tablets each having the above composition were prepared in a conventional manner. Tablets each having the above composition were prepared in a conventional manner. The above parabens, sodium metabisulfite and sodium chloride were dissolved in the distilled water at 80°C while stirring. The resulting solution was cooled to 40°C and the compound of the invention polyethylene glycol and polyoxyethylene sorbitan monooleate were dissolved therein. Then, distilled water for injection was added to adjust the volume to final one. The mixture was filtered using a suitable filter paper to sterilize and then filled in an ampoule of 1 ml, thus forming preparation for injection. Tablets each having the above composition were prepared in a conventional manner.

Claims: An oxindol compound of the formula(I): or its pharmaceutically acceptable salt, wherein A represents a C₁-C₆ alkylene group; R represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group, a benzoyl-C₁-C₆ alkyl group, a C₁-C₆ alkoxycarbonyl group, a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof; and m and n, which may be the same or different, each represents 0 or 1, with proviso that when A is an ethylene group and m is 1, then R should not be 3,4,5-trimethoxybenzoyl group, when n is 0, and m is 0, then R should not be a benzoyl group which is substituted with a C₁-C₆ alkyl group, and when n is 1 and m is 1, then R should not be a benzoyl group which is substituted with a C₁-C₆ alkoxy group. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 1, wherein n is 0. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 2, wherein m is 1. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 3, wherein R represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group, a benzoyl-C₁-C₆ alkyl group or a C₁-C₆ alkoxycarbonyl group. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 3, wherein R represents a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 4, wherein R represents a benzoyl-C₁-C₆ alkyl group. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 2, wherein m is 0. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 7, wherein R represents a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof. An oxindol compound our its pharmaceutically acceptable salt as claimed in claim 7, wherein R represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group, a benzoyl-C₁-C₆ alkyl group or a C₁-C₆ alkoxycarbonyl group. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 8, wherein R represents a benzoyl group which is substituted with 1 to 3 of a C₁-C₆ alkoxy group on the benzene ring thereof. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 10, wherein R represents a benzoyl group which is substituted with 1 to 3 of a methoxy group. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 1, wherein n is 1. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 12, wherein R represents a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof. An oxindol compound or its pharmaceutically acceptable salt as claimed in claim 12, wherein R represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group, a benzoyl-C₁-C₆ alkyl group or a C₁-C₆ alkoxycarbonyl group. 5-[4-(2-Benzoylethyl)-1-piperazinyl-carbonyl]oxindol. 5-[4-(2-Phenoxyethyl)-1-piperazinyl-carbonyl]oxindol. 5-[4-(3,4-Dimethoxybenzoyl)-1-piperazinyl]-oxindol. 5-[4-(4-Ethoxybenzoyl)-1-piperazinyl]-oxindol. 5-(4-Ethoxycarbonyl-1-piperazinyl)oxindol. An oxindol compound of the formula: or its pharmaceutically acceptable salt; wherein A represents a C₁-C₆ alkylene group; B represents a hydroxy group or a halogen atom; and n represents 0 or 1; provided that when n is 1 and A represents a group of the formula: wherein R¹ and R² are the same or different, each represent hydrogen atom or C₁-C₆ alkyl group, B should not be halogen atom: A process for preparing an oxindol compound of the formula (I) of claim 1 or its pharmaceutically acceptable salt, which comprises, a) reacting a compound of the formula (II): with a compound of the formula (III): to provide a compound of the formula (I): or its pharmaceutically acceptable salt, in the above formulae, x represents a halogen atom, a C₁-C₆ alkanesulfonyloxy group, an arylsulfonyloxy group, an aralkylsulfonyloxy group or a hydroxy group, and A, A, m and n have the same meanings as defined above, or b) reacting a compound of the formula (Ia): with a compound of the formula (IV): to provide a compound of the formula (Ib): or its pharmaeutically acceptable salt, in the above formulae, R' represents a C₁-C₆ alkoxycarbonyl group, a benzoyl group which may be substituted with 1 to 3 of a C₁-C₆ alkyl group or a C₁-C₆ alkoxy group on the benzene ring thereof; X¹ represents a hydroxy group; and A, m and n have the same meanings as defined above, c) reacting a compound of the formula (Ia): with a compound of the formula (V): to provide a compound of the formula (Ic): or its pharmaceutically acceptable salt, in the above formulae, R" represents a C₁-C₆ alkyl group, a phenoxy-C₁-C₆ alkyl group or a benzoyl-C₁-C₆ alkyl group, x² represents a halogen atom, a C₁-C₆ alkanesulfonyloxy group; an arylsulfonyloxy group or an aralkylsulfonyloxy group, and A, m and n have the same meanings as defined above, or d) reacting a compound of the formula (VI): with a compound of the formula (VII): to provide a compound of the formula (Id): or its pharmaceutically acceptable salt, in the above formulae, R has the same meaning as defined above, or e) reacting a compound of the formula (VIII): with a compound of the formula (VII): to provide a compound of the formula (Ie): or its pharmaceutically acceptable salt, in the above formulae, x³ represents a halogen atom, and R and A have the same meanings as defined above. A pharmaceutical composition comprising a therapeutically effective amount of the compound of the formula (I) of claim 1 or its pharmaceutically acceptable salt, and a pharmaceutically acceptable carrier. The use of a compound of the formula (I) of claim 1 or its pharmaceutically acceptable salt for the preparation of a pharmaceutical composition for treatment of heart disease.

Inventors: FUJIOKA, TAKAFUMI, NAKAGAWA, KAZUYUKI, OGAWA, HIDENORI, TOMINAGA, MICHIAKI
Applicants: OTSUKA PHARMACEUTICAL CO., LTD.
Application year: 1985
Main classification: C07D209
IPC codes: C07D209, C07D405