Thienopyridine Derivatives, their production and use

Abstract: Thienopyridine derivatives of the formula (I): wherein the ring A is an optionally substituted benzene ring; the ring B is an optionally substituted thiophene ring: X is a group of the formula: (wherein R¹ is hydrogen, alkyl or alkoxy; and n is 0 or 1) or a group of the formula: (wherein R² is hydrogen or alkyl); Y is a single bond, -NH-, alkylene having 1 or 2 carbon atoms or -CH=CH-; and R³ is an optionally substituted hydrocarbon group, or their salts are disclosed. They show strong ACAT inhibitory activities.

Description: FIELD OF THE INVENTION The present invention relates to thienopyridine derivatives having excellent acyl-CoA: cholesterol acyltransferase (ACAT) inhibitory activity. BACKGROUND OF THE INVENTION EP-A-0 368 258 discloses tetrahydropyridine derivatives having the formula wherein R₁ represents an unsubstituted or substituted saturated cyclic alkyl group; R₂ and R₃ each represents a halogen atom, an unsubstituted or substituted alkyl group, an unsubstituted or substituted aryl group, an unsubstituted or substituted alkenyl group, an unsubstituted or substituted acyl group or an unsubstituted or substituted arylcarbonyl group; and m and n each represents an integer of from 0 to 4; with the proviso that when m and n are 2 or more, said R₂s each may be the same or different or acid-addition salts thereof. It is further mentioned that said compounds act on the central nervous system of mammals and are useful as psychotropic drugs having psychoanaleptic effects, antianxiety effects and learning improvement effects. Howerer, among thienopyridine derivatives, compounds having phenyl group at the 4-position with respect to the nitrogen atom of the pyridine, and a nitrogen atom bound at the 3-position have not been known heretofore in the prior art and it has never been studied whether they are useful as a medicine for arteriosclerosis or a blood cholesterol lowering agent, or not. OBJECTS OF THE INVENTION The main object of the present invention is to provide novel thienopyridine derivatives which have excellent acyl-CoA: cholesterol acyltransferase inhibitory activity to inhibit absorption of cholesterol from the intestinal tract and accumulation of cholesterol at an arterial wall in mammal and are, therefore, useful as a medicine for preventing or treating hypercholesterolemia, atherosclerosis and various diseases caused therefrom (e.g., ischemic heart diseases such as cardiac infarction and the like, and cerebrovascular diseases such as cerebral infarction, cerebral paralysis and the like). Further, the present invention provides an industrially advantageous process for the production of the novel thienopyridine derivatives as well as a pharmaceutical composition containing the novel thienopyridine derivatives. SUMMARY OR THE INVENTION The present inventors have intensively studied thienopyridine derivatives. As a result, it has been found that thienopyridine derivatives of the formula (I): wherein the ring A is benzene or benzene having 1 to 4 substituents selected from the group consisting of halogen, optionally halogenated C₁₋₆ alkyl, optionally halogenated C₁₋₆ alkoxy, optionally halogenated C₁₋₆ alkylthio, C₁₋₃ acyloxy, hydroxy, di-C₁₋₆ alkylamino and mono-C₁₋₆ alkylamino; the ring B is thiophene or thiophene having 1 or 2 substituents selected from the group consisting of halogen, C₁₋₆ alkyl, C₃₋₆ cycloalkyl, nitro, amino and C₁₋₇ acylamino, or the adjacent carbon atoms on the ring B may bind to a group -(CH₂) q - (wherein q is an integer of 3 to 5) to form a 5 to 7 membered ring; X is a group of the formula: (wherein R¹ is hydrogen, C₁₋₆ alkyl or C₁₋₆ alkoxy; and n is 0 or 1) or a group of the formula: (wherein R² is hydrogen or C₁₋₆ alkyl); Y is a single bond, -NH-, alkylene having 1 or 2 carbon atoms or -CH=CH-; and R³ is C₁₋₈ alkyl, C₃₋₆ cycloalkyl, C₃₋₆ cycloalkyl-C₁₋₃ alkyl, C₆₋₁₀ aryl or C₇₋₁₆ aralkyl, which may have 1 to 5 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, C₁₋₄ alkylthio, hydroxyl, C₁₋₃ acyloxy and di-C₁₋₅ alkylamino, or their salts show strong ACAT inhibitory inhibitory activities, and they are useful as a blood cholesterol lowering agent and as a medicine for treating arteriosclerosis. Thus, the present invention has been completed. Namely, according to the present invention, there are provided: (1) a thienopyridine derivative of the formula (I) and a salt thereof; (2) a compound of the formula (II): wherein Q is C₁₋₄ alkoxy carbonyl carboxyl -NH₂ or -NCO, and the other symbols are as defined above, or a salt thereof; (3) a process for producing a thienopyridine derivative of the formula (V): or a salt thereof which comprises reacting a compound of the formula (III): or a salt thereof with a compound of the formula (IV): R³ - Q² or a salt thereof, wherein either one of Q¹ and Q² is -NH₂ and the other is -NCO, and the other symbols are as defined above; (4) a process for producing a thienopyridine derivative of the formula (VIII): wherein Y¹ is a single bond, an alkylene group having 1 or 2 carbon atoms or -CH=CH-, and the other symbols are as defined above, or a salt thereof which comprises reacting a compound of the formula (VI): wherein all the symbols are as defined above, or a salt thereof with a compound of the formula (VII): R³ - Y¹ - COOH wherein all the symbols are as defined above, or a reactive derivative thereof; (5) an acyl-CoA: cholesterol acyltransferase inhibitor comprising the thienopyridine derivative of the formula (I) or a salt thereof, and (6) a process for preparing the acyl-CoA : cholesterol acyl transferase inhibitor as defined in (5) above. DETAILED DESCRIPTION OF THE INVENTION In the above formulas, the ring A is benzene or benzene having 1 to 4 substituents selected from the group consisting of halogen, optionally halogenated C₁₋₆ alkyl, optionally halogenated C₁₋₆ alkoxy, optionally halogenated C₁₋₆ alkylthio, C₁₋₃ acyloxy, hydroxy, di-C₁₋₆ alkylamino and mono-C₁₋₆ alkylamino Examples of such C₁₋₃ acyloxy are formyloxy, acetox and propionyloxy. Examples of halogen as the substituent include fluorine, chlorine, bromine and iodine. The optionally halogenated C₁₋₆ alkyl group is a straight or branched chain alkyl having 1 to 6 carbon atoms. Such C₁₋₆ alkyl can be substituted with 2 to 5 halogen atoms as described above. For example, methyl, chloromethyl, difluoromethyl, trichloromethyl, trifluoromethyl, ethyl 2-bromoethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, propyl, 3,3,3-trifluoropropyl, isopropyl, 2-trifluoromethylethyl, butyl, 4,4,4-trifluorobutyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, 5,5,5-trifluoropentyl, 4-trifluoromethylbutyl, hexyl, 6,6,6-trifluorohexyl and 5-trifluoromethylpentyl are often used. As the optionally halogenated C₁₋₆ alkoxy and optionally halogenated C₁₋₆ alkylthio group, for example, there can be used those formed by binding the above C₁₋₆ alkyl or halogenated C₁₋₆ alkyl group with oxygen atom and sulfur atom, respectively. For example, optionally halogenated alkoxy such as methoxy, difluoromethoxy, trifluoromethoxy, ethoxy, 2,2,2-trifluoroethoxy, propoxy, isopropoxy, butoxy, 4,4,4-trifluorobutoxy, isobutoxy, sec-butoxy, pentoxy, hexyloxy, etc., and an optionally halogenated alkylthio such as methylthio, difluoromethylthio, trifluoromethylthio, ethylthio, propylthio, isopropylthio, butylthio, 4,4,4-trifluorobutylthio, pentylthio and hexylthio, are often used. As the di-C₁₋₆ alkylamino, there can be used, for example, dimethylamino, methyethylamino, diethylamino, methylpropylamino, ethylpropylamino and dipropylamino. As the mono-C₁₋₆ alkylamino, there can be used, for example, methylamino, ethylamino and propylamino. The ring A may be substituted at any position thereof. When two or more substituents are present, they may be the same or different and the number of the substituents may be 1 to 4. Preferred examples of the substituted ring A include a benzen ring substituted at 2-position with one substituent such as halogen atom (e.g., fluorine, chlorine), C₁₋₄ alkyl (e.g., methyl, ethyl), C₁₋₄ alkoxy (e.g., methoxy, ethoxy and C₁₋₄ alkylthio (e.g., methylthio). In the above formulas, the ring B is thiophene or thiophene having 1 or 2 substituents and its sulfur atom may be present at any position except for the positions for condensation with the condensed ring (i.e., the sulfur atom is not the bridgehead atom of the condensed ring). As the substituent, for example, there can be used halogen, C₁₋₆ alkyl, C₃₋₆ cycloalkyl, nitro,amino and acylamino or, the adjacent carbon atoms on the ring B may bind to a group of the formula -(CH₂) q - (q is an integer of 3 to 5) to form a 5 to 7 membered ring. As the halogen atom, there can be used fluorine, chlorine, bromine and iodine. The C₁₋₆ alkyl group is a straight or branched alkyl having 1 to 6 carbon atoms and, for example, there can be used methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl and hexyl. As the C₃₋₆ cycloalkyl group, for example, there can be used cyclopropyl, cyclopentyl and cyclohexyl. The C₁₋₇ acylamino group is a acylamino group having 1 to 7 carbon atoms and, for example, there can be used formylamino, acetylamino, propionylamino, butylylamino and benzoylamino. Such a substituent of the ring B may be the same or different. In the above formulas, R³ is a thienopyridine derivative according to claim 1, wherein R³ is C₁-₈ alkyl, C₃₋₆ cycloalkyl, C₃₋₆ cycloalkyl-C₁₋₃ alkyl, C₆₋₁₀ aryl or C₇₋₁₆ aralkyl, which may have 1 to 5 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, C₁₋₄ alkylthio, hydroxyl, C₁₋₃ acyloxy and di-C₁₋₅ alkylamino, the C₁₋₈ alkyl group represented by R³, is a straight or branched alkyl having 1 to 8 carbon atoms and, for example, there can be used methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl and octyl. As the C₃₋₆ cycloalkyl group, for example, there can be used cyclopropyl, cyclopentyl and cyclohexyl. As the C₃₋₆ cycloalkyl-C₁₋₃ alkyl group, for example, there can be used cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl and cyclohexylmethyl. As the C₆₋₁₀ aryl group represented by R³, for example, phenyl and naphthyl is preferred. As the C₇₋₁₆ aralkyl group represented by R³, for example, benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, diphenylmethyl is preferred. Further, these C₁₋₈ alkyl, C₃₋₆ cycloalkyl, C₃₋₆ cycloalkyl-C₁₋₃ alkyl, C₆₋₁₀ aryl and C₇₋₁₆ aralkyl groups represented by R³ may have 1 to 5 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, C₁₋₄ alkylthio, hydroxyl, C₁₋₃ acyloxy and di-C₁₋₅ alkylamino, which are the same or different. As the substituent, for example, that used in the above ring A is preferably used in addition to the substituents as described hereinafter. As the aryl group represented by R³, for example, phenyl group is preferred and the phenyl group may have 1 to 5 substituents such as halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, di-C₁₋₅ alkylamino, hydroxyl and C₁₋₃ acyloxy. Among them, those having 1 to 5 halogen atoms (e.g. fluorine, chlorine, bromine, iodine), particularly 1 to 5 chlorine or /and fluorine atoms are preferred. For example, 2,4-difluorophenyl is preferred. As the C₁₋₄ alkoxy group by which the phenyl group may be substituted, methyl, ethyl and isopropyl is preferably used. Particularly, as the alkyl substituted phenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2-methyl-6-ethylphenyl, 2-methyl-6-isopropylphenyl, 2-ethyl-6-isopropylphenyl, 2,6-diisopropylphenyl is preferred. As the C₁₋₄ alkoxy group by which the phenyl group may be substituted, methoxy, ethoxy and or the like is preferably used. As the di-C₁₋₅ alkylamino group by which the phenyl group may be substituted, dimethylamino, diethylamino, methylethylamino, dipropylamino is preferred. As the C₁₋₃ acyloxy group by which the phenyl group may be substituted, formyloxy, acetony, propionyloxy is preferred. Further, the phenyl group having the above C₁₋₄ alkyl or C₁₋₄ alkoxy group in combination with hydroxyl or C₁₋₃ acyloxy (e.g., formyloxy, acetoxy), for example, 4-acetoxy-3,5-dimethylphenyl, 4-hydroxy-3,5-dimethylphenyl, 4-acetoxy-3,5-dimethoxyphenyl and 4-hydroxy-3,5-dimethoxyphenyl is preferred as R³. As the C₇₋₁₆ aralkyl group represented by R³, benzyl, 1-phenylethyl are particularly preferred, and its benzene ring is preferably substituted with 1 to 5 substituents such as halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, di-C₁₋₅ alkylamino, hydroxyl, and C₁₋₃ acyloxy. As the halogen atom, fluorine and chlorine are particularly preferred. Among them, fluorine-substituted C₇₋₁₆ aralkyl group, particularly 2,4-difluorobenzyl group is preferred. As C₁₋₄ alkyl methyl, ethyl, isopropyl and tert-butyl is preferably used. As C₁₋₄ alkoxy methoxy and ethoxy is preferred. As di-C₁₋₅ alkylamino dimethylamino, diethylamino, methylethylamino and dipropylamino is preferred. As C₁₋₃ acyloxy formyloxy, acetoxy and propionyloxy is preferred. Benzyl having the C₁₋₄ alkyl or C₁₋₄ alkoxy in combination with hydroxyl or C₁₋₃ acyloxy (e.g., formyloxy, acetoxy), for example, 4-acetoxy-3,5-dimethylbenzyl, 4-hydroxy-3,5-dimethylbenzyl, 4-acetoxy-3,5-dimethoxybenzyl and 4-hydroxy-3,5-dimethoxybenzyl is particularly preferred as R³. In the above formulas, X is (wherein R¹ is hydrogen, C₁₋₆ alkyl or C₁₋₆ alkoxy; and n is 0 or 1) or (wherein R² is hydrogen or C₁₋₆ alkyl). The C₁₋₆ alkyl group represented by R¹ and R² is a straight or branched chain alkyl having 1 to 6 carbon atoms. For example, there can be used methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl and hexyl. The C₁₋₆ alkoxy group represented by R¹ is a straight or branched chain alkoxy having 1 to 6 carbon atoms. For example, there can be used methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, neopentyloxy and hexyloxy. Preferred examples of X include -N=CH-, In the above formulas, Y is a single bond, -NH-, alkylene having one or two carbon atoms or -CH=CH-. As the alkylene group having one or two carbon atoms, for example, there can be used -CH₂-, Preferred examples of Y include -NH-, -CH₂-, -CH₂CH₂- and -CH=CH-. The thienopyridine derivative represented by the formula (I) or a salt thereof can be produced, for example, according to the following processes. Firstly, the compound (III) or a salt thereof is reacted with the compound (IV) or a salt thereof to obtain the compound (V) corresponding to the compound (I) wherein Y is -NH- or a salt thereof. For example, the compound (V) or a salt thereof can be produced (1) by reacting a compound of the formula (IX): wherein the symbols are as defined above, with a compound of the formula (X): R₃ - NH₂ wherein the symbol is as defined above, or a salt thereof, or (2) by reacting a compound of the formula (VI) wherein the symbols are as defined above, or a salt thereof with a compound of the formula (XI): R³ - NCO wherein the symbols is as defined above, or a salt thereof. (3) The compound (VIII) corresponding to the compound (I) wherein Y is a single bond, alkylene having 1 or 2 carbon atoms or -CH=CH-, or a salt thereof can be produced by reacting the compound (VI) or a salt thereof with the compound (VII) or a reactive derivative thereof. (4) Further, the compound (I) wherein Y is -CH₂CH₂-, or a salt thereof can be produced by reducing the compound (I) wherein Y is -CH=CH-, or a salt thereof. Hereinafter, the above processes (1) to (4) are explained in detail. Process (1): In the case of reacting the compound (IX) with the compound (X) or a salt thereof (e.g., a salt with a mineral acid such as hydrochloric acid and sulfuric acid; a salt with an organic acid such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, oxalic acid, fumaric acid and malic acid), the reaction is normally conducted in a solvent. Any solvent can be used as the reaction solvent in so far as it does not interfer with the reaction. For example, ethers (e.g., ethyl ether, isopropyl ether, tetrahydrofuran, dioxane, dimethoxyethane), aromatic hydrocarbons (e.g., benzene, toluene, xylene), esters (e.g., methyl acetate, ethyl acetate), N,N-dimethylformamide and dimethylsulfoxide are preferably used. In the case of using the compound (X) in the form of a salt, the reaction significantly proceeds by desalting, if necessary. As the desalting agent, a tertiary amine such as trimethylamine, triethylamine and N-methylmorpholine or an aromatic amine such as pyridine, picoline and N,N-dimethylaniline is preferably used. The amount of the amine is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (X). The reaction temperature is normally -10 to 180°C, preferably 0 to 120°C. The reaction time is normally 15 minutes to 40 hours, preferably 30 minutes to 20 hours. The amount of the compound (X) or a salt thereof to be used is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (IX). Process (2): The reaction of the compound (VI) or a salt thereof (e.g., a salt with a mineral acid such as hydrochloric acid and sulfuric acid; a salt with an organic acid such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, oxalic acid, fumaric acid and malic acid) with the compound (XI) is conducted under the same conditions as those in the above process (1). In the case of using the compound (VI) in the form of a salt, the same desalting agent as that used in the process (1) can be used. The amount of the compound (XI) to be used is normally 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (VI). Process (3): In the case of reacting the compound (VI) or a salt thereof (e.g., a salt with a mineral acid such as hydrochloric acid and sulfuric acid; a salt with an organic acid such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, oxalic acid, fumaric acid and malic acid) with the compound (VII), it is normally preferred to use a suitable condensing agent, or to convert the compound (VII) once into a reactive derivative of its carboxyl group and then to react the derivative with the compound (VI) or a salt thereof. As such a condensing agent, for example, there can be used dicyclohexylcarbodimide (DCC), diethyl phosphorocyanidate (DEPC) and diphenylphosphoryl azide (DPPA). When using such a condensing agent, the reaction is preferably conducted in a solvent (e.g., tetrahydrofuran, dioxane, dimethoxyethane, ethyl acetate, benzene, toluene, N,N-dimethylformamide, dimethylsulfoxide). This reaction can be accelerated in the presence of a base and the reaction is conducted at -10 to 100°C, pereferably 0 to 60°C. The reaction time is normally 1 to 96 hours, preferably 1 to 72 hours. The amounts of the compound (VII) and the condensing agent are 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (VI) or a salt thereof, respectively. As the base, for example, there can be used alkylamines such as triethylamine and cyclic amines such as N-methylmorpholine and pyridine. The amount of the base to be used is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (VI) or a salt thereof. As the reactive derivative of the compound (VII), for example, there can be used an acid halide (e.g., chloride, bromide), an acid anhydride, a mixed acid anhydride (e.g., the anhydride with methylcarbonic acid, the anhydride with ethylcarbonic acid, the anhydride with isobutylcarbonic acid) and an active ester (e.g., the ester with hydroxysuccinimide, the ester with 1-hydroxybenzotriazole, the ester with N-hydroxy-5-norbornene-2,3-dicarboxyimide, the ester with p-nitrophenol, the ester with 8-oxyquinoline). Among them, an acid halide is particularly preferred. In the case of reacting the compound (VI) or a salt thereof with the reactive derivative of the compound (VII), the reaction is normally conducted in a solvent (e.g., chloroform, dichloromethane, ethyl ether, tetrahydrofuran, dioxane, dimethoxyethane, ethyl acetate, benzene, toluene, pyridine, N,N-dimethylformamide). The reaction can be accelerated in presence of a base. The reaction is normally conducted at -10 to 120°C, preferably 0 to 100°C. The reaction time is normally 1 to 48 hours, preferably 1 to 24 hours. The amount of the reactive derivative of the compound (VII) to be used is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (VI) or a salt thereof. As the base, for example, there can be used alkyl amines'such as triethylamine, cyclic amines such as N-methylmorpholine and pyridine, aromatic amines such as N,N-dimethylaniline and N,N-diethylaniline, alkali metal carbonates such as sodium carbonate and potassium carbonate and alkali metal bicarbonates such as sodium bicarbonate and potassium bicarbonate. The amount of the base to be used is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the compound (VI) or a salt thereof. Further, when a solvent which is immiscible with water is used in this reaction, water can be added to a reaction system to conduct the reaction in a two-phase system. Process (4): The compound (I) wherein Y is -CH=CH-, or a salt thereof can be reduced to convert it into the compound (I) wherein Y is -CH₂CH₂-, or a salt thereof. As a reducing agent to be used, there can be used a metal hydride, for example, lithium alminium hydride, sodium borohydride and lithium borohydride. The amount of the reducing agent is normally 0.5 to 5 molar equivalent, preferably 0.5 to 2 molar equivalent per 1 mole of the compound (I) [Y is -CH=CH-] or a salt thereof. The reaction is normally conducted in a solvent (e.g. methanol, ethanol, ethyl ether, tetrahydrofuran, dioxane). The reaction temperature is normally -5 to 120°C, preferably 0 to 100°C. The raction time is normally 30 minutes to 12 hours, preferably 30 minutes to 6 hours. This reduction reaction can also be conducted using a metal and an acid, or a metal and a base or alcohol, instead of using the above reducing agent. In the case of using zinc, tin and iron as the metal, an acid (e.g., hydrochloric acid, sulfuric acid, acetic acid) can be mainly used as a hydrogen supplying source. Further, in the case of using potassium, sodium and lithium as the metal, a base (e.g., ammonia, ethylamine, dimethylamine, ethylamine, diethylamine) as well as an alcohol (e.g., methanol, ethanol, propanol) can be used as a hydrogen supplying source. The amount of the * metal used in this reaction is 1 to 10 molar equivalent, preferably 1 to 5 molar equivalent per 1 mole of the compound (I) [Y is -CH=CH-], or a salt thereof. This reaction is normally conducted in a solvent (e.g., alcohols such as methanol, ethanol; ethers such as tetrahydrofuran, dioxane, dimethoxyethane). The above acid or base can also be utilized as the solvent. The reaction temperature is 0 to 120°C, preferably 0 to 80°C. The reaction time is normally 30 minutes to 12 hours, preferably 30 minutes to 6 hours. This reduction reaction can also be conducted by a catalytic reduction with a catalyst. As the catalyst, for example, there can be used palladium black, palladium carbon, platinum oxide, platinum black, Raney nickel and rhodium carbon. The reaction is normally conducted in a solvent (e.g., methanol, ethanol, isopropanol, tetrahydrofuran, dioxane, dimethoxyethane, formic acid, acetic acid, N,N-dimethylformamide). The reaction is normally conducted at a pressure of normal pressure to 20 atoms, preferably normal pressure to 5 atoms. The reaction temperature is 0 to 100°C, preferably 0 to 80°C. The reaction time is normally 30 minutes to 24 hours, preferably 30 minutes to 12 hours. When a C₁₋₆ alkoxy group is contained in the benzene ring of the compound (I) produced according to the above processes (1) to (4), or a salt thereof, if necessary, it can be converted into hydroxyl group, for example, by reacting it with boron tribromide. This reaction is normally conducted in a solvent (e.g., dichloromethane, chloroform, carbon tetrachloride, benzene, toluene) at -20 to 80°C, preferably 0 to 30°C. The amount of boron tribromide to be used is 1 to 10 molar equivalent, preferably 1 to 5 molar equivalent per one C₁₋₆ alkoxy group. The reaction time is normally 15 minutes to 24 hours, preferably 30 minutes to 12 hours. When a hydroxyl group is contained in the benzene ring of the compound (I) produced according to the above processes (1) to (4), or a salt thereof, if necessary, it can be converted into a C₁₋₆ alkoxy group or a C₁₋₃ acyloxy group by alkylation or acylation. The alkylation can be conducted by reaction with an alkylating agent such as a halide (e.g., chloride, bromide, iodide), sulfate or sulfonate (e.g., methane sulfonate, toluenesulfonate, benzenesulfonate) of an optionally substituted alkane, in a solvent (e.g., methanol, ethanol, propanol, dimethoxyethane, dioxane, tetrahydrofuran, acetone, N,N-dimethylformamide) in the presence of a base (e.g. an organic base such as trimethylamine, triethylamine, N-methylmorpholine, pyridine, picoline, N,N-dimethylaniline; an inorganic base such as potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide). The reaction temperature is normally -10 to 100°C, preferably 0 to 80°C. The amount of the alkylating agent to be used is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole of the starting phenolic derivative. The reaction time is normally 15 minutes to 24 hours, preferably 30 minutes to 12 hours. The acylation reaction is conducted by reaction with the desired carboxylic acid or a reactive derivative thereof. This reaction varies depending upon a kind of a particular acylating agent and a kind of a particular starting phenolic derivative, but the reaction is normally conducted in a solvent (e.g., benzene, toluene, ethyl ether, ethyl acetate, chloroform, dichloroethane, dioxane, tetrahydrofuran, N,N-dimethylformamide, pyridine). In order to accelerate the reaction, an appropriate base (e.g., sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium acetate, triethylamine, pyridine) can be added. As the reactive derivative of a carboxylic acid, there can be used an acid anhydride, a mixed acid anhydride or an acid halide (e.g., chloride, bromide). The amount of the acylating agent to be used is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent per 1 mole Of the starting phenolic derivative. The reaction temperature is normally 0 to 150°C, preferably 10 to 100°C. The reaction time is normally 15 minutes to 12 hours, preferably 30 minutes to 6 hours. When the compound (I) is obtained in the free form according to the above processes, for example, it can be converted into a salt with a mineral acid (e.g., hydrochloric acid, sulfuric acid, hydrobromic acid), an organic acids (e.g. methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, oxalic acid, fumaric acid, maleic acid, tartaric acid) according to a conventinal method. When the compound (I) is obtained in the form of a salt, it can be converted into the free form or other salts according to a conventional method. The desired compound (I) obtained according to the above processes, or a salt thereof can be purified and collected by conventional separation means (e.g. concentration, solvent extraction, column chromatography, recrystallization). The compounds (I) or pharmaceutically acceptable salts thereof have an excellent acyl-CoA: cholesterol acyltransferase (ACAT) inhibitory activity, and acute toxicity as well as toxicity due to continuous administration are low. It has been known that ACAT is an enzyme responsible for esterification of cholesterol with a higher fatty acid in cells and plays an important role in absorption of a cholesterol ester at the small intestine. Accordingly, a substance having ACAT inhibitory activity can inhibit adsorption of dietary cholesterol from the intestinal tract, depress increase in blood cholesterol level and intracellular accumulation of cholesterol ester at an arteriosclerotic lesion, as well as prevents evolution of atherosclerosis. Accordingly, the compounds (I) of the present invention having an excellent ACAT inhibitory activity, or salts thereof are useful as safe medicines for preventing and treating hypercholesterolemia, atherosclerosis and various diseases caused thereby (e.g. ischemic cardiopathy such as myocardial infarction; cerebrovascular disorder such as cerebral infarction and cerebral apoplexy) in mammal (e.g. mouse, rat, hamster, rabbit, cat, dog, horse, cattle, sheep, monkey, human). Among the compounds (I) or salts thereof, those having a lipid peroxidation inhibitory activity (antioxidant activity) are included. It has been known that peroxidation of lipid in the living body has significant relation to crises of arteriosclerosis as well as ischemic diseases in the cerebrovascular and cardiovascular systems. Accordingly, the compounds (I) having both ACAT inhibitory activity and antioxidation activity, or salts thereof are extremely useful as medicines because they can prevent and treat various angiopathy caused by blood cholesterol and peroxylipid. When the compounds of the formula (I) or pharmaceutically acceptable salts are used as the above medicines, they can be orally or parenterally administered in the form of powders, granules, tablets, capsules and injection preparations obtained by admixing with suitable pharmaceuticallly acceptable carriers, excepients and diluents. When they are used for depressing absorption of cholesterol, oral administration is preferred. The dose varies depending upon a kind of the compounds (I) or salts thereof, administration route, conditions of diseases and age of patients. For example, in the case of oral administration to an adult patient with hypercholesterolemia, a daily dose is 0.005 to 50 mg/kg body weight, preferably 0.05 to 10 mg/kg body weight, more preferably 0.2 to 4 mg/kg body weight and it is preferred that they are administered 1 to 3 times per day with the above daily dose. The starting compound (VI) or (IX) of the compound (I) of the present invention, or a salt thereof can be advantageously produced, for example, according to the processes as described below or modification thereof. wherein R 2' is a C₁₋₆ alkyl group, R⁴ is a C₁₋₄ alkyl group X' is Z is a leaving group, and the other symbols are as defined above; wherein R⁵ and R⁶ are the same or different and are C₁₋₄ alkyl, phenyl or benzyl, or R⁵ and R⁶ may bind each other and form together with the adjacent nitrogen atom a ring, and the other symbols are as defined above. wherein R 1' is hydrogen, or C₁₋₆ alkyl, R⁷ is C₁₋₄ alkyl, and the other symbols are as defined above. Process A: As the alkyl group represented by R 2' and R⁴, alkyl having 1 to 4 carbon atoms such as methyl, ethyl and isopropyl butyl is preferred. In the process A, the compound (XV) can be produced by reacting the aminobenzoylthiophene derivative (XII) with malonic acid diester (XVI), or by reacting the compound (XII) with the compound (XIII) and then dehydrating with a base to cyclize the resultant. In the case of producing the compound (XV) from the compounds (XII) and (XVI), the reaction is normally conducted by heating in the absence of a solvent. This reaction is preferably conducted in the presence of an amine such as piperidine, pyrrolidine, triethylamine, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO) or in the presence of potassium fluoride, cesium fluoride, tetrabutylammonium fluoride. The reaction temperature is normally 60 to 220°C, preferably 80 to 200°C. The reaction time is normally 30 minutes to 60 hours, preferably 1 to 24 hours. The amount of the compound (XVI) is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent based on the compound (XII). The reaction of the compound (XII) with the compound (XIII) is normally conducted in a solvent (e.g., ethers such as ethyl ether, tetrahydrofuran, dioxane, dimethoxyethane; aromatic hydrocarbons such as benzene, toluene, xylene; esters such as methyl acetate, ethyl acetate, halogenated hydrocarbons such as dichloromethane, chloroform; pyridine; and dimethylformamide), if necessary, in the presence of a base (e.g., triethylamine, pyridine potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate). In this reaction, a mixed solvent with water can be used, if necessary. The reaction temperature is normally -20 to 150°C, preferably -10 to 120°C. The reaction time is normally 10 minutes to 12 hours, preferably 20 minutes to 8 hours. The amount of the compound (XIII) is 1 to 5 molar equivalent, preferably 1 to 3 molar equivalent based on the compound (XII). The compound (XIV) formed by this reaction is cyclized by using a base to produce the compound (XV). This reaction is normally conducted in a solvent (e.g., benzene, toluene, xylene, tetrahydrofuran, dioxane, dimethoxyethane) in the presence of a base (e.g., potassium t-butoxide, sodium methoxide, sodium ethoxide, piperidine, pyrrolidine, triethylamine, DBN, DBU, DABCO). The reaction temperature is normally 0 to 200°C, preferably 20 to 170°C. The reaction time is normally 30 minutes to 12 hours, preferably 1 to 8 hours. The amount of the base to be used is 0,1 to 3 molar equivalent, preferably 0.1 to 2 molar equivalent based on the compound (XIV). If necessary, for accelerating the reaction, the reaction can also be conducted with removal of water formed in the reaction system by using a Dean-Stark apparatus. The N-alkyl compound (XIX) and/or O-alkyl compound (XX) are produced by reacting the compound (XV) with the compound (XVIII). This reaction is normally conducted in a solvent (e.g., alcohols such as methanol, ethanol; ethers such as tetrahydrofuran, dioxane, dimethoxyethane, ketones such as 2-butanone, dimethylformamide; and dimethylsulfoxide) in the presence of a base (e.g. sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium t-butoxide, sodium hydride, sodium amide, potassium carbonate, sodium carbonate, triethylamine, DBU). Normally, in this process, a mixture of the compounds (XIX) and (XX) is formed and, therefore, these compounds can be used by subjecting the mixture to recrystallization or chromatography to separate them. When suitably selecting a kind of the compound (XVII) and a solvent, or a reaction temperature, sometimes, one of them can be preferentially formed. The reaction temperature is normally -5 to 150°C, preferably 0 to 100°C. The reaction time is 30 minutes to 30 hours, preferably 1 to 15 hours. The amounts of the compound (XVIII) and the base to be used are 1 to 5 molar equivalent, preferably 1 to 2 molar equivalent based on the compound (XV), respectively. Then, the compounds (XV), (XIX) and (XX) are hydrolyzed to obtain the compounds (XVII), (XXI) and (XXII), respectively. This reaction can be normally conducted in a solvent (e.g., alcohols such as methanol, ethanol, propanol; ethers such as tetrahydrofuran, dioxane, dimethoxyethane; or a mixed solvent thereof) by using an alkali or alkaline earth metal hydroxide such as sodium hydroxide, potassium hydroxide and barium hydroxide. The reaction temperature is normally 0 to 120°C, preferably 15 to 100°C. The reaction time is 30 minutes to 36 hours, preferably 1 to 20 hours. Then, the carboxylic acids (XVII), (XXI) and (XXII) are converted into acid azides, respectively. Various methods have been known in literatures and any method can be applied to the compounds (XVII), (XXI) and (XXII). For example, by using diphenylphosphorylazide (DPPA) as the acid azides (XVII), (XXI) and (XXII) can be produced by using diphenylphosphorylazide (DPPA) as the azidating agent. This reaction can be normally conducted in an inert solvent (e.g., ethers such as ethyl ether, isopropyl ether, dimethoxyethane, tetrahydrofuran, dioxane; aromatic hydrocarbons such as benzene, toluene, xylene; esters such as methyl acetate, ethyl acetate, etc.; ketones such as acetone, 2-butanone; pyridine; and N,N-dimethylformamide. Further, the reaction can be conducted in the presence of a base (e.g., trimethylamine, triethylamine, N-methylmorpholine) to proceed the reaction. The reaction time is normally 5 minutes to 12 hours, preferably 10 minutes to 6 hours. The reaction temperature is normally -10 to 150°C, preferably -5 to 120°C. The amount of DPPA to be used is 1 to 3 molar equivalent, preferably 1 to 2 molar equivalent, based on the compound (XVII), (XXI) or (XXII). The acid azide formed can be isolated and purified by conventional means. However, the reaction mixture is normally heated as it is without isolation of the acid azide to convert it into the isocyanate compound (IX'). For this conversion reaction, it is preferred to use the same solvent as that used for azidation, and the reaction is normally conducted by heating to 20 to 200°C, preferably 30 to 150° C. The reaction time is normally 5 minutes to 10 hours, preferably 5 minutes to 6 hours. The compound (IX') thus obtained can be isolated by conventional means, or used for the production of the compound (I) without isolation thereof, or used as the starting material for the production of the compound (VI'). Namely, the compound (VI') can be obtained by hydrolyzing the compound (IX'). This hydrolysis reaction can be conducted by almost the same conditions as those for the conversion of the above compounds (XV), (XIX) and (XX) into the compounds (XVII), (XXI) and (XXII). Process B: As the C₁₋₄ alkyl group represented by R⁵ and R⁶ methyl, ethyl, propyl, isopropyl and butyl is preferred. R⁵ and R⁶ may bind each other and form together with the nitrogen atom a ring. Examples thereof include 5 to 7 membered rings such as a pyrrolidine ring, piperidine ring and homopiperidine ring. Further, such a ring may have additional one oxygen atom and examples thereof include morpholine ring. The compound (XXV) is produced by the reaction of the compound (XII) with the compound (XXIII) or (XXIV). The reaction is normally conducted in a solvent (e.g., esters such as methyl acetate, ethyl acetate, ketones such as acetone, 2-butanone; aromatic hydrocarbons such as benzene, toluene) in the presence of an acid. As the acid, for example, there can be used hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid and p-toluenesulfonic acid. The acid may be used in its anhydrous form or in the form of a solution. The reaction can be conducted in an uniform system or a two-layer system of a solvent and water. The amount of the compound (XXIII) or (XXIV) to be used is 1 to 10 molar equivalent, preferably 1 to 5 molar equivalent based on the compound (XII). Further, the amount of the acid to be used is 1 to 300 molar equivalent, preferably 5 to 100 molar equivalent based on the compound (XII). The reaction temperature is normally 0 to 120°C, preferably 10 to 100°C. The reaction time is 30 minutes to 15 hours, preferably 1 to 10 hours. Then, the compound (XXV) is subjected to a cyclization reaction by using a base to produce the compound (XXVI). The cyclization reaction is conducted by the same conditions as those in the production of the compound (XV) from the compound (XIV) in the Process A or modification thereof. Further, the compound (XXVI) is reduced to produce the compound (VI"). As the reducing agent to be used, for example, there can be used lithium aluminum hydride and lithium borohydride. The amount thereof is 0.5 to 10 molar equivalent, preferably 1 to 5 molar equivalent based on the compound (XXVI). The reaction is normally conducted in a solvent (e.g., methanol, ethanol, ethyl ether, tetrahydrofuran, dioxane, dimethoxyethane). The reaction temperature is normally -5 to 120°C, preferably 0 to 100°C. The reaction time is normally about 15 minutes to 12 hours, preferably 30 minutes to 8 hours. This reduction reaction can also be conducted by using a metal and an acid, a metal salt and an acid, or an acid and a base, instead of the above reducing agent. As the metal, there can be used zinc, tin and iron and, as the metal salt, there can be used tin(II) chloride. As the hydrogen supplying source, there can be used acids (e.g. hydrochloric acid, sulfuric acid, hydrobromic acid, acetic acid). In the case of using potassium, sodium and lithium as the metal, as the hydrogen supplying source, there can be mainly used bases (e.g., ammonia, methylamine, dimethylamine, ethylamine, diethylamine), as well as alcohols (e.g. methanol, ethanol, propanol). The amount of the metal or metal salt used in this reaction is 1 to 20 molar equivalent, preferably 1 to 10 molar equivalent based on the compound (XXVI). The reaction is normally conducted in a solvent (e.g., alcohols such as methanol, ethanol ; ethers such as tetrahydrofuran, dioxane, dimethoxyethane). The above acid or base can be utilized as the solvent. The,reaction temperature is normally 0 to 150°C, preferably 10 to 120°C. The reaction time is normally 15 minutes to 12 hours, preferably 30 minutes to 10 hours. This reduction reaction can also be conducted by a catalytic reduction with a catalyst. As such a catalyst, there can be used palladium black, palladium carbon, platinum oxide, platinum black, Raney nickel and rhodium carbon. The reaction is normally conducted in a solvent (e.g., methanol, ethanol, isopropanol, tetrahydrofuran, dioxane, diethoxyethane, formic acid, acetic acid, N,N-dimethylformamide). The reaction temperature is 0 to 120°C, preferably 10 to 100°C. The reaction pressure is normally at normal pressure to 50 atoms, preferably normal pressure to 10 atoms. Process C: As the C₁₋₄ alkyl group represented by R⁷, methyl, ethyl, propyl, isopropyl, butyl or the like is preferred. The compound (XXVIII) is produced by the reaction of the compound (XII) with the compound (XXVII). The reaction is normally conducted in a solvent (e.g., alcohols such as methanol, ethanol, propanol; ethers such as tetrahydrofuran, dioxane, dimethoxyethane; aromatic hydrocarbons such as benzene, toluene, xylene; organic acids such as formic acid, acetic acid, propionic acid). Or, the reaction is conducted without any solvent in the presence of an acid catalyst (e.g., hydrochloric acid, sulfuric acid, hydrobromic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfinic acid). The amount of the compound (XXVII) to be used is 1 to 10 molar equivalent, preferably 1 to 5 molar equivalent based on the compound (XII). Further, the amount of the acid catalyst is 0.01 to 2 molar equivalent, preferably 0.05 to 1 molar equivalent. The reaction temperature is normally 0 to 200°C, preferably 10 to 150°C. The reaction time is normally 15 minutes to 24 hours, preferably 30 minutes to 15 hours. The compound (XXVIII) produced is then converted into the compounds (XXIX), (IX") and then (VI'''). These reactions can be conducted under the same conditions as those in the Process A or modification thereof. Further, the starting compound (XII) can also be produced according to the process described in Journal of Medicinal Chemistry, p 214 (1973) or modification thereof. The compounds (I) of the present invention or salts thereof have an excellent ACAT inhibitory activity. Pharmacological test results are shown hereinafter. (1) Acyl CoA: cholesterol transferase (ACAT) inhibitory activity [Experimental method] An enzyme specimen ACAT was prepared from a microsome fraction of the tunica mucosa intestini tenuis of Spregue-Dawley male rat (six week old) which had been subjected to fasting for 20 hours according to the method described in Journal of Lipid Research, 24 , 1127 (1982). ACAT activity was calculated by measuring an amount of a labeled cholesterol ester formed from [1-¹⁴C]oleoyl-CoA and endogenous cholesterol according to the process of Helgerud et al. [Journal of Lipid Research, 22 , 271 (1981)]. [Results] ACTA inhibitory activity of compounds tested are shown in Table 1 by a labeled cholesterol ester formation inhibitory rate (%) obtained by addition of the test compounds in an amount of 10⁻⁶M. Test compound (Example No.) ACAT inhibitory rate (%) 10⁻⁶M 1 98.7 2 74.3 3 96.6 4 93.6 5 93.9 6 96.3 7 34.4 8 94.4 9 60.2 10 95.1 11 94.5 12 82.3 (0.5 x 10⁻⁶M) 13 97.5 14 91.9 As is seen from Table 1, the compounds (I) or salts thereof have an excellent ACAT inhibition. The following Reference Examples and Examples further illustrate the present invention in detail but are not to be construed to limit the scope thereof. In the following Examples and Reference Examples, elution of column chromatography was conducted with monitoring by TLC (thin layer chromatography). For monitoring by TLC, Kieselgel 60F₂₅₄ manufactured by Merck Co. was employed as a TLC plate. The developing solvent was the same as that used for elution of column chromatography and a UV detector was employed for the detection. Kieselgel 60 (70 to 230 mesh) manufactured by Merck Co. was used for a silica gel column. The abbreviations used in Examples and Reference Examples are as follows: mg : milligram, g : gram, ml : milliliter, mp : melting point. All the percents are by weight unless otherwise stated and room temperature is about 15 to 25°C. Example 1 To a solution of 5-amino-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine (288 mg) in tetrahydrofuran (3 ml) was added 2,4-difluorophenyl isocyanate (0.13 ml) and the mixture was stirred at room temperature for 18 hours, and then the solvent was distilled off. To the residue was added isopropyl ether to obtain N-[4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea as crystals (416 mg, 93.9 %). Colorless prisms were obtained by recrystallization from acetone-hexane, mp: 217-218°C. Elemental analysis for C₂₂H₁₆ClF₂N₃OS, Calcd.: C, 59.53; H, 3.63; N, 9.47 Found : C, 59.57; H, 3.60; N, 9.44 Example 2 To a mixture of 4-acetoxy-3,5-dimethoxycinnamic acid (638 mg), dimethylformamide (2 drops) and tetrahydrofuran (8 ml) was added oxazolyl chloride (0.25 ml). The mixture was stirred at room temperature for one hour and then the solvent was distilled off to obtain 4-acetoxy-3,5-dimethoxycinnamic acid chloride as crystals. To a solution of the crystals in dichloromethane (15 ml) were added 5-amino-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine (576 mg) and N,N-dimethylaniline (0.25 ml) with ice cooling. After warming to room temperature, the mixture was stirred for 5 hours, washed in turn with water, aqueous saturated NaHCO₃ solution and water, and then dried over MgSO₄. The solvent was distilled off and the residue was crystallized from ethanol (729 mg, 67.4%). 5-(4-Acetoxy-3,5-dimethoxycinnamoylamino)-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine was obtained as colorless prisms by recrystallization from acetone, mp: 133-135°C. Elemental analysis for C₂₈H₂₅ClN₂O₅S˙2/3(CH₃)₂CO, Calcd.: C, 62.12; H, 5.14; N, 4.83 Found : C, 62.24; H, 5.19; N, 4.71 Example 3 To a mixture of 4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridine-5-carboxylic acid (347 mg), diphenylphosphoryl azide (330 mg) and benzene (4 ml) was added dropwise triethylamine (0.14 ml). The mixture was stirred at room temperature for 30 minutes, stirred under reflux for 30 minutes and then 2,4-difluoroaniline (0.12 ml) was added. The mixture was refluxed for 4 hours, washed with water, dried over MgSO₄, and then the solvent was distilled off. The residue was chromatographed on a silica gel and eluted with chloroform/ethyl acetate/metanol (9 : 1 : 0.25). The solvent was distilled off to obtain N-[4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea as colorless powder (210 mg, 44.4%). Elemental analysis for C₂₃H₁₈ClF₂N₃O₂S, Calcd.: C, 58.29; H, 3.83; N, 8.87 Found : C, 58.60; H, 4.06; N, 8.59 Example 4 According to the same manner as that described in Example 1, N-(4-chlorophenyl)-N'-[4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridin-5-yl]urea was obtained as colorless needles (99.3%), mp: 230-231°C. Elemental analysis for C₂₂H₁₇Cl₂N₃OS, Calcd.: C, 59.73; H, 3.87; N, 9.50 Found : C, 59.70; H, 3.86; N, 9.47 Example 5 According to the same manner as that described in Example 1, N-[4-(2-chlorophenyl)-2,3-dimethylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea was obtained as colorless prisms (91.0%), mp: 202-203°C. Elemental analysis for C₂₂H₁₆ClF₂N₃OS, Calcd.: C, 59.53; H, 3.63; N, 9.47 Found : C, 59.72; H, 3.62; N, 9.54 Example 6 According to the same manner as that described in Example 1, N-[4-(2-chlorophenyl)-6,7-dihydro-5H-cyclopenta-[1',2':5,4]thieno[2,3-b]pyridin-3-yl]-N'-(2,4-difluorophenyl)urea was obtained as colorless prisms (88.8%), mp: 223-224°C. Elemental analysis for C₂₃H₁₆ClF₂N₃OS, Calcd.: C, 60.59; H, 3.54; N, 9.22 Found : C, 60.38; H, 3.47; N, 9.19 Example 7 To a solution of 3-amino-4-(2-chlorophenyl)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine (150 mg) and N,N-dimethylaniline (0.065 ml) in dichloromethane (3 ml) was added dropwise 2,4-difluorobenzoyl chloride (0.07 ml) with ice-cooling. The mixture was stirred for 10 minutes with ice-cooling and then stirred at room temperature for 2 hours. Then, the mixture was washed in turn with water, aqueous saturated NaHCO₃ splution and water, and dried over MgSO₄. The solvent was distilled off to obtain 4-(2-chlorophenyl)-3-(2,4-difluorobenzoylamino)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine (206 mg, 93.6%) as crystals. The crystals were recrystallized from acetone to obtain colorless prisms, mp: 219-220°C. Elemental analysis for C₂₃H₁₅ClF₂N₂OS, Calcd.: C, 62.66; H, 3.43; N, 6.35 Found : C, 62.60; H, 3.58; N, 6.31 Example 8 According to the same manner as that described in Example 2, 4-(2-chlorophenyl)-3-(2,4-difluorophenyl-acetylamino)-6,7-dihydro-5H-cyclopenta-[1',2':5,4]thieno-[2,3-b]pyridine (89.4%) was obtained, mp: 127-128°C. Elemental analysis for C₂₄H₁₇ClF₂N₂OS, Calcd.: C, 63.36; H, 3.77; N, 6.16 Found : C, 63.49; H, 4.00; N, 6.27 Example 9 According to the same manner as that described in Example 1, N-(2,4-difluorophenyl)-N'-[4-(2-methylphenyl)-thieno[2,3-b]pyridin-5-yl]urea was obtained as colorless needles (91.7%), mp: 223-224°C (recrystallized from ethanol). Elemental analysis for C₂₁H₁₅F₂N₃OS, Calcd.: C, 63.79; H, 3.82; N, 10.63 Found : C, 63.75; H, 4.03; N, 10.60 Example 10 According to the same manner as that described in Example 1, N-[4-(2-chlorophenyl)-2-methylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea was obtained as colorless needles (88.1%), mp: 196-198°C. Elemental analysis for C₂₁H₁₄ClF₂N₃OS, Calcd.: C, 58.68; H, 3.28; N, 9.77 Found : C, 58.90; H, 3.25; N, 9.74 Example 11 To a mixture of 5-amino-2-chloro-4-(2-methylphenyl)thieno[2,3-b]pyridine hydrochloride ethanol solvate (160 mg) and tetrahydrofuran (3 ml) were added dropwise triethylamine (0.07 ml) and 2,4-difluorophenyl isocyanate (0.12 ml). The mixture was stirred at room temperature for 5 hours and the solvent was distilled off. Water was added to the residue and the mixture was extracted with ethyl acetate. The extract was washed with water and dried over MgSO₄ and the solvent was distilled off. To the residue was added isopropyl ether to obtain N-[2-chloro-4-(2-methylphenyl)thieno[2,3-b]pyridin-5-yl]-N'-[2,4-difluorophenyl)urea (133 mg, 68.9%) as crystals. The crystals were recrystallized from ethanol to obtain colorless prisms, mp; 225-226°C. Elemental analysis for C₂₁H₁₄ClF₂N₃OS, Calcd.: C, 58.68; H, 3.28; N, 9.77 Found : C, 58.78; H, 3.41; N, 9.59 Example 12 According to the same manner as that described in Example 1, N-[4-(2-chlorophenyl)-5,6,7,8-tetrahydro[1]-benzothieno[2,3-b]pyridin-3-yl]-N'-(2,4-difluorophenyl)urea was obtained as colorless prisms (94.9%), mp: 228-230°C. Elemental analysis for C₂₄H₁₈ClF₂N₃OS, Calcd.: C, 61.34; H, 3.86; N, 8.94 Found : C, 61.62; H, 3.83; N, 8.90 Example 13 To a mixture of 4-acetoxy-3,5-dimethylbenzoic acid (270 mg), diphenylphosphoryl azide (DPPA, 430 mg) and benzene (6 ml) was added dropwise triethylamine (0.18 ml) and the mixture was stirred at room temperature for 30 minutes and then at reflux for 40 minutes to obtain a solution of 4-acetoxy-3,5-dimethylphenylisocyanate. To the solution was added 5-amino-2-ethyl-4-(2-methoxyphenyl)-thieno[2,3-b]pyridine (284 mg) and the mixture was heated under reflux for 5 hours. The mixture was washed with water and dried over MgSO₄ and the solvent was distilled off. To the residue was added ethanol to obtain N-(4-acetoxy-3,5-dimethylphenyl)-N'-[2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridin-5-yl]urea (350 mg, 71.6%) as crystals. The crystals were recrystallized from ethanol to obtain colorless needles, mp: 217-218°C. Elemental analysis for C₂₇H₂₇N₃O₄S, Calcd.: C, 66.24; H, 5.56; N, 8.58 Found : C, 66.55; H, 5.57; N, 8.18 Example 14 According to the same manner as that described in Example 13, N-(4-acetoxy-3,5-dimethoxyphenyl)-N'-[2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridin-5-yl]urea was obtained as colorless needles (60.8%), mp: 244-245°C. Elemental analysis for C₂₇H₂₇N₃O₆S, Calcd.: C, 62.17; H, 5.22; N, 8.06 Found : C, 62.22; H, 5.31; N, 7.99 Example 15 According to the same manner as that described in Example 13, N-(4-dimethylaminophenyl)-N'-[2-ethyl-4-(2-methoxypenyl)thieno[2,3-b]pyridin-5-yl]urea was obtained as colorless needles (74.4%), mp: 208-209°C (recrystallized from acetone). Elemental analysis for C₂₅H₂₆N₄O₂S, Calcd.: C, 67.24; H, 5.87; N, 12.55 Found : C, 67.18; H, 5.85; N, 12.44 Reference Example 1 (1) A mixture of 2-amino-3-(2-chlorobenzoyl)-5-ethylthiophene (5.30 g), 1-morpholino-2-nitroethene (3.16 g), 6N HCl (5 ml) and acetone (25 ml) was stirred at room temperature for one hour. Water was added to the mixture, which was extracted with ethene acetate. The extract was washed with water and dried over MgSO₄, and then the solvent was distilled off to obtain 3-(2-chlorobenzoyl)-2-(2-nitroethenylamino)-5-ethylthiophene as crystals (5.65 g, 84.1%). The crystals were recrystallized from acetone to obtain yellow plates, mp: 125-126°C. Elemental analysis for C₁₅H₁₃ClN₂O₃S, Calcd.: C, 53.49; H, 3.89; N, 8.32 Found : C, 53.52; H, 3.91; N, 8.32 (2) To a solution of DBU (5.1 g) in benzene (50 ml) was added dropwise a solution of 3-(2-chlorobenzoyl)-2-(2-nitroethenylamino)-5-ethylthiophene (5.1 g) in dioxane-benzene (1 : 1, 30 ml) over one hour with stirring under reflux. After refluxing for additional one hour, the mixture was washed with water and dried over MgSO₄. The solvent was distilled off and to the residue was added isopropyl ether to obtain 4-(2-chlorophenyl)-2-ethyl-5-nitrothieno[2,3-b]pyridine as crystals (4.3 g, 89.0%). The crystals were recrystallized from isopropyl ether to obtain pale yellow prisms, mp: 72-73°C. Elemental analysis for C₁₅H₁₁ClN₂O₂S Calcd.: C, 56.52; H, 3.48; N, 8.79 Found : C, 56.53; H, 3.48; N, 8.79 (3) To a mixture of 4-(2-chlorophenyl)-2-ethyl-5-nitrothieno[2,3-b]pyridine (4.0 g), dioxane (25 ml) and conc. hydrochloric acid (12.5 ml) was added tin(II) chloride ·dihydrate (8.5 g). After stirring at room temperature for one hour, water was added to the mixture, which was made strong alkaline with 6N NaOH and then extraced with chloroform. The extract was washed with water and dried over MgSO₄ and the solvent was distilled off. The residue was chromatographed on a silica gel column and eluted with hexane-ethyl acetate (4 : 1). The solvent was distilled off and to the residue was added hexane to obtain 5-amino-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine (3.1 g, 85.6%) as crystals. The crystals were recrystallized from isopropyl ether to obtain colorless prisms, mp: 87-88°C. Elemental analysis for C₁₅H₁₃ClN₂S, Calcd.: C, 62.38; H, 4.54; N, 9.70 Found : C, 62.49; H, 4.57; N, 9.70 Reference Example 2 (1) A mixture of 2-amino-3-(2-chlorobenzoyl)-5-ethylthiophene (5.30 g), ethylmalonyl chloride (4.50 g) and benzene (60 ml) was heated under reflux for one hour, washed with water and dried over MgSO₄, and then the solvent was distilled off. To the residue was added hexane to obtain 3-(2-chlorobenzoyl)-2-ethoxycarbonylacetylamino-5-ethylthiophene as crystals (7.1 g, 93.7%). The crystals were recrystallized from isopropyl ether to obtain colorless prisms, mp: 56-57°C. Elemental analysis for C₁₈H₁₈ClNO₄S, Calcd.: C, 56.91; H, 4.79; N, 3.69 Found : C, 56.78; H, 4.73; N, 3.86 (2) To a solution of DBU (5.2 g) in toluene (50 ml) was added dropwise a solution of 3-(2-chlorobenzoyl)-2-ethoxycarbonylacetylamino-5-ethylthiophene (6.5 g) in toluene (30 ml) over one hour with stirring under reflux. After refluxing for 7 hours, the mixture was washed with water and dried over MgSO₄, and then the solvent was distilled off. The residue was chromatographed on a silica gel column and eluted with hexane-acetone (5 : 1). The solvent was distilled off and hexane was added to obtain ethyl 4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-6-oxothieno[2,3-b]pyridine-5-carboxylate as crystals (2.05 g, 33.1%). The crystals were recrystallized from ethanol to obtain light yellow prisms, mp: 126-127°C. Elemental analysis for C₁₈H₁₆ClN₃OS, Calcd.: C, 59.75; H, 4.46; N, 3.87 Found : C, 59.78; H, 4.52; N, 3.85 (3) To a mixture of 4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-6-oxothieno[2,3-b]pyridine-5-carboxylate (1.80 g), potassium carbonate (0.7 g) and DMF (15 ml) was added dropwise methyl iodide (0.37 ml). After stirring at room temperature for 1.5 hours, water was added to the mixture, which was extracted with ethyl acetate. The extract was washed with water and dried over MgSO₄, and then the solvent was distilled off. To the residue was added isopropanol to obtain ethyl 4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridine-5-carboxylate as crystals (1.32 g, 70.6%). The crystals were recrystallized from isopropyl ether to obtain colorless needles, mp: 105-106°C. Elemental analysis for C₁₉H₁₈ClNO₃S, Calcd.: C, 60.71; H, 4.83; N, 3.73 Found : C, 60.53; H, 4.91; N, 3.62 (4) A mixture of ethyl 4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridine-5-carboxylate (1.10 g), KOH (0.49 g) and 80% ethanol (10 ml) was heated at 80°C for 20 minutes and water was added. Then, the mixture was made acidic with 2N HCl and extracted with ethyl acetate. The extract was washed with water and dried over MgSO₄, and then the solvent was distilled off. To the residue was added hexane to obtain 4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridine-5-carboxylic acid as crystals (0.91 g, 89.2%). The crystals were recrystallized from ethanol to obtain colorless prisms, mp: 155-156°C. Elemental analysis for C₁₇H₁₄ClNO₃S, Calcd.: C, 58.70; H, 4.06; N, 4.03 Found : C, 58.72; H, 4.06; N, 4.01 According to the same manner as that described in Reference Example 1, the following compounds of Reference Examples 3 to 9. Reference Example 3 (1) 3-(2-Chlorobenzoyl)-4,5-dimethyl-2-(2-nitro-ethenylamino)thiophene, mp: 171-173°C. (2) 4-(2-Chlorophenyl)-2,3-dimethyl-5-nitro-thieno[2,3-b]pyridine, mp: 136-137°C. (3) 5-Amino-4-(2-chlorophenyl)-2,3-dimethyl-thieno[2,3-b]pyridine, mp: 117-118°C. Reference Example 4 (1) 3-(2-Chlorobenzoyl)-5,6-dihydro-2-(2-nitroethenylamino)-4H-cyclopenta[b]thiophene, mp: 118-120°C. (2) 4-(2-Chlorophenyl)-6,7-dihydro-3-nitro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine, mp: 118-119°C. (3) 3-Amino-4-(2-chlorophenyl)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine, mp: 130-131°C. Reference Example 5 (1) 3-(2-Methylbenzoyl)-2-(2-nitroethenylamino)-thiophene, mp: 155-156°C. (2) 4-(2-Methylphenyl)-5-nitrothieno[2,3-b]pyridine, mp: 111-112°C. (3) 5-Amino-4-(2-methylphenyl)thieno[2,3-b]pyridine, mp: 98-99°C. Reference Example 6 (1) 3-(2-Chlorobenzoyl)-5-methyl-2-(2-nitroethenyl-amino)thiophene, mp: 160-162°C. (2) 4-(2-Chlorophenyl)-2-methyl-5-nitrothieno[2,3-b]pyridine, mp: 157-158°C. (3) 5-Amino-4-(2-chlorophenyl)-2-methylthieno[2,3-b]pyridine, mp: 114-115°C. Reference Example 7 (1) 5-Chloro-3-(2-methylbenzoyl)-2-(2-nitro-ethenylamino)thiophene, mp: 160-162°C. (2) 2-Chloro-4-(2-methylphenyl)-5-nitrothieno[2,3-b]pyridine, mp: 126-127°C. (3) 5-Amino-2-chloro-4-(2-methylphenyl)thieno[2,3-b]pyridine hydrochloride ethanol solvate, mp: 114-115°C. Reference Example 8 (1) 3-(2-Chlorobenzoyl)-2-(2-nitroethenylamino)-4,5,6,7-tetrahydrobenzo[b]thiophene, mp: 163-164°C. (2) 4-(2-Chlorophenyl)-3-nitro-5,6,7,8-tetrahydro[1]benzothieno[2,3-b]pyridine, mp: 157-159°C. (3) 3-Amino-4-(2-chlorophenyl)-5,6,7,8-tetrahydro[1]benzothieno[2,3-b]pyridine, mp: 148-150°C. Reference Example 9 (1) 5-Ethyl-3-(2-methoxybenzoyl)-2-(2-nitro-ethenylamino)thiophene, mp: 140-141°C. (2) 2-Ethyel-4-(2-methoxyphenyl)-5-nitro-thieno[2,3-b]pyridine, mp: 116-117°C. (3) 5-Amino-2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridine, mp: 91-92°C.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, DK, FR, GB, GR, IT, LI, LU, NL, SE A thienopyridine derivative of the formula (I): wherein the ring A is benzene or benzene having 1 to 4 substituents selected from the group consisting of halogen, optionally halogenated C₁₋₆ alkyl, optionally halogenated C₁₋₆ alkoxy, optionally halogenated C₁₋₆ alkylthio, C₁₋₃ acyloxy, hydroxy, di-C₁₋₆ alkylamino and mono-C₁₋₆ alkylamino; the ring B is thiophene or thiophene having 1 or 2 substituents selected from the group consisting of halogen, C₁₋₆alkyl, C₃₋₆ cycloalkyl, nitro, amino and C₁₋₇ acylamino, or the adjacent carbon atoms on the ring B may bind to a group -(CH₂) q - (wherein q is an integer of 3 to 5) to form a 5 to 7 membered ring; X is a group of the formula: (wherein R¹ is hydrogen, C₁₋₆ alkyl or C₁₋₆ alkoxy; and n is 0 or 1) or a group of the formula: (wherein R² is hydrogen or C₁₋₆ alkyl); Y is a single bond, -NH-, alkylene having 1 or 2 carbon atoms or -CH=CH-; and R³ is C₁₋₈ alkyl, C₃₋₆ cycloalkyl, C₃₋₆ cycloalkyl-C₁₋₃ alkyl, C₆₋₁₀ aryl or C₇₋₁₆ aralkyl, which may have 1 to 5 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, C₁₋₄ alkylthio, hydroxyl, C₁₋₃ acyloxy and di-C₁₋₅ alkylamino, or its salt. A thienopyridine derivative according to claim 1, wherein the ring A is benzene or benzene having 1 to 4 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy and C₁₋₄ alkylthio. A thienopyridine derivative according to claim 1, wherein X is -N=CH-, A thienopyridine derivative according to claim 1, wherein Y is a single bond, -NH-, -CH₂-, -CH₂CH₂- or -CH=CH-. A thienopyridine derivative according to claim 1 which is N-[4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is 5-(4-acetoxy-3,5-dimethoxycinnamoylamino)-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine. A thienopyridine derivative according to claim 1 which is N-[4-(2-chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is N-(4-chlorophenyl)-N'-[4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridin-5-yl]urea. A thienopyridine derivative according to claim 1 which is N-[4-(2-chlorophenyl)-2,3-dimethylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is N-[4-(2-chlorophenyl)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridin-3-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is 4-(2-chlorophenyl)-3-(2,4-difluorobenzoylamino)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine. A thienopyridine derivative according to claim 1 which is 4-(2-chlorophenyl)-3-(2,4-difluorophenyl-acetylamino]-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine. A thienopyridine derivative according to claim 1 which is N-(2,4-difluorophenyl)-N'-[4-(2-methylphenyl)-thieno[2,3-b]pyridin-5-yl]urea. A thienopyridine derivative according to claim 1 which is N-[4-(2-chlorophenyl)-2-methylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is N-[2-chloro-4-(2-methylphenyl)thieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is N-[4-(2-chlorophenyl)-5,6,7,8-tetrahydro[1]benzothieno[2,3-b]pyridin-3-yl]-N'-(2,4-difluorophenyl)urea. A thienopyridine derivative according to claim 1 which is N-(4-acetoxy-3,5-dimethylphenyl)-N'-[2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridin-5-yl]urea. A thienopyridine derivative according to claim 1 which is N-(4-acetoxy-3,5-dimethoxyphenyl)-N'-[2-ethyl-4-(2-methoxypheyl)thieno[2,3-b]pyridin-5-yl]urea. A thienopyridine derivative according to claim 1 which is N-(4-dimethylaminophenyl)-N'-[2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridin-5-yl]urea. A compound of the formula (II): wherein Q is C₁₋₄ alkoxycarbonyl, carboxyl -NH₂ or -NCO; and the other symbols are as defined in claim 1, or a salt thereof; A process for producing a thienopyridine derivative of the formula (V): or a salt thereof which comprises reacting a compound of the formula (III): or a salt thereof with a compound of the formula (IV): R³ - Q² or a salt thereof, wherein either one of Q¹ and Q² is -NH₂ and the other is -NCO, and the other symbols are as defined in claim 1. A process for producing a thienopyridine derivative of the formula (VIII): wherein Y¹ is a single bond, an alkylene group having 1 or 2 carbon atoms or -CH=CH-; and the other symbols are as defined in claim 1, or a salt thereof which comprises reacting a compound of the formula (VI): wherein all the symbols are as defined above, or a salt thereof with a compound of the formula (VII): R³ - Y¹ - COOH wherein all the symbols are as defined above, or a reactive derivative thereof. An acyl-CoA: cholesterol acyltransferase inhibitor comprising a thienopyridine derivative of the formula (I) as claimed in claim 1, or a pharmaceutically acceptable salt thereof. Use of a thienopyridine derivative of the formula (I) as claimed in claim 1, or a salt thereof in the production of an acyl-CoA: cholesterol acyltransferase inhibitor. A process for producing an acyl-CoA: cholesterol acyltransferase inhibitor which comprises admixing a thienopyridine derivative of formula (I) as claimed in claim 1, or a pharmaceutically acceptable salt thereof with a suitable pharmaceutically acceptable carrier, excipient or diluent. Claims for the following Contracting State : ES A process for producing a thienopyridine derivative of the formula (I): wherein the ring A is benzene or benzene having 1 to 4 substituents selected from the group consisting of halogen, optionally halogenated C₁₋₆ alkyl, optionally halogenated C₁₋₆ alkoxy, optionally halogenated C₁₋₆ alkylthio, C₁₋₃ acyloxy, hydroxy, di-C₁₋₆ alkylamino and mono-C₁₋₆ alkylamino; the ring B is thiophene or thiophene having 1 or 2 substituents selected from the group consisting of halogen, C₁₋₆alkyl, C₃₋₆ cycloalkyl, nitro, amino and C₁₋₇ acylamino, or the adjacent carbon atoms on the ring B may bind to a group -(CH₂) q - (wherein q is an integer of 3 to 5) to form a 5 to 7 membered ring; X is a group of the formula: (wherein R¹ is hydrogen, C₁₋₆ alkyl or C₁₋₆ alkoxy; and n is 0 or 1) or a group of the formula: (wherein R² is hydrogen or C₁₋₆ alkyl); Y is a single bond, -NH-, alkylene having 1 or 2 carbon atoms or -CH=CH-; and R³ is C₁₋₈ alkyl, C₃₋₆ cycloalkyl, C₃₋₆ cycloalkyl-C₁₋₃ alkyl, C₆₋₁₀ aryl or C₇₋₁₆ aralkyl, which may have 1 to 5 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, C₁₋₄ alkylthio, hydroxyl, C₁₋₃ acyloxy and di-C₁₋₅ alkylamino, or its salt, which process comprises A) for preparing a compound of the formula (I) wherein Y is -NH-: reacting a compound of the formula (III): or a salt thereof with a compound of the formula (IV): R³ - Q² or a salt thereof, wherein either one of Q¹ and Q² is -NH₂ and the other is -NCO, and the other symbols are as defined above; and B) for preparing a compound of the formula (I) wherein Y is a single bond, an alkylene group having 1 or 2 carbon atoms or -CH=CH-: reacting a compound of the formula (VI): wherein all the symbols are as defined above, or a salt thereof with a compound of the formula (VII): R³ - Y - COOH wherein all the symbols are as defined above, or a reactive derivative thereof. A process according to claim 1, wherein the ring A is benzene or benzene having 1 to 4 substituents selected from the group consisting of halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy and C₁₋₄ alkylthio. A process according to claim 1, wherein X is -N=CH-, A process according to claim 1, wherein Y is a single bond, -NH-, -CH₂-, -CH₂CH₂- or -CH=CH-. A process according to claim 1 wherein the produced thienopyridine derivative is N-[4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is 5-(4-acetoxy-3,5-dimethoxycinnamoylamino)-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine. A process according to claim 1 wherein the produced thienopyridine derivative is N-[4-(2-Chlorophenyl)-6,7-dihydro-2-ethyl-7-methyl-6-oxothieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-(4-chlorophenyl)-N'-[4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridin-5-yl]urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-[4-(2-chlorophenyl)-2,3-dimethylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-[4-(2-chlorophenyl)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridin-3-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is 4-(2-chlorophenyl)-3-(2,4-difluorobenzoylamino)-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine. A process according to claim 1 wherein the produced thienopyridine derivative is 4-(2-chlorophenyl)-3-(2,4-difluorophenyl-acetylamino]-6,7-dihydro-5H-cyclopenta[1',2':5,4]thieno[2,3-b]pyridine. A process according to claim 1 wherein the produced thienopyridine derivative is N-(2,4-difluorophenyl)-N'-[4-(2-methylphenyl)-thieno[2,3-b]pyridin-5-yl]urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-[4-(2-chlorophenyl)-2-methylthieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-[2-chloro-4-(2-methylphenyl)thieno[2,3-b]pyridin-5-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-[4-(2-chlorophenyl)-5,6,7,8-tetrahydro[1]benzothieno[2,3-b]pyridin-3-yl]-N'-(2,4-difluorophenyl)urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-(4-acetoxy-3,5-dimethylphenyl)-N'-[2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridin-5-yl]urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-(4-acetoxy-3,5-dimethoxyphenyl)-N'-[2-ethyl-4-(2-methoxypheyl)thieno[2,3-b]pyridin-5-yl]urea. A process according to claim 1 wherein the produced thienopyridine derivative is N-(4-dimethylaminophenyl)-N'-[2-ethyl-4-(2-methoxyphenyl)thieno[2,3-b]pyridin-5-yl]urea. A process for producing a compound of the formula (II): wherein Q is C₁₋₄ alkoxycarbonyl, carboxyl -NH₂ or -NCO; and the other symbols are as defined in claim 1, or a salt thereof; which process comprises reacting a compound of the formula (XII) with a compound of formulas (XIII), (XXIII), (XXIV) or ( XXVII) NO₂CH₂CH=NOH R 1' COCH₂COOR⁷ wherein R 1' is hydrogen or C₁₋₆ alkyl, R⁴ and R⁷ are C₁₋₄ alkyl and R⁵ and R⁶ are the same or different and are C₁₋₄ alkyl, phenyl or benzyl, or R⁵ and R⁶ may bind each other and form together with the adjacent nitrogen atom a ring, and the other symbols are as defined above. A process for producing an acyl-CoA: cholesterol acyltransferase inhibitor which comprises admixing a thienopyridine derivative of formula (I) as produced in claim 1, or a pharmaceutically acceptable salt thereof with a suitable pharmaceutically acceptable carrier, excipient or diluent.

Inventors: IKEDA HITOSHI, MEGURO KANJI, TAWADA HIROYUKI, IKEDA, HITOSHI, MEGURO, KANJI, TAWADA, HIROYUKI
Applicants: TAKEDA CHEMICAL INDUSTRIES LTD, TAKEDA CHEMICAL INDUSTRIES, LTD.
Application year: 1991
Main classification: C07D495
IPC codes: C07D495