Aminobenzene compounds, their production and use

Abstract: A compound useful for central antioxidant having inhibitory activity of degeneration and necrocytosis of cerebral cells of the formula (I): wherein A and B are independently (1) a group of the formula: wherein R₁ and R₂ are independently hydrogen atom, an optionally substituted hydrocarbon residue or an optionally substituted heterocyclic group, or R₁ together with R₂ and the nitrogen atom to which they are bound may form a cyclic amino group, provided that both R₁ and R₂ are not hydrogen atom at the same time, or (2) a group of the formula: wherein D is O or S, R₃ is hydrogen atom, an optionally substituted hydrocarbon residue or an optionally substituted acyl group, m is 1, 2, or 3 and n is 0, 1, 2, 3 or 4; p is 1 or 2, provided that both A may be the same or different when p is 2; and R₄, R₅ and R₆ are independently hydrogen atom, a lower alkyl or a lower alkoxy, or R₅ and R₆ may bond together to form -CH=CH-CH=CH-, or a salt thereof.

Description: FIELD OF THE INVENTION The present invention relates to aminobenzene compounds of the general formulas (I), (II), (III) and (IV) as shown hereinafter or salts thereof, their production and use as central antioxidants. BACKGROUND OF THE INVENTION It is considered that glutamic acid and aspartic acid which are stimulative amino acids are responsible for degeneration and necrocytosis of cerebral nerve cells caused by cerebral ischemia due to cerebral infarction, cerebral hemorrhage, suspension of heart beat, operation of the lung, cerebral injury and the like as well as anoxia. However, there are many unclear points in the mechanism thereof. Although a lot of efforts have been made heretofore so as to investigate antagonists of glutamate as the means for inhibiting degeneration and necrocytosis of cerebral nerve cells, any effective and satisfactory medicine has not yet been found out. OBJECTS OF THE INVENTION The main object of the present invention is to investigate compounds which can inhibit necrocytosis of cerebral nerve cells caused by addition of glutamic acid and to provide such effective compounds as central antioxidants. It is considered that the addition of glutamic acid to N-18-RE-105 cell line (Neuroblastoma-primary retina hybrid cells) causes inhibition of incorporation of cystine into cells as well as decrease in accompanying intracellular concentration of glutathione, whereby, oxidative stress of cells, namely, intracellular accumulation of active oxygen and peroxides is taken place, which results in degeneration and necrocytosis (Neuron, 2 , 1547 (1989); J. Pharmacol. Exp. Ther., 250 , 1132 (1989)]. EP-A 0 378 207 discloses cyclic amine compounds comprising a 5- to 7-membered aza-heterocyclic group and their use as therapeutic drugs for cerebral edema. N-[4-(amino-substituted)phenyl]methanesulfonamides and their use as cardiovascular agents are disclosed in EP-A 0 332 570. Piperidine derivatives and their use for preventing dementias and sequelae of cerebrovascular disease are disclosed in EP-A 0 229 391. FR 1,436,583 discloses aza-heterocyclic amino compounds as an inhibitor permitting the protection of a rubber against the harmful effects of aging. US 3,480,617 and US 3,586,655 disclose aza-heterocyclic amino compounds as antiozonant and antioxidant. The present inventors have investigated compounds for inhibiting necrocytosis caused by glutamic acid by employing this evaluation system. As a result, it has been found that compounds of the formula (I) as shown hereinafter have an inhibitory activity of necrocytosis. The present inventors have further studied the compounds and completed the present invention. SUMMARY OF THE INVENTION According to the present invention, the use of a compound of the formula (I): wherein A and B are independently (1) a group of the formula: wherein R₁ and R₂ are independently (i) hydrogen atom, (ii) a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆, alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, (iii) a 5- to 8-membered heterocyclic group which may contain 1 to 4 hetero atoms selected from the group consisting of a nitrogen, oxygen and sulfur in addition to carbon, which may be substituted by 1 to 3 substituents selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, or (iv) R₁ together with R₂ and the nitrogen atom to which they are bound may form a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, provided that both R₁ and R₂ are not hydrogen atom at the same time, or (2) a group of the formula: wherein D is O or S, R₃ is (i) hydrogen atom, (ii) a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7- membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, or (iii) a C₂₋₆ alkyl-carbonyl, C₂₋₈ alkyl- or aralkyloxycarbonyl or C₁₋₄ alkyl- or dialkylaminocarbonyl group which may be substituted by 1 to 3 substituents selected from the group consisting of a halogen, amino and primary- or secondary-C₁₋₆ alkyl amino, m is 1, 2, or 3 and n is 0, 1, 2, 3 or 4; p is 1 or 2, provided that both A may be the same or different when p is 2; and R₄, R₅ and R₆ are independently hydrogen atom, a C₁₋₆ alkyl or a C₁₋₆ alkoxy, or R₅ and R₆ may bond together to form -CH=CH-CH=CH-, or a salt thereof in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells caused by glutamic acid, is disclosed. Moreover, the compounds 4-[4-(4-nonylamino)-2-methylphenyloxy]piperidine or its salt, 4-(4-decanylamino-3-methylphenyloxy)piperidine or its salt, 4-(4-heptylaminophenyloxy)piperidine or its salt, 4-(4-octylaminophenyloxy)piperidine or its salt, 4-(4-nonylaminophenyloxy)piperidine or its salt, 4-[4-(3-phenyl-2-propenylamino)phenyloxy]piperidine or its salt and 4-[4-(1-phenyldecanylamino)phenyloxy]piperidine or its salt as well as their use in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells, are disclosed. Further, there is provided a central antioxidant having inhibitory activity of degeneration and necrocytosis of cerebral cells (hereinafter merely referred to as the central antioxidant) comprising as an effective component a compound of the formula (II), (III) or (IV) as defined hereinafter. DETAILED DESCRIPTION OF THE INVENTION Among the compounds of the formula (I), compounds of the formula (II): wherein each symbol is as defined above, or salts thereof; compounds of the formula (III): wherein R₁' is a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇-₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, except an alkyl group having no substituent, and the formula: represents a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, and the other symbols are as defined above, or salts thereof; and compounds of the formula (IV): wherein R₁''' is and the other symbols are as defined above, or salts thereof are novel compounds synthesized by the present inventors. Accordingly, another aspect of the present invention is to provide these novel compounds. In the above formula (I), as the "hydrocarbon residue" of the "optionally substituted hydrocarbon residue" represented by R₁, R₁', R₂ and R₃, there are an alkyl group having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl, 4-methylpentyl, etc.); an alkenyl group having 2 to 4 carbon atoms (e.g., vinyl, allyl 2-butenyl, etc.); an alkynyl group having 2 to 4 carbon atoms (e.g., propargyl, 2-butynyl, etc.); an aryl group having 6 to 12 carbon atoms (e.g., phenyl, naphthyl, etc.); and an aralkyl having 7 to 14 carbon atoms (e.g., benzyl, diphenylmethyl, phenylethyl, naphthylmethyl, naphthylethyl, etc.). The aryl and aralkyl groups in R₁, R₁', R₂ and R₃ may have 1 to 3 substituents on the rings thereof selected from the group consisting of an alkoxy group having 1 to 3 carbon atoms leg., methoxy, ethoxy, etc.), an alkyl group having 1 to 3 carbon atoms (e.g., methyl, ethyl, propyl, etc.), cyano group, amino group, mono- or di-C₁₋₆ alkylamino group, 5 to 7 membered cyclic amino group (e.g., as described hereinafter with respect to the cyclic amino group formed by R₁ and R₂ together with the nitrogen atom to which they are bound), hydroxyl group, nitro group and halogen (e.g., chlorine atom, fluorine atom, bromine atom, etc.). Further, the above alkyl, alkenyl and alkynyl groups represented by R₁, R₁', R₂ and R₃ may have 1 to 4, preferably 1 to 3 substituents selected from the group consisting of halogen, an alkoxy group having 1 to 3 carbon atoms, cyano group, amino group, mono- or di-C₁₋₆ alkylamino group, 5 to 7 membered cyclic amino group (e.g., as described hereinafter with respect to the cyclic amino group formed by R₁ and R₂ together with the nitrogen atom to which they are bound) and hydroxyl group, provided that R₁' is not an unsubstituted alkyl group. The "heterocyclic group" or the "optionally substituted heterocyclic group" represented by R₁ and R₂ is a 5 to 8 membered, preferably, 5 to 6 membered saturated or unsaturated heterocyclic group containing as ring-constituting atoms 1 to 4, preferably, 1 to 2 hetero atoms selected from the groups consisting of N, O and S. As the heterocyclic group, a nitrogen-containing saturated heterocyclic group such as piperidinyl group, pyrrolidinyl group or the like is particularly preferred. Accordingly, the group represented by the formula: wherein each symbol is as defined above, which is included in the formula (I) and (II), is preferred. Examples of the substituent of the heterocyclic group include those as described above with respect to the hydrocarbon residue. As the "acyl group" of the "optionally substituted acyl group" represented by R₃, there are a carboxylic acyl group (e.g., an alkyl carbonyl having 2 to 6 carbon atoms such as acetyl, propionyl, butyryl, etc.); a substituted oxycarbonyl group (e.g, alkyl- or aralkyloxycarbonyl having 2 to 8 carbon atoms such as methyloxycarbonyl, tert-butyloxycarbonyl, benzyloxycarbonyl, etc.); and a substituted aminocarbonyl group (e.g., alkyl- or dialkylaminocarbonyl having 1 to 4 carbo atoms such as methylaminocarbonyl, ethylaminocarbonyl, dimethylaminocarbonyl, diethylaminocarbonyl, etc.). The substituent which is optionally contained in the acyl group include halogen (e.g., iodine, bromine, fluorine, chlorine, etc.), amino group and primary or secondary amino group having an alkyl group having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, hexyl, etc.). The acyl group may have 1 to 3, preferably, 1 to 2 substituents. As the "cyclic amino group formed by R₁ and R₂ together with the nitrogen to which they are bound", there is a group of the formula : wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl, etc.); and R₈ is a substituent which is optionally contained in the cyclic amino group formed by R₁ and R₂ or hydrogen atom. The substituent is selected from an alkyl group having 1 to 3 carbon atoms (e.g., methyl, ethyl, propyl, etc.), an alkylcarbonyl group having 1 to 3 carbon atoms (e.g., acetyl, propionyl, butyryl, etc,), oxo, hydroxy group, phenyl group, benzyl group, diphenylmethyl group and amino group. Examples of the lower alkyl group represented by R₄, R₅, R₆ and R₇ include C₁₋₆ alkyl group as described above with respect to R₁ and the like, and examples of the lower alkoxy group include C₁₋₆ alkoxy group represented by R₄, R₅ and R₆ include similar C₁₋₆ alkyl containing C₁₋₆ alkyl. When p is 2, both A may be the same or different. When A is a group represented by the formula: p is preferably 1 or 2 and, when A is a group represented by the formula: p is preferably 1. Among the compounds represented by the above (I), the compound wherein A and B are or -NHR₁ (wherein R₁ is C₁₋₆ alkyl group, particularly C₆ alkyl group) is particularly preferred. Further, the compound wherein A is and B is (CH₃)₂CH(CH₂)₃-is particularly superior in the pharmacological activity as described hereinafter. Examples of a preferred embodiment of the compounds of the above formula (II) include the following compounds. R₁ and R₂ are preferably an alkyl group having 1 to 4 carbon atoms, phenylmethyl group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a cyclic amino group. More preferably, R₁ and R₂ are an alkyl group having 1 to 3 carbon atoms or R₁ and R₂ together with the nitrogen atom to which they are bound form a group of the formula: s is 0, 1 or 2; R₈ is hydrogen atom, phenyl group or benzyl group. Preferably, R₃ is hydrogen atom, an alkyl group having 1 to 4 carbon atoms; m is 1 or 2, particularly 2; and n is 0 or 1, particularly 0. Examples of another preferred embodiment of the compounds represented by the above formula (II) include the compounds wherein D is O, n is 0, and m is 2; and R₃ is hydrogen or alkyl having 1 to 6 carbon atoms, particularly hydrogen or alkyl having 1 to 4 carbon atoms. As the group of the compound (II), is preferred. Examples of the preferred embodiment of the compounds of the above formula (III) include the following compounds. In view of the pharmacological activity, R₁' is preferably alkyl group having 3 to 6 carbon atoms or cycloalkyl group and the group is preferably Examples of the preferred embodiment of the compounds of the above formula (IV) include the compounds wherein and R₁''' is In the compounds of the formulas (I) to (IV), R₄, R₅ and R₆ are preferably hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In the present invention, the compounds (I), (II), (III) and (IV) may form their acid addition salts, particularly, physiologically acceptable acid addition salts, and examples of the salts include those formed with inorganic acids (e.g., hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid, etc.), and organic acids (e.g., acetic acid, propionic acid, fumaric acid, maleic acid, tartaric acid, citric acid, malic acid, oxalic acid, benzoic acid, methanesulfonic acid, benzenesulfonic acid, etc.). The process for the production of the compounds of the present invention will be explained hereinafter. A part of the compounds represented by the above formula (I) are, for example, known compounds described in U.S. Patent Nos. 3,480,617 and 3,586,655 ; Canadian Journal of Chemistry, 45 , 195 (1967); Tetrahedron, 33 , 955 (1977), and these compounds of the formula (I) can be synthesized according to the methods described in the above references or modifications thereof. On the other hand, among the compounds represented by the formula (I) of the present invention, the compounds represented by the formula (II) are novel compounds as described above and, for example, they can also be produced by the following method. Among the compounds of the formula (II), compounds represented by the formula (Ia): wherein R₃' is an optionally substituted acyl group as defined in R₃ and the other symbols are as defined above (hereinafter, merely referred to as the "compound (Ia)") can be obtained, for example, by reacting a compound represented by the formula (II'): wherein each symbol is as defined above with a compound represented by the formula (II''): wherein X is halogen (e.g., fluorine, chlorine, bromine, iodine, etc.) and the other symbols are as defined above to form a compound represented by the formula (V): wherein each symbol is as defined above; reducing the compound (V) to obtain a compound represented by the formula (V'): wherein each symbol is as defined above; and then reacting the compound (V') with a compound represented by the formula (VI): R₁-X wherein R₁ is as defined above and X is halogen (e.g., bromine, chlorine, iodine, etc). Further, the compound represented by the formula (Ia) can also be obtained by reacting the compound represented by the formula (V') with a compound represented by the formula (VII): R₁''-CHO wherein R₁'' is such "an optionally substituted hydrocarbon residue" that R₁''CH₂ becomes the same as R₁. The reaction of the compound represented by the formula (II') with the compound represented by the formula (II'') can be conducted according to a known method. For example, the reaction can be conducted in the absence of a solvent, or in a solvent, at a temperature of -50 to 300°C, preferably 20 to 200°C. The solvent may be any solvent which is normally used, and examples thereof include water, methanol, ethanol, propanol, chloroform, dichloromethane, benzene, toluene, xylene, acetonitrile, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and the like. If necessary, the reaction can be conducted, for example, in the presence of an organic base such as pyridine, 4-dimethylaminopyridine, triethylamine, triethylenediamine, tetramethylethylenediamine, etc.; an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.; sodium hydride; potassium hydride or the like. The compound represented by the formula (II'') is normally used in an amount of about 1 to 3 moles, preferably 1 to 1.5 moles per 1 mole of the compound represented by the formula (II'). Further, the reaction time is normally about 0.5 to 24 hours, preferably 2 to 10 hours. In a known method for reducing the compound represented by the formula (V), as a solvent, any solvent which is normally used in the chemical reaction can be used in so far as it does not interfere with the reaction. For example, the reaction can be conducted in a solvent such as water, methanol, ethanol, dimethylformamide, tetrahydrofuran, dioxane or the like in the presence of a catalyst such as palladium, rhodium, platinum, raney nickel or the like, at about -10 to 100°C, preferably 20 to 50°C, under hydrogen pressure of 1 to 100 atm, preferably 1 to 5 atm, if necessary, in the presence of an acid. Examples of the acid to be used include inorganic acids (e.g., hydrochloric acid, nitric acid, phosphoric acid, hydrobromic acid) or organic acids (e.g., acetic acid, propionic acid, tartric acid, benzoic acid, methanesulfonic acid, toluenesulfonic acid, etc.) and the like. The reaction of the compound represented by the formula (V') with the compound represented by the formula (VI) can also be conducted according to a known method. For example, the reaction can be conducted in a solvent, at a temperature of about 20 to 200°C, preferably 50 to 100°C. The solvent can be any one which is normally used, and examples thereof include water, methanol, ethanol, propanol, chloroform, dichloromethane, benzene, toluene, xylene, acetonitrile, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and the like. If necessary, the reaction can be conducted, for example, in the presence of an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide or the like. The compound represented by the formula (VI) is normally used in an amount of about 0.3 to 2 moles, preferably 0.5 to 1 moles per 1 mole of the compound represented by the formula (V'). Further, the reaction time is normally about 1 to 48 hours, preferably about 10 to 20 hours. The reaction of the compound represented by the formula (V') with the compound represented by the formula (VII) can be conducted by subjecting to reductive amination in a solvent such as methanol, ethanol, propanol or the like by using sodium cyano borohydride. The compound represented by the formula (VII) is normally used in an amount of about 0.5 to 10 moles, preferably 1 to 2 moles per 1 mole of the compound represented by the formula (V'). The reaction time is normally about 1 to 2 hours, preferably about 2 to 5 hours. Among the compounds (II), compounds represented by the formula (Ib): wherein each symbol is as defined above can be obtained by reacting the compound represented by the above formula (Ia) with a compound of the formula (VIII): R₂-X wherein R₂ is as defined above and X is halogen (e.g., bromine, chlorine, iodine, etc.), or a compound of the formula (IX): R₂'-CHO wherein R₂, is such "an optionally substituted hydrocarbon residue" that R₂'CH₂ become the same group as that of R₂, under the same conditions as those in the reaction of the compounds of the above formulas (V') and (VI) or the compounds of the formulas (V') and (VII). Further, the compound of the formula (Ib) can be obtained by reacting the compound of the formula (V') with the compound of the formula (VI) or (VII). In this case, R₁ and R₂ are hydrocarbon residues which may have the same substituents. Further, the compound of the formula (Ib) can be obtained by reacting the compound of the formula (V') with a compound of the formula (X): PO(OR₉)₃ wherein R₉ is an alkyl group having 1 to 6 carbon atoms in the absence of a solvent, or in a solvent, at a temperature of about 100 to 300°C, preferably 150 to 200°C. Examples of the solvent include dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and the like. The compound represented by the formula (X) is normally used in an amount of about 1 to 3 moles, preferably about 1 to 1.5 moles per 1 mole of the compound represented by the formula (V'). The reaction time is normally about 1 to 10 hours, preferably 3 to 5 hours. Among the compounds (II), compounds represented by the formula (Ic): wherein each symbol is as defined above, provided that is as defined above and, among the cyclic amino group formed together with the nitrogen atom to which R₁ and R₂ are bound group, can be obtained by reacting the compound of the formula (V') with a compound represented by the formula (XI): wherein X is halogen (e.g., bromine, chlorine, iodine, etc.) and is a group corresponding to the above wherein N is removed therefrom. The reaction of the compound represented by the formula (V') with the compound represented by the formula (XI) can be conducted according to a known method. For example, the reaction can be conducted in the absence of a solvent, or in a solvent, at a temperature of about -50 to 300°C, preferably 20 to 200°C. The solvent can be any one which is normally used and examples thereof include water, methanol, ethanol, propanol, chloroform, dichloromethane, benzene, toluene, xylene, acetonitrile, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and the like. If necessary, the reaction can be conducted, for example, in the presence of an organic base such as pyridine, 4-dimethylaminopyridine, triethylamine, triethylenediamine, tetramethylethylenediamine, etc.; an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.; sodium hydride; potassium hydride or the like. The compound represented by the formula (XI) is normally used in an amount of about 0.1 to 3 moles, preferably 0.5 to 1 moles per 1 mole of the compound represented by the formula (V'). The reaction time is normally about 1 to 48 hours, preferably 3 to 20 hours. Among the compounds (II), compounds represented by the formula (Id): wherein each symbol is as defined above can be obtained by subjecting the compound represented by the formula (Ia), (Ib) or (Ic) to deacylation reaction in an aqueous solution of a mineral acid (e.g., nitric acid, hydrochloric acid, hydrobromic acid, iodic acid, sulfuric acid, etc.) or an alkali hydroxide (e.g., sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, etc.), at 10 to 150°C, preferably 50 to 100°C . The acid or base is normally used in an amount of about 10 to 100 equivalent amounts, preferably 20 to 40 equivalent amounts per 1 mole of the compound of the formula (Ia), (Ib) or (Ic). The strength of the acid or base is preferably about 1 to 10 N, preferably 4 to 10 N. The reaction time is varied according to the reaction temperature and is normally about 1 to 24 hours, preferably 2 to 10 hours. Among the compounds (II), compounds represented by the formula (Ie): wherein R₃'' is R₃ other than hydrogen atom, namely, "an optionally substituted hydrocarbon residue" and "an optionally substituted acyl group" and the other symbols are as defined above can be obtained by reacting the compound represented by the formula (Id) with a compound represented by the formula (XII): R₃''-X wherein R₃'' is as defined above and X is halogen (e.g., bromine, chlorine, iodine, etc.). In the reaction, the solvent to be used can be any one which is normally used. For example, the reaction can be conducted in a protic solvent (e.g., water, methanol, ethanol, propanol, etc.) or an aprotic solvent (e.g., ethyl ether, tetrahydrofuran, dioxane, dimethylformamide, acetonitrile, etc.), at -10 to 200°C, preferably 20 to 100°C. If necessary, this reaction can be conducted, for example, in the presence of an organic base such as pyridine, 4-dimethylaminopyridine, triethylamine, triethylenediamine, tetramethylethylenediamine, etc.; an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.; sodium hydride; potassium hydride or the like. The compound represented by the formula (XII) is normally used in an amount of about 1 to 10 moles, preferably 1 to 2 moles per 1 mole of the compound represented by the formula (Id). The reaction time is normally about 1 to 48 hours, preferably 1 to 10 hours. Among the objective compounds represented by the formula (II) according to the present invention, compound represented by the formula (If): wherein R₃''' is, among the group of R₃, "an optionally substituted hydrocarbon residue" and the other symbols are as defined above can be obtained, for example, by reacting a compound represented by the formula (XIII): wherein each symbol is as defined above with the compound represented by the formula (II'') under the same reaction conditions as those of the reaction of the above compounds (I') and (II') to form a compound represented by the formula (XIV): wherein each symbol is as defined above; converting the compound (XIV) into a compound represented by the formula (XV): wherein each symbol is as defined above under the same reaction conditions as those of conversion of the compound of the formula (V) into the compound of the formula (V'); reacting the compound (XV) with a compound represented by the formula (XVI): wherein R₁'' is as defined above and X is halogen (e.g., bromine, chlorine, iodine, etc.) to form a compound represented by the formula (XVII): wherein each symbol is as defined above; and then reducing the compound (XVII). The reaction of the compound represented by the formula (XV) with the compound of the (XVI) is a know reaction and, for example, can be conducted by reacting the compound represented by the formula (XV) with the compound of the (XVI) in the absence of a solvent, or in a solvent, at a temperature of about -50 to 100°C, preferably 20 to 50°C. The solvent to be used can be any one which is normally used, and examples thereof include water, chloroform, dichloromethane, benzene, toluen, xylene, acetonitrile, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and the like. If necessary, this reaction can be conducted, for example, in the presence of an organic base such as pyridine, 4-dimethylaminopyridine, triethylamine, triethylenediamine, tetramethylenediamine, etc.; an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.; sodium hydride; potassium hydride or the like. The compound represented by the formula (XVI) is normally used in an amount of about 1 to 10 moles, preferably 1.5 to 4 moles per 1 mole of the compound represented by the formula (XV). The reaction time is normally about 1 to 48 hours, preferably about 2 to 10 hours. The reduction of the compound of the formula (XVII) can be conducted in a solvent by treating it with a metallic hydride (e.g., diisobutylaluminum hydride, triphenyltin hydride, etc.) or a metallic hydrogen complex (e.g., lithium aluminum hydride, sodium aluminum hydride, sodium triethoxyaluminum hydride, etc.). In this reaction, the solvent to be used can be any one which is normally used in so far as it does not interfere with the reaction, for example, the reaction can be conducted in a protic solvent (e.g., water, methanol, ethanol, propanol, etc.) or an aprotic solvent (e.g., ethyl ether, tetrahydrofuran, dioxane, etc.), at -10 to 200°C, preferably 20 to 100°C. Among the compounds represented by the formula (II), compound represented by the formula (Ig): wherein each symbol is as defined above can be obtained, for example, by reacting the compound represented by the formula (If) with a compound represented by the formula (XVIII): wherein each symbol is as defined above and X is halogen (e.g., bromine, chlorine, iodine, etc.) under the same reaction conditions as those of the reaction of the compounds of the above formulas (XV) and (XVI) to form a compound represented by the formula (XIX): wherein each symbol is as defined above; reducing the compound (XIX) under the same conditions as those for reducing the compound of the formula (XVII) to the compound of the formula (If). Among the compounds represented by the formula (I), the compounds represented by the formula (III) are also novel compounds. The compounds (III) can be produced by a known method. Further, the compounds (III) can also be produced according to the following method. Namely, it can be obtained by reacting a compound represented by the formula (XX): wherein Y is halogen (e.g., fluorine, chlorine, bromine, iodine, etc.) with a compound represented by the formula (XXI): wherein each symbol is as defined above to form a compound represented by the formula (XXII): wherein each symbol is as defined above; converting the resulting compound into a compound represented by the formula (XXIII): wherein each symbol is as defined above; reacting the latter compound with a compound represented by the formula (XXIV): R₁'-CH₂-Y wherein each symbol is as defined above, or a compound represented by the formula (XXV): R₁'-CHO wherein R₁' is as defined above, or a compound represented by the formula (XXVI): wherein each symbol is as defined above, to form a compound represented by the formula (XXVII): wherein each symbol is as defined above; and then reducing the resulting compound. The reaction of the compound represented by the formula (XX) with the compound represented by the formula (XXI) does not necessarily require a solvent. However, in the case of using a solvent, it is preferred to use a hydrocarbon solvent (e.g., pentane, hexane, benzene, toluene, etc.); a halogenohydrocarbon solvents (e.g., dichloromethane, chloroform, dichloroethane, carbon tetrachloride, etc.); an ether solvent (e.g., ethyl ether, tetrahydrofuran, dioxane, dimethoxyethane, etc.); an amido solvent (e.g., dimethylformamide, hexamethylphosphonotriamide, etc.); dimethylsulfoxide or the like, normally. The reaction can be conducted at -10 to 200°C, preferably 0 to 50°C. The compound represented by the formula (XXI) is used in an amount of about 1 to 20 equivalent amounts, preferably 1 to 4 equivalent amounts per 1 equivalent of the compound represented by the formula (XX). The reaction time is varied according to the reaction temperature and is normally about 1 to 24 hours, preferably 2 to 20 hours. This reaction can be conducted, for example, in the presence of an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc., sodium hydride, potassium hydride, n-butyllithium or the like. The conversion of the compound represented by the formula (XX) into the compound represented by the formula (XXI) can be conducted according to a known method for converting nitro group of the compound represented by the formula (XXII) into amino group. Namely, the compound represented by the formula (XXII) can be produced by catalytic hydrogenation reduction thereof in a solvent in the presence of a catalyst. The solvent to be used can be any one which is normally used in chemical reactions in so far as it does not interfere with the reaction. For example, the reaction can be conducted in a solvent such as water, methanol, ethanol, dimethylformamide, tetrahydrofuran, dioxane, etc., in the presence of a catalyst such as palladium, rhodium, platinum, raney nickel, etc., at -10 to 100°C, preferably about 20 to 50°C, under pressure of hydrogen of 1 to 100 atm, preferably 1 to 5 atm and, if necessary, in the presence of a acid. Examples of the acid to be used include mineral acids (e.g., hydrochloric acid, nitric acid, phosphoric acid, hydrobromic acid, etc.) or organic acids (e.g., acetic acid, propionic acid, tartaric acid, benzoic acid, methanesulfonic acid, toluenesulfonic acid, etc.) and the like. In the reaction of the compound represented by the formula (XXIII) with the compound represented by the formula (XXIV), any solvent which is normally used in chemical reaction can be used in so far as it does not interfere with the reaction. For example, the reaction can be conducted in a protic solvent (e.g., water, methanol, ethanol, propanol, etc.) or an aprotic solvent (e.g., ethyl ether, tetrahydrofuran, dioxane, dimethylformamide, acetonitrile, etc.), at a temperature of -10 to 200°C, preferably 20 to 100°C. If necessary, the reaction can be conducted, for example, in the presence of an organic base such as pyridine, 4-dimethylaminopyridine, triethylamine, triethylenediamine, tetramethylethylenediamine, etc.; an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.; sodium hydride, potassium hydride or the like. The compound represented by the formula (XXIV) is normally used in an amount of about 1 to 5 moles, preferably 1 to 2 moles per 1 mole of the compound represented by the formula (XXIII). The reaction time is normally about 1 to 48 hours, preferably 1 to 10 hours. In the reaction of the compound represented by the formula (XXI) with the compound represented by the formula (XXV), the solvent to be used can be any one which is normally used in the chemical reaction in so far as it does not interfere with the reaction. For example, the reaction can be normally conducted by reducing with lithium cyano borohydride, lithium aluminum hydride, diborane, etc. in a solvent such as water, methanol, ethanol, propanol, etc. The reaction temperature is -30 to 100°C, preferably 10 to 30°C. The compound represented by the formula (XXV) is normally used in an amount of 1 to 10 moles, preferably 1 to 2 moles per 1 mole of the compound represented by the formula (XXIII). Further, the reaction time is normally about 0.5 to 10 hours, preferably 1 to 4 hours. In the reaction of the compound represented by the formula (XXIII) with the compound represented by the formula (XXVI), it is preferred to use a hydrocarbon solvent (e.g., pentane, hexane, benzene, toluene, etc.); a halogenohydrocarbon solvent (e.g., dichloromethane, chloroform, dichloroethane, carbon tetrachloride, etc.); an ether solvent (e.g., ethyl ether, tetrahydrofuran, dioxane, dimethoxyethane, etc.); an amide solvent (e.g., dimethylformamide, hexamethylphosphonotriamide, etc.); dimethylsulfoxide or the like. The reaction can be conducted at -10 to 100°C, preferably 10 to 40°C. If necessary, this reaction can be conducted, for example, in the presence of an organic base such as pyridine, 4-dimethylaminopyridine, triethylamine, triethylenediamine, tetramethylethylenediamine, etc.; an inorganic base such as sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.; sodium hydride, potassium hydride, n-butyllithium or the like. The compound represented by the formula (XXVI) is normally used in an amount of about 1 to 5 moles, preferably 1 to 2 moles per 1 mole of the compound represented by the formula (XXIII). The reduction of the compound represented by the formula (XXVII) can be conducted by a known method in a hydrocarbon solvent (e.g., pentane, hexane, toluene, etc.), a halogen solvent (e.g., dichloromethane, chloroform, dichloroethane, etc.), or preferably an ether solvent (e.g., diethyl ether, dipropyl ether, tetrahydrofuran, dioxane, etc.), at a reaction temperature of -30 to 200°C, preferably 0 to 60°C by using lithium aluminum hydride, sodium aluminum hydride, etc. The compounds represented by the formula (IV), namely, the compound represented by the formula: wherein each symbol is as defined above can be produced, for example, by reacting the compound represented by the formula (XXIII) with a compound represented by the formula (XXVIII): wherein each symbol is as defined above. As the solvent to be used can be any one which is normally used in chemical reactions in so far as it does not interfere with the reaction and, normally, the above compound can be produced by reducing with sodium cyano borohydride, lithium aluminum hydride, diborane, etc. in a solvent such as water, methanol, ethanol, propanol, etc. The reaction temperature is -30 to 100°C, preferably 10 to 30°C. The compound represented by the formula (XXVIII) is normally used in an amount of 1 to 10 moles, preferably 1 to 2 moles per 1 mole of the compound represented by the formula (XXIII). The reaction time is normally about 0.5 to 10 hours, preferably 1 to 4 hours. The compounds represented by the formula (IV) can be produced according to a modification of the above method or a known method. When the objective products thus obtained are in the free form, they can be converted into acid addition salts according to a conventional method. On the other hand, when the objective products obtained are in the form of salts, they can be converted into the free form according to a conventional technique. The reaction product can be isolated and purified by conventional means such as solvent extraction, change of solvent properties, transfer to another solvent, salting-out, crystallization, recrystallization, chromatography and the like. It has been found that the compounds (I), (II), (III) and (IV) of the present invention (hereinafter generically referred to as the "compounds (I)") show cerebral nerve cell protective activity and central antioxidation activity useful for inhibiting degeneration and necrocytosis of cerebral nerve cell in various symptoms accompanied by intracerebral anoxia and cerebral ischemia, various symptoms accompanied by head injury and various symptoms upon operations by inhibiting accumulation of active oxygen and peroxides in cells, and they can be used for preventing and treating diseases caused by active oxygen and peroxides in cells. When the compounds (I) are used for preventing and treating the above symptoms, they can be used as they are. However, normally, the compounds (I) are orally or parenterally administered in the form of pharmaceutical compositions combined with known pharmaceutically acceptable carriers. Dosage forms of the pharmaceutical compositions are not specifically limited and examples thereof include tablets, powder, granules, capsules, injection preparations, suppositories and the like. The pharmaceutical compositions of the compounds (I) or salts thereof can be prepared according to a conventional method. As carriers for oral preparations, materials which are normally used in the pharmaceutical field, for example, starch, mannit, crystalline cellulose, sodium carboxymethylcellulose and the like can be used. As carriers for injection preparations, distilled water, saline, glucose solution, transfusion and the like can be used. The dosage of the compounds (I) of the present invention or salts thereof is varied according to a kind of particular diseases, symptoms, age and body weight of patients and the like. However, for a adult patient, in the case of administration by injection, a daily dosage is preferably 0.1 mg to 3 g, more preferably 3 to 50 mg. In the case of oral administration, a daily dose is preferably 1 mg to 1 g, more preferably 10 to 300 mg. As described hereinabove, the compounds (I) and salts thereof are useful as medicines for protecting cerebral nerve cells as well as central antioxidants and they can be used for prevention or treatment of, for example, various symptoms caused by cerebral ischemia due to cerebral infarction, cerebral hemorrhage, suspension of heart beat, operation of the lung or cerebral injury, various symptoms caused by anoxia, various symptoms accompanied by elevation of intracranial pressure due to intracerebral neoplasm and injury pressure, cerebral edema, dementia and the like. Particularly, according to the present invention, there is provided medicines useful for treating cerebral hemorrhage sequela, more particularly, medicines for protecting cerebral nerve cells as well as central antioxidants. The following Examples, Preparations and Experiment further illustrate the present invention Example 1 1-Acetyl-4-(4-pyrrolidinophenyloxy)piperidine (1) 1-Acetyl-4-hydroxypiperidine (3.7 g) was dissolved in dimethylformamide (20 ml) and to the solution was added sodium hydride (oily, 60 %, 1.04 g), followed by stirring at room temperature for 30 minutes. Then, p-fluoronitrobenzene (2.8 ml) was added dropwise, followed by stirring at room temperature for 30 minutes. Water (50 ml) was added to the mixture and the mixture was extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and the solvent was distilled off. The residue was separated and purified by silica gel column chromatography (developing solvent: ethyl acetate) and then recrystallized from ethyl acetate/ethyl ether to obtain pale yellow crystals (5.5 g), m.p. 91-92°C. (2) 1-Acetyl-4-(4-nitrophenyloxy) piperidine (4.72 g) was dissolved in ethanol (50 ml) and to the mixture was added conc. hydrochloric acid (2.5 ml). By using 10% palladium/carbon as a catalyst, catalytic reduction was conducted at a normal temperature and normal pressure. After completion of the reaction, the catalyst was removed and the solvent was distilled off. To the residual oily compound was added water (20 ml). The solution was made basic with addition of solid potassium carbonate and extracted with ethyl acetate. After drying over anhydrous magnesium sulfate, the solvent was distilled off to obtain an oily compound of 1-acetyl-4-(4-aminophenyloxy) piperidine (3.9 g). The oily compound (1.77 g) was dissolved in dimethylformamide (10 ml) and to the mixture were added potassium carbonate (2.1 g) and 1,4-dibromobutane (0.9 ml), followed by heating with stirring at 100°C for one hour. After completion of the reaction, water (50 ml) was added to the reaction mixture and the mixture was extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and then the solvent was distilled off. The residual oily compound was separated and purified by silica gel column chromatography and then recrystallized from ethyl acetate/ethyl ether to obtain colorless crystals (1.5 g), m.p. 69-70°C. Elemental analysis, Calcd. for C₁₇H₂₄N₂O₂: C, 70.80; H, 8.39; N, 9.71 Found: C, 70.63; H, 8.61; N, 9.70 Example 2 1-Acetyl-4-(4-morpholinophenyloxy)piperidine 1-Acetyl-4-(4-aminophenyloxy)piperidine (1.77 g) obtained in Example 1 was dissolved in dimethylformamide (10 ml) and to the mixture were added potassium carbonate (2.1 g), potassium iodide (0.2 g) and 2,2'-dichloroethyl ether (0.9 ml), followed by heating with stirring at 100°C overnight. The mixture was worked up according to the same manner as that described in Example 1 to obtain a colorless oily compound (1.4 g). Elemental analysis, Calcd. for C₁₇H₂₄N₂O₃: C, 67.08; H, 7.95; N, 9.20 Found: C, 66.83; H, 7.86; N, 9.17 NMR (CDCl₃) δ: 1.5-2.0 (4H, m), 2.12 (3H, s), 3.0-3.2 (4H, m), 3.2-3.9 (4H, m), 3.75-3.95 (4H, m), 4.2-4.6 (1H, m), 6.86 (4H, s) Example 3 1-Acetyl-4-(4-isoindolynophenyloxy)piperidine 1-Acetyl-4-(4-aminophenyloxy)piperidine (0.94 g) obtained in Example 1 was dissolved in dimethylformamide (10 ml) and to the mixture were added potassium carbonate (1.1 g) and α, α'-dibromo-o-xylene (1.06 g), followed by heating with stirring at 100°C for one hour. The mixture was worked up according to the same manner as that described in Example 1 to obtain a solid and it was recrystallized from ethanol/ethyl acetate to obtain colorless crystals (1.1 g), m.p. 198-199°C. Elemental analysis, Calcd. for C₂₁H₂₄N₂O₂: C, 74.97; H, 7.19; N, 8.33 Found: C, 74.75; H, 7.02; N, 8.32 Example 4 1-Acetyl-4-(4-dimethylaminophenyloxy)piperidine To 1-acetyl-4-{4-aminophenyloxy)piperidine (2.34 g) obtained in Example 1 was added trimethyl phosphate (1.17 ml), followed by heating with stirring at 200°C for 2 hours. To the mixture were added water (10 ml) and sodium hydroxide (1.5 g) and the mixture was stirred at room temperature for additional 2 hours. After extraction with ethyl acetate, the extract was dried over anhydrous magnesium sulfate and then the solvent was distilled off. The residue was separated and purified by silica gel column chromatography (developing solvent: ethyl acetate). The solid thus obtained was recrystallized from ethyl acetate/ethyl ether to obtain colorless crystals (1.2 g), m.p. 78-80°C. Elemental analysis, Calcd. for C₁₅H₂₂N₂O₂: C, 68.67; H, 8.45; N, 10.68 Found: C, 68.40; H, 8.56; N, 10.47 Example 5 4-(4-Pyrrolidinophenyloxy)piperidine fumarate 1-Acetyl-4-(4-pyrrolidinopheyloxy)piperidine (1.5 g) obtained in Example 1 was dissolved in a mixed solvent of ethanol (5 ml), water (5 ml) and conc. hydrochloric acid (5 ml), followed by heating with stirring at 100°C for 15 hours. The solution was made basic with potassium carbonate and then extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and the solvent was distilled off. The residual oily compound (1.22 g) was dissolved in methanol (30 ml). After fumaric acid (0.52 g) was dissolved in the solution, the solvent was distilled off to leave a solid which was recrystallized from ethanol to obtain colorless crystals (1.4 g), m.p. 199-201°C. Elemental analysis, Calcd. for C₁₉H₂₆N₂O₅: C, 62.97; H, 7.23; N, 7.73 Found: C, 62.92; H, 7.21; N, 7.63 Example 6 4-(4-Morpholinophenyloxy)piperidine fumarate According to the same manner as that described in Example 5, colorless crystal (1.1 g), m.p. 208-209°C, was obtained from 1-acetyl-4-(4-morpholinophenyloxy)piperidine (1.3 g) obtained in Example 2. Elemental analysis, Calcd. for C₁₉H₂₆N₂O₆: C, 60.30; H, 6.93; N, 7.40 Found: C, 60.35; H, 7.09; N, 7.34 Example 7 4-(4-Dimethylaminophenyloxy)piperidine fumarate According to the same manner as that described in Example 5, colorless crystals (0.99 g), m.p. 191-192°C was obtained from 1-acetyl-4-(4-dimethylaminophenyloxy)piperidine (1.0 g) obtained in Example 4. Elemental analysis, Calcd. for C₁₇H₂₄N₂O₅: C, 60.70; H, 7.19; N, 8.33 Found: C, 60.77; H, 7.17; N, 8.31 Example 8 4-(4-Isoindolynophenyloxy)piperidine dihydrochloride 1-Acetyl-4-(4-isoindolynophenyloxy)piperidine (1.1 g) obtained in Example 3 was dissolved in a mixed solvent of ethanol (5 ml), water (5 ml) and conc. hydrochloric acid (5 ml), followed by heating with stirring at 100°C for 15 hours. The solvent was distilled off and the solid thus obtained was rectrystallized from water/ethanol to obtain a colorless solid (0.9 g), m.p. 222-226°C. Elemental analysis, Calcd. for C₁₉H₂₄Cl₂N₂O: C, 62.13; H, 6.59; N, 7.63 Found: C, 61.92; H, 6.64; N, 7.35 Example 9 1,3-Di(1-acetyl-4-piperidyloxy)-4-pyrrolidinobenzene (1) 1-Acetyl-4-hydroxypiperidine (3.7 g) was dissolved in dimethylformamide (20 ml) and to the mixture was added sodium hydride (oily, 60 %, 1.04 g), followed by stirring at room temperature for 30 minutes. Then, 2,4-difluorobenzene (1.42 ml) was added dropwise. The mixture was worked up according to the same manner as that described in Example 1 and separated and purified by silica gel column chromatography (developing solvent: methanol/dichloromethane = 1/19 (v/v)) to obtain colorless crystals (3.6 g) of 1,3-di(1-acetyl-4-piperidyloxy)-4-nitrobenzene. (2) 1,3-Di(1-acetyl-4-piperidyloxy)-4-nitrobenzene (3.7 g) was dissolved in a mixed solution of ethanol (30 ml) and conc. hydrochloric acid (1 ml) and then catalytic reduction was conducted according to the same manner as that described in Example 1, (2). After completion of the reaction, the catalyst was removed and then the solvent was distilled off to obtain 2,4-di(1-acetyl-4-piperidyloxy)aniline hydrochloride (3.9 g) as an amorphous solid. The amorphous solid (1.23 g) was dissolved in dimethylformamide (5 ml) and potassium carbonate (1.24 g) and 1,4-dibromobutane (0.36 ml) were added to the mixture, which was heated with stirring at 100°C for one hour. After completion of the reaction, water (50 ml) was added to the reaction mixture, which was extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and then the solvent was distilled off. The residual oily compound was separated and purified by silica gel column chromatography (developing solvent: methanol/dichloroethane = 1/19 (v/v)) to obtain an oily compound (0.9 g). Elemental analysis, Calcd. for C₂₄H₃₅N₃O₄: C, 67.11; H, 8.21; N, 9.78 Found: C, 67.39; H, 8.15; N, 9.66 NMR (CDCl₃) δ: 1.5-2.1 (12H, m) 2.15 (6H, s), 3.1-3.3 (4H, m), 3.3-4.1 (8H, m), 4.2-4.6 (2H, m), 6.35-6.80 (2H, m), 8.03 (1H, s) Example 10 1,3-Di(4-piperidyloxy)-4-pyrrolidinobenzene 2 fumarate According to the same manner as that described in Example 5, a colorless amorphous solid (1.1 g) was obtained from 1,3-di(1-acetyl-4-piperidiloxy)-4-pyrrolidinobenzene (0.8 g). NMR (D₂O + DMSO₄-d₆) δ: 1.5-2.3 (12H, m), 2.8-3.5 (12H, m) 4.3-4.8 (2H, m), 6.4-6.8 (3H, m), 6.60 (4H, s) Example 11 1-Methylaminocarbonyl-4-(4-pyrrolidinophenyloxy)piperidine hydrochloride 4-(4-Piperidinophenyloxy)piperidine (0.62 g) obtained during the synthesis of the compound of Example 5 was dissolved in ethyl acetate (10 ml) and to the mixture was added methylisocyanate (0.45 ml), followed by stirring at room temperature for one hour. The solvent was distilled off and the residual oily compound was separated and purified by silica gel column chromatography (developing solvent: ethyl acetate) and then converted into the hydrochloride to obtain a colorless amorphous solid (0.6 g). Elemental analysis, Calcd. for C₁₇H₂₆ClN₃O₂: C, 60.01; H, 7.71; N, 12.36 Found: C, 59.81; H, 7.43; N, 12.12 NMR (DMSO-d₆) δ: 1.2-1.7 (2H, m), 1.7-2.4 (6H, m), 2.63 (3H, s), 2.9-3.4 (2H, m), 3.4-3.9 (6H, m) 4.4-4.8 (1H, m), 6.95-7.20 (2H, m), 7.60-7.85 (2H, m) Example 12 4-[4-(4-Methylpentylamino)phenyloxy]piperidine fumarate (1) 1-Acetyl-4-(4-nitrophenyloxy)piperidine (13.2 g) obtained in Example 1, (1) was dissolved in a mixed solvent of ethanol (40 ml) and conc. hydrochloric acid (40 ml), followed by heating with stirring at 100°C for 15 hours. After the solvent was distilled off, water (100 ml) was added and to the mixture were added solid sodium bicarbonate (12.6 g) and di-tert-butyl-dicarbonate (16.4 g), followed by stirring at room temperature for 8 hours. The solution was extracted with ethyl acetate, the extract was dried over anhydrous magnesium sulfate and then the solvent was distilled off. The residual oily compound was separated and purified by silica gel column chromatography (developing solvent: dichloromethane) to obtain 1-tert-butyloxycarbonyl-4-(4-nitrophenyloxy)piperidine (13 g). NMR (CDCl₃) δ: 1.50 (9H, s), 1.5-2.2 (4H, m), 3.2-3.9 (4H, m), 4.50-4.80 (1H, m), 6.9-7.1 (2H, m), 8.15-8.35 (2H, m) (2) 1-tert-Butyloxycarbonyl-4-(4-nitrophenyloxy)piperidine (5.47 g) was dissolved in ethanol (100 ml). After conc. hydrochloric acid (2 ml) was added to the mixture, catalystic reduction was conducted according to the same manner as that described in Example 1, (2). After completion of the reaction, the catalyst was removed and then the solvent was distilled off to obtain an oily compound (5.6 g). To a solution of the oily compound (3.17 g) in dichloromethane (30 ml) were added triethylamine (4.2 ml) and isocaproic chloride (2.0 g), followed by stirring at room temperature for 30 minutes. To the reaction mixture was added water (50 ml) and the aqueous layer was made basic with solid potassim carbonate. Then, the organic layer was dried over anhydrous magnesium sulfate and the solvent was distilled off. The oily compound thus obtained was separated and purified by silica gel column chromatography (developing solvent: methanol/dichloromethane = 1:99 (v/v)) to obtain an oily compound (1.9 g). NMR (CDCl₃) δ: 0.93 (6H, d), 1.50 (9H, s), 1.5-2.1 (7H, m), 2.33 (2H, t), 3.1-3.5 (2H, m), 3.5-3.9 (2H, m), 4.3-4.6 (1H, m), 6.8-7.0 (2H, s), 7.30 (1H, broad), 7.35-7.55 (2H, m) (3) 1-tert-Butyloxycarbonyl-4-[4-(4-methylvaleroylamino)phenyloxy]piperidine (1.90 g) was dissolved in trifluoroacetic acid (10 ml) which was allowed to stand at room temperature for 10 minutes. To this was added 6 N solution of hydrogen chloride in dioxane (3 ml) and the solvent was distilled off. The solid thus obtained was recrystallized from ethanol/ethyl acetate to obtain colorless crystals (1.3 g), m.p. 258-263°C. (4) 4-[4-(4-methylvaleroylamino)phenyloxy]piperidine hydrochloride (1.3 g) was suspended in tetrahydrofuran (30 ml) and to this was added lithium aluminum hydride (1.44 g) by portions. After completion of addition, the suspension was heated with stirring at 60°C for 30 minutes. To this were added water (2.4 ml) and 10% aqueous solution of sodium hydroxide (1.9 ml), followed by stirring at room temperature for 10 minutes. After the insoluble substance was filtered off, water (50 ml) and ethyl acetate (50 ml) were added. The organic layer was dried over anhydrous magnesium sulfate and the solvent was distilled off to obtain a colorless oily compound (1.1 g). The compound was dissolved in ethanol (20 ml) and to the mixture was added fumaric acid (0.42 g). The solvent was distilled off and the residual solid was recrystallized from ethanol/ethyl acetate to obtain colorless crystals (1.25 g), m.p. 138-140°C. Elemental analysis, Calcd. for C₂₁H₃₂N₂O₅: C, 64.26; H, 8.22; N, 7.14 Found: C, 64.14; H, 8.03; N, 7.18 Example 13 1-tert-Butyloxycarbonyl-4-[(4-dimethylaminophenyloxy)methyl]piperidine (1) 1-tert-Butyloxycarbonyl-4-piperidine acetic acid N-hydroxysuccinimide ester (15.0 g) was dissolved in dioxane (30 ml). The mixture was added dropwise to a suspension of sodium boron hydride (1.8 g) in a mixture of metanol and water (4 : 1) with ice cooling, followed by stirring with ice cooling for one hour. The reaction mixture was concentrated under reduced pressure, followed by addition of a water, saturation of salt and exraction with methylene chloride (100 ml x 3). The combined extract was washed with saturated saline and dried over anhydrous magnesium sulfate and then the solvent was distilled off under reduced pressure. The residue thus obtained was purified by silica gel column chromatography (developing solvent: hexane/ethylacetate = 1/1 (v/v)) to obtain 1-tert-butyloxycarbonyl-4-hydroxymethylpiperidine (3.2 g) as colorless crystals, m.p. 76-78°C. Elemental analysis, Calcd. for C₁₁H₂₁NO₃: C, 61.36; H, 9.83; N, 6.51 Found: C, 61.57; H, 10.11; N, 6.68 (2) 1-tert-Butyloxycarbonyl-4-hydroxymethylpiperidine (2.8 g) was dissolved in dimethylformamide (10 ml), followed by stirring for 30 minutes. To the mixture was added p-fluoronitrobenzene (2.1 g), followed by stirring at room temperature overnight. Aqueous saturated solution of sodium bicarbonate was added to the mixture which was extracted with methylene chloride (50 ml x 3). The combined organic layer was washed with saturated saline and dried over sodium sulfate. The solvent was distilled off under reduced pressure and the residue thus obtained was purified by silica gel column chromatography (developing solvent: hexane/ethylacetate = 5/1 (v/v)) to obtain 1-tert-butyloxycarbonyl-4-[(4-nitrophenyloxy)methyl]piperidine (1.9 g) as pale yellow crystals, m.p. 130-131°C. Elemental analysis, Calcd. for C₁₇H₂₄N₂O₅: C, 60.70; H, 7.19; N, 8.33 Found: C, 60.90; H, 7.20; N, 8.37 (3) 1-tert-Butyloxycarbonyl-4-[(4-nitrophenyloxy)methyl]piperidine (1.9 g) was dissolved in ethanol (40 ml) and to the mixture was added conc. hydrochloric acid (0.5 ml). By using 10% palladium/carbon as a catalyst, catalystic reduction was conducted at normal pressure and room temperature overnight. After completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. The concentrate was diluted with methylene chloride and washed with aqueous saturated solution of sodium bicarbonate. The organic layer was dried over sodium sulfate and concentrated under reduced pressure. The residue thus obtained was purified by silica gel column chromatography (developing solvent: hexane/ethyl acetate = 1/1 (v/v)) to obtain 1-tert-butyloxycarbonyl-4-[(4-aminophenyloxy)methyl]piperidine (1.0 g) as white crystals, m.p. 100-101°C. Elemental analysis, Calcd. for C₁₇H₂₆N₂O₃: C, 66.64; H, 8.55; N, 9.14 Found: C, 66.42; H, 8.62; N, 9.07 (4) To 1-tert-Butyloxycarbonyl-4-[(4-aminophenyloxy)methyl]piperidine (0.9 g) was added trimethyl phosphate (0.7 ml) and the mixture was heated to 180°C and stirred for 5 hours. 5% aqueous solution of sodium hydroxide (10 ml) was added to the reaction mixture which was heated under reflux for one hour, diluted with water and extracted with ethyl acetate (50 ml x 3). The combined organic layer was dried over sodium sulfate and concentrated under reduced pressure. The residue thus obtained was purified by silica gel column chromatography (developing solvent: hexane/ethyl acetate = 5/1 (v/v)) to obtain 1-tert-butyloxycarbonyl-4-[(4-dimethylphenyloxy)methyl]piperidine (0.13 g) as pale yellow crystals, m.p. 91-93°C. Elemental analysis, Calcd. for C₁₉H₃₀N₂O₃: C, 68.23; H, 9.04; N, 8.38 Found: C, 68.13; H, 8.89; N, 8.51 Example 14 4-[(4-Dimethylaminophenyloxy)methyl)piperidine 1/2 fumarate To 1-tert-Butyloxycarbonyl-4-[(4-dimethylaminophenyloxy)methyl]piperidine (0.1 g) obtained in Example 13 was added trifluoroacetic acid (0.5 ml) followed by stirring at room temperature for 10 minutes. The reaction mixture was concentrated under reduced pressure, and the concentrate was diluted with methylene chloride (100 ml) and washed with aqueous saturated solution of sodium bicarbonate. The organic layer was separated, dried over sodium sulfate and concentrated under reduced pressure. The residue was treated with fumaric acid and the resulting fumarate was recrystallized from methanol to obtain 4-[(4-dimethylaminophenyloxy)methyl]piperidine 1/2 fumarate (0.1 g) as pale yellow crystals, m.p. 210-213°C. Elemental analysis, Calcd. for C₁₆H₂₄N₂O₃: C, 65.72; H, 8.27; N, 9.58 Found: C, 65.43; H, 8.38; N, 9.57 Example 15 1-tert-Butyloxycarbonyl-4-[(4-pyrrolidinophenyloxy) methyl]piperidine To 1-tert-butyloxycarbonyl-4-[(4-aminophenyloxy)methyl]piperidine (0.75 g) obtained in Example 13 were added dimethylformamide (10 ml), potassium carbonate (1.4 g) and dibromobutane (0.54 g) and the mixture was heated to 70°C and stirred overnight. To the reaction solution was added water which was extracted with ethyl acetate (50 ml x 3). The combined extract was dried over sodium sulfate and concentrated under reduced pressure. The residue thus obtained was purified by silica gel column chromatography (developing solvent: hexane/ethyl acetate = 5/1 (v/v)) to obtain 1-tert-butyloxycarbonyl-4-[(4-pyrrolidinophenyloxy)methyl]piperidine (0.55 g) as colorless crystals, m.p. 141-145°C. Elemental analysis, Calcd. for C₂₁H₃₂N₂O₃: C, 69.96; H, 8.95; N, 7.77 Found: C, 69.71; H, 8.88; N, 7.85 Example 16 4-[(4-Pyrrolidinophenyloxy)methyl]piperidine fumarate To 1-tert-butyloxycarbonyl-4-[(4-pyrrolidinophenyloxy)methyl]piperidine (0.55 g) obtained in Example 15 was added trifluoroacetic acid (2 ml), followed by stirring at room temperature for 10 minutes. The mixture was worked up according to the same manner as that described in Example 14 to obtain a fumarate and the fumarate was recrystallized from water/ethanol (1/2) to obtain 4-[(4-pyrrolidinophenyloxy)methyl]piperidine fumarate (0.5 g) as colorless crystals, m.p. 200-205°C. Elemental analysis, Calcd. for C₂₀H₂₈N₂O₅: C, 63.81; H, 7.50; N, 7.44 Found: C, 63.57; H, 7.53; N, 7.44 Example 17 N-(4-ethylaminophenyl)piperidine dihydrochloride (1) A solution of p-fluoronitrobenzene (31.8 ml) in dimethylformamide (200 ml) was ice-cooled and to this was added piperidine (60 ml) dropwise, followed by stirring with ice cooling for 2 hours. After the solvent was distilled off, the residual oily product was dissolved in ethyl acetate ester (200 ml), followed by washing in turn with aqueous saturated solution of sodium bicarbonate and water. Then, the solution was dried over anhydrous magnesium sulfate. After the solvent was distilled off, the residue was recrystallized from n-hexane to obtain N-(4-nitrophenyl)piperidine as yellow crystals (52.8 g). (2) To a solution of N-(4-nitrophenyl)piperidine (12 g) in methanol (50 ml) was added conc. hydrochloric acid (12 ml) and, by using 10% palladium/carbon as a catalyst, catalystic reduction was conducted at normal temperature and normal pressure. After completion of the reaction, the catalyst was removed and the solvent was distilled off. To the residue was added ethyl ether which was filtered off to obtain N-(4-aminophenyl)piperidine dihydrochloride (13.7 g) as a colorless solid. (3) A solution of N-(4-aminophenyl)piperidine dihydrochloride (2.49 g) and triethylamine (5.6 g) in dichloroform (30 ml) was ice-cooled and to this was added dropwise acetyl chloride (1.42 ml). After stirred at room temperature for 30 minutes, water (10 ml) was added to the mixture and the organic layer was dried over anhydrous magnesium sulfate. The solvent was distilled off and then the residue was recrystallized from ethyl ether to obtain N-(4-acetylaminophenyl)piperidine (2 g) as colorless crystals, m.p. 150-152°C. Elemental analysis, Calcd. for C₁₃H₁₈N₂O: C, 71.53; H, 8.31; N, 12.83 Found: C, 71.51; H, 8.31; N, 12.80 (4) N-(4-Acetylaminophenyl)piperidine (1.96 g) was suspended in tetrahydrofuran (30 ml) and to the mixture was added lithium aluminum hydride (0.54 g), followed by stirring at 60°C for 30 minutes. To the mixture was added water (0.9 ml) and 10% aqueous solution of sodium hydroxide (0.72 ml) which was stirred at room temperature for 30 minutes. Then, the precipitate was filtered off and 6 N hydrogen chloride in dioxane was added to the mother liquor to form a white precipitate. The precipitate was filtered off and recrystallized from ethanol to obtain colorless crystals (2.10 g), m.p. 182-197°C. Elemental analysis, Calcd. for C₁₃H₂₀N₂ ·2HCl: C, 56.33; H, 8.00; N, 10.11 Found: C, 56.60; H, 7.95; N, 9.94 Example 18 According to the same maner as that described in Example 17, the compounds shown in Table 1 were obtained. Example 19 1-acetyl-4-[4-(piperidin-1-yl)phenylamino]piperidine dihydrochloride To a solution of N-(4-aminophenyl)piperidine dihydriochloride obtained in Example 17 and 1-acetyl-4-piperidone (0.70 g) in methanol (10 ml) was added sodium cyano borohydride (0.63 g), followed by stirring at room temperature for 5 hours. To the mixture was added ethyl acetate ester (20 ml) and water (30 ml). After the organic layer was dried over anhydrous sodium sulfate, to the solution was added 6 N solution of hydrogen chloride in dioxane (2 ml) and the solvent was distilled off. The residue was recrystallized from ethanol to obtain colorless crystals, m.p. 187-193°C. Elemental analysis, Calcd. for C₁₈H₂₉Cl₂N₃O: C, 57.75; H, 7.81; N, 11.22 Found: C, 57.79; H, 7.61; N, 11.02 Example 20 4-[4-(piperidin-1-yl)phenylamino]piperidine trihydrochloride A solution of 1-acetyl-4-[4-(piperidin-1-yl)phenylamino]piperidine dihydrochloride (0.70 g) in conc. hydrochloric acid (5 ml) was heated with stirring at 100°C for 15 hours. After the solvent was distilled off, the residue was recrystallized from ethanol to obtain colorless crystals (0.5 g), m.p. 185-189°C. Elemental analysis, Calcd. for C₁₆H₂₈Cl₃N₃: C, 52.11; H, 7.65; N, 11.39 Found: C, 52.23; H, 7.63; N, 11.14 Example 21 1-Acetyl-4-[3-(piperidin-1-yl)phenylamino]piperidine dihydrochloride (1) A mixture of m-fluoronitrobenzene (9 g) and piperidine (40 ml) was heated with stirring at 100°C for 15 hours and to the mixture were added ethyl acetate ester (100 ml) and aqueous saturated solution of potassium carbonate (100 ml). The organic layer was washed with water and dried over anhydrous sodium sulfate. The solvent was distilled off to obtain N-(3-nitrophenyl)piperidine (13.5 g) as a yellow oily compound. (2) To a solution of N-(3-nitrophenyl)piperidine (12 g) in methanol (50 ml) was added conc. hydrochloric acid (12 ml) and, by using 10% palladium/carbon as a catalyst, catalytic reduction was conducted at normal temperature under normal pressure. After completion of the reaction, the catalyst was removed and the solvent was distilled off. Ethyl ether was added to the residue and the mixture was filtered off to obtain N-(3-aminophenyl)piperidine dihydrochloride (13.2 g) as a colorless solid. (3) To a solution of N-(3-aminophenyl)piperidine dihydrochloride (3.73 g) and 1-acetyl-4-piperidone (2.1 g) in methanol (30 ml) was added sodium cyano borohydride (1.9 g), followed by stirring at room temperature for 5 hours. To the mixture were added ethyl acetate ester (20 ml) and water (30 ml), the organic layer was dried over anhydroud sodium sulfate and then the solvent was distilled off. The residual oily compound was separated and purified by silica gel column chromatography (developing solvent: ethyl acetate ester). The oily compound was dissolved in dioxane (10 ml) and to the mixture was added 6 N solutuion of hydrogen chloride in dioxane (2 ml). Then, the solvent was removed to obtain a colorless amorphous solid (3.7 g). NMR (D₂O) δ: 1.2-2.3 (10H, m), 2.03 (3H, s), 2.5-2.9 (1H, m), 3.0-3.5 (1H, m), 3.5-3.8 (5H, m), 3.8-4.2 (2H, m), 7.1-7.8 (4H, m) Example 22 4-[3-(Piperidin-1-yl)phenylamino]piperidine trihydrochloride According to the same manner as that described in Example 20, colorless crystals (0.84 g) having m.p. of 176-179°C was obtained from 1-acetyl-4-[3-(piperidin-1-yl)phenylamino]piperidine trihydrochloride (1.0 g). Elemental analysis, Calcd. for C₁₆H₂₈Cl₃N₃: C, 52.11; H, 7.65; N, 11.39 Found: C, 52.02; H, 7.69; N, 11.01 Ref. Example 23 4-[4-(4-Hexadecanylamino)-2-methylphenyloxy]piperidine 2 fumarate (1) 1-Acetyl-4-hydroxypiperidine (9.2 g) was dissolved in dimethylformamide (20 ml) and to the solution was added sodium hydride (oily, 60%, 2.6 g). The mixture was stirred at room temperature for 30 minutes, followed by adding dropwise 2-fluoro-5-nitrotoluene (10 g). The mixture was stirred at room temperature for 10 minutes. To the reaction mixture was added water (50 ml) which was extracted with methylene chloride (50 ml x 3). The extract was dried over anhydrous sodium sulfate and the solvent was distilled off. The residue was purified by silica gel chromatography (developing solvent: methylene chloride/methanol = 20/1 (v/v)) to obtain 1-acetyl-4-(4-nitro-2-methylphenyloxy)piperidine (12.6 g) as yellow crystals, m.p. 139-141°C. (2) To 1-acetyl-4-(4-nitro-2-methylphenyloxy)piperidine (11.8 g) were added conc. hydrochloric acid (15 ml), ethanol (15 ml) and water (15 ml) and the mixture was heated under reflux overnight. The reaction mixture was concentrated under reduced pressure, the residue thus obtained was washed with ethyl ether and crystals were filtered off to obtain 4-(4-nitro-2-methylphenyloxy)piperidine hydrochloride (8.3 g) as white crystals, m.p. 204-226°C. (3) To a suspension of 4-(4-nitro-2-methylphenyloxy)piperidine hydrochloride (7.5 g) in methylene chloride (30 ml) were added dropwise triethylamine (5.56 g) and di-tert-butyl dicarbonate (7.2 g) and the mixture was stirred with ice cooling for 10 minutes. To the reaction mixture was added water, which was extracted with methylene chloride (50 ml x 3). The combined extract was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was washed with n-hexane to obtain 1-tert-butyloxycarbonyl-4-(4-nitro-2-methylphenyloxy)piperidine (9.7 g) as yellow crystals, m.p. 82-83°C. (4) To a solution of 1-tert-butyloxycarbonyl-4-(4-nitro-2-methylphenyloxy)piperidine (9.0 g) in ethanol (100 ml) was added conc. hydrochrolic acid (2.3 ml) and, by using 10% palladium/carbon (containing 48% of water, 1 g) as a catalyst, catalytic reduction was conducted under normal pressure for 1.5 hours. The catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to obtain 1-tert-butyloxycarbonyl-4-(4-amino-2-methylphenyloxy)piperidine (8.7 g) as a light brown amorphous material. (5) To a solution of 1-tert-butyloxycarbonyl-4-(4-amino-2-methylphenyloxy)piperidine (1.5 g) in methylene chloride (30 ml) were added triethylamine (1.3 g) and palmitoyl chloride (1.2 g) with ice-cooling and the mixture was stirred at room temperature for 1 hour. Aqueous saturated solution of sodium bicarbonate was added to the reaction mixture and the organic layer was separated. The aqueous layer was further extracted with methyene chloride (50 ml x 2) and the combined orgnaic layer was dried over sodium sulfate and concentrated under reduced pressure. To the solidified residue was added trifluoroacetic acid (5 ml) and the mixture was stirred at room temperature for 30 minutes. After concentration of the reaction mixture under reduced pressure, the resulting residue was dissolved in ethanol and conc. hydrochloric acid (0.37 ml) was added. The resulting solution was concentrated under reduced pressure and the residue was washed with hexane to obtain 4-(4-palmitoylamino-2-methylphenyloxy)piperidine hydrochloride (1.8 g) as white crystals, m.p. 125-137°C. Elemental analysis, Calcd. for C₂₈H₄₉N₂O₂Cl: C, 69.89; H, 10.27; N, 5.82 Found: C, 70.01; H, 10.22; N, 5.93 (6) According to the same manner as that described in Example 12, (4), coloress crystals (1.3 g) having m.p. of 116-160°C were obtained from 4-(4-palmitoylamino-2-methylphenyloxy)piperidine hydrochloride (1.5 g). Elemental analysis, Calcd. for C₃₆H₅₈N₂O₉: C, 65.23; H, 8.82; N, 4.23 Found: C, 65.62; H, 8.99; N, 4.60 Examples 24-25 According to the same manner as that described in Ref. Example 23, the compounds shown in Table 2 were obtained. Example 26 4-(4-Decanylamino-3-methylphenyloxy)piperidine fumarate (1) 1-Acetyl-4-hydroxypiperidine (9.2 g) was dissolved in dimethylformamide (20 ml) and to the solution was added sodium hydride (oily, 60%, 2.6 g). The mixture was stirred at room temperature for 30 minutes and 5-fluoro-2-nitortoluene (10 g) was added dropwise thereto. The mixture was stirred at room temperature for 10 minutes. Water (50 ml) was added to the reaction mixture which was extracted with methylene chloride (50 ml x 3). The extract was dried over anhydrous sodium sulfate and the solvent was distilled off. To the resulting residue were added conc. hydrochloric acid (15 ml), ethanol (15 ml) and water (15 ml) and the mixture was heated at reflux overnight. The reaction mixture was concentrated under reduced pressure and the resulting residue was washed with ethyl ether and crystals were filtered off to obtain 4-(4-nitro-3-methylphenyloxy)piperidine hydrochloride (2.8 g) as yellow crystals, m.p. 233-236°C. (2) To a suspension of 4-(4-nitro-3-methylphenyloxy)piperidine hydrochloride (2,8 g) in methylene chloride (20 ml) were added dropwise triethylamine (2.1 g) and di-tert-butyl dicarbonate (2.7 g) and the mixture was stirred with ice-cooling for 20 minutes. Water was added to the reaction mixture, which was extracted with methylene chloride (50 ml x 3). The combined extract was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was washed with ethyl ether to obtain 1-tert-butyloxycarbonyl-4-(4-nitro-3-methylphenyloxy)piperidine (3.6 g) as yellow crystals, m.p. 104-106°C. (3) To a solution of 1-tert-butyloxycarbonyl-4-(4-nitro-3-methylphenyloxy)piperidine (3.6 g) in ethanol (30 ml) was added conc. hydrochloric acid (0.9 ml). By using 10% palladium/carbon (containing 48% water, 0.3 g) as a catalyst, catalytic reduction was conducted under reduced pressure for 1.5 hours. The catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to obtain 1-tert-butyloxycarbonyl-4-(4-amino-3-methylphenyloxy)piperidine hydrochloride (1.7 g) as light brown crystals, m.p. 160-180°C. (4) To a solution of 1-tert-butyloxycarbonyl-4-(4-amino-3-methylphenyloxy)piperidine hydrochloride (0.7 g) in methylene chloride (10 ml) were added triethylamine (0.62 g) and decanoyl chloride (0.39 g) with ice-cooling and the mixture was stirred at room temperature for 1 hour. Aqueous saturated solution of sodium dicarbonate was added to the reaction mixture and the organic layer was separated. The aqueous layer was further extracted with methylene chloride (50 ml x 2) and the combined organic layer was dried over sodium sulfate and concentrated under reduced pressure. To the solidified residue was added trifluoroacetic acid (5 ml) and the mixture was stirred at room temperature for 30 minutes. The reaction mixture was concentrated under reduced pressure, the resulting residue was dissolved in ethanol and conc. hydrochloric acid (0.20 ml) was added thereto. The resulting solution was concentrated under reduced pressure and the residue was washed with hexane to obtain 4-(4-decanoylamino-3-methylphenyloxy)piperidine hydrochloride (0.93 g) as white crystals, m.p. 177-195°C. Elemental analysis, Calcd. for C₂₂H₃₇N₂O₂Cl: C, 66.56; H, 9.39; N, 7.06 Found: C, 66.39: H, 9.36; N, 6.91 (5) According to the same manner as that described in Example 12, (4), colorless crystals (0.43 g) having m.p. of 110-129°C were obtained from 4-(4-decanylamino-3-methylphenyloxy)piperidine hydrochloride (0.8 g). Elemental analysis, Calcd. for C₂₆H₄₂N₂O₅: C, 67.50; H, 9.15; N, 6.06 Found: C, 67.66; H, 9.10; N, 6.17 Example 27 4-4-(Hexylamino-3-methylphenyloxy)piperidine fumarate According to the same manner as that described in Example 26, colorless crystals having m.p. of 131-140°C were obtained. Elemental analysis, Calcd. for C₂₂H₃₄N₂O₅: C, 65.00; H, 8.43; N, 6.85 Found: C, 65.18; H, 8.54; N, 7.06 Example 28 1-Acetyl-4-(4-pentylaminophenyloxy)piperidine 1-Acetyl-4-(4-aminophenyloxy)piperidine hydrochloride (2.5 g) obatined in Example 1, (2) was dissolved in methanol (20 ml) and to the solution were added sodium cyano borohydride (1.2 g) and pentylaldehyde (0.8 g) at room temperature. The mixture was stirred at room temperature for 1 hour. To the mixture was added aqueous saturated solution of sodium bicarbonate (50 ml) and the mixture was extracted with methylene chloride (50 ml x 3). The combined extract was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (delveoping solvent: ethyl acetate/hexane = 3/1 (v/v)) to obtain 1-acetyl-4-(4-pentylaminophenyloxy)piperidine (2.1 g) as white crystals, m.p. 69-71°C. Elemental analysis, Calcd. for C₁₈H₂₈N₂O₂: C, 71.02; H, 9.27; N, 9.20 Found: C, 70.92; H, 9.37; N, 9.09 Examples 29-39 According to the same manner as that described in Example 28, the compounds shown in Table 3 were obtained. Example 40 1-Acetyl-4-[4-(1-methylpentyl)amino-2-methyl]piperidine (1) To a solution of 1-Acetyl-4-(4-nitro-2-methylphenyoxy)piperidine (4.5 g) obtained in Example 23, (1) in ethanol (70 ml) was added conc. hydrochloric acid (1.4 ml) and, by using 10% palladium/carbon (containing 48% water, 0.5 g) as a catalyst, catalytic reduction was conducted under normal pressure for 2 hours. The catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to obtain 1-acetyl-4-(4-amino-2-methylphenyloxy)piperidine hydrochloride (5.1 g) as a light brown amorphous material. NMR (D₂O) δ: 1.72-2.01 (4H, m), 2.09 (3H, s), 2.21 (3H, s), 3.40-3.53 (2H, m), 3.64-3.75 (2H, m), 7.07-7.19 (3H, m) (2) According to the same manner as that described in Example 28, 1-acetyl-4-[4-(1-methylpentyl)amino-2-methylphenyloxy]piperidine (0.78 g) as a light brown oil from 1-acetyl-4-(4-amino-2-methylphenyloxy)piperidine hydrochloride (1.0 g). NMR (CDCl₃) δ: 0.87-0.94 (3H, m), 1.14 (3H, d, J=6.4 Hz), 1.30-1.58 (6H, m), 1.75-1.93 (4H, m), 2.11 (3H, s), 2.18 (3H, s), 3.28-3.42 (2H, m), 3.51-3.85 (3H, m), 4.25-4.35 (1H, m), 6.35 (1H, dd, J=2.8, 8.6 Hz), 6.43 (1H, d, J=2.8 Hz), 6.69 (1H, d, J=8.6 Hz) Example 41 According to the same manner as that described in Example 40, the compound shown in Table 4 was obtained. Examples 42-54 According to the same manner as that described in Example 5, the compounds shown in Tables 5 and 6 were obtained from the compounds of Examples 28, 29 and 31 to 41. Example 55 1-tert-Butyloxycarbonyl-4-(4-hexylaminophenyloxy)piperidine According to the same manner as that described in Example 28, colorless crystals having m.p. of 46-47°C was obtained by using 1-tert-butyloxycarbonyl-4-(4-aminophenyloxy)piperidine. Elemental analysis, Calcd. for C₂₂H₃₆N₂O₃: C, 70.17; H, 9.64; N, 7.44 Found: C, 69.96; H, 9.48; N, 7.38 Example 56 4-(4-Hexylaminophenyloxy)-1-methylpiperidine dihydrochloride To a solution of the compound of Example 55 (1.5 g) in tetrahydrofuran (20 ml) was added lithium aluminum hydride (0.15 g) and the mixture was heated under reflux for 4 hours. Water was added to the mixture and the precipitate formed was filtered off and the filtrate was concentrated. The residue was purified by silica gel column chromatography (developing solvent: methylene chloride/methanol = 10/1 (v/v)) to obtain 4-(4-hexylaminophenyloxy)-1-methylpiperidine (0.92 g) as a brown oil. The oil was dissolved in ethanol (20 ml), conc. hydrochloric acid (0.53 ml) was added to the solution and the solvent was distilled off to leave a solid. The solid was recrystallized from ethanol/ethyl ether to obtain 4-(4-hexylaminophenyloxy)-1-methylpiperidine dihydrochloride (0.76 g) as white crystals, m.p. 163-172°C. Elemental analysis, Calcd. for C₁₈H₃₂N₂OCl₂: C, 59.50; H, 8.88; N, 7.71 Found: C, 59.76; H, 8.94; N, 7.49 Example 57 4-(4-Hexylaminophenyloxy)-1-ethylpiperidine dihydrochloride According to the same manner as that described in Example 56, 4-(4-hexylaminophenyloxy)-1-ethylpiperidine dihydrochloride (0.62 g) was obtained by using the compound of Example 32 (0.98 g) as a non-crystalline solid. Elemental analysis, Calcd. for C₁₉H₃₄N₂OCl₂: C, 60.47; H, 9.08; N, 7.42 Found: C, 60.35; H, 9.32; N, 7.20 NMR (D₂O) δ: 0.78-0.85 (3H, m), 1.20-1.38 (9H, m), 1.58-1.73 (2H, m), 1.84-2.43 (4H, m), 3.02-3.69 (8H, m), 7.14, 7.15 (total 2H, each in 1:2 ratio, J-9.0 Hz), 7.40 (2H, d, J=9.0 Hz) Example 58 4-(4-Hexylaminophenyloxy)-1-phenylmethylpiperidine dihydrochloride (1) To a solution of the compound of Example 55 (11.3 g) in methylene chloride (50 ml) were added triethylamine (8.4 ml) and acetyl chloride (2.4 g) with ice-cooling. The mixture was allowed to warm to room temperaterature and stirred for 2 hours. Aqueous saturated solution of sodium bicarbonate was added to the reaction mixture and the organic layer was separated. The aqueous layer was further extracted with methylene chloride (50 ml x 2). The combined extract was dried over anhydrous sodium sulfate and the solvent was distilled off to obtain 1-tert-butyloxycarbonyl-4-(N-acetyl-N-hexylaminophenyloxy)piperidine (12.5 g) as a brown oil. (2) Trifluoroacetic acid (25 ml) was added to 1-tert-butyloxycarbonyl-4-(N-acetyl-N-hexylaminophenyloxy)piperidine (12.5 g) with ice-cooling and the mixture was stirred at room temperature for 1 hour. The reaction mixture was concentrated and methylene chloride (50 ml) was added to the residue and the mixture was washed with aqueous saturated solution of sodium bicarbonate. The aqueous layer was extracted with methylene chloride (50 ml x 3), the combined organic layer were dried over anhydrous sodium sulfate and the solvent was distilled off to obtain 4-(N-acetyl-N-hexylaminophenyloxy)piperidine (9.7 g) as a brown oil. (3) To a solution of 4-(N-acetyl-N-hexylaminophenyloxy)piperidine (1.4 g) in ethanol (10 ml) were added potassium carbonate (1.2 g) and benzyl chloride (0.54 g) and the mixture was heated under reflux overnight. Water was added to the reaction mixture, which was extracted with ethyl acetate (50 ml x 3). The combined extract was dried over anhydrous sodium sulfate and the solvent was distilled off. The residue was purified by silica gel column chromatography (developing solvent: methylene chloride/methanol = 10/1 (v/v)) to obtain 4-(N-acetyl-N-hexylaminophenyloxy)-1-phenylmethylpiperidine (1.2 g) as a pale yellow oil. NMR (CDCl₃) δ: 0.82-0.88 (3H, m), 1.25 (6H, m), 1.40-1.52 (2H, m), 1.80 (3H, s), 1.75-2.08 (4H, m), 2.32 (2H, ddd, J=3.4, 8.8, 11.4 Hz), 2.76 (2H, ddd, J=3.8, 5.8, 11.4 Hz), 3.54 (2H, s), 3.63 (2H, t, J=7.6 Hz), 4.26-4.36 (1H, m), 6.90 (2H, d, J=9.0 Hz), 7.03 (2H, d, J=9.0 Hz), 7.27-7.34 (5H, m) (4) According to the same manner as that described in Example 5, 4-(N-acetyl-N-hexylaminophenyloxy)-1-phenylmethylpiperidine (0.5 g) was subjected to deacetylation to obtain colorless crystals (0.41 g), m.p. 187-197°C. Elemental analysis, Calcd. for C₂₄H₃₆Cl₂N₂O: C, 65.59; H, 8.26; N, 6.37 Found: C, 65.79; H, 8.48; N, 6.35 Examples 59 and 60 According to the same manner as that described in Example 58, the compounds as shown in Table 7 were obtained. Found: C, 67.63; H, 8.18; N, 8.97 Example 61 1-Acetyl-4-(2-piperidin-1-ylphenyloxy)piperidine hydrochloride (1) According to the same manner as that described in Example 1, (1), 1-acetyl-4-(2-nitrophenyloxy)piperidine (4.0 g) as a brown oil was obtained from 1-acetyl-4-hydroxypiperidine (3.0 g) and o-fluoronitrobenzene (3.3 g). (2) According to the same manner as that described in Example 1, (2), 1-acetyl-4-(2-nitrophenyloxy)piperidine (4.0 g) was subjected to catalytic reduction to obtain 1-acetyl-4-(2-aminophenyloxy)piperidine (3.4 g) as a brown oil. This was dissolved in dimethylformamide (20 ml) and to the solution were added dibromopentane (3.6 g) and potassium carbonate (5.8 g). The mixture was heated to 100°C and stirred overnight. Water was added and the mixture was extracted with ethyl acetate (50 ml x 3). The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was dissolved in ethanol (30 ml), conc. hydrochloric acid (1.2 ml) was added thereto and the solvent was distilled off. The solid obtained was recrystallized from ethanol/ethyl ether to obtain 1-acetyl-4-(2-piperidin-1-ylphenyloxy)piperidine (4.9 g) as brown crystals, m.p. 69-70°C. Elemental analysis, Calcd. for C₁₈H₂₇N₂O₂Cl: C, 63.80; H, 8.03; N, 8.27 Found: C, 63.62; H, 8.07; N, 8.04 Example 62 1-Acetyl-4-(3-piperidin -1-ylphenyloxy)piperidine hydrochloride (1) According to the same manner as that described in Example 1, (1), 1-acetyl-4-(3-nitrophenyloxy)piperidine (2.1 g) as a brown oil was obtained from 1-acetyl-4-hydroxypiperidine (3.0 g) and m-fluoronitrobenzene (3.3 g). (2) Accoding to the same manner as that described in Example 1, (2), 1-acetyl-4-(3-nitorphenyloxy)piperidine (2.0 g) was subjected to catalytic reduction to obtain 1-acetyl-4-(3-aminophenyloxy)piperidine (2.0 g) as a brown oil. The oil and dibromopentane (2.2 g) were reacted according to the same manner as that described in Example 78, (2) to obtain 1-acetyl-4-(3-piperidin-1-ylphenyloxy)piperidine hydrochloride (2.3 g) as a brown amorphous material. Elemental analysis, Calcd. for C₁₈H₂₇N₂O₂Cl: C, 63.80; H, 8.03; N, 8.27 Found: C, 63.91; H, 8.11; N, 8.14 NMR (D₂O) δ: 1.67, 1.92 (total 10 H, brm), 2.04 (3H, s), 3.33-3.72 (8H, m), 4.66(1H, m), 7.05-7.14, 7.39-7.47 (total 4H, m) Example 63 4-(2-Piperidin-1-ylphenyloxy)piperidine 1/2 fumarate According to the same manner as that described in Example 5, 4-(2-piperidin-1-ylphenyloxy)piperidine 1/2 fumarate (0.94 g) as gray crystals having m.p. of 175-199°C was obtained from the compound of Example 78 (2.8 g). Elemental analysis, Calcd. for C₁₈H₂₆N₂O₃: C, 67.89; H, 8.23; N, 8.80 Found: C, 67.64; H, 8.27; N, 8.68 Example 64 4-(3-piperidin-1-ylphenyloxy)piperidine dihydorchloride According to the same manner as that described in Example 8, 4-(3-piperidine-1-ylphenyloxy)piperidine dihydrochloride (0.53 g) as light brown crystals having m.p. of 220-223°C was obtained form the compound of Example 79 (1.3 g). Elemental analysis, Calcd. for C₁₆H₂₆N₂OCl₂: C, 57.66; H, 7.86; N, 8.40 Found: C, 57.43; H, 7.80; N, 8.38 Examples 65-67 According to the same manner as that described in Example 12, the compounds shown in Table 8 were obtained. Preparation 1 (1) 4-(4-Pentylaminophenyloxy)piperidine fumarate (the compound of Example 43) 50 g (2) Lactose 198 g (3) Corn starch 50 g (4) Magnesium stearate 2 g The components (1) and (2) and corn starch (20 g) were admixed and the mixture was granulated with a paste prepared from corn starch (15 g) and water (25 ml). To this was added corn starch (15 g) and the component (4) and the resulting mixture was compressed to produce 1000 tablets of 5 mm in diameter containing the component (1) in an amount of 50 mg per one tablet. Preparation 2 4-(4-Pentylaminophenyloxy)piperidine fumarate (2 g) and mannitol (1.25 g) were dissolved in a water, pH was adjusted to 5 to 7 with 0.1 N NaOH and the total volume of the solution was made up to 100 ml. The solution thus obtained was sterilized by filtration through a filter of 0.2 µ. This was distributed into one hundred or 1 ml-ampoules. Preparation 3 (1) 4-[(4-Pyrrolidinophenyloxyl)methyl]piperidine fumarate (the compound of Example 16) 50 g (2) Lactose 198 g (3) Corn starch 50 g (4) Magnesium stearate 2 g The componenets (1) and (2) and corn starch (20 g) were admixed and the mixture was granulated with a paste prepared from corn starch (15 g) and water (25 ml). To this was added corn starch (15 g) and the component (4) and the resulting mixture was compressed to produce 1000 tablets of 5 mm in diameter containing the component (1) in an amount of 50 mg per one tablet. Preparation 4 4-[(4-Pyrrolidinophenyoxy)methyl]piperidine fumarate (the compound of Example 16, 2 g) and mannitol (1.25 g) were dissolved in water, pH was adjusted to 5 to 7 with 0.1 N NaOH and the total amount of the solution was made up to 100 ml. The solution thus obtained was sterilized by filtration through a filter of 0.2 µ. This was distributed into one hundred of 1 ml-ampoules. Experiment Protective activity to glutamic acid-induced necrocytosis in N18-RE-105 cells When a high concentration of glutamic acid (1 to 10 mM) is added to N18-RE-105 cells, neocrocytosis caused by oxidative stress due to inhibition of incorporation of cystine into cells is observed [Neuron 2 , 1547 (1989); J. Pharmacol. Exp. Ther. 250 , 1132 (1989)]. Activity of various compounds against this glutamic acid-induced necrocytosis was studied. About 10,000 cells were inoculated into a culture dish of 35 mm in diameter containing DMEM medium (1 ml). After cultivation for 24 hours, glutamic acid and a compound to be tested were added. After the medium was changed to DMEM mediums containing the compound in various concentrations and then glutamic acid (10 mM) was added. After addition of glutamic acid, cultivation was further continued for 24 hours. Then, surviving cells were collected and lactose dehydration enzyme (LDE) activity contained in the cells and medium was determined. A cell lethal ratio (%) was calculated according to the following formula: Cell lethal ratio (%) = LDH activity in medium LDH activity in cells + LDH activity in medium x 100 Regarding the typical compounds of the present invention, minimum concentrations for depressing cell lethal ratio to not more than 50% (IC₅₀) is shown in Table 9. Effect on glutamic acid cytotoxicity (cell lethal ratio) Example No. IC₅₀ (nM) 5 300 7 3000 15 10 16 0.8 24 2.5 26 1.6 27 10 43 10 44 8 45 5.5 46 1.1 49 6.4 52 10 As seen from Table 9, the compounds (I) of the present invention or salts thereof strongly inhibit necrosytosis due to glutamic acid.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, DK, FR, GB, IT, LI, LU, NL, SE Use of a compound of the formula (I): wherein A and B are independently (1) a group of the formula: wherein R₁ and R₂ are independently (i) hydrogen atom, (ii) a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, (iii) a 5- to 8-membered heterocyclic group which may contain 1 to 4 hetero atoms selected from the group consisting of a nitrogen, oxygen and sulfur in addition to carbon, which may be substituted by 1 to 3 substituents selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, or (iv) R₁ together with R₂ and the nitrogen atom to which they are bound may form a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, provided that both R₁ and R₂ are not hydrogen atom at the same time, or (2) a group of the formula: wherein D is O or S, R₃ is (i) hydrogen atom, (ii) a C₁₋₆, alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, or (iii) a C₂₋₆ alkyl-carbonyl, C₂₋₈ alkyl- or aralkyloxycarbonyl or C₁₋₄ alkyl- or dialkylaminocarbonyl group which may be substituted by 1 to 3 substituents selected from the group consisting of a halogen, amino and primary- or secondary-C₁₋₆ alkyl amino, m is 1, 2, or 3 and n is 0, 1, 2, 3 or 4; p is 1 or 2, provided that both A may be the same or different when p is 2; and R₄, R₅ and R₆ are independently hydrogen atom, a C₁₋₆ alkyl or a C₁₋₆ alkoxy, or R₅ and R₆ may bond together to form -CH=CH-CH=CH-, or a salt thereof in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells caused by glutamic acid. Use as claimed in claim 1, wherein A and B are or -NHR₁, wherein R₁ is a C₁₋₆ alkyl group. Use as claimed in claim 2, therein A is and R₁ is (CH₃)₂CH(CH₂)₃. Use as claimed in claim 1, wherein the effective component is N-[4-(4-methylpentylamino)phenyl]piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-pyrrolidinophenyloxy)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-dimethylaminophenyloxy)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 1-tert-butyloxycarbonyl-4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-[4-(4-pentylamino)-2-methylphenyloxy]piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-hexylamino -3-methylphenyloxy)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-pentylaminophenyloxy)piperidine or its salt. Use of 4-[4-(4-nonylamino)-2-methylphenyloxy]piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-decanylamino-3-methylphenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-heptylamino-phenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-octylamino-phenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-nonylamino-phenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells Use of 4-[4-(3-phenyl-2-propenylamino)phenyloxy]piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-[4-(1-phenyldecanylamino)phenyloxy]piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. A compound or the formula (II): wherein all symbols have the same meanings as defined in claim 1, or a salt thereof. A compound according to claim 19, wherein R₁ and R₂ are a C₁₋₄ alkyl group phenylmethyl group or R₁ and R₂ together with the nitrogen atom to which they are bound form a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group ; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen. A compound according to claim 20, wherein R₁ and R₂ are a C₁₋₃ alkyl group or R₁ and R₂ together with the nitrogen atom to which they are bound form a group of the formula: wherein s is 0, 1 or 2; and R₈ is hydrogen atom, phenyl or benzyl. A compound according to claim 19, wherein D is O, m is 2, n is 0 and R₃ is hydrogen atom or a C₁₋₆ alkyl group. A compound according to claim 19, wherein the group is A compound according to claim 19 which is 4-(4-pyrrolidinophenyloxy)piperidine or its salt. A compound according to claim 19 which is 4-(4-dimethylaminophenyloxy)piperidine or its salt. A compound according to claim 19 which is 1-tert-butyloxycarbonyl-4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. A compound according to claim 19 which is 4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. A compound according to claim 19 which is 4-[4-(4-pentylamino)-2-methylphenyloxy]piperidine or its salt. A compound according to claim 19 which is 4-(4- hexylamino -3-methylphenyloxy)piperidine or its salt. A compound according to claim 19 which is 4-(4-pentylaminophenyloxy)piperidine or its salt. 4-[4-(4-nonylamino)-2-methylphenyloxy]piperidine or its salt. 4-(4-decanylamino-3-methylphenyloxy)piperidine or its salt. 4-(4-heptylaminophenyloxy)piperidine or its salt. 4-(4-octylaminophenyloxy)piperidine or its salt. 4-(4-nonylaminophenyloxy)piperidine or its salt. 4-[4-(3-phenyl-2-propenylamino)phenyloxy]piperidine or its salt. 4-[4-(1-phenyldecanylamino)phenyloxy]piperidine or its salt. A process for producing a compound of the formula (II) according to claim 19, which comprises: (1) reacting a compound of the formula (II'): wherein R₃' is a C₂₋₆ alkyl-carbonyl, C₂₋₈ alkyl- or aralkyloxycarbonyl or C₁₋₄ alkyl- or dialkylaminocarbonyl group which may be substituted by 1 to 3 substituents selected from the group consisting of a halogen, amino and primary- or secondary-C₁₋₆ alkyl amino and the other symbols have the same meanings as defined in claim 1, with a compound of the formula (II''): wherein X is halogen and the other symbols have the same meanings as defined in claim 1, to obtain a compound of the formula (V ): wherein all symbols have the same menings as defined above, reducing the compound of the formula (V ) to obtain a compound of the formula (V'): wherein all symbols have the same meanings as defined above, and reacting the compound (V') with a compound of the formula (VI): R₁-X wherein R₁ has the same meaning as defined in claim 1 and X is halogen, to obtain a compound of the formula (Ia): wherein all symbols have the same meanings as defined above; or (2) reacting the above compound of the formula (V') with a compound of the formula (VII): R₁''-CHO wherein R₁'' is a C₁₋₅ alkyl, C₂₋₃ alkenyl or C₂₋₃ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₃ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, so that R₁''CH₂ becomes R₁ to obtain the compound or the formula (Ia); or (3) reacting the compound of the above formula (Ia) with a compound of the formula (VIII): R₂-X wherein R₂ has the same meaning as defined in claim 1 and X is halogen, or a compound of the formula (IX): R₂'-CHO wherein R₂' is a C₁₋₅ alkyl, C₂₋₃ alkenyl or C₂₋₃ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₃ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen so that R₂'CH₂ becomes R₂, to obtain a compound of the formula (Ib): wherein all symbols have the same meanings as defined above; or (4) reacting the above compound of the formula (V') with the above compound of the fromula (VI) or (VII) to obtain the above compound of the formula (Ib); or (5) reacting the above compound of the formual (V') with a compound of the formula (X): PO(OR₉)₃ wherein R₉ is a C₁₋₆ alkyl group, to obtain the above compound of the formula (Ib); or (6) reacting the above compound of the formula (V') with a compound of the formula (XI): wherein X is halogen and R₁ and R₂ are a divalent group corresponding to NR₁R₂ from which N is removed, to obtain a compound of the formula (Ic): wherein is a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group ; and R₈ is a C₁₋₃ alkyl, C₁-₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, or (7) subjecting the above compound of the formula (Ia), (Ib) or (Ic) to deacylation in the presence of a mineral acid to obtain a compound of the formula (Id): wherein all symbols have the same meanings as defined above; or (8) reacting the above compound of the formula (Id) with a compound of the formula (XII): R₃''-X wherein R₃'' is R₃ other than hydrogen atom and X is halogen, to obtain a compound of the formula (Ie): wherein all symbols have the same meanings as defined above; or (9) reacting the above compound of the formula (II'') with a compound of the formula (XIII): wherein R₃''' is a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, and the other symbols have the same meanings as defined above, to obtain a compound of the formula (XIV): wherein all symbols have the same meanings as defined above, reducing the compound of the formula (XIV) to obtain a compound of the formula (XV): wherein all symbols have the same meanings as defined above, reacting the compound of the formula (XV) with a compound of the formula (XVI): R₁''-CO-X wherein R₁'' has the same meaning as defined above and X is halogen, to obtain a compound of the formula (XVII): wherein all symbols have the same meanings as defined above, and reducing the compound of the formula (XVII) to obtain a compound of the formula (If): wherein all symbols have the same meanings as defined above; or (10) reacting the above compound of the formula (If) with a compound or the formula (XVIII) R₂'-CO-X wherein R₂' has the same meaning as defined above and X is halogen to obtain a compound of the formula (XIX): wherein all symbols have the same meanings as defined above, and reducing the compound of the formula (XIX) to obtain a compound of the formula (Ig): wherein all symbols have the same meanings as defined above. A compound of the formula (III): wherein R₁' is a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, except an alkyl group having no substituent; the group of the formula: represents a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, and the other symbols have the same meanings as defined in claim 1, or a salt thereof. A compound according to claim 39, wherein R₁' is a C₃₋₆ alkyl or cycloalkyl group and A compound according to claim 39 which is 4-[4-(4-methylpentylamino)phenyl]piperidine or its salt. A process or producing a compound of the formula (III) according to claim 39, which comprises: reacting a compound of the formula (XX): wherein Y is halogen, with a compound of the formula (XXI): wherein all symbols have the same meanings as defined in claim 39 to obtain a compound of the formula (XXII): wherein all symbols have the same meanings as defined in claim 39, reducing the compound of the formula (XXII) to obtain a compound of the formula (XXIII): wherein all symbols have the same meanings as defined above, reacting the compound of the formula (XXIII) with a compound of the formula (XXIV), (XXV) or (XXVI): R₁'CH₂-Y R₁'CHO R₁'-CO-Y wherein all symbols have the same meanings as defined in claim 39, to obtain a compound of the formula (XXVII): wherein all symbols have the same means as defined above, and reducing the compound of the formula (XXVII). A compound of the formula (IV): wherein R₁''' is the group of the formula: represents the same meaning as defined in claim 39, and the other symbols have the same meanings as defined in claim 1, or a salt thereof. A compound according to claim 43, wherein is A compound according to claim 43, wherein R₁''' is A compound according to claim 43 which is 4-[4-(piperidin -1-yl)phenylamino]piperidine or its salt. A process for producing a compound of the formula (IV) according to claim 43, which comprises: reacting a compound of the formula (XXIII): wherein all symbols have the same meanings as defined in claim 43, with a compound of the formula (XXVIII): wherein all symbols have the same meanings as defined in claim 43. N-[4-(4-methylpentylamino)phenyl]piperidine or a salt thereof, preferably its dihydrochloride salt. A central antioxidant having inhibitory activity of degeneration and necrocytosis of cerebral cells comprising as an effective component a compound as claimed in claims 19 to 37, 39 to 41, 43 to 46 and 48. Claims for the following Contracting States : ES, GR Use of a compound of the formula (I): wherein A and B are independently (1) a group of the formula: wherein R₁ and R₂ are independently (i) hydrogen atom, (ii) a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, (iii) a 5- to 8-membered heterocyclic group which may contain 1 to 4 hetero atoms selected from the group consisting of a nitrogen, oxygen and sulfur in addition to carbon, which may be substituted by 1 to 3 substituents selected from the group consisting or a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, or (iv) R₁ together with R₂ and the nitrogen atom to which they are bound may form a group of the formula: wherein s is 0, 1 or 2: t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, provided that both R₁ and R₂ are not hydrogen atom at the same time, or (2) a group of the formula: wherein D is O or S, R₃ is (i) hydrogen atom, (ii) a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7- membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, or (iii) a C₂₋₆ alkyl-carbonyl, C₂₋₈ alkyl- or aralkyloxycarbonyl or C₁₋₄ alkyl- or dialkylaminocarbonyl group which may be substituted by 1 to 3 substituents selected from the group consisting of a halogen, amino and primary- or secondary-C₁₋₆ alkyl amino, m is 1, 2, or 3 and n is 0, 1, 2, 3 or 4; p is 1 or 2, provided that both A may be the same or different when p is 2; and R₄, R₅ and R₆ are independently hydrogen atom, a C₁₋₆ alkyl or a C₁₋₆ alkoxy, or R₅ and R₆ may bond together to from -CH=CH-CH=CH-, or a salt thereof in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells caused by glutamic acid. Use as claimed in claim 1, wherein A and B are or -NHR₁, wherein R₁ is a C₁₋₆ alkyl group. Use as claimed in claim 2, wherein A is and R₁ is (CH₃)₂CH(CH₂)₃. Use as claimed in claim 1, wherein the effective component is N-[4-(4-methylpentylamino)phenyl]piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-pyrrolidinophenyloxy)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-dimethylamniophenyloxy)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 1-tert-butyloxycarbonyl-4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-[4-(4-pentylamino)-2-methylphenyloxy]piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-hexylamino -3-methylphenyloxy)piperidine or its salt. Use as claimed in claim 1, wherein the effective component is 4-(4-pentylaminophenyloxy)piperidine or its salt. Use of 4-[4-(4-nonylamino)-2-methylphenyloxy]piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-decanylamino-3-methylphenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-heptylamino-phenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-octylamino-phenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-(4-nonylamino-phenyloxy)piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. Use of 4-[4-(3-phenyl-2-propenylamino)phenyloxy]piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells, Use of 4-[4-(1-phenyldecanylamino)phenyloxy]piperidine or its salt in the preparation of a pharmaceutical composition for inhibiting the degeneration and necrocytosis of cerebral nerve cells. A process for producing a compound of the formula (II): wherein all symbols have the same meanings as defined in claim 1, or a salt thereof, which comprises: (1) reacting a compound or the formula (II'): wherein R₃' is a C₂₋₆ alkyl-carbonyl, C₂₋₈ alkyl- or aralkyloxycarbonyl or C₁₋₄ alkyl- or dialkylaminocarbonyl group which may be substituted by 1 to 3 substituents selected from the group consisting of a halogen, amino and primary- or secondary-C₁₋₆ alkyl amino and the other symbols have the same meanings as defined above, with a compound of the formula (II''): wherein X is halogen and the other symbols have the same meanings as defined above, to obtain a compound of the formula (V): wherein all symbols have the same meanings as defined above, reducing the compound of the formula (V) to obtain a compound of the formula (V'): wherein all symbols have the same meanings as defined above, and reacting the compound (V') with a compound of the formula (VI): R₁-X wherein R₁ has the same meaning as defined above and X is halogen, to obtain a compound of the formula (Ia): wherein all symbols have the same meanings as defined above; or (2) reacting the above compound of the formula (V') with a compound of the formula (VII): R₁''-CHO wherein R₁'' is a C₁₋₅ alkyl, C₂₋₃ alkenyl or C₂₋₃ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₃ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, so that R₁''CH₂ becomes R₁ to obtain the compound of the formula (Ia); or (3) reacting the compound of the above formula (Ia) with a compound of the formula (VIII): R₂-X wherein R₂ has the same meaning as defined above and X is halogen, or a compound of the formula (IX): R₂'-CHO wherein R₂' is a C₁₋₁₅ alkyl, C₂₋₃ alkenyl or C₂₋₃ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₃ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selects from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen so that R₂'CH₂ becomes R₂, to obtain a compound of the formula (Ib): wherein all symbols have the same meanings as defined above; or (4) reacting the above compound of the formula (V') with the above compound of the fromula (VI) or (VII) to obtain the above compound of the formula (Ib); or (5) reacting the above compound of the formual (V') with a compound of the formula (X): PO(OR₉)₃ wherein R₉ is a C₁₋₆ alkyl group, to obtain the above compound of the formula (Ib); or (6) reacting the above compound of the formula (V') with a compound of the formula (XI): wherein X is halogen and R₁ and R₂ are a divalent group corresponding to NR₁R₂ from which N is removed, to obtain a compound of the formula (Ic): wherein is a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, or (7) subjecting the above compound of the formula (Ia), (Ib) or (Ic) to deacylation in the presence of a mineral acid to obtain a compound of the formula (Id): wherein all symbols have the same meanings as defined above; or (8) reacting the above compound of the formula (Id) with a compound of the formula (XII): R₃''-X wherein R₃'' is R₃ other than hydrogen atom and X is halogen, to obtain a compound of the formula (Ie): wherein all symbols have the same meanings as defined above; or (9) reaching the above compound of the formula (II'') with a compound of the formula (XIII): wherein R₃''' is a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, and the other symbols have the same meanings as defined above, to obtain a compound of the formula (XIV): wherein all symbols have the same meanings as defined above, reducing the compound of the formula (XIV) to obtain a compound of the formula (XV): where all symbols have the same meanings as defined above, reacting the compound of the formula (XV) with a compound of the formula (XVI): R₁''-CO-X wherein R₁'' has the same meaning as defined above and X is halogen, to obtain a compound of the formula (XVII): wherein all symbols have the same meanings as defined above, and reducing the compound of the formula (XVII) to obtain a compound of the formula (If): wherein all symbols have the same meanings as defined above; or (10) reacting the above compound of the formula (If) with a compound of the formula (XVIII) R₂'-CO-X wherein R₂' has the same meaning as defined above and X is halogen to obtain a compound of the formula (XIX): wherein all symbols have the same meanings as defined above; or and reducing the compound of the formula (XIX) to obtain a compound of the formula (Ig): wherein all symbols have the same meanings as defined above. A process according to claim 19, wherein R₁ and R₂ are a C₁₋₄ alkyl group, phenylmethyl group or R₁ and R₂ together with the nitrogen atom to which they are bound form a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen. A process according to claim 20, wherein R₁ and R₂ are a C₁₋₃ alkyl group or R₁ and R₂ together with the nitrogen atom to which they are bound form a group of the formula: wherein s is 0, 1 or 2; and R₈ is hydrogen atom, phenyl or benzyl. A process according to claim 19 , wherein D is O, m is 2, n is 0 and R₃ is hydrogen atom or a C₁₋₆ alkyl group. A process according to claim 19 , wherein the group is A process according to claim 19 for producing 4-(4-pyrrolidinophenyloxy)piperidine or its salt. A process according to claim 19 for producing 4-(4-dimethylaminophenyloxy)piperidine or its salt. A process according to claim 19 for producing 1-tert-butyloxycarbonyl-4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. A process according to claim 19 for producing 4-(4-pyrrolidinophenyloxymethyl)piperidine or its salt. A process according to claim 19 for producing 4-[4-(4-pentylamino)-2-methylphenyloxy]piperidine or its salt. A process according to claim 19 for producing 4-(4-hexylamino -3-methylphenyloxy)piperidine or its salt. A process according to claim 19 for producing 4-(4-pentylaminophenyloxy)piperidine or its salt. A process for producing a compound of the formula (III): wherein R₁' is a C₁₋₆ alkyl, C₂₋₄ alkenyl or C₂₋₄ alkynyl group which may be substituted by 1 to 4 substituents selected from the group consisting of a halogen, C₁₋₃ alkoxy, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino and hydroxylgroup, or a C₆₋₁₂ aryl or C₇₋₁₄ aralkyl which may be substituted by 1 to 3 substituents on the rings thereof selected from the group consisting of a C₁₋₃ alkoxy, C₁₋₃ alkyl, cyano, amino, mono- or di-C₁₋₆ alkylamino, 5- to 7-membered cyclic amino, hydroxyl, nitro and halogen, except an alkyl group having no substituent; the group of the formula: represents a group of the formula: wherein s is 0, 1 or 2; t is 1 or 2; R₇ is hydrogen atom or a C₁₋₆ alkyl group; and R₈ is a C₁₋₃ alkyl, C₁₋₃ alkylcarbonyl, oxo, hydroxy, phenyl, benzyl, diphenylmethyl, amino or hydrogen, and the other symbols have the same meanings as defined in claim 1, or a salt thereof, which comprises: reacting a compound of the formula (XX): wherein Y is halogen, with a compound of the formula (XXI): wherein all symbols have the same meanings as defined above to obtain a compound of the formula (XXII): wherein all symbols have the same meanings as defined above, reducing the compound of the formula (XXII) to obtain a compound of the formula (XXIII): wherein all symbols have the same meanings as defined above, reacting the compound of the formula (XXIII) with a compound of the formula (XXIV), (XXV) or (XXVI): R₁'CH₂-Y R₁'CHO R₁'-CO-Y wherein all symbols have the same meanings as defined above, to obtain a compound of the formula (XXVII): wherein all symbols have the same meanings as defined above, and reducing the compound of the formula (XXVII). A process according to claim 31, wherein R₁' is a C₃₋₆ alkyl or cycloalkyl group and is A process according to claim 31 for producing 4-[4-(4-methylpentylamino)phenyl]piperidine or its salt. A process according to claim 31 for producing N-[4-(4-methylpentylamino)phenyl]piperidine or a salt thereof, preferably its dihydrochloride salt. A process for producing a compound of the formula (IV): wherein R₁''' is the group of the formula: represents the same meaning as defined in claim 31, and the other symbols have the same meanings as defined in claim 1, or a salt thereof, which comprises: reacting a compound of the formula (XXIII): wherein all symbols have the some meanings as defined above, with a compound of the formula (XXVIII): wherein all symbols have the same meanings as defined above. A process according to claim 35, wherein is A process according to claim 35, wherein R₁''' is A process according to claim 35 for producing 4-[4-(piperidin -1-yl)phenylamino]piperidine or its salt. Use of a compound according to claims 19 to 38 as an effective component for the manufacture of a central antioxidant having inhibitory activity of degeneration and necrocytosis of cerebral cells.

Inventors: GOTO GIICHI, MIYAMOTO MASAOMI, YUKIMASA HIDEFUMI, GOTO, GIICHI, MIYAMOTO, MASAOMI, YUKIMASA, HIDEFUMI
Applicants: TAKEDA CHEMICAL INDUSTRIES LTD, TAKEDA CHEMICAL INDUSTRIES, LTD.
Application year: 1991
Main classification: C07D211
IPC codes: A61P25, C07D207, C07D223, C07D401, A61K31, C07D211, C07D295, A61P9