Bisphosphonic acid derivatives, their production and use

Abstract: A compound of the formula (I): wherein W is a group of the formula: A ○-O-(CH₂) n - wherein A ○ is a cyclic group which may be substituted, n is an integer of 2 to 10, or W is a group of the formula: R¹-X-(CH₂) n' - wherein R¹ is an alkyl group which may be substituted, X is an oxygen atom or a sulfur atom which may be oxidized, n' is an integer of 4 to 10; R² is a hydrogen atom or a lower alkanoyl group; R³, R⁴, R⁵ and R⁶ are the same or different and are a hydrogen atom or a lower alkyl group, or a salt thereof, is useful as a bone resorption inhibitor.

Description: Field of The Invention The present invention relates to alkylaminomethylenebisphosphonic acid derivatives, lower alkyl esters thereof and pharmaceutically acceptable salts thereof, which are useful as a medicament having bone resorption inhibitory activity as well as antiinflammatory activity, antirheumatic activity, for example, and to pharmaceutical compositions containing them as active ingredients. Prior Art Substituted aminomethylenebisphosphonic acid derivatives wherein the substituent is 3-methoxypropyl, 2-ethoxyethyl and 2-ethylthioethyl are specifically described in Japanese Patent Laid Open Publication No. 37829/1979. Although these compounds are described as being usable as herbicides and fungicides, there is no suggestion about the utility thereof as drugs. Although various bisphosphonic acid derivatives have heretofore been produced for use as bone resorption inhibitors (Japanese Patent Laid Open Publication Nos. 258695/1989, 308290/1989, 184/1990 and 185/1990, and EP-A-0337706), none of them are as satisfactory as desired in terms of activity and side effects. The present invention relates to (1) novel bisphosphonic acid derivatives having excellent bone resorption inhibitory activity and (2) bone resorption inhibitory compositions containing said novel compounds and the use of said novel compounds or known bisphosphonic acid derivatives that the present inventors first have found to be useful as possessing bone resorption inhibitory activity in the preparation of a therapeutic composition for osteoporosis. The present inventors have studied intensely to develop bisphosphonic acid derivatives which are more useful as bone resorption inhibitors. As a result, it has been found that bisphosphonic acid derivatives of the following formula (I) as shown hereinafter can directly affect thebone to manifest excellent bone resorption inhibitory activity. Summary of The Invention The compound according to the present invention is structurally characterized in that it has a hydroxy group substituted with a cyclic group; alkoxy, alkylthio, alkylsulfinyl, or alkylsulfonyl group on the alkyl side chain of the alkylamino group, and the compound can be used as a bone resorption inhibitor. According to the present invention, there is provided, (1) a compound of the formula (I): wherein W is a group of the formula: A ○-O-(CH₂) n - wherein A ○ is a cyclic group which may be substituted, n is an integer of 2 to 10, or W is a group of the formula: R¹-X-(CH₂) n' - wherein R¹ is an alkyl group which may be substituted, X is an oxygen atom or a sulfur atom or a thioether sulfinyl or sulfonyl group, n is an integer of 4 to 10; R² is a hydrogen atom or a lower alkanoyl group; R³, R⁴, R⁵ and R⁶ are the same or different and are a hydrogen atom or a lower alkyl group, or a salt thereof. (2) Use of a compound of formula (II) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier, diluent or excipient in the preparation of a therapeutic composition for osteoporosis, wherein formula (II) is: wherein W' is a group of the formula: A ○-O-(CH₂) n - wherein each symbol is as defined above, or W' is a group of the formula: R¹-X-(CH₂) n - wherein each symbol is as defined above; the other symbols are as defined above, or a salt thereof, and (3) a process for producing the compound of the formula (I) or a salt thereof which comprises reacting an amine derivative of the formula (III): W"-NH₂ (III) wherein W" is a group of the formula: A ○-O-(CH₂) n - wherein each symbol is as defined above, or W" is a group of the formula: R¹-Y-(CH₂) n' - wherein Y is an oxygen or sulfur atom and the other symbols are as defined above, with an orthoformate derivative of the formula (IV): CH(OR⁷)₃ (IV) wherein R⁷ is a lower alkyl group, and a phosphite derivative of the formula (V): wherein R⁸, R⁹, R¹⁰ and R¹¹ are the same or different and are a lower alkyl group, and then optionally subjecting the resultant compound to acylation, oxidation and/or hydrolysis. Detailed Disclosure of The Invention In the above-mentioned formula, the cyclic group in the cyclic group which is represented by A ○, includes aromatic or non-aromatic homo- and heterocyclic groups. Examples of the aromatic homo-cyclic group include C₆₋₁₄ aromatic hydrocarbon groups such as phenyl, naphthyl and anthryl. Preferable examples of the aromatic heterocyclic group include 5- or 6-membered aromatic heterocyclic groups having 1 to 4 nitrogen atoms, oxygen atoms and/or sulfur atoms (e.g. pyridyl, pyrimidinyl, pyridazinyl, furyl, thienyl, imidazolyl, thiazolyl, oxazolyl, isoxazolyl, thiadiazolyl and pyrazinyl) and condensed aromatic heterocyclic groups (e.g. benzothiazolyl, benzoxazolyl, benzimidazolyl, s-triazolo[1,2-a]pyridyl, imidazo[1,2-b]pyrazinyl and imidazo[1,2-a]pyridyl,). Preferable examples of the non-aromatic heterocyclic group include 5- or 6-membered non-aromatic heterocyclic groups having 1 to 4 nitrogen atoms, oxygen atoms and/or sulfur atoms (e.g. thiazolin-2-yl, oxazolin-2-yl, etc.). Preferable examples of the non-aromatic homo-cyclic group include C₃₋₇ cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. Examples of substituents of these cyclic groups include a halogen atom, nitro group, an optionally substituted alkyl group, an optionally substituted hydroxyl group and an optionally substituted thiol group. One to four, preferably one or two, of these substituents, which may be the same or different, can take any position on the cyclic group. The term "halogen atom" used herein includes fluorine, chlorine, bromine and iodine. The alkyl in the optionally substituted alkyl group is preferably, a C₁₋₇ straight-chain or branched alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl or heptyl; or a C₃₋₇ cycloalkyl group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or cycloheptyl. These groups may be substituted with one to three substituents such as a halogen atom (e.g. fluorine, chlorine, bromine or iodine), hydroxyl group or C₁₋₆ alkoxy group (e.g. methoxy, ethoxy, propoxy, butoxy and hexyloxy). The examples of the substituted alkyl group include trifluoromethyl, 2,2,2-trifluoroethyl, trichloromethyl, hydroxymethyl, 2-hydroxyethyl and 2-methoxyethyl. The substituent of the substituted hydroxyl group is exemplified by a protecting group for a hydroxyl group, for example, alkoxy, alkenyloxy, aralkyloxy, acyloxy and aryloxy. Examples of the alkoxy include C₁₋₆ straight-chain or branched alkoxy groups (e.g. methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentoxy, isopentoxy, neopentoxy and hexyloxy,) and C₄₋₆ cycloalkoxy groups (e.g. cyclobutoxy, cyclopentoxy and cyclohexyloxy), and examples of the alkenyloxy preferably include C₂₋₆ alkenyloxy groups (e.g. allyloxy, crotyloxy, 2-pentenyloxy, 3-hexenyloxy and 2-cyclopentenylmethoxy). As the aralkyloxy group, preferably, C₆₋₁₉ aralkyloxy groups, more preferably, C₆₋₁₄ aryl-C₁₋₄ alkyloxy groups (e.g. benzyloxy or phenethyloxy) can be used. As the acyloxy group, preferably, alkanoyloxy groups, for example, C₂₋₇ alkanoyloxy groups (e.g. acetyloxy, propionyloxy, n-butylyloxy, iso-butylyloxy or hexanoyloxy) can be used. As the aryloxy group, preferably, C₆₋₁₄ aryloxy groups (e.g. phenoxy or biphenyloxy) can be used. These groups may be further substituted with one to three substituents such as the above-mentioned halogen atom, hydroxyl group and C₁₋₆ alkoxy groups and the like. Specific examples of the substituted hydroxyl group include trifluoromethoxy, difluoromethoxy, 2,2,2-trifluoroethoxy, 2-methoxyethoxy, 4-chlorobenzyloxy and 2-(3,4-dimethoxyphenyl)ethoxy. The substituted thiol group is a thiol group having a suitable substituent, particularly, a protecting group for a thiol group, for example, alkylthio, aralkylthio or acylthio. As the alkylthio group, preferably, a C₁₋₆ straight-chain or branched alkylthio group (e.g. methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, sec-butylthio, tert-butylthio, pentylthio, isopentylthio, neopentylthio and hexylthio), and a C₄₋₇ cycloalkylthio group (e.g. cyclobutylthio, cyclopentylthio, cyclohexylthio and cycloheptylthio) can be used. As the aralkylthio group, preferably, a C₇₋₁₉ aralkylthio group, more preferably, a C₆₋₁₄ aryl-C₁₋₄ alkylthio group such as benzylthio or phenethylthio can be used. As the acylthio group, preferably, C₂₋₇ alkanoylthio (e.g. acetylthio propionylthio, n-butyrylthio, iso-butyrylthio and hexylthio) can be used. These groups may be further substituted with one to three substituents such as the above-mentioned halogen atom, hydroxyl group and C₁₋₆ alkoxy group. Specific examples of the substituted thiol group include trifluoromethylthio, difluoromethylthio, 2,2,2-trifluoriethylthio, 2-methoxyethylthio, 4-chlorobenzylthio, 3,4-dichlorobenzylthio, 4-fluorobenzylthio and 2-(3,4-dimethoxyphenyl)ethylthio. Specific examples of the substituted aromatic hydrocarbon group include 4-chlorophenyl, 2-fluorophenyl, 4-nitrophenyl, 3-methylphenyl, 3-trifluoromethylphenyl, 5,6,7,8-tetrahydro-2-naphthyl, 4-methoxyphenyl, 3,4-methylenedioxyphenyl, 4-(4-chlorobenzyloxy)phenyl, 4-acetoxyphenyl, 3-methylthiophenyl, 2-acetamidophenyl and 6-methoxy-2-naphthyl. Specific examples of the substituted aromatic heterocyclic group include 2-chloropyridyl, 5-nitro-2-pyridyl, 3-hydroxy-2-pyridyl, 6-methoxy-2-pyridyl, 2-methyl-4-pyridyl, 4-methyl-2-pyrimidinyl, 4-hydroxy-6-methyl-pyrimidinyl, 5-trifluoromethyl-2-benzothiazolyl and 5-chloro-2-triazolo[1,2-a]pyrid-3-yl. Specific examples of the substituted heterocyclic group include 5-phenyl-2-thiazolin-2-yl and 5-methyl-2-oxazolin-2-yl. A ○ is, preferably, a phenyl, pyridyl, pyrimidinyl or pyridazinyl group, which is unsubstituted or substituted with a halogen atom, a C₁₋₆ alkyl group or a C₁₋₆ alkoxy group. As the alkyl of the alkyl group which may be substituted, which is represented by R¹, is preferable a C₁₋₇ straight-chain or branched alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl or hexyl heptyl. These groups may be substituted with 1 to 3 substituents such as halogen (e.g. fluorine, chlorine, bromine, iodine), hydroxyl, an optionally substituted C₆₋₁₄ aromatic hydrocarbon group such as phenyl, naphthyl or anthryl, optionally substituted 5- or 6-membered aromatic heterocyclic group having 1 to 4 nitrogen atoms, oxygen atoms and/or sulfur atoms (e.g. pyridyl, pyrimidinyl, furyl, thienyl, imidazolyl, thiazolyl, oxazolyl, isoxazolyl, thiadiazolyl, pyrazolyl, pyrazinyl and triazolyl), an optionally substituted condensed aromatic heterocyclic group (e.g. benzothiazolyl, benzoxazolyl or benzimidazolyl), C₁₋₆ alkoxy group (e.g. methoxy, ethoxy, propoxy, butoxy, hexyloxy) and carboxyl which may be esterified. More preferably, R¹ is a C₁₋₇ straight-chain or branched alkyl group or a C₁₋₇ straight-chain or branched alkyl substituted with phenyl. Examples of substituents of said C₆₋₁₄ aromatic hydrocarbon group, 5- or 6-membered aromatic heterocyclic group or condensed aromatic heterocyclic group include a halogen atom; nitro group; a C₁₋₇ straight-chain or branched alkyl or C₃₋₇ cycloalkyl group which may be substituted with 1 to 3 substituents such as a halogen atom, hydroxyl group and C₁₋₆ alkoxy group; a hydroxy group; a C₁₋₆ straight-chain or branched alkoxy group; a C₄₋₆ cycloalkoxy group; a C₂₋₆ alkenyloxy group; a C₆₋₁₄ aryl-C₁₋₄alkoxy group; a C₂₋₇ alkanoyloxy group; a C₆₋₁₄ aryloxy group; a thiol group; a C₁₋₆ straight-chain or branched alkylthio group; a C₄₋₇ cycloalkylthio group; a C 6-14, aryl-C₁₋₄ alkylthio group; C₂₋₇ alkanoylthio group. Examples of the esterified carboxyl group are a group of the formula -COOR (R is an ester residue). Examples of the ester residues of R are C₁₋₇ straight-chain or branched alkyl, C₃₋₇ cycloalkyl, C₇₋₁₀ aralkyl (e.g. phenyl-C₁₋₄ alkyl), C₂₋₁₀ alkenyl and C₆₋₁₄ aryl (e.g. phenyl, naphthyl, anthryl, phenanthryl). Specific examples of the substituted alkyl represented by R¹ include trifluoromethyl, 2,2,2-trifluoroethyl, trichloromethyl, hydroxymethyl, 2-hydroxyethyl, benzyl, 4-(2-methoxyethyl)benzyl, 4-chlorobenzyl, 2-phenylethyl, 2-pyridylmethyl and 2-methyl-4-thiazolylmethyl. The lower alkanoyl group represented by R² is preferably an C₁₋₆ alkyl-carbonyl group, such as acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl and hexanoyl, or a sulfonic acyl group having a C₁₋₆ hydrocarbon moiety (e.g. methanesulfonyl, ethanesulfonyl, propanesulfonyl, hexanesulfonyl, benzenesulfonyl). The lower alkyl groups represented by R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹, include C₁₋₄ straight-chain or branched alkyl groups, such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl or tert-butyl. The sulfur atom which may be oxidized, which is represented by X, forms a thioether, sulfinyl or sulfonyl linkage between R¹ and (CH₂) n or (CH₂) n' . The symbol n stands for a whole number of 2 through 10 while n' means a whole number of 4 through 10. The symbol n is preferably 3, 4 or 5 and n' is preferably 4 or 5, more preferably, n and n' are 4. W and W' are preferably a group of the formula A ○-(O-(CH₂) n - wherein each symbol is as defined above. The compound of the formulas (I) and (II) or a salt thereof can be produced by the process described in Japanese Patent Laid Open Publication No. 37829/1979 or by per se known method. For example, the compound (I) or a salt thereof can be produced by the following processes. The salts of the compounds described hereinafter may be the same as those described with respect to the compound (I). Process A [wherein W" is a group of the formula: A ○-O-(CH₂) n - wherein each symbol is defined hereinbefore, or W" is a group of the formula: R¹-Y-(CH₂) n' - wherein Y is an oxygen atom or a sulfur atom and R¹ and n' are as defined above; the other symbols are as defined hereinbefore] Process B [wherein R 2' is a lower acyl group; each symbol is as defined hereinbefore] Process C [wherein k is 1 or 2; the other symbols are as defined hereinbefore] Process D [wherein each symbol is as defined hereinbefore] Process E-1 (I-1) → a bisphosphonic acid diester. Process E-2 (I-1), (I-2) or (I-4) → a bisphosphonic acid mono- or tri-ester. The respective processes are now described in detail. Process A This process comprises reacting an amine derivative (VI) with an orthoformate derivative (IV) and a phosphite derivative (V) to give a bisphosphonate derivative (I-1). The relative amount of the compounds (VI), (V) and (IV) may be 2:4:1. The reaction may be carried out in a conventional solvent but use of the solvent is not essential. This reaction is usually conducted at 80°C to 200°C, preferably at 100°C to 170°C for 10 minutes to 15 hours. Process B This process comprises acylating the compound (I-1) prepared in accordance with Process A. This acylation is carried out by reacting the compound (I-1) with 1 to 2 equivalents of an acylating agent, i.e. an acid corresponding to the lower alkanoyl group represented by R² or its reactive derivative (acid anhydride or acid halide) in a solvent or without using a solvent. The solvent may for example be benzene, xylene, toluene, chloroform, dichloromethane, ethyl acetate, ether or tetrahydrofuran. The reaction is conducted at 0°C to 100°C for 30 minutes to 10 hours. Process C This oxidation reaction is carried out by the conventional procedure using an oxidizing agent. The oxidizing agent is preferably a mild oxidizing agent which does not substantially affect the skeletal structure of compound (I-3), such as m-chloroperbenzoic acid, hydrogen peroxide, peresters or sodium metaperiodate. This reaction is conducted in an organic solvent which does not adversely interfere with the reaction. As the solvent, for example, a halogenated hydrocarbon (e.g. methylene chloride, chloroform or dichloroethane), hydrocarbon (e.g. benzene or toluene), or alcohol (e.g. methanol, ethanol or propanol) or a mixed solvent thereof can be used. When an equimolar amount or less of the oxidizing agent is used based on the compound (I-3), the compound of formula (I-4) wherein k is 1 is preferentially produced. When more than anequimolar amount of the oxidizing agent is used, the compound (I-4) wherein k is 1 is further oxidized to produce the compound (I-4) wherein k is 2. This reaction proceeds at a temperature below room temperature (20°C to 30°C). Preferably, the reaction temperature is in the range of -50°C to 20°C. The reaction time is 30 minutes to 10 hours. Process D In this process, the bisphosphonate (I-1), (I-2) or (I-4), synthesized by process A, B or C as the case may be, is hydrolyzed to the corresponding bisphosphonic acid (I-5). This reaction is conducted using an inorganic acid, such as hydrochloric acid or hydrobromic acid, or a halotrialkylsilane in a solvent which does not interfere with the reaction. When an inorganic acid such as hydrochloric acid or hydrobromic acid is used, the solvent may be alcohol, such as methanol, ethanol, 2-methoxyethanol, ethylene glycol, propanol, butanol, acetic acid or water or mixed solvent thereof. The acid is generally used in large excess, the reaction temperature is in the range of 0°C to 150°C, preferably 30°C to 100°C, and the reaction time is 1 to 50 hours. When a halogenated alkylsilane such as chlorotrimethylsilane, bromotrimethylsilane, iodotrimethylsilane, etc. is used, a halogenated hydrocarbon such as carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane or 1,1,2,2-tetrachloroethane, or acetonitrile, or a mixed solvent thereof can be used as a solvent. The proportion of the halogenated alkylsilane is 4 to 10 equivalents, preferably 4 to 8 equivalents, based on the compound (I-1), (I-2) or (I-4). The reaction temperature is in the range of -30°C to 100°C, preferably -10°C to 50°C, and the reaction time is 30 minutes to 100 hours. Process E-1 This process comprises subjecting bisphosphonic acid tetraester (I-1) produced by Process A to hydrolysis with a base to give bisphosphonic acid diester. The proportion of the base (sodium hydroxide or potassium hydroxide, for example) is 2 to 2.2 molar equivalents, based on the compound (I-1), and the hydrolysis is conducted in an aqueous solvent in accordance with a conventional method. Process E-2 In this process, the bisphosphonic acid tetraester (I-I), (I-2) or (I-4), produced by process A, process B or process C, is subjected to partial hydrolysis with a halogenated alkylsilane to give bisphosphonic acid mono- or tri-ester. The proportion of the halogenated alkylsilane (chlorotrimethylsilane, bromotrimethylsilane, iodotrimethylsilane, etc.) is, in the case of producing triester, 1 to 1.2 molar equivalent, and, in the case of producing monoester, 3 to 3.3 molar equivalents, based on the compound (I-1) or (I-2), and the reaction is conducted in accordance with the process D. The bisphosphonic acid derivative (I) thus obtained can be isolated and purified according to known means for separation and purification, for example, by concentration, concentration under reduced pressure, solvent extraction, precipitation, recrystallization, chromatography and the like. For conversion of such bisphosphonic acid to a salt, the acid is treated with a base such as potassium hydroxide, sodium hydroxide, sodium methoxide, ammonia or an organic amine in the per se conventional manner. The starting compound (III) of the present invention can be prepared by the following and other processes. Process F [wherein Z is a leaving group; the other symbols are as defined hereinbefore] This process comprises reacting the compound (VII) or (VIII) with the compound (IX) in the presence of a base to give the compound (X). The leaving group represented by Z includes halogen atoms, preferably chlorine, bromine and iodine, hydroxyl activated in the form of an ester, organic sulfonic acid residues (e.g. p-toluenesulfonyloxy), C₁₋₄ alkylsulfonyloxy (e.g. methanesulfonyloxy) and organic phosphoric acid residues such as diphenylphosphoryloxy, dibenzylphosphoryloxy, dimethylphosphoryloxy and so on. The reaction of the compounds (VII) or (VIII) with (IX) is conducted in an appropriate solvent. This solvent includes aromatic hydrocarbons such as benzene, toluene or xylene, ethers such as dioxane, tetrahydrofuran or dimethoxyethane, alcohols such as methanol, ethanol or propanol, ethyl acetate, acetonitrile, pyridine, N,N-dimethylformamide, dimethyl sulfoxide, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, acetone, 2-butanone, and a mixed solvent thereof. The reaction of the compounds (VII) or (VIII) with (IX) is carried out in the presence of an appropriate base, which may for example be an alkali metal salt such as sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate or sodium hydrogen carbonate, sodium hydride, potassium hydride or an amine such as pyridine, triethylamine, N,N-dimethylaniline and so on. The preferred proportion of the base is about 1 to 5 moles based on the compound (VII) or (VIII). This reaction is usually conducted at -20°C to 150°C and preferably at 0°C to 130°C for 1 to 10 hours. Process G Production of the starting material compound (X) First-stage reaction [wherein each symbol is as defined hereinbefore] In this process, the compound (VII) or (VIII) is reacted with the compound (XI) in a substantially equimolar ratio in the presence of a base to give the compound (XII) in the first place. This reaction of the compounds (VII) or (VIII) with (XI) is carried out in the same manner as Process F. Second-stage reaction In this process, the compound (XII) prepared by the first-stage reaction of Process G is reacted with potassium phthalimide in a substantially equimolar ratio to give the compound (X). This reaction between the compound (XII) and potassium phthalimide is carried out in an appropriate solvent. The solvent includes aromatic hydrocarbons such as benzene, toluene or xylene; ethers such as dioxane, tetrahydrofuran or dimethoxyethane; alcohols such as methanol, ethanol or propanol; and such other solvents as ethyl acetate, acetonitrile, pyridine, N,N-dimethyl-formamide, dimethyl sulfoxide, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, acetone, 2-butanone, and a mixed solvent thereof. This reaction is usually conducted at -20°C to 150°C and preferably 30°C to 130°C for 1 to 10 hours. Process H Production of the compound (III) This process comprises reacting the compound (X) prepared by Processes F and G with hydrazine hydrate to give a compound of the formula (III). The reaction between the compound (X) and hydrazine hydrate is carried out in an appropriate solvent. The solvent includes aromatic hydrocarbons such as benzene, toluene or xylene; ethers such as dioxane, tetrahydrofuran or dimethoxyethane; alcohols such as methanol, ethanol or propanol, and such other solvents as N,N-dimethylformamide, dimethyl sulfoxide, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane and a mixed solvent thereof. The proportion of hydrazine hydrate is 1 to 10 mole equivalents, preferably 1.2 to 5 mole equivalents, based on the compound (X). This reaction is usually conducted at -20°C to 150°C and preferably at 0°C to 100°C for 1 to 10 hours. The compound (III) thus obtained can be isolated and purified by the known workup procedures such as concentration, concentration under reduced pressure, solvent extraction, crystallization, recrystallization, redistribution, chromatography and so on. The preferred salts of the compound (I) are pharmaceutically acceptable salts, e.g. inorganic salts including alkali metal salts such as sodium salt or potassium salt, alkaline earth metal salts such as calcium salt, magnesium salt or ammonium salts; organic base salts such as methylamine salt, ethylamine salt, propylamine salt, isopropylamine salt, butylamine salt, tert-butylamine salt, dimethylamine salt, diethylamine salt, trimethylamine salt, triethylamine salt, pyridine salt, picoline salt, dicyclohexylamine salt or N,N-dibenzylethylenediamine salt; organic acid addition salts such as formate, acetate, trifluoroacetate, maleate, tartrate, methanesulfonate, benzenesulfonate or toluenesulfonate; inorganic acid addition salts such as hydrochloride, hydrobromide or sulfonate; and amino acid salts such as glutamic acid. The compound (I) or a salt thereof provided by the present invention has bone resorption inhibitory activity and, as such, inhibit the loss of bone caused by bone resorption. The compound (I) has low toxicity and little side effect. Therefore, the compound (I) of the invention can be used in the prevention or treatment of osteoporosis in mammalian animals (e.g. mouse, rat, rabbit, dog, cat, cattle, pig or man). For administration of the compound to human beings, the oral and other routes can be selectively employed. Compositions for oral administration may be solid or liquid, and specifically tablets (including dragees and film-coated tablets), pills, granules, powders, capsules (including soft capsules), syrups, emulsions, suspensions etc. may be mentioned. Such compositions can be manufactured by the per se known methods and may contain the carrier or excipient which is commonly employed in the pharmaceutical practice. Thus, lactose, starch, sucrose, magnesium stearate, etc. may be mentioned as examples of the carrier/excipient for powders or tablets. Compositions for non-oral administration include injections and suppositories, for instance, and the injections include subcutaneous, intradermal and intramuscular injections, for instance. Such injections can be manufactured by the per se known method, viz. suspending or emulsifying compound (I) in a sterile aqueous or oily vehicle which is commonly used in the manufacture of injections. The aqueous vehicle for injection includes, among others, physiological saline, other isotonic solutions for example, and, if necessary, may contain an appropriate suspending agent such as carboxymethylcellulose sodium, nonionic surfactants. The oily vehicle includes, among others, sesame oil, soybean oil, for example and, as cosolvents or solubilizers, benzyl benzoate, benzyl alcohol, for example can be employed. The injections so prepared are filled into appropriate ampules. For use as a prophylactic or therapeutic agent for osteoporosis, the useful daily dosage of compound (I) or a salt thereof for oral administration is estimated to be 1 to 500 mg and preferably 10 to 200 mg. The method for estimating the bone resorption inhibitory activity, and hence the therapeutic effect on osteoporosis, of compound (I) and the results of assessments are presented below. [Prophylactic and therapeutic effect on osteoporosis] The test compound was administered intraperitoneally to 6-week-old Sprague-Dawley rats for 2 days. On the day following the last administration (third day), right sciatic neurotomy was performed and the bilateral tibias were removed on the 17th day. The proximal half of each tibia was cut off at right angles with its major axis, dried at 110°C for 6 hours and, then, weighed to find dry weights. The mean ± S.E. of the values for 6 animals per group was calculated. The results are shown in Tables 1 and 2. Reference Example 1 A mixture of phenol (3.0 g), N-(4-bromobutyl)-phthalimide (9.0 g), potassium carbonate (4.4 g) and N,N-dimethylformamide (DMF) (50 ml) was stirred at 100°C for 4 hours. The reaction mixture was poured into water and extracted with ethyl acetate. The ethyl acetate layer was washed with water and dried (MgSO₄), then the solvent was distilled off under reduced pressure to give 4-(4-phenoxybutyl)phthalimide (8.1 g, 87%). Recrystallization of the product from acetone gave colorless prisms, m.p.102°C to 103°C. Reference Examples 2 and 3 By substantially the same procedure as Reference Example 1, compounds shown in Table 3 were obtained. Reference Example 4 A mixture of 2-hydroxypyridine (6.0 g), N-(4-bromobutyl)phthalimide (17.8 g), potassium carbonate (8.7 g) and N,N-dimethylformamide (DMF) (80 ml) was stirred at 100°C for 3 hours. The reaction mixture was poured into water and extracted with ethyl acetate. The ethyl acetate layer was washed with water and dried (MgSO₄), then the solvent was distilled off under reduced pressure. The oily residue was subjected to a silica gel column chromatography. From the fraction eluted with chloroform - ethyl acetate (4:1 v/v), N-[4-(2-pyridyloxy)butyl]phthalimide (4.4 g, 23%) was obtained. Recrystallization of the product from ether gave colorless prisms, m.p. 77°C to 78°C. Reference Example 5 A mixture of N-(4-phenoxybutyl)phthalimide (7.8 g), hydrazine hydrate (7 ml) and ethanol (150 ml) was stirred for one hour under reflux. Crystalline precipitate was filtered off, then the filtrate was concentrated under reduced pressure to give 4-phenoxybutylamine (4.2 g, 95%) as an oily product. NMR(in CDCl₃, δ ppm): 1.53-1.90 (4H,m), 2.77 (2H,t, J =7Hz), 3.98 (2H,t, J =7Hz), 6.85-6.99 (3H,m), 7.22-7.34 (2H,m). Reference Examples 6 - 8 By substantially the same procedure as Reference Example 5, compounds shown in Table 4 were obtained. Reference Examples 9-21 By substantially the same procedure as Reference Example 1, compounds shown in Table 5 were obtained. Reference Examples 22-34 By substantially the same procedure as Reference Example 5, compounds shown in Tables 6 and 7 were obtained. Example 1 A mixture of 4-phenoxybutylamine (4.15 g), ethyl orthoformate (5.6 g) and diethyl phosphite [HP(O)(OC₂H₅)₂] (13.9 g) was stirred for two hours at 150°C. The reaction mixture was concentrated under reduced pressure. The oily residue was subjected to a silica gel column chromatography. From the fraction eluted with chloroform - ethyl acetate - methanol (20:20:1, v/v), tetraethyl 4-phenoxybutylaminomethylenebisphosphonate (3.6 g, 32%) was obtained as an oily product. NMR(in CDCl₃, δ ppm): 1.35 (12H,t, J =7Hz), 1.50-2.10 (4H,m), 2.92 (2H,t, J =7Hz), 3,27 (1H,t, J =22Hz), 3.97 (2H,t, J =7Hz), 4.10-4.35 (8H,m), 6.85-6.99 (3H,m), 7.22-7.35 (2H,m). Examples 2 - 4 By substantially the same procedure as Example 1, compounds shown in Table 8 were obtained. Example 5 A mixture of tetraethyl 4-phenoxybutylaminomethylenebisphosphonate (1.37 g) and concentrated hydrochloric acid (20 ml) was heated for two hours under reflux. The reaction mixture was concentrated under reduced pressure. The concentrate was treated with water to give 4-phenoxybutylaminomethylenebisphosphonic acid (0.549 g, 53%), m.p. 206°C to 208°C. NMR (in d₆-DMSO, δ ppm): 1.60-1.95 (4H,m), 3.23 (2H,t, J =7Hz), 3.42 (1H,t, J =18Hz), 3.94 (2H,t, J =7Hz), 6.86-6.97 (3H,m), 7.20-7.33 (2H,m). Elemental Analysis for C₁₁H₁₉NO₇P₂ : Calcd.: C, 38.95; H, 5.65; N, 4.13 Found : C, 39.24; H, 5.84; N, 3.99 Example 6 By substantially the same procedure as Example 5, 3-phenoxypropylaminomethylenebisphosphonic acid hemihydrate was obtained, m.p. 226°C to 227°C. NMR (in d₆-DMSO, δ ppm): 2.07-2.27 (2H,m), 3.38 (2H,t, J =7Hz), 3.51 (1H,t, J =18Hz), 4.02 (2H,t, J =7Hz), 6.88-6.99 (3H,m), 7.22-7.33 (2H,m). Elemental Analysis for C₁₀H₁₇NO₇P₂·1/2H₂O: Calcd.: C, 35.94; H, 5.43; N, 4.19 Found : C, 35.80; H, 5.68; N, 4.02 Example 7 A mixture of tetraethyl 4-(2-pyridyloxy)butylaminomethylenebisphosphonate (0.85 g) and conc. hydrochloric acid (10 ml) was heated for 2 hours under reflux. The reaction mixture was concentrated under reduced pressure. The concentrate was treated with methanol to give a solid matter, which was recrystallized from water-methanol to give 4-(2-pyridyloxy)butylaminomethylenebisphosphonic acid hydrochloride hemihydrate (0.471 g, 65%), m.p. 155°C to 157°C. NMR (in D₂O, δ ppm): 1.93-2.12 (4H,m), 3.52 (2H,t, J =7Hz), 3.57 (1H,t, J =18Hz), 4.54 (2H,t, J =7Hz), 7.44-7.55 (2H,m), 8.28 (1H,d, J =6Hz), 8.45 (1H,t,J=9Hz). Elemental Analysis for C₁₀H₁₈N₂O₇P₂·HCl·1/2H₂O: Calcd.: C, 31.14; H, 5.23; N, 7.26 Found : C, 31.05; H, 5.70; N, 7.16 Example 8 4-Phenoxybutylaminomethylenebisphosphonic acid (0.54 g) was suspended in methanol (20 ml), to which was added a methanol solution of sodium methoxide (28%, 0.782 g), and the mixture was stirred for 3 hours at room temperature. The reaction mixture was concentrated under reduced pressure. The concentrate was treated with acetone to give a solid matter, which was recrystallized from water-methanol to give 4-phenoxybutylaminomethylenebisphosphonic acid disodium salt 1.5 hydrate (0.56 g, 85%), m.p. >300°C. NMR (in D₂O, δ ppm) : 1.86-1.99 (4H,m), 3.05 (1H,t, J =16Hz), 3.44 (2H,t, J =7Hz), 4.15 (2H,t, J =7Hz), 7.01-7.11 (3H,m), 7.33-7.45 (2H,m). Elemental Analysis for C₁₁H₁₇NO₇P₂Na₂·1.5H₂O: Calcd.: C, 32.21; H, 4.91; N, 3.41 Found : C, 32.02; H, 4.90; N, 3.26 Example 9 By substantially the same procedure as Example 8, 3-phenoxypropylaminomethylenebisphosphonic acid disodium salt 1.5 hydrate was obtained, m.p.> 300°C . NMR (in D₂O, δ ppm): 2.26 (2H,m), 3.13 (1H,t, J =16Hz), 3.60 (2H,t, J =7Hz), 4.24 (2H,t, J =7 Hz), 7.02-7.14 (3H,m), 7.34-7.45 (2H,m). Elemental Analysis for C₁₀H₁₅NO₇P₂Na₂·1.5H₂O: Calcd.: C, 30.32; H, 4.58; N, 3.54 Found : C, 30.05; H, 4.66; N, 3.43 Example 10 To a solution of tetraethyl 4-(4-chlorophenoxy)butylaminomethylenebisphosphonate (5.9g) in acetonitrile (90 ml) was added bromotrimethylsilane (11.2 g). The mixture was stirred for 15 hours at room temperature. To the reaction mixture was added water (3 ml), which was concentrated under reduced pressure. The residual oily product was dissolved in methanol (50 ml), to which was added a methanol solution of sodium methoxide (28%, 14.2 ml), followed by processing with ether (150 ml), then resulting precipitate was collected by filtration. Recrystallization from water-methanol gave 4-(4-chlorophenoxy)butylaminomethylenebisphosphonic acid tetrasodium salt (2.56 g, 42%), m.p. > 300°C. NMR (in D₂O, δ ppm): 1.90 (4H,m), 3.01 (1H,t, J =16Hz), 3.40 (2H,s), 4.11 (2H,s), 6.99 (2H,d, J =9Hz), 7.35 (2H,d, J =9Hz). Elemental Analysis for C₁₁H₁₄NO₇P₂ClNa₄·1/2H₂O·CH₃OH: Calcd.: C, 28.67; H, 3.81; N, 2.79 Found : C, 28.92; H, 4.09; N, 3.03 Examples 11-23 By substantially the same procedure as Example 1, compounds shown in Tables 9 and 10 were obtained. Example 24 By substantially the same procedure as Example 10, 5-phenoxypentylaminomethylenebisphosphonic acid disodium salt trihydrate was obtained, which was recrystallized form water-methanol. m.p. > 300°C Elemental Analysis for C₁₂H₁₉NO₇P₂Na₂·3H₂O: Calcd.: C, 31.94; H, 5.58; N, 3.10 Found : C, 32.04; H, 5.39; N, 2.96 Example 25 5-Phenoxypentylaminomethylenebisphosphonic acid disodium salt trihydrate (1.0 g) was dissolved in water (5 ml). The solution was processed with a column of CG-50 (H⁺ type, 32 ml). The solid matter obtained from the acidic portion eluted with water was recrystallized from water-methanol to afford 5-phenoxypentylaminomethylenebisphosphonic acid monosodium salt hemihydrate (0.58 g, 68%) as colourless prisms, m.p. > 300°C. Elemental Analysis for C₁₂H₂₀NO₇P₂Na·1/2H₂O: Calcd.: C, 37.51; H, 5.51; N, 3.65 Found : C, 37,62; H, 5.53; N, 3.55 Examples 26-30 By substantially the same procedure as Example 5, compounds shown in Table 11 were obtained. Examples 31-33 By substantially the same procedure as Example 8, compounds shown in Table 12 were obtained. Example 34 By substantially the same procedure as Example 10, 4-(3,4-methylenedioxyphenoxy)butylaminomethylenebisphosphonic acid trisodium salt monohydrate was obtained, which was recrystallized from water-methanol. m.p.>300°C. Elemental Analysis for C₁₂H₁₆NO₉P₂Na₃·H₂O: Calcd.: C, 30.85; H, 3.88; N, 3.00 Found : C, 31.07; H, 4.02; N, 2.99 Examples 35 and 36 By substantially the same procedure as Example 7, compounds shown in Table 13 were obtained. Example 37 To a solution of tetraethyl 4-(2-pyrimidinyloxy)butylaminomethylenebisphosphonate (5.0 g) in acetonitrile (90 ml) was added bromotrimethylsilane (10.1 g), and the mixture was stirred for 16 hours at room temperature. To the reaction mixture was added water (2 ml), which was stirred for one hour at room temperature, followed by concentration under reduced pressure. The concentrate was suspended in water (5 ml), to which was added an aqueous solution of sodium hydroxide (1 N, 11.7 ml). To the reaction mixture was added ethanol, then precipitating crystals were collected by filtration, followed by recrystallization from water-acetone to give 4-(2-pyrimidinyloxy)butylaminomethylenebisphosphonic acid monosodium salt dihydrate (1.4 g, 31%) as colorless crystals, m.p.>300°C. Elemental Analysis for C₉H₁₆N₃O₇P₂Na·2H₂O: Calcd.: C, 27.08; H, 5.05; N, 10.53 Found : C, 27.31; H, 5.02; N, 10.60 Example 38 By substantially the same procedure as Example 37, 3-(2-pyrimidinyloxy)propylaminomethylenebisphosphonic acid disodium salt dihydrate was obtained, which was recrystallized from water-ethanol. m.p. >300°C. Elemental Analysis for C₈H₁₃N₃O₇P₂ Na₂·2H₂O: Calcd.: C, 23.60; H, 4.21; N, 10.32 Found : C, 23.70; H, 4.35; N, 10.05 Example 39 By substantially the same procedure as Example 37, 4-(2-pyrazinyloxy)butylaminomethylenebisphosphonic acid monosodium salt 2.5 hydrate was obtained, which was recrystallized from water-acetone. m.p. >300°C. Elemental Analysis for C₉H₁₆N₃O₇P₂Na·2.5H₂O: Calcd.: C, 26.48; H, 5.19; N, 10.29 Found : C, 26.45; H, 4.88; N, 10.29 Example 40 By substantially the same procedure as Example 37, 4-(2-quinoxalinyloxy)butylaminomethylenebisphosphonic acid monosodium trihydrate was obtained, which was recrystallized from water-ethanol. m.p.>300°C. Example 41 A mixture of tetraethyl 4-(2-pyridyloxy)butylaminomethylenebisphosphonate (5.5 g) and acetic anhydride (12.3 g) was stirred for 52 hours at room temperature. The reaction mixture was concentrated under reduced pressure, then the concentrate was subjected to a silica gel column chromatography, followed by elution with ethyl acetate - ethanol (50:1,v/v). From the fraction thus eluted, tetraethyl N-acetyl-4-(2-pyridyloxy)butylaminomethylenebisphosphonate (2.9 g, 49%) as an oily product. NMR(in CDCl₃, δ ppm): 1.33(12H,t, J =7 Hz), 1.70-2.05(4H,m), 2.19(3H,s), 3.62-3.75(2H,m), 4.10-4.30(8H,m), 4.27(2H,t, J =6 Hz), 5.92(1H,t, J =25.5 Hz), 6.72(1H,ddd, J =8, 1 and 1 Hz), 6.85(1H,ddd, J =7, 5 and 1 Hz), 7.57(1H,ddd, J =8, 7 and 2 Hz), 8.17(1H,ddd, J =5, 2 and 1 Hz). Example 42 To a solution of tetraethyl N-acetyl-4-(2-pyridyloxy)butylaminomethylenebisphosphonate (2.8 g) in acetonitrile (50 ml) was added bromotrimethylsilane (5.2 g), and the mixture was stirred for 15 hours at room temperature. To the reaction mixture was added water (1.2 ml), which was stirred for one hour at room temperature, followed by concentration under reduced pressure. The concentrate was dissolved in methanol (10 ml), to which was added a methanol solution of sodium methoxide (28%, 2.2 g). The reaction mixture was concentrated under reduced pressure. The residual crystals were collected by filtration and recrystallized from methanol-acetone to give N-acetyl-4-(2-pyridyloxy)butylaminomethylenebisphosphonic acid disodium salt trihydrate (2.0 g, 71%) as colorless crystals, m.p. 133°C to 135°C. Elemental Analysis for C₁₂H₁₈N₂O₈P₂Na₂·3H₂O: Calcd.: C, 30.01; H, 5.04; N, 5.83 Found : C, 29.91; H, 5.20; N, 6.02 Example 43 4-(2-Pyridyloxy)butylaminomethylenebisphosphonic acid hydrochloride (1.1 g) was dissolved in water (25 ml), to which was added an aqueous solution of sodium hydroxide (1N, 3 ml). To the mixture was added methanol to cause precipitation of a solid matter, which was collected by filtration and recrystallized from water-methanol to afford 4-(2-pyridyloxy)butylaminomethylenebisphosphonic acid trihydrate (0.6 g, 51%) as colorless crystals, m.p. 186°C to 187°C. Elemental Analysis for C₁₀H₁₈N₂O₇P₂·3H₂O: Calcd.: C, 30.47; H, 6.14; N, 7.11 Found : C, 30.40; H, 5.98; N, 6.93 Example 44 4-(2-Pyridyloxy)butylaminomethylenebisphosphonic acid hydrochloride (2.0 g) was dissolved in water (50 ml), to which was added an aqueous solution of sodium hydroxide (1N, 15.9 ml). The reaction mixture was concentrated and then dissolved in water (50 ml). To the solution was added methanol to cause precipitation of a solid matter. The solid matter was collected by filtration and washed with methanol to give 4-(2-pyridyloxy)butylaminomethylenebisphosphonic acid disodium salt monohydrate (1.3 g, 62%) as colorless crystals, m.p.>300°C. Elemental Analysis for C₁₀H₁₆N₂O₇P₂Na₂·H₂O: Calcd.: C, 29.86; H, 4.51; N, 6.97 Found : C, 29.70; H, 4.74; N, 6.73 Example 45 A mixture of 3-methylthiopropylamine (5.47 g), ethyl orthoformate (19.27 g) and diethyl phosphite (35.91 g) was refluxed for 3 hours. The reaction mixture was concentrated under reduced pressure and the oily residue was subjected to a silica gel column chromatography. Elution with ethyl acetate-chloroformmethanol (5:5:1, v/v) gave tetraethyl 3-methylthiopropylaminomethylenebisphosphonate as an oil (8.91 g, 44%). NMR (δ ppm in CDCl₃) : 1.36 (12H, t, J =7 Hz), 1.75 (1H, s), 1.76 (2H, quintet, J =7 Hz), 2.10 (3H, s), 2.57 (2H, t, J =7 Hz), 2.95 (2H, t, J =7 Hz), 3.25 (1H, t, J =22 Hz), 4.14-4.30 (8H, m). Example 46 To a solution of tetraethyl 3-methylthiopropylaminomethylenebisphosphonate (5.28 g) in acetonitrile (100 ml) was added bromotrimethylsilane (12.39 g) and the mixture was stirred at room temperature for 15 hours. The reaction mixture was diluted with water (3.2 ml) and concentrated under reduced pressure. The solid residue was collected by filtration and recrystallized from water-methanol to give 3-methylthiopropylaminomethylenebisphosphonic acid hemihydrate (1.84 g, 47%). Colorless prisms, m.p. 120-122°C Elemental Analysis for C₅H₁₅NO₆S·0.5H₂O: Calcd.: C, 20.84; H, 5.60; N, 4.86 Found : C, 20.86; H, 5.91; N, 4.79 Examples 47-57 By substantially the same procedure as Example 45, compounds shown in Tables 14 and 15 were obtained. Examples 58-62 By substantially the same procedure as Example 45, compounds shown in Table 16 were obtained. Example 63 To a solution of tetraethyl 2-(2-phenylethylthio)ethylaminomethylenebisphosphonate (4.4 g) in acetonitrile (90 ml) was added bromotrimethylsilane (8.6 g), and the mixture was stirred for 16 hours at room temperature. The reaction mixture was diluted with water (2 ml), which was stirred for one hour at room temperature, followed by concentration under reduced pressure. The residual solid was suspended in methanol (50 ml), to which was added a methanol solution of sodium methoxide (28%, 3.2 g). To the solution was added ether to cause precipitation crystals. The crystals collected by filtration were recrystallized from water-methanol to give 2-(2-phenylethylthio)ethylaminomethylenebisphosphonic acid disodium salt 1.5 hydrate (2.0 g, 49%) as colorless crystals, m.p.>300°C. Elemental Analysis for C₁₁H₁₇NO₆P₂SNa₂·1.5H₂O: Calcd.: C, 30.99; H, 4.73; N, 3.29 Found : C, 30.80; H, 4.67; N, 3.16 Example 64 By substantially the same procedure as Example 63, disodium 4-tert·butylthiobutylaminomethylenebisphosphonate was obtained. Recrystallization was conducted from water-methanol. m.p.>300°C Elemental Analysis for C₉H₂₁NO₆P₂SNa₂·2.5H₂O: Calcd.: C, 25.48; H, 6.18; N, 3.30 Found : C, 25.59; H, 6.32; N, 3.23 Example 65 By substantially the same procedure as Example 63, trisodium 3-methoxypropylaminomethylenebisphosphonate was obtained. Recrystallization was performed from water-methanol. m.p.>300°C Example 66 In water (5 ml) was dissolved 3-methoxypropylaminomethylenebisphosphonic acid trisodium salt trihydrate (1.0 g), and the solution was passed through a column packed with Amberlite CG-50 (H+ type, 75 ml). Elution was conducted with water. From the acidic fraction thus eluted, 3-methoxypropylaminomethylenebisphosphonic acid monosodium salt hemihydrate (0.67 g, 87%) was obtained as colorless prisms, m.p. 277-279°C. Elemental Analysis for C₅H₁₄NO₇P₂Na·1/2H₂O: Calcd.: C, 20.42; H, 5.14; N, 4.76 Found : C, 20.64; H, 5.40; N, 4.80 Example 67 To a solution of tetraethyl 3-ethoxypropylaminomethylenebisphosphonate (8.3 g) in acetonitrile (100 ml) was added bromotrimethylsilane (19.6 g), which was stirred for 16 hours at room temperature. The reaction mixture was diluted with water (10 ml), which was stirred for one hour at room temperature, followed by concentration under reduced pressure. The concentrate was dissolved in methanol (20 ml), to which was added a methanol solution of sodium methoxide (28%, 30 g). To the reaction mixture was added ether to cause precipitation of a solid matter. The solid matter was collected by filtration and dissolved in water (10 ml), which was processed with a column of CG-50 (H+ type, 200 ml). From the acidic fraction eluted with water, monosodium 3-ethoxypropylaminomethylenebisphosphonate (3.8 g, 58%) was obtained. Recrystallization was performed from water - methanol. m.p.>300°C. Elemental Analysis for C₆H₁₆NO₇P₂Na·1/2H₂O: Calcd.: C, 23.39; H, 5.56; N, 4.55 Found : C, 23.32; H, 5.59; N, 4.29

Claims: A compound of the formula (I): wherein W is a group of the formula: A ○-O-(CH₂) n - wherein A ○ is a cyclic group which may be substituted, n is an integer of 2 to 10 or W is a group of the formula: R¹-X-(CH₂) n' - wherein R¹ is an alkyl group which may be substituted, X is an oxygen atom or a sulfur atom or a thioether sulfinyl or sulfony group, n' is an integer of 4 to 10; R² is a hydrogen atom or a lower alkanoyl group; R³, R⁴, R⁵ and R⁶ are the same or different and are a hydrogen atom or a lower alkyl group, or a pharmaceutically acceptable salt thereof. A compound of claim 1 wherein W is a group of the formula: A ○ -O-(CH₂) n - wherein A ○ is a cyclic group which may be substituted, n is an integer of 2 to 10. A compound of claim 1 wherein A ○ is a phenyl, pyridyl, pyrimidinyl or pyridazinyl group which is unsubstituted or substituted with a halogen atom, a C₁₋₆ alkyl or C₁₋₆ alkoxy group. A compound of claim 1 wherein R¹ is a C₁₋₇ straight-chain or branched alkyl group which is unsubstituted or substituted with a phenyl group. A compound of claim 1 wherein n is 3, 4 or 5. A compound of claim 1 wherein n is 4. A compound of claim 1 wherein n' is 4 or 5. A compound of claim 1 which is 4-phenoxybutylaminomethylenebisphosphonic acid. A compound of claim 1 which is 4-(2-pyridyloxy)butylaminomethylenebisphosphonic acid. A compound of claim 1 which is 4-(2-pyrimidinyloxy) butylaminomethylenebisphosphonic acid. A process for producing the compound of the formula (I) as claimed in claim 1 or a salt thereof which comprises reacting an amine derivative of the formula (III): W"-NH₂ (III) wherein W" is a group of the formula: A ○-O-(CH₂) n - wherein A ○ is a cyclic group which may be substituted, n is an integer of 2 to 10, or W" is a group of the formula: R¹-Y-(CH₂) n' - wherein R¹ is an alkyl group which may be substituted, Y is an oxygen atom or a sulfur atom, n' is an integer of 4 to 10, with an orthoformate derivative of the formula (IV): CH(OR⁷)₃ (IV) wherein R⁷ is a lower alkyl group, and a phosphite derivative of the formula (V): wherein R⁸, R⁹, R¹⁰ and R¹¹ are the same or different and are a lower alkyl group, and then optionally subjecting the resultant compound to acylation, oxidation and/or hydrolysis. A bone resorption inhibitory composition which comprises an effective inhibitory amount of the compound of the formula (I) as claimed in claim 1 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier, diluent or excipient. Use of a compound of formula (II) wherein W' is a group of the formula: A ○-O-(CH₂) n - wherein A ○ is a cyclic group which may be substituted, n is an integer of 2 to 10, or W' is a group of the formula:i R¹-X-(CH₂) n - wherein R¹ is an alkyl group which may be substituted, X is an oxygen atom or a sulfur atom or a thioether sulfinyl or sulfonyl group, n is an integer of 2 to 10; R² is a hydrogen atom or a lower alkanoyl group; R³, R⁴, R⁵ and R⁶ are the same or different and are a hydrogen atom or a lower alkyl group or a pharmaceutically acceptable salt thereof in the preparation of a therapeutic composition for osteoporosis. Use of 3-methylthiopropylaminomethylenebisphosphonic acid according to claim 13. Use of 2-(2-phenylethylthio)ethylaminomethylenebisphosphonic acid according to claim 13.

Inventors: SHODA TAKASHI, TAKETOMI SHIGEHISA, SHODA, TAKASHI, TAKETOMI, SHIGEHISA
Applicants: TAKEDA CHEMICAL INDUSTRIES LTD, TAKEDA CHEMICAL INDUSTRIES, LTD.
Application year: 1991
Main classification: C07F9
IPC codes: C07F9