PROCESS FOR PRODUCING AZACYCLOALKANE DERIVATIVE

Abstract: A process for producing an azacycloalkane derivative represented by general formula (II), wherein m represents an integer of 1 to 3, n₂ represents an integer of 2 to 10, and R represents C₃ to C₁₂ alkyl, which comprises reacting 1-(n-alkenyl)azacycloalkan-2-one represented by general formula (I) wherein, m is as defined above and n₁ represents an integer of 0 to 8, with an alkyl mercaptan in the presence of a radical initiator in an organic solvent, treating the reaction product with a reducing agent in a watery organic solvent, followed by purification through distillation.

Description: [Technical Field] The present invention relates to a process for producing an azacycloalkane derivative which is useful in the fields of medicines and agricultural chemicals as a compound having an action of promoting absorption. [Background Art] Azacycloalkane derivatives are compounds which are useful as absorption promoters capable of enhancing the penetrability and permeability of drugs while scarcely irritating biomembranes and having little systemic toxicity. Among these compounds, 1-[2-(decylthio)ethyl]azacyclopentan-2-one exerts remarkable effects and, therefore, is expected as highly useful in medicines and agricultural chemicals. As will be described hereinafter, however, the existing process for producing 1-[2-(decylthio)ethyl]azacyclopentan-2-one with such a high purity as to be applicable to medicines and agricultural chemicals are far from satisfactory from the industrial and economic viewpoints. Therefore, it has been urgently required to develop a process for readily producing such compound at a low cost. More specifically, the existing processes for producing azacycloalkane derivatives include the following ones, as described in JP-A-62-238261 (238261/1987): (1) a process comprising reacting an azacycloalkan-2-one with a dihalogenoalkyl in excess in the presence of an alkali metal hydride catalyst to obtain a reaction product and then reacting the product with a halogenoalkyl in the presence of a phase transfer catalyst in an alkaline aqueous solution of sodium sulfide; (2) a process comprising adding a dihalogenoalkyl in large excess to an azacycloalkan-2-one in the presence of an alkali metal hydride catalyst to obtain a reaction product and then reacting the product with an alkyl mercaptan in the presence of a dehydrohalogenating agent in an inert solvent which does not participate in the reaction; (3) a process comprising reacting a 1-(n-alkenyl)azacycloalkan-2-one with an alkyl mercaptan in the presence of a radical initiator in benzene or the like; (4) a process comprising reacting an alkyl mercaptan with a dihalogenoalkyl in excess in the presence of a dehydrohalogenating agent to obtain a reaction product and then reacting the product with an azacycloalkan-2-one; and (5) a process comprising adding a halogenoalkyl mercaptan to an alkali salt of an azacycloalkan-2-one to obtain a reaction product and then reacting the product with a halogenoalkyl in the presence of a dehydrohalogenating agent. However, each of these processes has some serious industrial problems and, therefore, is not satisfactory. In the above processes (1), (2), (4) and (5), for example, it is necessary to use an alkali metal hydride which is expensive and difficult to handle. In addition, the reaction time is as long as about 12 hours and a product with a high purity can be hardly obtained. Therefore, much labor is required for purifying the product. Thus, these processes cannot be regarded as industrially advantageous ones. Furthermore, it requires a long time and a large cost to secure a high purity by these processes. On the other hand, the above process (3) is a relatively easy one. However, a considerably large amount of dialkyl disulfides having boiling points closely similar to those of azacycloalkane derivatives are formed as by-products in this case. Accordingly, a product of such a high purity as to be applicable to medicines and agricultural chemicals can be hardly obtained by simple procedures such as distillation (see Comparative Example 1 which will be given hereinafter). In order to remove these by-products, it is necessary to perform troublesome operations such as column chromatography or recrystallization prior to distillation (see JP-A-63-30466). Thus, this process cannot be regarded as an economically advantageous one. Further, it has been confirmed that the use of benzene or the like as the reaction solvent causes the formation of isomers which lowers the purity of the product, since it is impossible to completely remove these isomers by column chromatography, recrystallization or distillation. An object of the present invention is to solve these problems encountering in the prior art and more particularly it is to provide an industrially advantageous process for producing an azacycloalkane derivative whereby the target compound with a high purity can be easily obtained and good economic and operation characteristics can be achieved. [Disclosure of the Invention] The present inventors have conducted intensive studies in order to solve the above problems and, as the result of their studies, found that an azacycloalkane derivative with a high purity can be obtained through distillation without resort to, for example, column chromatography by performing a radical reaction between a 1-(n-alkenyl)azacycloalkan-2-one and an alkyl mercaptan and converting the dialkyl disulfides thus formed as the by-products into alkyl mercaptans by treating with a reducing agent. The present invention is based on this finding. The present invention is a process for producing an azacycloalkane derivative represented by the following general formula (II): wherein m is an integer of from 1 to 3, n 2 is an integer of from 2 to 10, and R represents an alkyl group having 3 to 12 carbon atoms, characterized by reacting a 1-(n-alkenyl)-azacycloalkan-2-one represented by the following general formula (I): wherein m is an integer of from 1 to 3, and n 1 is an integer of from 0 to 8, with an alkyl mercaptan in the presence of a radical initiator in an organic solvent, treating the reaction mixture thus obtained with a reducing agent in a water-containing organic solvent, and then purifying the treated mixture by distillation. In the present invention, the 1-(n-alkenyl)-azacycloalkan-2-one represented by the above general formula (I) is reacted with an alkyl mercaptan in the presence of a radical initiator in an organic solvent. The 1-(n-alkenyl)azacycloalkan-2-ones which can be used for the present invention are exemplified by l-vinyl-2-pyrrolidone, l-allyl-2-pyrrolidone, 1-butenyl-2-pyrrolidone, 1-pentenyl-2-pyrrolidone, 1-hexenyl-2-pyrrolidone, 1-heptenyl-2-pyrrolidone, 1-octenyl-2-pyrrolidone, 1-vinylazacyclohexan-2-one, 1-propenylazacyclohexan-2-one, 1-butenylazacyclohexan-2-one, 1-vinylazacyclopentan-2-one, 1-allylazacycloheptan-2-one and 1-butenylazacycloheptan-2-one. The alkyl mercaptans are exemplified by linear and branched ones such as propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan and dodecyl mercaptan. The molar ratio of the alkyl mercaptan to the 1-(n-alkenyl)azacycloalkan-2-one may range from 0.8 to 2.0, preferably from 0.9 to 1.1, namely, allowing a nearly equimolar reaction. The radical initiators which can be used for the present invention are exemplified by benzoyl peroxide, acetyl peroxide, tert-butyl peroxide, cumene hydroperoxide, 4-bromobenzenediazonium hydroxide, triphenylmethylazobenzene, N-nitrosoacylanilide, 2,2'-azobisisobutyronitrile, tetraphenylsuccinonitrile and hydrogen peroxide, among which benzoyl peroxide and 2,2'-azobisisobutyronitrile are preferable. The organic solvents are exemplified by benzene, toluene, xylene, methanol, ethanol, 1-propanol, 2-propanol, cyclohexane, acetonitrile, ethyl acetate, acetic acid, tetrahydrofuran, dioxane and N,N-dimethylformamide. It is preferable to use an alcohol, still preferably ethanol or propanol, therefor. When an alcohol is used as the organic solvent, the formation of by-products other than dialkyl disulfides, i.e., isomers formed by the radical reaction can be suppressed. Thus, the treatment with a reducing agent, as will be described hereinbelow, can achieve relatively good results. The radical reaction is conducted at a temperature of from 50 to 150°C, preferably from 70 to 120°C, for about 0.5 to 20 hours, preferably for 1 to 5 hours. In the present invention, the reaction mixture thus obtained is treated with a reducing agent in a water-containing organic solvent and further purified by distillation. The reducing agents which are used for the present invention are metal sulfides such as sodium hydrogensulfide and sodium sulfide; metals such as tin and zinc with acids; trialkylphosphines such as trimethylphosphine, triethylphosphine, tripropylphosphine and tributylphosphine; triphenylphosphine and sodium arsenate, among which trialkylphosphines are preferable and tributylphosphine is still preferable. The reducing agent is used in an amount of from 0.1 to 50% by mole, preferably from 1 to 15% by mole, based on the 1-(n-alkenyl)azacycloalkan-2-one. The water-containing organic solvent which can be used in the reduction treatment are exemplified by methanol, ethanol, 1-propanol, 2-propanol, acetonitrile, acetic acid, tetrahydrofuran and N,N-dimethylformamide, among which alcohols are preferable. The water content of the water-containing organic solvent may range from 3 to 50%, preferably from 10 to 30%. The reduction treatment is conducted at a temperature of from 0 to 100°C and preferably at room temperature (10 to 40°C). The treatment time ranges from about 0.5 to 5 hours, preferably from 0.5 to 1.5 hours. In the present invention, the conditions for the radical reaction closely relate to the conditions for the reduction treatment. It is, therefore, necessary to design consistent production conditions. When an alkyl mercaptan is used in molar excess in order to complete the reaction, for example, the amount of the reducing agent required in the reduction treatment is elevated with an increase in the amount of the alkyl mercaptan. When the 1-(n-alkenyl)-azacycloalkan-2-one is used in molar excess in order to minimize the formation of dialkyl disulfides, the treatment with the reducing agent is also necessary and the amount of the reducing agent can be reduced correspondingly. In the present invention, the amount of the reducing agent required should vary as the molar ratio of the 1-(n-alkenyl)azacycloalkan-2-one to the alkyl mercaptan changes. There is the optimum level of the amount of the reducing agent and the use of the reducing agent in an amount exceeding the optimum level causes an economic disadvantage. When the amount of the reducing agent is bellow the optimum level, on the other hand, the dialkyl disulfides cannot be completely removed. Thus, in the present invention, the reaction conditions and the treatment conditions closely relate to each other so as to exhibit the effects. The azacycloalkane derivative obtained by the above process scarcely contains any dialkyl disulfide as a by-product. Therefore, the target compound with a high purity can be very easily obtained through a simple distillation operation. [Best Mode for Carrying Out the Invention] To further illustrate the present invention in greater detail, the following Examples and Comparative Examples will be given, but the present invention is not restricted to the embodiments described in these Examples. Example 1 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 87.2 g (0.5 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. After allowing the reaction mixture to cool to room temperature, 50 ml of water and 1.8 g of tributylphosphine were added thereto and the obtained mixture was stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 500 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 87.2 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.4% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product were as follows. The column temperature was measured with a rotary glass tube oven GTO-250 R (mfd. by Shibata Kagaku Kikai Kogyo Co., Ltd.). Form: colorless, transparent oil, Column temperature: 130-134°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N:4.91, found C: 67.19, H: 10.84, N:4.87. Example 2 11.1g (0.1 mol) of 2-vinylpyrrolidone, 17.4 g (0.1 mol) of n-decyl mercaptan, 0.1 g of benzoyl peroxide and 100 ml of benzene were introduced in a 300-ℓ reactor and then refluxed under heat for 3 hours. After removing insoluble matters from the reaction mixture by filtering, the filtrate was freed from the solvent under a reduced pressure, incorporated with 100 ml of methanol, 20 ml of water and 0.45 g of tributylphosphine and then stirred at room temperature for 40 minutes. Next, the reaction mixture was incorporated with 100 ml of ethyl acetate, washed with water, dried and then concentrated under a reduced pressure. The oily product thus obtained was distilled to thereby give 18.7 g of 1-[2-(decylthio)-ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.3% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 135°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.43, H: 11.03, N: 4.86. Example 3 11.1 g (0.1 mol) of 2-vinylpyrrolidone, 17.4 g (0.1 mol) of n-decyl mercaptan, 0.08 g of 2,2'-azobisisobutyronitrile and 100 ml of toluene were introduced in a 300-ℓ reactor and then refluxed under heat for 2 hours. The reaction mixture was washed with water, dried, freed from the solvent under a reduced pressure, incorporated with 200 ml of methanol, 100 ml of water and 4.3 g of sodium sulfide and then stirred at room temperature for 2 hours. Next, the reaction mixture was freed from the solvent under a reduced pressure, incorporated with 100 ml of ethyl acetate, washed with water, dried and then concentrated under a reduced pressure. The oily product thus obtained was distilled to thereby give 17.3 g of 1-[2-(decylthio)-ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.1% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 135°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.23, H: 10.86, N: 4.90. Example 4 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 87.2 g (0.5 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 250 ml of 2-propanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. The reaction mixture was incorporated with 50 ml of water and 1.8 g of tributylphosphine and then stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 250 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 90.1 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.4% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 134°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H:10.94, N: 4.91, found C: 67.19, H:10.77, N: 4.95. Example 5 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 78.5 g (0.45 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 300 ml of acetonitrile were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. The reaction mixture was incorporated with 300 ml of ethanol, 100 ml of water and 15.0 g of sodium sulfide were added to the reaction mixture and then stirred at 60°C for 30 minutes. Next, the reaction mixture was freed from the solvent under a reduced pressure, incorporated with 300 ml of ethyl acetate, washed with water, dried and then concentrated under a reduced pressure. The oily product thus obtained was distilled to thereby give 81.3 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.5% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows: Form: colorless, transparent oil, Column temperature: 130 - 135°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.27, H: 11.12, N: 4.84. Example 6 11.1 g (0.1 mol) of 2-vinylpyrrolidone, 17.4 g (0.1 mol) of n-decyl mercaptan, 0.1 g of 2,2'-azobisisobutyronitrile and 100 ml of ethyl acetate were introduced in a 300-ml reactor and then refluxed under heat for 2 hours. The reaction mixture was washed with water, dried, concentrated under a reduced pressure, incorporated with 50 ml of methanol, 10 ml of water and 0.45 g of tributylphosphine and then stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 50 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 17.4 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.5 % and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 135°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.39, H: 10.98, N: 4.78. Example 7 11.1 g (0.1 mol) of 2-vinylpyrrolidone, 17.4 g (0.1 mol) of n-decyl mercaptan, 0.1 g of 2,2'-azobisisobutyronitrile and 50 ml of acetic acid were introduced in a 300-ml reactor and then stirred at 90°C for 2 hours. The reaction mixture was incorporated with 0.29 g of zinc powder and then stirred under heat for 4 hours. Next, the reaction mixture was incorporated with 300 ml of ethyl acetate, freed from the insoluble matters by filtering, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 15.9 g of 1-[2-(decylthio)ethyl]-azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.0% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 134°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.10, H: 10.81, N: 4.79. Example 8 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 87.2 g (0.5 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 250 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. After allowing the reaction mixture to cool to room temperature, 125 ml of water and 21.4 g of sodium sulfide were added thereto and the obtained mixture was stirred at room temperature for 2 hours. Next, the reaction mixture was incorporated with 300 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 78.3 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.3% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 131 - 135°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.30, H: 11.20, N: 4.87. Example 9 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 104.6 g (0.6 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. After allowing the reaction mixture to cool to room temperature, 50 ml of water and 3.1 g of tributylphosphine were added thereto and the obtained mixture was stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 500 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 84.1 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.3% and no didecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 135°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.21, H: 10.85, N: 4.88. Example 10 69.5 g (0.5 mol) of 1-(3-butenyl)azacyclopentan-2-one, 73.0 g (0.5 mol) of n-octyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. After allowing the reaction mixture to cool to room temperature, 50 ml of water and 1.7 g of tributylphosphine were added thereto and the obtained mixture was stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 500 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 82.3 g of 1-[4-(octylthio)-butyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.6% and no dioctyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 130 - 134°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.06, H: 10.69, N: 4.87. Example 11 69.5 g (0.5 mol) of 1-(2-propenyl)-azacyclohexan-2-one, 80 g (0.5 mol) of n-nonyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. After allowing the reaction mixture to cool to room temperature, 50 ml of water and 1.7 g of tributylphosphine were added thereto and the obtained mixture was stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 500 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 88.9 g of 1-[3-(nonylthio)propyl]azacyclohexan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.1% and no dodecyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 138 - 143°C/0.2 mmHg, Elemental analysis (C 17 H 33 NOS) calcd. C: 68.17, H: 11.10, N: 4.68, found C: 67.95, H: 11.01, N: 4.63. Example 12 83.5 g (0.5 mol) of 1-(3-butenyl)-azacycloheptan-2-one, 59.1 g (0.5 mol) of n-hexyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. After allowing the reaction mixture to cool to room temperature, 50 ml of water and 1.8 g of tributylphosphine were added thereto and the obtained mixture was stirred at room temperature for 1 hour. Next, the reaction mixture was incorporated with 500 ml of ethyl acetate, washed with water, dried and then freed from the solvent under a reduced pressure. The oily product thus obtained was distilled to thereby give 86.9 g of 1-[4-(hexylthio)butyl]azacycloheptan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 99.4% and no dihexyl disulfide was detected. The form, column temperature and elemental analysis data of this product determined by the same methods as those described in the above Example 1 were as follows. Form: colorless, transparent oil, Column temperature: 134 - 139°C/0.2 mmHg, Elemental analysis (C 16 H 31 NOS) calcd. C: 67.31, H: 10.94, N: 4.91, found C: 67.06, H: 10.81, N: 4.81. Examples 13 - 56 In accordance with the production process of the above Example 1, various azacycloalkane derivatives represented by the above general formula (II) were obtained. Table 1 summarizes the azacycloalkane derivative obtained in each of the Examples 13 - 56, namely, the values of m and n 2 and the structure of R in the general formula (II) and the column temperature thereof. Comparative Example 1 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 87.2 g (0.5 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of benzene were introduced in a 1-ℓ reactor and then stirred under heat for 2 hours. The reaction mixture was washed with water, dried and then freed from the solvent. The oily product thus obtained was distilled to thereby give 85.6 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 96.4%, while the content of didecyl disulfide determined based on the percentage of the area in gas chromatography was 2.4%. Comparative Example 2 55.6 g (0.5 mol) of 2-vinylpyrrolidone, 87.2 g (0.5 mol) of n-decyl mercaptan, 0.4 g of 2,2'-azobisisobutyronitrile and 500 ml of ethanol were introduced in a 1-ℓ reactor and then refluxed under heat for 2 hours. The reaction mixture was incorporated with 500 ml of ethyl acetate, washed with water, dried and then concentrated under a reduced pressure. The oily product thus obtained was distilled to thereby give 79.1 g of 1-[2-(decylthio)ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 96.9%, while the content of didecyl disulfide determined based on the percentage of the area in gas chromatography was 2.3%. Comparative Example 3 A mixture comprising 0.69 g of 60% sodium hydride and 100 ml of anhydrous toluene was incorporated dropwise with a toluene solution of 1.46 g of azacyclopentan-2-one and then refluxed under heat for 1 hour. Next, the reaction mixture was incorporated with 11.9 g of 1,2-dibromoethane and then refluxed under heat for additional 12 hours. Then the reaction mixture was washed with water, dried and then freed from the solvent under a reduced pressure. A mixture comprising 2.64 g of the oily product thus obtained, 2.40 g of n-decyl mercaptan, 2.30 g of 1,8-diazabicyclo[5.4.0]undecene-7 and 100 ml of benzene was stirred at room temperature for about 1 day. The reaction mixture was washed with water, dried, freed from the solvent under a reduced pressure, incorporated with 100 ml of ethanol, 10 ml of water and 0.12 g of tributylphosphine and then stirred at room temperature for 1 hour. Subsequently, the reaction mixture was incorporated with 100 ml of ethyl acetate, washed with water, dried, freed from the solvent under a reduced pressure and then distilled to thereby give 2.75 g of 1-[2-(decylthio)-ethyl]azacyclopentan-2-one. The purity of the obtained product determined based on the percentage of the area in gas chromatography was 92.1%. Although no didecyl disulfide was detected, various kinds of other impurities were detected. [Industrial Applicability] A chemical to be used as a drug should have excellent qualities and a high purity, since it is applied to the human body. When such a chemical is contaminated with impurities, it is feared that these impurities might exert toxicity and some side effects on the human body. Under the existing circumstances, it is therefore necessary to spend a great cost and much labor in order to clarify the biological profiles of impurities so as to secure the safety. Accordingly, it largely affects the development cost or the production cost of a drug how a chemical as pure as possible can be supplied. Namely, it is an important problem in the medicinal industry to secure a chemical having a high purity. According to the process of the present invention, an azacycloalkane derivative with a high purity can be easily produced within a short period of time, as compared with conventional processes, by treating a reaction mixture with a reducing agent after the completion of the reaction, as described above. When an azacycloalkane derivative having nearly the same purity as that of the one synthesized according to the present invention is to be produced by the conventional process, it is necessary to purify the product via distillation after carrying out troublesome operation(s) such as column chromatography or recrystallization. Thus, a long time, a lot of operation devices and much solvent are conventionally required for the purifying treatment. In contrast, little dialkyl disulfides are formed as by-products in the present invention, which makes purification easy. For example, an azacycloalkane derivative with a high purity can be produced by employing a simple distillation operation for purification.

Claims: A process for producing an azacycloalkane derivative represented by the following general formula (II): wherein m is an integer of from 1 to 3, n 2 is an integer of from 2 to 10, and R represents an alkyl group having 3 to 12 carbon atoms, by reacting a 1-(n-alkenyl)azacycloalkan-2-one represented by the following general formula (I): wherein m is an integer of from 1 to 3, and n 1 is an integer of from 0 to 8, with an alkyl mercaptan in the presence of a radical initiator in an organic solvent, characterized by treating the reaction mixture obtained by the above reaction with a reducing agent in a water-containing organic solvent and then purifying the treated mixture by distillation, said reducing agent being a member selected from the group consisting of metal sulfides, metals with acids, trialkylphosphines, triphenylphosphine and sodium arsenate. A process according to claim 1, wherein 2-vinylpyrrolidone and n-decyl mercaptan are reacted in the presence of a radical initiator in an organic solvent, treated with a reducing agent in a water-containing organic solvent and then purified by distillation to thereby give 1-[2-(decylthio)ethyl]-azacyclopentan-2-one. A process according to claim 2, wherein 2-vinylpyrrolidone and n-decyl mercaptan are reacted in the presence of 2,2'-azobisisobutyronitrile in ethanol or propanol, treated with tributylphosphine in water-containing ethanol and then purified by distillation. A process according to claim 1, wherein the water-containing organic solvent is an organic solvent having a water content of 3-50% and being at least one member selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, acetonitrile, acetic acid, tetrahydrofuran and N,N-dimethylformamide. A process according to claim 1, wherein the reducing agent is used in an amount of from 0.1 to 50% by mole based on the 1-(n-alkenyl)-azacycloalkan-2-one. A process according to claim 1, wherein the treatment with the reducing agent is conducted at a temperature of from 0 to 100°C for 0.5 to 5 hours.

Inventors: HACHIYA TERUMI, INOUE HISATAKA, NODA KANJI, SAITA MASARU, YAHIRO SHIGENORI, HACHIYA, TERUMI, INOUE, HISATAKA, NODA, KANJI, SAITA, MASARU, YAHIRO, SHIGENORI, HACHIYA, TERUMI 1000, WATASE CHIYODAMACHI, INOUE, HISATAKA 1473-10, TSUBUKUHONMACHI, NODA, KANJI 320-93, OOAZATSUNEMATSU, SAITA, MASARU 855-75, KOKURA KIYAMAMACHI, YAHIRO, SHIGENORI 1175, OOKUMA
Applicants: HISAMITSU PHARMACEUTICAL CO, HISAMITSU PHARMACEUTICAL CO. INC.
Application year: 1991
Main classification: C07D207
IPC codes: C07D211, C07D223, C07D207, C07D227