CA2564300C - Process for preparation of 3-substituted benzisothiazole - Google Patents
Process for preparation of 3-substituted benzisothiazole Download PDFInfo
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Abstract
The present invention provides a process for preparation of 3-substituted benzisothiazole represented by the general formula (IV) (see formula IV) wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms, which comprises halogenating a 2-cyanophenylthio derivative represented by the general formula (II): (see formula II) wherein R1 represents H, alkaline metal, 2-cyanophenylthio group or straight or branched alkyl group having 1 to 4 carbon atoms, to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I) (see formula I) wherein X represent Cl or Br, then reacting the halide represented by the general formula (I) with a piperazine compound represented by the general formula (III): (see formula III) wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms.
Description
The present invention has been divided out of Canadian Patent Application Serial No. 2,174,797 filed April 23, 1996.
The invention relates to a novel process for preparation of 3-substituted benzismthiazole using the 2-cyanobenzenesulfenyl halides. 2-C~anobenzenesulfenyl halides are novel canards which have not been previously known, and are useful compounds, in particular, as intermediates in the preparation of 3-substituted benzisothiazole derivatives. The 3-substituted benzisothiazole derivatives are important as intermediates in the preparation of pharmaceuticals.
Hitherto, as a process for preparation of 3-substituted benzisothiazole derivatives, there have been known a number of processes where 3-halo-1,2-benzisothiazole is reacted with a piperazine compound according to the following Reaction Scheme r H
N
CI r-1 N
HN NH
U , ~ ~~N
,N ~ ~ i S S
See, for example, JP-A 63-83067; JP-A 63-83085; EP-A 196096;
J. Chem. Soc., Perkin. Trans., 1(8?. 2141, 1988; Ger.
Offen., 3530089; J. Med. Chem., 29(3), 359; 1986; J. Org.
Chem., 43(8?, 1604, 1978.
However, 3-halo-1,2-benzisothiazole used in the above mentioned processes as a raw material is not easily available.
A method for chlorinating 1,2-benzisothiazol-3-one and a method using thiosalicylic acid as a starting material are described in the above references. However, these methods use an expensive raw material, have lower yields and are therefore not considered to be industrially advantageous.
As described above, it is difficult to advantageously prepare 3-substituted benzisothiazole derivatives on an industrial scale.
Accordingly, one object of the present invention is to provide an industrially advantageous process for preparation of 3-substituted benzisothiazole derivatives.
Another object of the present invention is to provide a useful intermediate which can be used in the preparation of 3-substituted benzisothiazole derivatives.
Still another object of the present invention is to provide a process for preparation of the above intermediates.
These objects as well as other objects and advantages of the present invention will become apparent to those skilled in the art from. the following description.
In view of the above circumstances, the present inventors have studied extensively to find an industrially advantageous process which can prepare a 3-substituted benzisothiazole derivative easily and economically without the use of expensive raw materials. As a result, the inventors have found that 2-cyanobenzenesulfenyl halide represented by the formula (I) below can be an important intermediate for preparation of a 3-substituted benzisothiazole derivative, have investigated the physical properties of the halide and have studied hard to provide an industrially advantageous and easy process for preparation of the halides and the 3-substituted benzisothiazole derivatives.
2-Cyanobenzenesulfenyl halide is a novel compound which has never been described in the literature. The physical properties thereof and a process for preparation of the same are not known.
The present inventors have found that the present novel 2-cyanobenzenesulfenyl halide can be easily obtained by halogenating a 2-cyanophenylthio derivative represented by the general formula (II) below, and a 3-substituted benziso-thiazole derivative can be easily obtained by reacting the 2-cyanobenzenesulfenyl halide with a piperazine compound.
Further, the present inventors have found that a 3-substituted benzisothiazole derivative can be effectively obtained by a process of successively performing the above two reactions, that is, by halogenating a 2-cyanophenylthio derivative to obtain 2-cyanobenzenesulfenyl halide which is subsequently reacted with a piperazine compound.
The present invention has been completed by such findings and provides:
(1) 2-cyanobenzenesulfenyl halide represented by the general formula (I):
CN
(I) SX
wherein X represents C1 or Br, (2) a process for preparation of 2-cyanobenzenesulfenyl halide represented by the general formula (I) which comprises halogenating a 2-cyanophenylthio derivative represented by the general formula (II):
CN
(II) SRS
wherein R1 represents H, alkaline metal, 2-cyanophenylthio group or straight or branched alkyl group having 1 to 4 carbon atoms, (3) a process for preparation of 3-substituted benzisothiazole represented by the general formula (IV):
N
C~
N
(IV) ~~N
~S
The invention relates to a novel process for preparation of 3-substituted benzismthiazole using the 2-cyanobenzenesulfenyl halides. 2-C~anobenzenesulfenyl halides are novel canards which have not been previously known, and are useful compounds, in particular, as intermediates in the preparation of 3-substituted benzisothiazole derivatives. The 3-substituted benzisothiazole derivatives are important as intermediates in the preparation of pharmaceuticals.
Hitherto, as a process for preparation of 3-substituted benzisothiazole derivatives, there have been known a number of processes where 3-halo-1,2-benzisothiazole is reacted with a piperazine compound according to the following Reaction Scheme r H
N
CI r-1 N
HN NH
U , ~ ~~N
,N ~ ~ i S S
See, for example, JP-A 63-83067; JP-A 63-83085; EP-A 196096;
J. Chem. Soc., Perkin. Trans., 1(8?. 2141, 1988; Ger.
Offen., 3530089; J. Med. Chem., 29(3), 359; 1986; J. Org.
Chem., 43(8?, 1604, 1978.
However, 3-halo-1,2-benzisothiazole used in the above mentioned processes as a raw material is not easily available.
A method for chlorinating 1,2-benzisothiazol-3-one and a method using thiosalicylic acid as a starting material are described in the above references. However, these methods use an expensive raw material, have lower yields and are therefore not considered to be industrially advantageous.
As described above, it is difficult to advantageously prepare 3-substituted benzisothiazole derivatives on an industrial scale.
Accordingly, one object of the present invention is to provide an industrially advantageous process for preparation of 3-substituted benzisothiazole derivatives.
Another object of the present invention is to provide a useful intermediate which can be used in the preparation of 3-substituted benzisothiazole derivatives.
Still another object of the present invention is to provide a process for preparation of the above intermediates.
These objects as well as other objects and advantages of the present invention will become apparent to those skilled in the art from. the following description.
In view of the above circumstances, the present inventors have studied extensively to find an industrially advantageous process which can prepare a 3-substituted benzisothiazole derivative easily and economically without the use of expensive raw materials. As a result, the inventors have found that 2-cyanobenzenesulfenyl halide represented by the formula (I) below can be an important intermediate for preparation of a 3-substituted benzisothiazole derivative, have investigated the physical properties of the halide and have studied hard to provide an industrially advantageous and easy process for preparation of the halides and the 3-substituted benzisothiazole derivatives.
2-Cyanobenzenesulfenyl halide is a novel compound which has never been described in the literature. The physical properties thereof and a process for preparation of the same are not known.
The present inventors have found that the present novel 2-cyanobenzenesulfenyl halide can be easily obtained by halogenating a 2-cyanophenylthio derivative represented by the general formula (II) below, and a 3-substituted benziso-thiazole derivative can be easily obtained by reacting the 2-cyanobenzenesulfenyl halide with a piperazine compound.
Further, the present inventors have found that a 3-substituted benzisothiazole derivative can be effectively obtained by a process of successively performing the above two reactions, that is, by halogenating a 2-cyanophenylthio derivative to obtain 2-cyanobenzenesulfenyl halide which is subsequently reacted with a piperazine compound.
The present invention has been completed by such findings and provides:
(1) 2-cyanobenzenesulfenyl halide represented by the general formula (I):
CN
(I) SX
wherein X represents C1 or Br, (2) a process for preparation of 2-cyanobenzenesulfenyl halide represented by the general formula (I) which comprises halogenating a 2-cyanophenylthio derivative represented by the general formula (II):
CN
(II) SRS
wherein R1 represents H, alkaline metal, 2-cyanophenylthio group or straight or branched alkyl group having 1 to 4 carbon atoms, (3) a process for preparation of 3-substituted benzisothiazole represented by the general formula (IV):
N
C~
N
(IV) ~~N
~S
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms, which comprises reacting 2-cyanobenzenesulfenyl halide represented by the general formula (I) with a piperazine compound represented by the general formula (III):
n HN~~NR2 ( III ) wherein Rz is as defined in the general formula (IV), and (4) a process for preparation of 3-substituted benzisothiazole represented by the general formula (IV) which comprises halogenating a 2-cyanophenylthio derivative represented by the general formula (II) to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I), then reacting the halide represented by the general formula (I) with a piperazine compound represented by the general formula (III).
The present invention is explained in detail below.
In the novel compound, 2-cyanobenzenesulfenyl halide represented by the general formula (I), the group represented by X is Cl or Br. That is, the compound represented by the general formula (I) is 2-cyanobenzenesulfenyl chloride or 2-cyanobenzenesulfenyl bromide.
The compound represented by the general formula (I) can be prepared by halogenating a 2-cyanophenylthio derivative represented by the general formula (II).
Group R1 in the compound represented by the general formula (II) is H, alkaline metal such as sodium, potassium and the like, 2-cyanophenylthio group, straight or branched alkyl group having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl and the like. The particular compounds represented by the general formula (II) are 2-cyanobenzenethiol, 2,2'-dicyanodiphenyl disulfide, 2-cyanophenyl methyl sulfide, 2-cyanophenyl ethyl sulfide, 2-cyanophenyl n-propyl sulfide, 2-cyanophenyl isopropyl _ sulfide, 2-cyanophenyl n-butyl sulfide, 2-cyanophenyl t-butyl ' sulfide and the like.
To halogenate the compound represented by the general formula (II), chlorine, sulfuryl chloride, bromine, sulfuryl 5 bromide, and mixtures thereof can be used as a halogenating agent. Among them, chlorine and bromine are preferred. The amount of halogenating agent to be used varies depending upon the type of compound represented by the general formula (II) and is usually in a range of 0.5 to 7-fold in mole terms relative to the compound represented by the general formula (II) .
The reaction temperature for halogenation varies depending upon the type of compound represented by the general formula (II) and is usually in a range of about -10°C to about 160°C, preferably about -5°C to about 130°C. When the reaction temperature is too low, the reaction rate becomes slow. On the other hand, when the reaction temperature is too high, side reactions occur, which leads to decreased yield.
The halogenating reaction can be carried out without any solvent or in a solvent. Examples of the solvent include, but are not limited to, hydrocarbons such as hexane, cyclohexane, heptane and the like, halogenated hydrocarbons such as dichloroethane, dichloromethane, chloroform and the like, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene and the like, polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide and the like. When a solvent is used, the amount of solvent to be used is usually, though not limited to, 0.1 to 10-fold in weight terms relative to the compound represented by the general formula (II).
2-Cyanobenzenesulfenyl halide, thus obtained, represented by the general formula (I) can be isolated by a method such as distillation, crystallization or the like.
2-Cyanobenzenesulfenyl halide, thus obtained, represented by the general formula (I) can be reacted with a piperazine compound represented by the general formula (III) to obtain -3-substituted benzisothiazole represented by the general formula (IV) .
Examples of the piperazine compound are piperazine, 1-alkyl-piperazine such as 1-methyl-piperazine, 1-ethyl piperazine, 1-n-butyl-piperazine and the like, and 1-substituted alkylene-piperazine such as 1-imidobutylene-piperazine, 1-amidobutylene-piperazine, 1-((5-indole)ethylene)-piperazine and the like.
The amount of the piperazine compound to be used is usually in a range of 1 to 10-fold, preferably 3 to 6-fold in mole terms relative to 2-cyanobenzenesulfenyl halide represented by the general formula (I).
The reaction temperature is usually in a range of about 80°C to about 150°C, preferably about 100°C to about 130°C.
When the reaction temperature is too low, the reaction rate becomes slow. On the other hand, when the reaction temperature is too high, side reactions occur, which leads to decreased yields.
A solvent is not necessarily required and the reaction is preferably carried out without a solvent.
Alternatively, the reaction may be carried out in a solvent. Examples of the solvent are hydrocarbons such as cyclohexane, heptane and the like, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene and the like, and polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide and the like. When a solvent is used, the amount of solvent to be used is usually, though not limited to, a range of 0.1 to 10-fold in weight terms relative to the compound represented by the general formula (I).
3-Substituted benzisothiazole, thus obtained, represented by the general fo-rmula (IV) can be isolated from a reaction mixture and purified by a known method such as crystallization or the like.
Examples of the particular 3-substituted benzisothiazole are 3-(1-piperazinyl)-1,2-benzisothiazole, 3-(4-ethylpipera-zinyl)-1,2-benzisothiazole, 3-(4-n-butyl-1-piperazinyl)-_ 7 -1,2-benzisothiazole, 3-(4-cyclohexyl-1-piperazinyl)-1,2-benzisothiazole and the like. These compounds can be isolated as a mineral acid salt such as hydrochloride, sulfate or the like under acidic conditions in the presence of hydrochloric acid, sulfuric acid or the like.
3-Substituted benzisothiazole represented by the general formula (IV) can also be prepared by a process where the above two reactions are successively carried out in series, that is, by halogenating 2-cyanophenylthio halide represented by the general formula (II) to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I) which is subsequently reacted with a piperazine compound represented by the general formula (III).
A halogenating reaction and a reaction with the piperazine compound in this process can be carried out as described for each reaction.
A compound represented by the general formula (II) used as a raw material for preparation of a compound represented by the general formula (I) can be easily obtained according to a process described in Japanese patent application No. 6-289763.
That is, 2-cyanochlorobenzene is converted into 2-cyanophenyl methyl sulfide with a sodium salt of methylmercaptane, then the methyl group thereof is halogenated and hydrolyzed to obtain 2-cyanobenzenethiol, which is further treated with an alkali to obtain an alkaline metal salt thereof, which is oxidized to obtain 2,2'-dicyanodiphenyl disulfide.
The following Examples illustrate the present invention in detail but are not to be construed to limit the scope thereof.
Example 1 67.5 g (0.500 mol) of 2-cyanobenzenethiol and 150 g of chlorobenzene were placed in a 300 ml four-neck flask equipped with a stirrer, a thermometer, a chlorine blowing inlet and a condenser and 39 g (0.55 mol) of chlorine was blown therein at about 80°C over 2 hours while stirring. The solvent was distilled, followed by evaporation under reduced pressure to obtain 81.7 g of white crystals, which were identified to be 2-cyanobenzenesulfenyl chloride from the following data.
The yield starting from 2-cyanobenzenethiol was 96.40.
Physical properties 2-Cyanobenzenesulfenyl chloride Appearances: white crystals Melting point: 38.5-39.0°C
NMR: 8 (ppm) 7.37-8.09 (m) IR: (KBr, cm-1) 1595, 1467, 1248, 1012, 760 Elementary analysis:
Calculated C:49.56;H:2.38;N:8.26;5:18.90 Found C:49.60;H:2.34;N:8.25;5:18.88 Example 2 67.2 g (0.250 mol) of 2,2'-dicyanodiphenyl disulfide and 150 g of chlorobenzene were placed in a 300 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 84.0 g (0.525 mol) of bromine was added dropwise at about 80°C over one hour while stirring.
The excess bromine was removed with an aqueous sodium carbonate solution, followed by crystallization with cyclohexane to obtain 101.9 g of white crystals, which were identified to be 2-cyanobenzenesulfenyl bromide from the following data. The yield starting from 2, 2'-dicyanodi-phenyl disulfide was 95.2%.
Physical properties 2-Cyanobenzenesulfenyl bromide Appearances: white crystals Melting point: 59.5-60.5°C
NMR: b (ppm) 7.38-8.07 (m) IR: (KBr, ctril) 1589, 1462, 1242, 958, 760 Elementary analysis:
Calculated C:39.27;H:1.88;N:6.54;5:14.98 Found C:39.32;H:1.88;N:6.52;5:15.00 - g _ t Example 3 74.5 g (0.500 mol) of 2-cyanophenyl methyl sulfide and 250 g of chlorobenzene were placed in a 500 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 96.0 g (0.600 mol) of bromine was added dropwise thereto at about 100°C over five hours while stirring. The excess bromine was removed with an aqueous sodium carbonate solution, followed by distillation under reduced pressure to obtain 90.4 g of 2-cyanobenzenesulfenyl bromide. The yield starting from 2-cyanophenyl methyl sulfide was 84.50.
Example 4 86.2 g (1.00 mol) of piperazine and 7.5 g of chlorobenzene were placed in a 500 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 42.4 g (0.25 mol) of molten 2-cyanobenzene-sulfenyl chloride was added dropwise thereto at about 130°C
over one hour while stirring, followed by stirring for four hours to complete the reaction. The excess piperazine was removed with water, followed by acidification with hydrochloric acid and extraction into the aqueous layer. The aqueous layer was basified with an aqueous sodium hydroxide solution to obtain 40.9 g (m.p.. 89-90°C) of 3-(1-piperazinyl)-1,2-benzisothiazole as crystals. The yield starting from 2-cyanobenzenesulfenyl chloride was 74.7%.
Example 5 Using the same method as in Example 4, except that 2-cyanobenzenesulfenyl bromide was used instead of 2-cyanobenzenesulfenyl chloride as a raw material, afforded, after cooling of an aqueous solution acidified with hydrochloric acid,,46.5 g of 3-(1-piperazinyl)-1,2-benzisothiazole hydrochloride as crystals (decomposition temperature 275-280°C). The yield starting from 2-cyanobenzenesulfenyl chloride was 73.0o.
Example 6 74.5 g (0.500 mol) of 2-cyanophenyl methyl sulfide and 250 g of chlorobenzene were placed in a 500 m1 four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 96.0 g (0.600 mol) of bromine was added dropwise thereto at about 100°C over five hours while stirring, followed by stirring for two hours to complete the reaction. The excess bromine was removed with an aqueous sodium carbonate solution and the solvent was distilled off to obtain 92.0 g of crude 2-cyanobenzenesulfenyl bromide.
Separately, 172.4 g (2.00 mol) of piperazine and 15 g of chlorobenzene were placed in a 1000 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and the molten crude 2-cyanobenzenesulfenyl bromide obtained above was added dropwise thereto at about 130°C over one hour while stirring, followed by stirring for five hours to complete the reaction. The excess piperazine was removed with water and the reaction mixture was acidified with hydrochloric acid, followed by extraction into an aqueous layer. The aqueous layer was basified with an aqueous sodium hydroxide solution to obtain 65.9 g of 3-(1-piperazinyl)-1,2-benzisothiazole as crystals. The yield starting from 2-cyanophenyl methyl sulfide was 60.20.
Example 7 Using the same method as in Example 5, except that 100 g (1.00 mol) of N-methylpiperazine was used instead of piperazine, afforded 55.9 g of 3-(4-methyl-1-piperazinyl)-1,2-benzisothiazole hydrochloride as crystals, m.p.. 250-252°C. The yield starting from 2-cyanobenzene-sulfenyl bromide was 83.0a.
As described above, according to the present invention, there is provided a novel 2-cyanobenzenesulfenyl halide and a process for preparation of the same, and by using the compound, a 3-substituted benzisothiazole derivative important as an intermediate for preparation of pharmaceuticals can be industrially prepared advantageously, effectively and economically.
n HN~~NR2 ( III ) wherein Rz is as defined in the general formula (IV), and (4) a process for preparation of 3-substituted benzisothiazole represented by the general formula (IV) which comprises halogenating a 2-cyanophenylthio derivative represented by the general formula (II) to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I), then reacting the halide represented by the general formula (I) with a piperazine compound represented by the general formula (III).
The present invention is explained in detail below.
In the novel compound, 2-cyanobenzenesulfenyl halide represented by the general formula (I), the group represented by X is Cl or Br. That is, the compound represented by the general formula (I) is 2-cyanobenzenesulfenyl chloride or 2-cyanobenzenesulfenyl bromide.
The compound represented by the general formula (I) can be prepared by halogenating a 2-cyanophenylthio derivative represented by the general formula (II).
Group R1 in the compound represented by the general formula (II) is H, alkaline metal such as sodium, potassium and the like, 2-cyanophenylthio group, straight or branched alkyl group having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl and the like. The particular compounds represented by the general formula (II) are 2-cyanobenzenethiol, 2,2'-dicyanodiphenyl disulfide, 2-cyanophenyl methyl sulfide, 2-cyanophenyl ethyl sulfide, 2-cyanophenyl n-propyl sulfide, 2-cyanophenyl isopropyl _ sulfide, 2-cyanophenyl n-butyl sulfide, 2-cyanophenyl t-butyl ' sulfide and the like.
To halogenate the compound represented by the general formula (II), chlorine, sulfuryl chloride, bromine, sulfuryl 5 bromide, and mixtures thereof can be used as a halogenating agent. Among them, chlorine and bromine are preferred. The amount of halogenating agent to be used varies depending upon the type of compound represented by the general formula (II) and is usually in a range of 0.5 to 7-fold in mole terms relative to the compound represented by the general formula (II) .
The reaction temperature for halogenation varies depending upon the type of compound represented by the general formula (II) and is usually in a range of about -10°C to about 160°C, preferably about -5°C to about 130°C. When the reaction temperature is too low, the reaction rate becomes slow. On the other hand, when the reaction temperature is too high, side reactions occur, which leads to decreased yield.
The halogenating reaction can be carried out without any solvent or in a solvent. Examples of the solvent include, but are not limited to, hydrocarbons such as hexane, cyclohexane, heptane and the like, halogenated hydrocarbons such as dichloroethane, dichloromethane, chloroform and the like, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene and the like, polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide and the like. When a solvent is used, the amount of solvent to be used is usually, though not limited to, 0.1 to 10-fold in weight terms relative to the compound represented by the general formula (II).
2-Cyanobenzenesulfenyl halide, thus obtained, represented by the general formula (I) can be isolated by a method such as distillation, crystallization or the like.
2-Cyanobenzenesulfenyl halide, thus obtained, represented by the general formula (I) can be reacted with a piperazine compound represented by the general formula (III) to obtain -3-substituted benzisothiazole represented by the general formula (IV) .
Examples of the piperazine compound are piperazine, 1-alkyl-piperazine such as 1-methyl-piperazine, 1-ethyl piperazine, 1-n-butyl-piperazine and the like, and 1-substituted alkylene-piperazine such as 1-imidobutylene-piperazine, 1-amidobutylene-piperazine, 1-((5-indole)ethylene)-piperazine and the like.
The amount of the piperazine compound to be used is usually in a range of 1 to 10-fold, preferably 3 to 6-fold in mole terms relative to 2-cyanobenzenesulfenyl halide represented by the general formula (I).
The reaction temperature is usually in a range of about 80°C to about 150°C, preferably about 100°C to about 130°C.
When the reaction temperature is too low, the reaction rate becomes slow. On the other hand, when the reaction temperature is too high, side reactions occur, which leads to decreased yields.
A solvent is not necessarily required and the reaction is preferably carried out without a solvent.
Alternatively, the reaction may be carried out in a solvent. Examples of the solvent are hydrocarbons such as cyclohexane, heptane and the like, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene and the like, and polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide and the like. When a solvent is used, the amount of solvent to be used is usually, though not limited to, a range of 0.1 to 10-fold in weight terms relative to the compound represented by the general formula (I).
3-Substituted benzisothiazole, thus obtained, represented by the general fo-rmula (IV) can be isolated from a reaction mixture and purified by a known method such as crystallization or the like.
Examples of the particular 3-substituted benzisothiazole are 3-(1-piperazinyl)-1,2-benzisothiazole, 3-(4-ethylpipera-zinyl)-1,2-benzisothiazole, 3-(4-n-butyl-1-piperazinyl)-_ 7 -1,2-benzisothiazole, 3-(4-cyclohexyl-1-piperazinyl)-1,2-benzisothiazole and the like. These compounds can be isolated as a mineral acid salt such as hydrochloride, sulfate or the like under acidic conditions in the presence of hydrochloric acid, sulfuric acid or the like.
3-Substituted benzisothiazole represented by the general formula (IV) can also be prepared by a process where the above two reactions are successively carried out in series, that is, by halogenating 2-cyanophenylthio halide represented by the general formula (II) to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I) which is subsequently reacted with a piperazine compound represented by the general formula (III).
A halogenating reaction and a reaction with the piperazine compound in this process can be carried out as described for each reaction.
A compound represented by the general formula (II) used as a raw material for preparation of a compound represented by the general formula (I) can be easily obtained according to a process described in Japanese patent application No. 6-289763.
That is, 2-cyanochlorobenzene is converted into 2-cyanophenyl methyl sulfide with a sodium salt of methylmercaptane, then the methyl group thereof is halogenated and hydrolyzed to obtain 2-cyanobenzenethiol, which is further treated with an alkali to obtain an alkaline metal salt thereof, which is oxidized to obtain 2,2'-dicyanodiphenyl disulfide.
The following Examples illustrate the present invention in detail but are not to be construed to limit the scope thereof.
Example 1 67.5 g (0.500 mol) of 2-cyanobenzenethiol and 150 g of chlorobenzene were placed in a 300 ml four-neck flask equipped with a stirrer, a thermometer, a chlorine blowing inlet and a condenser and 39 g (0.55 mol) of chlorine was blown therein at about 80°C over 2 hours while stirring. The solvent was distilled, followed by evaporation under reduced pressure to obtain 81.7 g of white crystals, which were identified to be 2-cyanobenzenesulfenyl chloride from the following data.
The yield starting from 2-cyanobenzenethiol was 96.40.
Physical properties 2-Cyanobenzenesulfenyl chloride Appearances: white crystals Melting point: 38.5-39.0°C
NMR: 8 (ppm) 7.37-8.09 (m) IR: (KBr, cm-1) 1595, 1467, 1248, 1012, 760 Elementary analysis:
Calculated C:49.56;H:2.38;N:8.26;5:18.90 Found C:49.60;H:2.34;N:8.25;5:18.88 Example 2 67.2 g (0.250 mol) of 2,2'-dicyanodiphenyl disulfide and 150 g of chlorobenzene were placed in a 300 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 84.0 g (0.525 mol) of bromine was added dropwise at about 80°C over one hour while stirring.
The excess bromine was removed with an aqueous sodium carbonate solution, followed by crystallization with cyclohexane to obtain 101.9 g of white crystals, which were identified to be 2-cyanobenzenesulfenyl bromide from the following data. The yield starting from 2, 2'-dicyanodi-phenyl disulfide was 95.2%.
Physical properties 2-Cyanobenzenesulfenyl bromide Appearances: white crystals Melting point: 59.5-60.5°C
NMR: b (ppm) 7.38-8.07 (m) IR: (KBr, ctril) 1589, 1462, 1242, 958, 760 Elementary analysis:
Calculated C:39.27;H:1.88;N:6.54;5:14.98 Found C:39.32;H:1.88;N:6.52;5:15.00 - g _ t Example 3 74.5 g (0.500 mol) of 2-cyanophenyl methyl sulfide and 250 g of chlorobenzene were placed in a 500 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 96.0 g (0.600 mol) of bromine was added dropwise thereto at about 100°C over five hours while stirring. The excess bromine was removed with an aqueous sodium carbonate solution, followed by distillation under reduced pressure to obtain 90.4 g of 2-cyanobenzenesulfenyl bromide. The yield starting from 2-cyanophenyl methyl sulfide was 84.50.
Example 4 86.2 g (1.00 mol) of piperazine and 7.5 g of chlorobenzene were placed in a 500 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 42.4 g (0.25 mol) of molten 2-cyanobenzene-sulfenyl chloride was added dropwise thereto at about 130°C
over one hour while stirring, followed by stirring for four hours to complete the reaction. The excess piperazine was removed with water, followed by acidification with hydrochloric acid and extraction into the aqueous layer. The aqueous layer was basified with an aqueous sodium hydroxide solution to obtain 40.9 g (m.p.. 89-90°C) of 3-(1-piperazinyl)-1,2-benzisothiazole as crystals. The yield starting from 2-cyanobenzenesulfenyl chloride was 74.7%.
Example 5 Using the same method as in Example 4, except that 2-cyanobenzenesulfenyl bromide was used instead of 2-cyanobenzenesulfenyl chloride as a raw material, afforded, after cooling of an aqueous solution acidified with hydrochloric acid,,46.5 g of 3-(1-piperazinyl)-1,2-benzisothiazole hydrochloride as crystals (decomposition temperature 275-280°C). The yield starting from 2-cyanobenzenesulfenyl chloride was 73.0o.
Example 6 74.5 g (0.500 mol) of 2-cyanophenyl methyl sulfide and 250 g of chlorobenzene were placed in a 500 m1 four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and 96.0 g (0.600 mol) of bromine was added dropwise thereto at about 100°C over five hours while stirring, followed by stirring for two hours to complete the reaction. The excess bromine was removed with an aqueous sodium carbonate solution and the solvent was distilled off to obtain 92.0 g of crude 2-cyanobenzenesulfenyl bromide.
Separately, 172.4 g (2.00 mol) of piperazine and 15 g of chlorobenzene were placed in a 1000 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser and the molten crude 2-cyanobenzenesulfenyl bromide obtained above was added dropwise thereto at about 130°C over one hour while stirring, followed by stirring for five hours to complete the reaction. The excess piperazine was removed with water and the reaction mixture was acidified with hydrochloric acid, followed by extraction into an aqueous layer. The aqueous layer was basified with an aqueous sodium hydroxide solution to obtain 65.9 g of 3-(1-piperazinyl)-1,2-benzisothiazole as crystals. The yield starting from 2-cyanophenyl methyl sulfide was 60.20.
Example 7 Using the same method as in Example 5, except that 100 g (1.00 mol) of N-methylpiperazine was used instead of piperazine, afforded 55.9 g of 3-(4-methyl-1-piperazinyl)-1,2-benzisothiazole hydrochloride as crystals, m.p.. 250-252°C. The yield starting from 2-cyanobenzene-sulfenyl bromide was 83.0a.
As described above, according to the present invention, there is provided a novel 2-cyanobenzenesulfenyl halide and a process for preparation of the same, and by using the compound, a 3-substituted benzisothiazole derivative important as an intermediate for preparation of pharmaceuticals can be industrially prepared advantageously, effectively and economically.
Claims (4)
1. A process for preparation of 3-substituted benzisothiazole represented by the general formula (IV):
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms, which comprises reacting 2-cyanobenzenesulfenyl halide represented by the general formula (I):
wherein X represents Cl or Br, with a piperazine compound represented by the general formula (III):
wherein R2 is as defined for the general formula (IV) above.
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms, which comprises reacting 2-cyanobenzenesulfenyl halide represented by the general formula (I):
wherein X represents Cl or Br, with a piperazine compound represented by the general formula (III):
wherein R2 is as defined for the general formula (IV) above.
2. The process according to claim 1, wherein the piperazine compound represented by the general formula (III) is piperazine.
3. A process for preparation of 3-substituted benzisothiazole represented by the general formula (IV):
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms, which comprises chlorinating or brominating a 2-cyanophenylthio derivative represented by the general formula (II):
wherein R1 represents H, alkaline metal, 2-cyanophenylthio group or straight or branched alkyl group having 1 to 4 carbon atoms, to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I):
wherein X represents Cl or Br, then reacting the halide represented by the general formula (I) with a piperazine compound represented by the general formula (III):
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms.
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms, which comprises chlorinating or brominating a 2-cyanophenylthio derivative represented by the general formula (II):
wherein R1 represents H, alkaline metal, 2-cyanophenylthio group or straight or branched alkyl group having 1 to 4 carbon atoms, to obtain 2-cyanobenzenesulfenyl halide represented by the general formula (I):
wherein X represents Cl or Br, then reacting the halide represented by the general formula (I) with a piperazine compound represented by the general formula (III):
wherein R2 represents H, alkyl group having 1 to 6 carbon atoms or substituted alkylene group having 1 to 6 carbon atoms.
4. The process according to claim 3, wherein the compound of formula (I) is reacted with a piperazine compound represented by the general formula (III) wherein R2 is H to produce 3-(1-piperazinyl)-1,2-benzisothiazole as the 3-substituted benzisothiazole represented by the general formula (IV).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP098387/1995 | 1995-04-24 | ||
| JP09838795A JP3701044B2 (en) | 1995-04-24 | 1995-04-24 | Cyanobenzenesulfenyl halide and method for producing 3-substituted benzisothiazole using the same |
| CA002174797A CA2174797C (en) | 1995-04-24 | 1996-04-23 | Cyanobenzenesulfenyl halide and process for preparation of 3-substituted benzisothiazole using the same |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002174797A Division CA2174797C (en) | 1995-04-24 | 1996-04-23 | Cyanobenzenesulfenyl halide and process for preparation of 3-substituted benzisothiazole using the same |
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| Publication Number | Publication Date |
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| CA2564300A1 CA2564300A1 (en) | 1996-10-25 |
| CA2564300C true CA2564300C (en) | 2010-09-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA2564300A Expired - Fee Related CA2564300C (en) | 1995-04-24 | 1996-04-23 | Process for preparation of 3-substituted benzisothiazole |
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| Country | Link |
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| CA (1) | CA2564300C (en) |
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| CA2564300A1 (en) | 1996-10-25 |
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