JP4162320B2 - Process for producing benzoisothiazole derivative - Google Patents

Description

【０００６】
式中、Ｘは水素原子又は置換基を表す。
【０００７】
以下に本発明について詳細に説明する。
一般式（１）について説明する。
一般式（１）においてＸは、水素原子または置換基を表し、置換基としてはハロゲン原子、アルキル基（炭素数１〜１２）、アリール基（炭素数６〜１８）、アルコキシ基（炭素数１〜１２）、アシルアミノ基（炭素数２〜１８）が好ましい。
Ｘの置換位置は特に限定されないが、好ましくはアミノ基に対してオルト位又はパラ位が好ましい。スルホ基の置換位置も特に限定はされないが、出発原料の入手のし易さからＸがアミノ基に対してオルト位の場合にはスルホ基はパラ位が好ましく、Ｘがアミノ基に対してパラ位の場合にはスルホ基はオルト位が好ましい。一般式（１）において最も好ましいものはＸが水素原子で、スルホ基がアミノ基に対してパラ位の場合であり、アゾ染料のジアゾ成分、さらには拡散転写法カラー写真感光材料に用いられる画像形成化合物の合成中間体として特に重要である。
なお、一般式（１）の化合物は一般に２シアノアニリン誘導体のスルホン化により簡便に高収率で得られる。
【０００８】
次に一般式（１）の出発原料から一般式（２）を経由して一般式（３）を合成する方法について説明する。
一般に、３−アミノ−２，１−ベンゾイソチアゾ−ル誘導体の合成法としては、Ｄｙｅｓ ａｎｄ Ｐｉｇｍｅｎｔｓ ３，８１−１２１（１９８２）及びその引用文献に記載の方法が知られており、本発明の合成においても適用が可能である。
一般式（１）の化合物を塩基の存在下、硫化水素ガスを作用させて一般式（２）の化合物が得られる。用いる反応溶媒としては水溶性溶媒が好ましく、特にメタノール、エタノール、iso-プロパンノール等のアルコール系溶媒が好ましい。塩基としては苛性ソーダ、苛性カり、炭酸ナトリウム、炭酸水素ナトリウム、酢酸カリ等の無機塩基も使用可能であるが、トリエチルアミン、ピリジン等の有機塩基がより好ましい。反応温度は０〜溶媒沸点温度、好ましくは室温〜６０℃である。
【０００９】
次いで一般式（２）の化合物を塩基の存在下、過酸化水素で酸化的に閉環することにより一般式（３）の目的とするスルホ基を有する３−アミノ−２，１−ベンゾイソチアゾ−ル誘導体を得ることができる。なお、中間体（２）は一旦スルホン酸または用いた塩基とから得られるスルホン酸塩として単離してから次の工程を行ってもよいが、単離することなくそのまま次の工程を行い、ワンポットで一般式（３）の化合物を得ることも可能である。
反応によって得られた化合物（３）は酸析等によってスルホン酸として単離できるし、用いた塩基とから得られるスルホン酸塩として単離することもできる。
【００１０】
本発明の合成法によって得られる化合物（３）の具体例を表１に示す。ただし、本発明はこれらによって限定されるものではない。
【００１１】
【表１】

【００１２】
前述したように、表１の中でも化合物（３−１）が最も有用であり好ましい化合物である。
【００１３】
【実施例】
以下に本発明の具体的合成例を示すが、これらによって本発明が限定される物ではない。
実施例１．化合物（３−１）の合成（その１）
（合成スキーム）
【００１４】
【化５】

【００１５】
化合物（１−１）５００ｇ（アントラニトリルのスルホン化により収率８０％以上で容易に得られる。）をエタノール２０００ｍｌに仕込み、撹拌しながら４０℃以下でトリエチルアミン４５０ｍｌを滴下して加えた。この溶液に硫化水素ガスをガス導入管を通して４５℃で２時間かけて理論量の１．２倍を吹き込んだ。後反応（前記の温度で攪拌しながら反応させること）３時間後、窒素ガスを吹き込んで過剰の硫化水素ガスを追い出した。次いで水冷下、３０℃以下で３０％過酸化水素水２８０ｍｌを１時間かけて滴下した。
３０℃で後反応３０分後、水冷下、濃塩酸３００ｍｌを水５００ｍｌで希釈した塩酸水を滴下し、撹拌を３０分間続けた。析出した結晶をろ過し、メタノールと水（１：１）の混合溶媒にて洗浄した後に風乾して化合物（３−１）４７２ｇを得た。（収率８２％）
¹ＨＮＭＲ（ＤＭＳＯ−ｄ₆ ）ＴＭＳ基準 δ＝７．４（１Ｈ，ｄ）、７．８５（１Ｈ，ｄ）、８．５（１Ｈ，ｓ）、９．６（２Ｈ，broad）
【００１６】
実施例２．化合物（３−１）の合成（その２）
アントラニトリル２５０ｇをスルホラン４５０ｍｌに仕込み、１２５℃で加熱撹拌しながらアミド硫酸２５０ｇを１時間かけて添加した。反応を２時間続けた後に４０℃まで温度を下げ、メタノール５００ｍｌ、次いでトリエチルアミン４１０ｍｌを添加した。この反応液に硫化水素ガスをガス導入管を通して４５℃で２時間かけて理論量の１．２倍を吹き込んだ。後反応３時間後、窒素ガスを吹き込んで過剰の硫化水素ガスを追い出した。次いで水冷下、３０℃以下でメタノール２５０ｍｌ、メタンスルホン酸２３０ｍｌを添加し、さらに４０℃以下で３０％過酸化水素水２０５ｍｌを滴下した。４０℃で後反応１時間後、水冷して２５℃以下にして撹拌を３０分間続けた。析出した結晶をろ過し、メタノールと水（１：１）の混合溶媒にて洗浄した後に風乾して化合物（３−１）３９６ｇを得た。（収率８０％）
【００１７】
ちなみにUS 5,691,458号に記載されている化合物（３−１）の合成例では下記の合成ルートにより、アントラニトリルからトータル収率３０％（硫化水素を用いた第一工程が収率８２％、過酸化水素を用いた第二工程が収率６５％、硫酸を用いた第三工程が収率５７％）で化合物（３−１）を得ており、本発明の合成法が非常に有用であることがわかる。
【００１８】
【化６】

【００１９】
実施例３．化合物（３−３）の合成
アントラニトリルの代わりに２−クロロ−６−シアノアニリン３２．３ｇを用いて実施例２．と同様の操作を行った。（１０分の１のスケール）その結果、化合物（３−３）２３．２ｇを得た。（収率７２％）融点２５０℃以上
【００２０】
【発明の効果】
本発明によれば、スルホ基を有する３−アミノ−２，１−ベンゾイソチアゾ−ル誘導体を、簡便かつ高収率で得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for synthesizing a 3-amino-2,1-benzisothiazol derivative having a sulfo group. The benzoisothiazol derivative obtained by the present invention is useful as a diazo component of an azo dye, and is also important as an intermediate for synthesizing an image forming compound used in a diffusion transfer color photographic light-sensitive material.
[0002]
[Prior art]
3-amino-2,1-benzisothiazol derivatives having a sulfo group are partially described in DE 24 13 169, DT 26 01 603, DE 28 05 304, US 5,691,458, 5,716,754, etc. However, these synthesis methods are not described at all or, even if described, sulfuric acid is used after synthesizing a 3-amino-2,1-benzisothiazol derivative having no sulfo group. In this method, a 3-amino-2,1-benzisothiazol derivative having a target sulfo group is synthesized by sulfonation. However, in this method, the regioselectivity of sulfonation is low, the reaction rate of sulfonation is low, and a decomposition product is easily produced as a by-product. The benzisothiazol derivative had a drawback that it could not be easily obtained in a high yield.
[0003]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a method for producing a 3-amino-2,1-benzisothiazol derivative having a target sulfo group in a high yield and simply.
[0004]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found a production method that achieves the above object. That is, the 3-amino-2,1-benzoisothiazole derivative represented by the general formula (3) is represented by the general formula (2) using a compound represented by the following general formula (1) as a starting material. It can be obtained easily and in high yield via an intermediate.
[0005]
[Formula 4]

[0006]
In the formula, X represents a hydrogen atom or a substituent.
[0007]
The present invention is described in detail below.
The general formula (1) will be described.
In the general formula (1), X represents a hydrogen atom or a substituent, and the substituent includes a halogen atom, an alkyl group (having 1 to 12 carbon atoms), an aryl group (having 6 to 18 carbon atoms), an alkoxy group (having 1 carbon atom). To 12) and acylamino groups (having 2 to 18 carbon atoms) are preferred.
The substitution position of X is not particularly limited, but is preferably ortho or para with respect to the amino group. The substitution position of the sulfo group is not particularly limited, but from the viewpoint of easy availability of the starting material, when X is ortho to the amino group, the sulfo group is preferably in the para position, and X is para to the amino group. In the case of the position, the sulfo group is preferably in the ortho position. Most preferred in the general formula (1) is a case where X is a hydrogen atom and the sulfo group is para to the amino group, and is an image used for a diazo component of an azo dye, and further for a diffusion transfer color photographic light-sensitive material. Of particular importance as a synthetic intermediate for forming compounds.
The compound of the general formula (1) can be easily obtained in a high yield by sulfonation of a 2-cyanoaniline derivative.
[0008]
Next, a method for synthesizing the general formula (3) from the starting material of the general formula (1) via the general formula (2) will be described.
In general, as a method for synthesizing 3-amino-2,1-benzisothiazol derivatives, the methods described in Dies and Pigments 3, 81-121 (1982) and references cited therein are known, and in the synthesis of the present invention, Is also applicable.
A compound of the general formula (2) is obtained by reacting the compound of the general formula (1) with hydrogen sulfide gas in the presence of a base. The reaction solvent used is preferably a water-soluble solvent, and particularly preferably an alcohol solvent such as methanol, ethanol, iso-propanol. As the base, inorganic bases such as caustic soda, caustic potash, sodium carbonate, sodium hydrogen carbonate and potassium acetate can be used, but organic bases such as triethylamine and pyridine are more preferable. The reaction temperature is 0 to the boiling point of the solvent, preferably room temperature to 60 ° C.
[0009]
Subsequently, the 3-amino-2,1-benzisothiazol derivative having the target sulfo group of the general formula (3) is obtained by oxidative ring closure of the compound of the general formula (2) with hydrogen peroxide in the presence of a base. Can be obtained. The intermediate (2) may be once isolated as a sulfonate obtained from the sulfonic acid or the base used, and then the next step may be performed. It is also possible to obtain a compound of general formula (3).
The compound (3) obtained by the reaction can be isolated as a sulfonic acid by acid precipitation or the like, or can be isolated as a sulfonate obtained from the base used.
[0010]
Specific examples of the compound (3) obtained by the synthesis method of the present invention are shown in Table 1. However, the present invention is not limited by these.
[0011]
[Table 1]

[0012]
As described above, compound (3-1) is the most useful and preferred compound in Table 1.
[0013]
【Example】
Although the specific synthesis example of this invention is shown below, this invention is not limited by these.
Example 1. Synthesis of Compound (3-1) (Part 1)
(Synthesis scheme)
[0014]
[Chemical formula 5]

[0015]
500 g of compound (1-1) (which can be easily obtained in a yield of 80% or more by sulfonation of anthronitrile) was added to 2000 ml of ethanol, and 450 ml of triethylamine was added dropwise at 40 ° C. or lower with stirring. Hydrogen sulfide gas was blown into this solution through the gas introduction pipe at a rate of 1.2 times the theoretical amount at 45 ° C. over 2 hours. After 3 hours of post-reaction (reacting with stirring at the above temperature), nitrogen gas was blown to expel excess hydrogen sulfide gas. Subsequently, 280 ml of 30% hydrogen peroxide solution was added dropwise over 1 hour at 30 ° C. or lower under water cooling.
After 30 minutes of post-reaction at 30 ° C., under cooling with water, hydrochloric acid diluted with 500 ml of concentrated hydrochloric acid with 500 ml of water was added dropwise, and stirring was continued for 30 minutes. The precipitated crystals were filtered, washed with a mixed solvent of methanol and water (1: 1), and then air-dried to obtain 472 g of compound (3-1). (Yield 82%)
¹ HNMR (DMSO-d ₆ ) TMS standard δ = 7.4 (1H, d), 7.85 (1H, d), 8.5 (1H, s), 9.6 (2H, broad)
[0016]
Example 2 Synthesis of Compound (3-1) (Part 2)
250 g of anthronitrile was added to 450 ml of sulfolane, and 250 g of amidosulfuric acid was added over 1 hour while heating and stirring at 125 ° C. The reaction was continued for 2 hours before the temperature was lowered to 40 ° C. and 500 ml of methanol and then 410 ml of triethylamine were added. Hydrogen sulfide gas was blown into the reaction solution through the gas introduction pipe at a theoretical amount of 1.2 times over 45 hours at 45 ° C. After 3 hours of post-reaction, nitrogen gas was blown to drive off excess hydrogen sulfide gas. Subsequently, 250 ml of methanol and 230 ml of methanesulfonic acid were added at 30 ° C. or less under water cooling, and 205 ml of 30% hydrogen peroxide solution was added dropwise at 40 ° C. or less. After 1 hour of post-reaction at 40 ° C., the mixture was cooled to 25 ° C. or lower with water and stirred for 30 minutes. The precipitated crystals were filtered, washed with a mixed solvent of methanol and water (1: 1), and then air-dried to obtain 396 g of compound (3-1). (Yield 80%)
[0017]
By the way, in the synthesis example of the compound (3-1) described in US 5,691,458, the total synthesis yield of 30% from anthronitrile (the first step using hydrogen sulfide is 82% yield, peroxidation) by the following synthesis route. Compound (3-1) is obtained in a yield of 65% in the second step using hydrogen and 57% in the third step using sulfuric acid), and the synthesis method of the present invention is very useful. I understand.
[0018]
[Chemical 6]

[0019]
Example 3 Synthesis of Compound (3-3) Example 2 except that 32.3 g of 2-chloro-6-cyanoaniline was used instead of anthronitrile. The same operation was performed. As a result, 23.2 g of compound (3-3) was obtained. (Yield 72%) Melting point 250 ° C. or higher
【The invention's effect】
According to the present invention, a 3-amino-2,1-benzisothiazol derivative having a sulfo group can be obtained simply and at a high yield.

Claims (3)

In a reaction solvent, hydrogen sulfide gas is allowed to act on the compound represented by the following general formula (1) in the presence of a base, and then hydrogen peroxide is allowed to act on the compound represented by general formula (3). -A process for producing a benzisothiazole derivative characterized in that an amino-2,1-benzisothiazole derivative is obtained.

In the formula, X represents a hydrogen atom or a substituent. In a reaction solvent, the compound represented by the following general formula (1), the presence of a base, via an intermediate represented by the general formula (2) obtained by the action of hydrogen sulfide gas, further A benzoisothiazole derivative characterized in that a 3-amino-2,1-benzoisothiazole derivative represented by the general formula (3) is obtained by reacting hydrogen peroxide in the presence of a base in a reaction solvent Manufacturing method.

In the formula, X represents a hydrogen atom or a substituent. In a reaction solvent, a compound represented by the following general formula (2) is reacted with hydrogen peroxide in the presence of a base to give 3-amino-2,1-benzoate represented by the following general formula (3). A method for producing a benzisothiazole derivative, characterized by obtaining an isothiazole derivative.

In the formula, X represents a hydrogen atom or a substituent.