JP2012153645A - Production method of 3-(2-alkoxyphenyl)-5-aminopyrazole intermediate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for obtaining 3-(2-alkoxyphenyl)-5-aminopyrazole with a purity of 95% or more, which is an intermediate for the synthesis of 1H-pyrazolo[1,5-b][1,2,4]triazole coupler.SOLUTION: The method for obtaining a 3-(2-alkoxyphenyl)-5-aminopyrazole intermediate expressed by formula (II) comprises reacting a corresponding 2-benzoylacetonitrile with hydrazine in the presence of an acid. In the formula, Rrepresents a straight-chain or branched alkyl group having 1 to 3 carbon atoms.

Description

  The present invention relates to a method for producing a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate, and more specifically, 1H-pyrazolo [1,5-b] [1,2,2] which is a coupler of an azomethine dye. 4] A method for producing a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate, which is an intermediate in the synthesis of triazole.

  The heat-sensitive sublimation transfer method uses a thermal transfer film that carries a dye layer in which a sublimable dye is dissolved or dispersed in a binder resin. The thermal transfer film is layered on the image-receiving film and is transferred to a heating device such as a thermal head. By applying energy according to the above, the sublimation dye contained in the dye layer on the thermal transfer film is transferred to the image receiving film to form an image.

  This heat-sensitive sublimation transfer method can control the amount of dye transfer in dot units according to the amount of energy applied to the thermal transfer film, so that it is excellent in forming a gradation image and has advantages such as easy formation of characters, symbols, etc. have. The image obtained by such a thermal transfer method can form a high-quality image similar to a silver salt photograph, and accordingly, there is an extremely high demand for prevention of image quality degradation due to factors such as light, heat, and humidity of the image. Development of various sublimation dyes for improving image storage stability has been made.

  For example, as a thermal transfer dye having excellent transferability and storage stability, Patent No. 3013137 (Patent Document 1) and Patent No. 3078308 (Patent Document 2) include 1H-pyrazolo [5,1-C] [1 , 2,4] An azomethine compound having a structure in which a triazole ring is a coupler and a pyridyl group is bonded to the coupler via a nitrogen atom is disclosed. Japanese Patent No. 2840901 (Patent Document 3) uses a 1H-pyrazolo [1,5-b] [1,2,4] triazole ring as a coupler, and a phenylamino group is bonded to the coupler via a nitrogen atom. An azomethine compound of structure is disclosed. Further, JP-A-5-239367 (Patent Document 4) discloses that a pyridyl group is added to a 1H-pyrazolo [1,5-b] [1,2,4] triazole ring coupler which is a combination of both. An azomethine compound having a structure bonded to a coupler via a nitrogen atom is disclosed.

  Although the azomethine dyes disclosed in the above patents 3013137 and 3078308 are excellent in light resistance, the 1H-pyrazolo [5,1-C] [1,2,4] triazole ring is used as a coupler. There is a cost problem. The azomethine dye described in Japanese Patent No. 2840901 using a 1H-pyrazolo [1,5-b] [1,2,4] triazole ring compound as a raw material coupler has a merit that it can be produced at a relatively low cost. May be insufficient.

On the other hand, the dye described in JP-A-5-239367, which is a combination of 1H-pyrazolo [1,5-b] [1,2,4] triazole ring coupler and a pyridyl group, can be produced at low cost and has light resistance. Also has the advantage of being superior. In particular, a phenyl group introduced as a substituent R ₆ of the 1H-pyrazolo [1,5-b] [1,2,4] triazole ring proposed in JP-A-5-239367 (9, (10, 11, 22, 112) is excellent in that the color tone of the pigment is close to the required color gamut.

However, the compound described in JP-A-5-239367, particularly a compound into which an unsubstituted pyridyl group is introduced as the substituent R ₆ of the triazole ring is excellent in terms of production cost and light resistance, but the reaction of the coupling reaction The rate is low, and the yield is about 20% as described in JP-A-5-239367.

Patent No. 3013137 Japanese Patent No. 3078308 Japanese Patent No. 2840901 JP-A-5-239367

  In the previous application (Japanese Patent Application No. 2009-85637, filing date: March 31, 2009), the present inventors have added nitrogen to the 1H-pyrazolo [1,5-b] [1,2,4] triazole ring. In the azomethine compound in which the pyridine ring is bonded via an atom, the azomethine compound having a specific substituent is excellent in terms of light resistance and manufacturing cost, has high purity, and has a high sensitivity and solubility when used as a dye. It also proposes to be excellent. And in that prior application, the present inventors made 2-benzoylacetonitrile by reacting benzoic acid ester compound as a starting material with acetonitrile in the presence of potassium t-butoxide, and then obtained 2-benzoylacetonitrile. Reacting benzoylacetonitrile with hydrazine to obtain 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate, which was reacted with imidate hydrochloride to form an amidine compound, and then hydroxylamine was reacted with it. Then, the resulting amide oxime derivative is reacted with p-toluenesulfonic acid chloride and heated to reflux in the presence of pyridine to give 1H-pyrazolo [1,5-b] [1, It is also proposed that a 2,4] triazole coupler is obtained. However, although the purity of the 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate is as high as about 94%, in order to obtain a highly pure coupler, the intermediate 3- (2-alkoxyphenyl)- It was necessary to purify 5-aminopyrazole once.

  The present inventors have recently prepared 3- (2-alkoxyphenyl) -5-aminopyrazole, which is an intermediate in the synthesis of 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler. In the synthesis by reacting hydrazine with 2-alkoxybenzoylacetonitrile, a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate is obtained with a purity of 95% or more by using a specific acid, As a result, the intermediate was subjected to imidate hydrochloride to act as an amidine compound without purification, and then hydroxylamine was allowed to act on it to obtain an amide oxime derivative. By reacting the amide oxime derivative with p-toluenesulfonic acid chloride and heating to reflux in the presence of pyridine, the desired compound is obtained. Can the synthesizing 1H- pyrazolo [1,5-b] [1,2,4] triazole couplers is to obtain a knowledge that. The present invention is based on this finding.

Therefore, an object of the present invention is to prepare 3- (2-alkoxyphenyl) -5-aminopyrazole, which is an intermediate in the synthesis of 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler. It is to provide a method that can be obtained with a purity of 95% or more by purifying only the liquid separation.

（式中、Ｒ_１は炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基である。）

（式中、Ｒ_１は炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基である。） The method for producing a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate according to the present invention comprises reacting 2-alkoxybenzoylacetonitrile represented by the following formula (I) with hydrazine in the presence of an acid. And obtaining a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate represented by the formula (II).

(In the formula, R ₁ is a linear or branched alkyl group having ₁ to 3 carbon atoms.)

(In the formula, R ₁ is a linear or branched alkyl group having ₁ to 3 carbon atoms.)

  Moreover, in the aspect of this invention, it is preferable that the said acid is an acetic acid, hydrochloric acid, or a benzoic acid derivative.

  Moreover, in the aspect of this invention, it is preferable that the density | concentration of the said acid is 1-5 mol%.

In the embodiment of the present invention, R _{1 in the} formulas (I) and (II) is preferably an ethyl group.

  In another aspect of the present invention, a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate obtained by the above production method is also provided.

（式中、Ｒ_１は炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基である。） In another embodiment of the present invention, a 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler is produced using a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate. How to
Without purifying the 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate represented by the formula (II) obtained by the above production method, imidate hydrochloride was allowed to act to obtain an amidine compound,
Hydroxylamine is allowed to act on the amidine compound to form an amide oxime derivative,
The obtained amidoxime derivative is reacted with p-toluenesulfonic acid chloride and heated to reflux in the presence of pyridine, whereby 1H-pyrazolo [1,5-b] [1 represented by the following formula (III) is obtained. , 2, 4] to obtain a triazole coupler.

(In the formula, R ₁ is a linear or branched alkyl group having ₁ to 3 carbon atoms.)

（式中、Ｒ_２およびＲ_３はそれぞれ独立して、炭素数Ｃ２〜４のアルキル基を示す。）

（式中、Ｒ_１は、炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基であり、Ｒ_２およびＲ_３は、それぞれ独立して、炭素数Ｃ２〜４のアルキル基を示す。） In another embodiment of the present invention, the method for producing an azomethine compound is a 1H-pyrazolo [1,5-b] [1] represented by the above formula (III) obtained by the above production method. , 2,4] A triazole coupler and a pyridyldiamino derivative represented by the following formula (IV) are reacted with an oxidizing agent in the presence of a base to obtain an azomethine compound represented by the following formula (V). It is characterized by comprising.

(In the formula, R ₂ and R ₃ each independently represent an alkyl group having 2 to 4 carbon atoms.)

(In the formula, R ₁ is a linear or branched alkyl group having 1 to ₃ carbon atoms, and R ₂ and R ₃ each independently represents an alkyl group having ₂ to 4 carbon atoms.)

  Furthermore, in another aspect of the present invention, there is also provided a thermal transfer recording dye comprising the azomethine compound obtained by the above production method.

  In the present invention, when a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate is obtained by reacting 2-alkoxybenzoylacetonitrile with hydrazine, a purity of 95% or more is obtained by using a specific acid. 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate is obtained. In addition, since the intermediate is obtained with high purity, the intermediate is directly purified without any purification, and then the imidate hydrochloride is allowed to act on the resulting intermediate to obtain an amidine compound, which is then reacted with hydroxylamine. Then, the resulting amide oxime derivative is reacted with p-toluenesulfonic acid chloride and heated to reflux in the presence of pyridine, whereby 1H-pyrazolo, which is a coupler for the synthesis of an azomethine compound, is used. 1,5-b] [1,2,4] triazole can be efficiently synthesized.

（式中、Ｒ_１は、炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基であり、Ｒ_２およびＲ_３は、それぞれ独立して、炭素数Ｃ２〜４のアルキル基を示す。） <3- (2-alkoxyphenyl) -5-aminopyrazole intermediate>
As described above, the 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate is 1H-pyrazolo [1,5-b] [1] which is a coupler material of an azomethine compound represented by the following formula (V). , 2,4] is a material useful as an intermediate in the synthesis of a triazole ring coupler.

(In the formula, R ₁ is a linear or branched alkyl group having 1 to ₃ carbon atoms, and R ₂ and R ₃ each independently represents an alkyl group having ₂ to 4 carbon atoms.)

（式中のＲ_１は炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基を示す） The 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate represented by the following formula (II) is converted into 2-alkoxybenzoylacetonitrile represented by the following formula (I) as shown in the following synthesis scheme. Further, it can be obtained by reacting hydrazine.

(Wherein R ₁ represents a linear or branched alkyl group having ₁ to 3 carbon atoms)

  In the present invention, it has been found that by performing the above reaction in the presence of an acid, the reaction yield is improved to the extent that it is not necessary to isolate the intermediate of formula (II) from the reaction solution. . The reason is not clear, but it is thought as follows. That is, in the cyclization reaction in which the compound of the formula (I) is reacted with hydrazine, the nucleophilic substitution reaction of hydrazine to the carbonyl group of the 2-alkoxybenzoylacetonitrile of the formula (I) is considered to be rate-limiting. It is considered that the use of an acid increases the reaction rate of the nucleophilic substitution reaction, and as a result, the reaction yield of the intermediate is improved.

  The acid can be used without particular limitation as long as it is a Bronsted acid capable of releasing protons. For example, organic sulfonic acids such as hydrochloric acid, sulfuric acid, methanesulfonic acid, propanesulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, etc. Acetic acid, butyric acid, octanoic acid, lauric acid, benzoic acid, p-methylbenzoic acid, alkoxybenzoic acid such as 2-methoxybenzoic acid and 2-ethoxybenzoic acid, organic carboxylic acids such as phthalic acid, dimethyl phosphate, phosphorus Acid phosphates such as butyl phosphate, propyl phosphate, dipropyl phosphate, butyl phosphate, dibutyl phosphate, octyl phosphate, dioctyl phosphate, lauryl phosphate, phenyl phosphate, diphenyl phosphate, etc. . In the present invention, among these, hydrochloric acid, acetic acid, benzoic acid, and alkoxybenzoic acid are more preferable.

  The above-mentioned acid can be added by dissolving or suspending in water or alcohol, but among these, it is preferable to use it by dissolving or suspending in methanol or propanol.

  The addition amount of the acid is preferably 1 to 5 mol% with respect to the reaction system. When the amount of acid added is less than 1 mol%, improvement in reaction yield cannot be expected, and when it exceeds 5 mol%, depending on the acid used, it is forced to use a glass vessel as the reaction vessel. General purpose is no longer a synthesis method.

In the present invention, R ₁ of 2-alkoxybenzoylacetonitrile which is the compound of the above formula (I) is preferably a methyl group (C1), an ethyl group (C2), or a propyl group (C3). More excellent solubility and light resistance due to the ethoxyphenyl group or propoxyphenyl group at the 6-position of the pyrazolotriazole mother nucleus when the azomethine dye is synthesized via the intermediate of the above formula (II) become. More preferred R ₁ is an ethyl group.

（式中、Ｒはメチル基、プロピル基等のアルキル基であり、Ｒ１は、炭素数Ｃ１〜３の直鎖または分枝を有するアルキル基を示す。） The compound of the above formula (I) can be synthesized by reacting benzoate compound as a starting material with acetonitrile in the presence of potassium t-butoxide as in the following synthesis scheme.

(In the formula, R represents an alkyl group such as a methyl group or a propyl group, and R1 represents a linear or branched alkyl group having 1 to 3 carbon atoms.)

  The hydrazine to be reacted with the 2-alkoxybenzoylacetonitrile of the above formula (I) is preferably added to the reaction system at a concentration of 1.0 to 1.1 mol / l.

<1H-pyrazolo [1,5-b] [1,2,4] triazole coupler>
The intermediate represented by the formula (I) obtained as described above is obtained with a purity of 95 to 100%. Therefore, as described later, when the 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler is synthesized, the intermediate is not purified once, and the following reaction is described below. Through such a reaction, 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler can be synthesized.

The 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler is obtained by the following synthesis scheme. That is, the intermediate (the compound of formula (II)) as a starting material is reacted with imidate hydrochloride to obtain an amidine compound, and then hydroxylamine is allowed to act thereon to obtain compound c. Next, the compound c is reacted with p-toluenesulfonic acid chloride and heated to reflux in the presence of pyridine, whereby 1H-pyrazolo [1,5-b] [1,1 which is a compound represented by the formula (III) is obtained. 2,4] triazole couplers can be obtained.

（式中、Ｒ_２およびＲ_３は、それぞれ独立して、炭素数Ｃ２〜４のアルキル基を示す。）

<Azomethine compound>
By coupling the above formula (III) and the pyridyldiamine derivative represented by the following formula (IV) by reacting with an oxidizing agent in the presence of a base, the compound represented by the following formula (V), An azomethine compound in which a pyridine ring is bonded to a 1H-pyrazolo [1,5-b] [1,2,4] triazole ring via a nitrogen atom can be synthesized. This reaction is performed, for example, within 40 ° C. under water cooling for about 1 hour. The obtained azomethine compound is excellent not only in terms of production cost and light resistance but also in terms of hue sensitivity and solubility.

(In the formula, R ₂ and R ₃ each independently represents an alkyl group having 2 to 4 carbon atoms.)

The pyridyldiamine derivative represented by the above formula (IV) is prepared by, for example, dropping a dialkylamine into a solution obtained by dissolving 6-chloro-3-nitro-2-picoline and potassium carbonate in acetonitrile, and stirring the oil layer. Separation yields compound d. Next, as shown in the following scheme, palladium-carbon was added to the obtained ethanol solution of compound d and reacted with hydrogen gas at 1 atm. Then, the reaction solution was filtered, and dioxane hydrochloride was added to the filtrate. In addition, the hydrochloride compound of formula (IV) can be obtained by stirring. Thus, an azomethine compound synthesized using a pyridyldiamine derivative in which R ₂ and R ₃ are all ethyl, propyl, or butyl groups is not only excellent in terms of production cost and light resistance but also in hue. It is also excellent from the viewpoint of sensitivity and solubility.

  The above-mentioned azomethine compound is useful as a heat-sensitive thermal transfer material. For example, the azomethine compound represented by the above formula (V) can be used as a magenta dye for sublimation thermal transfer, and can be suitably used in combination with other known yellow dyes, cyan dyes, other dyes, and the like. In addition to the magenta dye, a plurality of dye layers such as yellow, cyan, and black can be provided on the substrate in the surface order to form a thermal transfer sheet. In addition to the plurality of dye layers, a transferable protective layer may be provided in the surface order. In addition, you may provide black of a heat-meltable ink layer further. Conventionally known dyes for sublimation type thermal transfer such as yellow, cyan, and black, and heat-meltable dyes can be used.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

Example 1
<Preparation of reagents>
To a 1000 ml four-head flask, 100 g of ethyl 2-ethoxybenzoate (0.52 mol), 500 ml of toluene and 21.1 g of acetonitrile (0.52 mol) were added and stirred in an ice bath. Thereafter, 57.7 g of potassium tert-butoxide (0.52 mol) was added over about 10 minutes. The reaction solution was in a white slurry state. Thereafter, the reaction system was returned to room temperature and stirred for 1 hour. When 100 ml of water was dropped into the reaction system in the water bath over 3 minutes, the reaction solution was separated into two layers. The aqueous layer was recovered, the oil layer was washed twice with 50 ml of water, and the wash water was also recovered as an aqueous layer.
When the obtained aqueous layer was neutralized to about pH 1 with 50 ml (0.55 mol) of 11.1M concentrated hydrochloric acid in a water bath, crystals were precipitated. This was filtered and the crystals were dried at 60 ° C. overnight to obtain 57.2 g (0.32 mol) of the target compound A1. The yield was 59%, and the purity was 94% by HPLC simple area ratio. A synthesis scheme is shown below.

  A 1000 ml four-head flask was charged with 86.4 g of methyl 2-anisate (0.52 mol), 300 ml of toluene, and 21.1 g of acetonitrile (0.52 mol), and stirred in an ice bath. Thereafter, 57.8 g of potassium tert-butoxide (0.52 mol) was added to the reaction system over about 10 minutes. The reaction solution was in a white slurry state. Thereafter, the reaction system was returned to room temperature and stirred for 1 hour. After confirming the completion of the reaction by HPLC, 100 ml of water was added dropwise to the reaction system over 3 minutes in a water bath. When stirred as it was, the crystals of the reaction system dissolved and the reaction solution was separated into two layers. The reaction solution was separated and the aqueous layer was collected. The oil layer was washed with 100 ml of water, and the washing water was also collected as an aqueous layer. When the obtained aqueous layer was neutralized to about pH 2 in a water bath using concentrated hydrochloric acid, crystals were precipitated. The crystals were dissolved in 300 ml of ethyl acetate and separated again, and the aqueous layer was extracted twice with 200 ml of ethyl acetate. The oil layer was concentrated at about 50 ° C. using a rotary evaporator to obtain 56.5 g of Compound A2. The yield was 62%, and the purity was 93% by HPLC simple area ratio. A synthesis scheme is shown below.

<Synthesis of 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate>
To a 500 ml four-headed flask, 89.0 g of compound A1 (0.47 mol) and 90 ml of methanol were added. At that time, the reaction system was in a slurry state although the solution was colored. Next, 0.282 g of acetic acid (0.0048 mol) was added to the reaction system, and then 23.5 g of hydrazine hydrate (0.47 mol) was dropped into the flask over 5 minutes, followed by 3 hours. Heating to reflux was performed. Thereafter, the reaction solution was recovered under reduced pressure at 50 ° C. using a rotary evaporator, dissolved in 300 ml of ethyl acetate, and separated using 100 ml of saturated sodium bicarbonate water. Then, it dried using saturated salt solution, and concentrated the oil layer at 50 degreeC with the rotary evaporator, and obtained the brown oil-like intermediate body 1 (3- (2-ethoxyphenyl) -5-aminopyrazole). . When the obtained intermediate 1 was analyzed by HPLC, the purity of the intermediate 1 was 95.77% (calculated by the simple area method).

Example 2
In Example 1, intermediate 2 (3- (2-ethoxysiphenyl) -5-aminopyrazole) was obtained in the same manner as in Example 1 except that the amount of acetic acid added was changed to 0.0141 g (0.0024 mol). Got. Further, when the obtained intermediate 2 was subjected to HPLC analysis in the same manner as in Example 1, the purity of the intermediate 2 was 100%.

Example 3
In Example 2, intermediate 4 (3- (2-ethoxycyphenyl) -5 was obtained in the same manner as in Example 2 except that the amount of hydrazine monohydrate added dropwise was changed to 26.0 g (0.52 mol). -Aminopyrazole) was obtained. Further, when the obtained intermediate 3 was subjected to HPLC analysis in the same manner as in Example 1, the purity of the intermediate 4 was 100%.

Example 4
In Example 3, Intermediate 5 (3- (2-ethoxysiphenyl) -5-aminopyrazole) was obtained in the same manner as in Example 3 except that the heating reflux time after addition of acetic acid was changed to 1 hour. It was. Further, when the obtained intermediate 4 was subjected to HPLC analysis in the same manner as in Example 1, the purity of the intermediate 5 was 99.48%.

Example 5
In Example 4, the acetic acid to be added was changed to 0.57 g of benzoic acid (0.0047 mol), and the time of heating reflux was changed to 3 hours. 2-Ethoxysiphenyl) -5-aminopyrazole) was obtained. The obtained intermediate 5 was subjected to HPLC analysis in the same manner as in Example 1. As a result, the purity of intermediate 6 was 99.48%.

Example 6
In Example 5, the starting material was changed from Compound A1 to 82.3 g of Compound A2 (0.47 mol), and the benzoic acid added was changed to 0.78 g of 2-ethoxybenzoic acid (0.0047 mol). In the same manner as in Example 5, intermediate 6 (3- (2-methoxyphenyl) -5-aminopyrazole) was obtained. The obtained intermediate 6 was subjected to HPLC analysis in the same manner as in Example 1. As a result, the purity of intermediate 6 was 99.48%.

Example 7
In Example 7, intermediate 7 (3- (2- (2- Methoxyphenyl) -5-aminopyrazole) was obtained. About the obtained intermediate body 7, when the HPLC analysis was conducted like Example 1, the purity of the intermediate body 8 was 100%.

Comparative Example 1
In Example 1, Intermediate 8 (3- (2-ethoxycyphenyl) -5-aminopyrazole) was obtained in the same manner as Example 1 except that acetic acid was not added. Further, when the obtained intermediate 8 was subjected to HPLC analysis in the same manner as in Example 1, the purity of the intermediate 8 was 94.12%.

Comparative Example 2
In Comparative Example 1, intermediate 9 (3- (2-methoxyphenyl) -5-amino was prepared in the same manner as in Comparative Example 1 except that the starting material was changed from Compound A1 to 78.1 g of Compound A2 (0.47 mol). Pyrazole) was obtained. Further, when the obtained intermediate 9 was subjected to HPLC analysis in the same manner as in Example 1, the purity of the intermediate 9 was 94.51%.

Claims (8)

A process for producing a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate comprising the steps of:
A 2-benzoylacetonitrile represented by the following formula (I) is reacted with hydrazine in the presence of an acid to give a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate represented by the above formula (II). A method comprising obtaining a body.

(In the formula, R ₁ is a linear or branched alkyl group having ₁ to 3 carbon atoms.)

(In the formula, R ₁ is a linear or branched alkyl group having ₁ to 3 carbon atoms.)   The method of claim 1, wherein the acid is selected from the group consisting of hydrochloric acid, sulfuric acid, and carboxylic acid.   The method according to claim 1 or 2, wherein the acid concentration is 1 to 5 mol%. The method according to any one of claims 1 to 3, wherein R _{1 in the} formulas (I) and (II) is an ethyl group.   A 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate obtained by the production method according to any one of claims 1 to 4. A process for producing a 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler using a 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate,
The imidate hydrochloride without purifying the 3- (2-alkoxyphenyl) -5-aminopyrazole intermediate represented by the formula (II) obtained by the method according to any one of claims 1 to 4. Let the salt act to form an amidine compound,
Hydroxylamine is allowed to act on the amidine compound to form an amide oxime derivative,
The obtained amidoxime derivative is reacted with p-toluenesulfonic acid chloride and heated to reflux in the presence of pyridine, whereby 1H-pyrazolo [1,5-b] [1 represented by the following formula (III) is obtained. , 2, 4] obtaining a triazole coupler.

(In the formula, R ₁ is a linear or branched alkyl group having ₁ to 3 carbon atoms.) A method for producing an azomethine compound, the 1H-pyrazolo [1,5-b] [1,2,4] triazole coupler represented by the formula (III) obtained by the production method according to claim 6 And an pyridyldiamino derivative represented by the following formula (IV) with an oxidizing agent in the presence of a base to obtain an azomethine compound represented by the following formula (V) And the method.

(In the formula, R ₂ and R ₃ each independently represent an alkyl group having 2 to 4 carbon atoms.)

(In the formula, R ₁ is a linear or branched alkyl group having 1 to ₃ carbon atoms, and R ₂ and R ₃ each independently represents an alkyl group having ₂ to 4 carbon atoms.)   A dye for thermal transfer recording, comprising the azomethine compound obtained by the production method according to claim 7.