JP3118596B2 - Method for producing aryldialkylthiocarbamate, 2-mercaptobenzaldehyde and 2-substituted benzo [b] thiophene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for producing 2-mercaptobenzaldehyde, wherein salicylaldehyde is used as a raw material, and via a novel compound, O- and S-o-formylphenyldialkylthiocarbamate. The present invention relates to a method for producing a 2-substituted benzo [b] thiophene, which comprises reacting a halo compound with the compound. More specifically, a novel substance, O-o-formylphenyldialkylthiocarbamate, So-formylphenyldialkylthiocarbamate, a method for producing the same, and 2-mercaptobenzaldehyde and 2-substituted compounds derived from the novel compound The present invention relates to a method for producing benzo [b] thiophene. 2-mercaptobenzaldehyde and 2-substituted benzo [b] thiophenes are
It is a compound useful as an intermediate for agricultural chemicals and functional polymers.

[0002]

2. Description of the Related Art Heretofore, several methods for producing mercaptobenzaldehyde have been known. For example, the following method can be used.

(A) Method using 2,2'-dithiosalicylic acid as a raw material

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(B) Method using 2-nitrobenzaldehyde as a raw material

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(C) Method using thiosalicylic acid as a raw material

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(D) A method using 4-methylmercaptobenzaldehyde as a raw material

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However, such a known method for producing mercaptobenzaldehyde has disadvantages such as a high raw material cost, a long number of steps, and a low yield, and therefore cannot be said to be an industrially advantageous method.

On the other hand, conventionally, as a method for producing 2-substituted benzo [b] thiophene, for example, the following method has been known as an example of producing 2-acetylbenzo [b] thiophene.

(1) A method of reacting butyl [b] thiophene with butyllithium and subsequently reacting with N, N-dimethylacetamide

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(2) A method of reacting sodium salt of 2-mercaptobenzaldehyde with chloroacetone in the presence of sodium hydroxide

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(3) A method in which thiosalicylic acid is reduced with lithium aluminum hydride to form 2-mercaptobenzyl alcohol salt, subsequently reacted with chloroacetone to form a sulfide, and then cyclized with pyridine-sulfuric anhydride.

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However, such known methods are:
Each has the following disadvantages.

The method (1) is not industrially advantageous because benzo [b] thiophene used as a raw material is expensive.

The method (3), like the method (1), is not industrially advantageous because it uses raw material costs and expensive auxiliary raw materials.

The method (2) has a problem in the production method and stability of 2-mercaptobenzaldehyde or its alkali metal mercaptide used as a raw material.

[0016]

Means for Solving the Problems In view of the above situation, the present inventors have intensively studied to provide a method for producing 2-mercaptobenzaldehyde simply and economically advantageously. As a result, as shown in the following reaction formula, it is represented by the general formula (I) obtained by reacting salicylaldehyde with N, N-dialkylthiocarbamoyl chloride represented by the general formula (III) in the presence of a base. By thermally rearranging O-o-formylphenyldialkylthiocarbamate to form S-o-formylphenyldialkylthiocarbamate represented by the general formula (II), and subsequently performing a hydrolysis reaction in the presence of a base, It has been found that the desired 2-mercaptobenzaldehyde can be obtained , and the present invention has been achieved. The compounds represented by the general formula (I) and the general formula (II) are new compounds which have not been known so far.

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The above general formulas (I), (II) and (II)
In I), R represents an alkyl group having 1 to 4 carbon atoms,
This alkyl group may be linear or branched. Specific examples of such an alkyl group include a methyl group, an ethyl group, and n-
Examples include a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group and a t-butyl group.

Further, the compounds represented by the general formulas (I) and (I)
Specific examples of the novel compound of I) include the following. O-o-formylphenyldimethylthiocarbamate,
O-o-formylphenyl diethylthiocarbamate,
O-formylphenyldi-n-propylthiocarbamate, O-formylphenyldi-n-butylthiocarbamate, So-formylphenyldimethylthiocarbamate, So-formylphenyldiethylthiocarbamate Mart, So-formylphenyldi-n-propylthiocarbamate, So-formylphenyldi-
n-butylthiocarbamate.

Further, in view of the above situation, the present inventors have intensively studied to provide a method for industrially advantageously producing a 2-substituted benzo [b] thiophene. As a result, as shown in the following reaction formula, by reacting 2-mercaptobenzaldehyde or its alkali metal mercaptide obtained by the above-mentioned method with the halo compound represented by the general formula (IV), the desired general formula (IV) The present inventors have found that a 2-substituted benzo [b] thiophene represented by V) can be produced, and have reached the inventions described in claims 3 and 4 .

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[0020] The gist of the invention described in claims 1 and 2 is that a novel O obtained by reacting salicylaldehyde with N, N-dialkylthiocarbamoyl chloride in the presence of a base.
-Production of 2-mercaptobenzaldehyde, which comprises subjecting -o-formylphenyldialkylthiocarbamate to thermal rearrangement to form a novel S-o-formylphenyldialkylthiocarbamate, followed by a hydrolysis reaction in the presence of a base. Is the way. The method for producing 2-mercaptobenzaldehyde according to the present invention is a completely novel method which has never been seen before, and is characterized by using salicylaldehyde which is industrially easily available as a raw material,
The novel O-o-formylphenyldialkylthiocarbamate obtained by reacting N, N-dialkylthiocarbamoyl chloride can be easily produced by thermal rearrangement and hydrolysis.

As the N, N-dialkylthiocarbamoyl chloride used in the present invention, those in which the alkyl group is a methyl group, an ethyl group, a propyl group, or a butyl group can be used. hand,
Usually 0.8 to 1.5 times mol, preferably 1.0 to 1.
It is in the range of 3 moles. If the amount of N, N-dialkylthiocarbamoyl chloride used is less than 0.8 moles, unreacted salicylaldehyde increases, while
Even if it is used in excess of 1.5 moles, the effect corresponding to it is not obtained, and it is economically disadvantageous.

The base used in the reaction of salicylaldehyde with N, N-dialkylthiocarbamoyl chloride is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide; an alkali metal carbonate such as sodium carbonate or potassium carbonate; hydrogen. Alkali metal hydrides such as sodium hydride and potassium hydride; metal alcoholates such as sodium methylate and sodium ethylate; and the like can be used. Sodium hydroxide is preferred from an economic standpoint. The amount of the base to be used is generally 0.8 to 1.5 times mol, preferably 1.0 to 1.0 times mol of salicylaldehyde.
It is in the range of 3 moles. If the amount of the base used is less than 0.8 times, the amount of unreacted salicylaldehyde increases, and
When used in an amount of more than 5 moles, N, N-dialkylthiocarbamoyl chloride is decomposed and does not effectively participate in the reaction, and unreacted salicylaldehyde increases.

The reaction solvent of salicylaldehyde with N, N-dialkylthiocarbamoyl chloride is not particularly limited, and water; polar solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide and the like. Lower alcohols such as methanol, ethanol, propanol and isopropanol; aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; halogenated hydrocarbons such as methylene chloride and chloroform; ethers such as tetrahydrofuran and dioxane; Although a mixture of two or more of these can be mentioned, water or a mixed solution of water and a water-soluble solvent is preferably used because of easy handling and economical reasons. The amount of the solvent used is usually 3 to 30 times the weight of salicylaldehyde.

The reaction temperature of the reaction between salicylaldehyde and N, N-dialkylthiocarbamoyl chloride varies depending on the type of solvent and the type of base used, and cannot be specified unconditionally, but is usually -10 to 100 ° C, preferably 0 to 100 ° C. It is in the range of 40 ° C. If the reaction temperature is lower than −10 ° C., the reaction rate is low, and if it exceeds 100 ° C., the yield decreases due to side reactions, which is not preferable. The reaction time is usually in the range of 0.5 to 10 hours.

The novel O-o-formylphenyldialkylthiocarbamate thus obtained is filtered,
It can be obtained and isolated by appropriately using ordinary means such as an extraction operation.

In the thermal rearrangement reaction of O-formylphenyldialkylthiocarbamate, it is not necessary to use a solvent, but a solvent may be used if necessary. The reaction solvent is not particularly limited as long as it is inert in this reaction. For example, N, N-dimethylformamide, N, N-dimethylacetamide, sulfolane, N-methyl-2-pyrrolidone, dimethyl High boiling solvents such as sulfoxide, trichlorobenzene, diphenyl ether and the like can be mentioned.

Particularly when trichlorobenzene or diphenyl ether is used, good results are obtained.

Although the reaction temperature of the thermal rearrangement reaction of O-formylphenyldialkylthiocarbamate varies depending on the boiling point of the solvent used, it cannot be specified unconditionally.
It is in the range of 0-250C, preferably 170-210C. When the reaction temperature exceeds 250 ° C., S
This is because the yield of -o-formylphenyldialkylthiocarbamate decreases, and when the reaction temperature is less than 150 ° C, the reaction rate is practically too slow. The reaction time is usually in the range of 0.5 to 20 hours.

The novel So-formylphenyldialkylthiocarbamate thus obtained can be obtained and isolated by distillation under reduced pressure.

By hydrolyzing So-formylphenyldialkylthiocarbamate in the presence of a base, 2-mercaptobenzaldehyde can be obtained. As the base used in the above, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide;
Alkali metal carbonates such as sodium carbonate and potassium carbonate;
Metal alcoholates such as sodium methylate and sodium ethylate are exemplified. Among them, sodium hydroxide is preferably used from an economic viewpoint. The amount of the base to be used is generally 0.8 to 2.5 times, preferably 1.5 to 2.0 times, the molar amount of O-o-formylphenyldialkylthiocarbamate. When the amount of the base used is less than 0.8 mole, unreacted S-o-
Formylphenyldialkylthiocarbamate is increased, while using it in an amount of more than 2.5 moles is not economically disadvantageous because the effect corresponding thereto cannot be obtained.

The anti 応温 degree of hydrolysis of S-o-formylphenyl dialkyl thiocarbamates is usually 30
120 ° C, preferably in the range of 50-100 ° C. When the reaction temperature exceeds 120 ° C., a side reaction occurs, while
If the temperature is lower than 30 ° C., the reaction rate is too slow for practical use. The reaction time varies depending on the reaction temperature and the type of the reaction solvent, and cannot be specified unconditionally, but is usually in the range of 1 to 20 hours.

As a reaction solvent for the hydrolysis reaction of S-o-formylphenyldialkylthiocarbamate, water or a solvent inert to water with the present reaction, for example, lower aliphatic alcohols such as methanol, ethanol and isopropanol; Aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; halogenated hydrocarbons such as methylene chloride and chloroform; ethers such as tetrahydrofuran and dioxane; N, N-dimethylformamide, N, N-dimethylacetamide and the like Acid amides; and a mixture of two or more of these. Examples of the solvent include water alone or a mixture of water and the solvent used in the previous thermal rearrangement reaction because there is no need to recover the solvent. It is preferred to use. The amount of the solvent used is usually 3 to 30 times by weight based on the weight of O- and S-o-formylphenyldialkylthiocarbamate.

The thus obtained 2-mercaptobenzaldehyde can be obtained and isolated by a usual treatment such as neutralization with hydrochloric acid and extraction.

Next, the gist of the invention described in claims 3 and 4 is that
A 2-substituted benzo [b] represented by the general formula (V), characterized by reacting 2-mercaptobenzaldehyde or its alkali metal mercaptide obtained by the above-mentioned method with a halo compound represented by the general formula (IV). This is a method for producing thiophene. Furthermore, according to the method of the present invention, the novel O-o represented by the general formula (I)
So-formylphenyldialkylthiocarbamate and 2-mercaptobenzaldehyde represented by the general formula (II) derived from -formylphenyldialkylthiocarbamate are isolated without isolation from a so-called one-pot compound of the general formula (V It is also possible to easily produce the 2-substituted benzo [b] thiophene represented by the formula (1). When reacting 2-mercaptobenzaldehyde or its alkali metal mercaptide with the halo compound represented by the general formula (IV), a base may be added as necessary.

The halo compound represented by the general formula (IV) used in the present invention includes chloroacetone, bromoacetone, chloroacetic acid, sodium chloroacetate, potassium chloroacetate, bromoacetic acid, sodium bromoacetate, methyl chloroacetate, chloroacetate. Ethyl acetate, ethyl bromoacetate and the like can be mentioned.

The amount of the halo compound represented by the general formula (IV) is usually 0.1 to 0 based on O-o-formylphenyldialkylthiocarbamate represented by the general formula (I).
It is in the range of 7-2.0 moles, preferably 0.8-1.5 moles. When the use amount of the halo compound is less than 0.7 mole, the yield of the 2-substituted benzo [b] thiophene decreases. Is not economically advantageous.

Examples of the base to be added include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; metal alcoholates such as sodium methylate and sodium ethylate. Although possible, sodium hydroxide is preferred from an economic standpoint. However, when an excess base remains during the above-mentioned hydrolysis reaction of So-formylphenyldialkylthiocarbamate,
Since it is an alkali metal mercaptide of 2-mercaptobenzaldehyde, it may not be necessary to additionally use a base.

The reaction temperature of 2-mercaptobenzaldehyde or its alkali metal mercaptide with the halo compound represented by the general formula (IV) is usually in the range of 0 to 120 ° C, preferably 5 to 100 ° C. If the reaction temperature is lower than 0 ° C., the reaction rate is low, and if it exceeds 120 ° C., the yield decreases due to side reactions. The reaction time is usually 0.5 to
The range is 6 hours.

Thus, the 2-substituted benzo [b] thiophene represented by the general formula (V) formed by the one-pot reaction includes 2-acetylbenzo [b] thiophene and 2-benzo [b] thiophenecarboxylic acid. And 2-benzo [b] thiophenecarboxylic acid methyl ester, 2-benzo [b] thiophenecarboxylic acid ethyl ester, and the like. Isolation of the 2-substituted benzo [b] thiophene from the reaction solution can be usually performed by adding water to the reaction solution, extracting the solution, and performing crystallization or acid precipitation.

[0040]

According to the present invention, the desired 2-mercaptobenzaldehyde can be easily obtained from salicylaldehyde as a raw material via the novel compounds O- and S-o-formylphenyldialkylthiocarbamate. This method is economically and industrially advantageous because it can be obtained efficiently.

Further, using the obtained 2-mercaptobenzaldehyde as a raw material, the desired 2-substituted benzo [b] is obtained.
Since thiophene can be obtained by a simple operation and in a one-pot reaction from the aforementioned O-o-formylphenyldialkylthiocarbamate, the industrial value is great.

[0042]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

Example 1 O-o-formylphenyldimethyl
Synthesis stirrer Ji Lucio carbamate, thermometer, 200ml four-necked flask equipped with a condenser, under nitrogen atmosphere, sodium hydroxide 4.0g
(0.10 mol) and 60 g of water were added, and under stirring, 12.21 g (0.10 mol) of salicylaldehyde was added dropwise at room temperature over about 30 minutes. After cooling the reaction solution to 5 ° C., DMF in which 12.35 g (0.10 mol) of N, N-dimethylthiocarbamoyl chloride was dissolved
(N, N-dimethylformamide) solution (20 ml)
The mixture was added dropwise over a period of time, and further reacted at the same temperature for 2 hours.
After the reaction, the slurry reaction solution was filtered, washed with water, dried, and crude O-
o-formylphenyldimethylthiocarbamate 20.
48 g were obtained. This was recrystallized with a mixed solvent of methanol and water to obtain 19.46 g (yield 93.1%) of white crystals.

Melting point, elemental analysis, H-NM of this compound
The R spectrum data and the molecular weight by mass spectrometry are shown. Melting point: 85.0-85.9 ° C Elemental analysis: C% H% N% S% Measured 57.30 5.10 6.50 15.20 Calculated 57.40 5.30 6.69 15.32 NMR (δ ppm CDCl ₃ ): 3.40-3.53
_{(D, 6H, CH 3)} , 7.09~8.01 (m, 4
H, aromatic, 10.05 (S, 1H, CH
O) Molecular weight: 209

Examples 2 to 4 O-o-formylphenyl
Synthesis of dimethylthiocarbamate Example 1 was used except that the bases and reaction solvents shown in Table 1 were used.
The reaction was carried out in the same manner as described above, and the results shown in Table 1 were obtained. The isolation and purification of O-formylphenyldimethylthiocarbamate were performed in the same manner as in Example 1.

[0046]

[Table 1]

Example 5 O-o-formylphenyldie
Synthesis of tylthiocarbamate N, N-dimethylthiocarbamoyl chloride is converted to N, N
15.15 g of diethylthiocarbamoyl chloride
(0.10 mol), except that the reaction was carried out in the same manner as in Example 1. After the reaction, chloroform was added to the reaction solution, and the mixture was extracted, separated, concentrated, and distilled under reduced pressure.
o-formylphenyldiethylthiocarbamate 20.
80 g (87.8% yield) were obtained.

The boiling point, elemental analysis, and H-NM of this compound
The R spectrum data and the molecular weight by mass spectrometry are shown. Boiling point: 163 to 165 ° C./2 mmHg Elemental analysis: C% H% N% S% Measured 60.65 6.30 5.80 13.45 Calculated 60.73 6.37 5.90 13.51 NMR ( δ ppm CDCl ₃ ): 1.31-1.68
_{(Dt, 6H, CH 3)} , 3.90~4.40 (m, 4
_{H, CH 2), 7.60~8.65 (} m, 4H, aro
magnetic), 10.94 (S, 1H, CHO) Molecular weight: 237

Example 6 So-formylphenyldim
Synthesis stirrer Ji Lucio carbamate, thermometer, 200ml four-necked flask equipped with a condenser, under nitrogen atmosphere, O-o-formylphenyl dimethyl thiocarbamate 20.90g (0.10 mol), 1 And 150 g of 2,2,4-trichlorobenzene were charged and subjected to a thermal rearrangement reaction at 195 to 200 ° C. for 2 hours with stirring. After the reaction, 1,2,4-trichlorobenzene was distilled off under reduced pressure, and further distilled under reduced pressure to obtain 18.89 g of pale yellow, transparent So-formylphenyldimethylthiocarbamate.
(90.4% yield).

The boiling point, elemental analysis, and H-NM of this compound
The R spectrum data and the molecular weight by mass spectrometry are shown. Boiling point: 161-163 ° C./7 mmHg Elemental analysis: C% H% N% S% Measured 57.35 5.10 6.58 15.25 Calculated 57.40 5.30 6.69 15.32 NMR ( δ ppm CDCl ₃ ): 3.11 (bs, 6)
_{H, CH 3), 7.47~7.66 (} m, 3H, aro
magnetic), 7.96 to 8.13 (m, 1H, aro
magnetic), 10.33 (S, 1H, CHO) Molecular weight: 209

Examples 7-9 So-formylphenyl
Synthesis of dimethylthiocarbamate The reaction was carried out in the same manner as in Example 6 except that the reaction solvent, reaction temperature and reaction time shown in Table 2 were obtained, and the results in Table 2 were obtained.

[0052]

[Table 2]

Example 10 So-formylphenyldi
Synthesis of ethylthiocarbamate O-formylphenyldimethylthiocarbamate was converted to O-formylphenyldiethylthiocarbamate 2
Except that the amount was changed to 3.70 g (0.10 mol), 21.88 g of pale yellow transparent So-formylphenyldiethylthiocarbamate was obtained in the same formulation as in Example 6 (yield: 92.3).
%).

The boiling point, elemental analysis value, and H-NM of this compound
The R spectrum data and the molecular weight by mass spectrometry are shown. Boiling point: 168-170 ° C / 2 mmHg Elemental analysis: C% H% N% S% Measured 60.60 6.35 5.85 13.48 Calculated 60.73 6.37 5.90 13.51 NMR ( δ ppm CDCl ₃ ): 1.08 to 1.56
_{(M, 6H, CH 3)} , 3.60~4.00 (q, 4
_{H, CH 2), 7.83~8.35 (} m, 3H, aro
magnetic), 8.69-8.87 (m, 1H, aro)
magnetic), 11.32 (S, 1H, CHO) Molecular weight: 237

Example 11 2-mercaptobenzarde
Synthesis of Hyde 8.0 g of sodium hydroxide was added to a 1,2,4-trichlorobenzene reaction solution of So-formylphenyldimethylthiocarbamate obtained in Example 6 under a nitrogen atmosphere.
(0.2 mol), 100 g of water and 70-
The hydrolysis reaction was performed at 80 ° C. for 2 to 3 hours. The reaction solution was cooled to room temperature, neutralized with concentrated hydrochloric acid, and separated to obtain a 1,2,4-trichlorobenzene solution containing 2-mercaptobenzaldehyde. When this solution was quantified by high performance liquid chromatography, 11.85 g of 2-mercaptobenzaldehyde was produced. The yield based on O-o-formylphenyldimethylthiocarbamate is 8
It was 5.9%.

Example 12 2-Mercaptobenzarde
Synthesis of Sodium Mercaptide of Hyd 8.0 g (0.20 mol) of sodium hydroxide and 100 g of water were charged to the So-formylphenyldimethylthiocarbamate reaction solution obtained in Example 9 under a nitrogen atmosphere. The mixture was subjected to a hydrolysis reaction at 70 to 80 ° C. for 2 hours with stirring. The reaction solution was cooled to room temperature to obtain an aqueous solution containing sodium salt of 2-mercaptobenzaldehyde (mercaptide). When this solution was quantified by high performance liquid chromatography, 10.94 g of sodium salt of 2-mercaptobenzaldehyde had been formed. O-o-
The yield based on formylphenyldimethylthiocarbamate was 68.4%.

Example 13 2-mercaptobenzarde
Except that the raw material for synthesis of the hide was changed to the 1,2,4-trichlorobenzene solution of So-formylphenyldiethylthiocarbamate obtained in Example 10, the same formulation as in Example 11 was used.
A 1,2,4-trichlorobenzene solution containing 2-mercaptobenzaldehyde was obtained. When this solution was quantified by high performance liquid chromatography, 12.09 g of 2-mercaptobenzaldehyde was produced. O-
The yield based on o-formylphenyldiethylthiocarbamate was 87.6%.

Example 14 2-acetylbenzo [b] thi
Synthesis of Ophen In a 200 ml four-necked flask equipped with a stirrer, thermometer and condenser, under a nitrogen atmosphere, O-o-formylphenyldimethyldimethylthiocarbamate 20.90 (0.10 mol),
100 g of 1,2,4-trichlorobenzene was charged and subjected to a thermal rearrangement reaction at 195 to 200 ° C. for 2 hours with stirring. After the reaction, the reaction mixture was cooled to around room temperature, 80 g of an aqueous solution containing 8.0 g (0.20 mol) of sodium hydroxide was added, and a hydrolysis reaction was performed at 75 to 80 ° C. for 2 hours. After cooling to room temperature, the mixture was separated into an aqueous layer and a 1,2,4-trichlorobenzene layer to obtain an aqueous layer containing a sodium salt of 2-mercaptobenzaldehyde. To this aqueous layer, 9.25 g (0.10 mol) of chloroacetone was added dropwise at 10 to 15 ° C over about 15 minutes, and further reacted at the same temperature for 1 hour. After the reaction, the slurry reaction solution was filtered, washed with water, and dried,
14.32 g of crude 2-acetylbenzo [b] thiophene was obtained. This was recrystallized with a methanol-water mixed solvent to obtain 13.60 g of pale yellowish white crystals. The yield based on O-o-formylphenyldimethylthiocarbamate is 77.3.
%Met.

Example 15 2-benzo [b] thiophene
Synthesis of carboxylic acid O-o-formylphenyldimethylthiocarbamate and chloroacetone were respectively converted to O-o-formylphenyldiethylthiocarbamate by 23.70 g (0.10 g).
Mol), 12.81 g of sodium chloroacetate (0.11 g)
(Mol) and the reaction temperature with sodium chloroacetate was changed to 90 to 100 ° C., except that the reaction was carried out in exactly the same manner as in Example 14. After the reaction,
Acid precipitation with concentrated hydrochloric acid, filtration and washing with water were performed to obtain 14.15 g of crude 2-benzo [b] thiophenecarboxylic acid. This was recrystallized with a methanol-water mixed solvent to obtain 13.44 g of a pale yellowish white powder.
I got The yield based on O-o-formylphenyldiethylthiocarbamate was 75.5%.

Example 16 2-benzo [b] thiophene
Synthesis of carboxylic acid methyl ester 11.94 g of methyl chloroacetate (0.
The reaction and post-treatment were carried out in exactly the same manner as in Example 14 except that the amount was changed to 11 mol), and 2-benzo [b] thiophenecarboxylic acid methyl ester 14.05 as pale yellowish white crystals
g was obtained. The yield based on O-o-formylphenyldimethylthiocarbamate was 73.2%.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahito Nakano 1 at 346 Miyanishi, Harima-cho, Kako-gun, Hyogo Pref. Within Sumitomo Seika Co., Ltd. (56) References Japanese Patent Publication No. Sho 43-6770 JP-B-41-15292 (JP, B1) Synthesis, 1992, No. 1; 1-2, p. 112-118 (58) Fields surveyed (Int. Cl. ⁷ , DB name) C07C 319/12 C07C 323/22 C07C 333/04 CA (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A O-o-represented by the following general formula (I)
The formylphenyl dialkyl thiocarbamates by thermal rearrangement, S-o-formylphenyl dialkyl thiocarbamates and without represented by the following formula (II), subsequently, characterized in that is hydrolyzed in the presence of a base 2 -A method for producing mercaptobenzaldehyde. Embedded image 2. A method according to claim 1 base is sodium hydroxide
The manufacturing method as described. 3. O-o-represented by the following general formula (I)
The formylphenyl dialkyl thiocarbamates by thermal rearrangement, to give the S-o-formylphenyl dialkyl thiocarbamates represented by the following formula (II), subsequently, in the presence of a base by hydrolyzing 2-mercapto benzaldehyde or A method for producing a 2-substituted benzo [b] thiophene represented by the following general formula (V), characterized by reacting with the alkali metal mercaptide and subsequently reacting with a halo compound represented by the following general formula (IV). Embedded image 4. The halo compound represented by the general formula (IV) is chloroacetone or bromoacetone.
3. The production method according to 3 .