JPH0588711B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a new compound, 2-(α-alkoxyimino)ethylthiophene, and a method for producing the same. 2-(α-alkoxyimino)ethylthiophene can be widely used as an important intermediate for producing medicines, agricultural chemicals, and the like. For example, 2-
By acetylating (α-alkoxyimino)ethylthiophene, a new compound, 5-acetyl-
A novel compound, 5-(α-alkoxyimino)ethyl-2-thiophenecarboxylic acid, can be obtained by converting 2-(α-alkoxyimino)ethylthiophene into oxidation using a haloform reaction. By hydrolyzing this new compound with acid, it can be easily converted into a known compound, 5.
-Acetyl-2-thiophenecarboxylic acid can be obtained. This compound, for example,
It is an important intermediate of thienyrithiazolylthioamino alcohol derivatives, which are therapeutic agents for arrhythmia, various heart diseases, and hypertension, as described in JP-A No. 25562 and JP-A-50-76069. In addition, the new compound 5-acetyl-2
By hydrolyzing -(α-alkoxyimino)ethylthiophene with an acid, 2,5-diacetylthiophene, which is a known compound, can be easily obtained. BACKGROUND TECHNOLOGY However, no method has been known to date for producing 5-acetyl-2-thiophenecarboxylic acid and 2,5-diacetylthiophene industrially easily and in high yield. For example, 5-acetyl-
As a method for producing 2-thiophenecarboxylic acid, 5
- Method by hydrolysis of diano-2-acetylthiophene (J.Chem.Soc., 1937 , 911), 2,5-
Method by oxidation of diacetylthiophene (J.Am.
Chem.Soc., 69 , 1012 (1947)), method by acylation of 2-thenoyl ester (Ann.der
Chem., 1 (1962)) and the carboxylation reaction of 2-methyl-2'-thienyl-1,3-dioxolane. This is not a preferable method from the viewpoint of controllability. Therefore, in order to solve the problems in these methods, Japanese Patent Application Laid-Open No. 53-23963 was published.
As described in Publication No. 141264, a method has been proposed in which 5-acetyl-2-thienyl acetic acid or its ester obtained by acetylation of 2-thienyl acetic acid is oxidized; control is not always easy. Further, as a method for producing the 2,5-diacetylthiophene, for example, a method of acetylating 2-acetylthiophene (J.Am.Chem.Soc.,
69, 1012 (1947)), but the yield is extremely low. Problems to be Solved by the Invention The present inventors, for example, have conducted extensive research in order to find an industrially advantageous manufacturing method for the above-mentioned 5-acetyl-2-thiophenecarboxylic acid and 2,5-diacetylthiophene. , focused on using 2-acetylthiophene, which is easily available as an industrial raw material. However, since 2-acetylthiophene has a low electron density in the thiophene ring due to the electron-withdrawing acetyl group, it is difficult to perform an electrophilic substitution reaction at the 5-position. for example,
As mentioned above, by the method of directly acetylating 2-acetylthiophene, 2,5-diacetylthiophene can only be obtained in an extremely low yield. Therefore, as a result of intensive research into derivatives that increase the electron density in the thiophene ring of 2-acetylthiophene, the present inventors O-alkylated 2-acetylthiophene oxime to transform the acetyl group into an electron-donating group. Convert to α-alkoxyiminoethyl group, 2-(α-alkoxyimino)
When converted into ethylthiophene, this compound can be easily and in high yield obtained by an electrophilic substitution reaction.
-acetyl-substituted compounds. That is, 2-(α-alkoxyimino)ethylthiophene is easily acetylated at the 5-position with acetic anhydride etc. for the reasons mentioned above, and the 5-
Converted to acetyl-2-(α-alkoxyimino)ethylthiophene. By hydrolyzing this compound with an acid, known 2,5-diacetylthiophene can be obtained. In addition, 5-acetyl-2-(α-
If the acetyl group at the 5-position of alkoxyimino)ethylthiophene is oxidized to a carboxyl group, 5
-(α-alkoxyimino)ethyl-2-thiophenecarboxylic acid can be obtained. Also, in the same way as above, if this compound is hydrolyzed with acid,
Known 5-acetyl-2-thiophenecarboxylic acid can be obtained. Thus, the novel compound 2-(α-alkoxyimino)ethylthiophene according to the present invention is very useful as an intermediate in the organic synthetic chemical industry. As mentioned above, the present invention discloses a novel method of utilizing oxime as an industrial raw material, which has been conventionally commonly used as a method for identifying organic compounds. An object of the present invention is to provide 2-(α-alkoxyimino)ethylthiophene and a method for producing the same. On the other hand, as a result of further research on the method for producing the above-mentioned 2-(α-alkoxyimino)ethylthiophene, the present inventors found that 2-acetylthiophene was directly O-
By alkyl oximation, 1
The present invention was based on the discovery that 2-(α-alkoxyimino)ethylthiophene can be obtained in a higher yield and with higher purity in this step. Means for Solving the Problems 2-(α-alkoxyimino)ethylthiophene, which is a novel compound according to the present invention, has the general formula [Formula] (wherein R represents an alkyl group having 1 to 4 carbon atoms). expressed. In the above general formula (), R has 1 to 4 carbon atoms
represents an alkyl group, and this alkyl group may be linear or branched. Therefore, specific examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl and t-butyl.
Specific examples of preferred compounds according to the invention therefore also include 2-(α-methoxyimino)ethylthiophene, 2-(α-ethoxyimino)ethylthiophene, 2-(α-n-propoxyimino)ethylthiophene, 2-(α- -isopropoxyimino)ethylthiophene, 2-(α-n-butoxyimino)ethylthiophene, 2-(α-s-butoxyimino)ethylthiophene, 2-(α-t-
butoxyimino)ethylthiophene and the like. Generally, as is well known, oximes exist in two types of geometric isomers: syn and anti. Similarly, 2 according to the invention
-(α-alkoxyimino)ethylthiophene also has two types of geometric isomers: a syn form in which the alkoxy group is on the same side as the thiophene ring, and an anti form in which the alkoxy group is on the opposite side to the thiophene ring. According to the method of the present invention described below, a mixture of these syn- and anti-isomers is obtained. In the present invention, 2-
(α-alkoxyimino)ethylthiophene is
It shall mean these syn-isomers, anti-isomers, and mixtures thereof. 2- represented by the general formula () according to the present invention
(α-alkoxyimino)ethylthiophene is
It can be obtained by reacting 2-acetylthiophene oxime with an alkylating agent in the presence of a base. 2-acetylthiophene oxime is, for example,
As described in Compt.Rend., 234, 847 (1952), it is an already known compound, and 2-acetylthiophene can be converted into an oxime with, for example, hydroxylamine according to a conventional method. Therefore, it can be obtained in high yield. For example, 2-acetylthiophene oxime is
Usually, a hydroxylamine salt, such as a hydrochloride or It can be obtained by reacting sulfates. Since this reaction proceeds almost quantitatively, the amount of hydroxylamine salt need only be at least the equivalent of the 2-acetylthiophene used to completely oximeize it; It is used in a molar amount of 1.0 to 1.2 times that of thiophene. As the base, for example, hydroxides and carbonates of alkali metals and alkaline earth metals are preferably used, and particularly sodium hydroxide and sodium carbonate are most preferably used. The amount of this base to be used is not particularly limited, but usually
The amount may be at least equivalent to completely neutralize the hydroxylamine salt. The reaction temperature is usually in the range of 30-100°C,
The reaction time is usually 3 to 8 hours. The oximation reaction of 2-acetylthiophene can be accelerated by adjusting the pH of the reaction mixture to a range of 2 to 6 in the presence of an organic acid. That is, if other reaction conditions are the same, by adjusting the pH of the reaction mixture to a range of 2 to 6 in the presence of an organic acid, the reaction time is usually shortened by 1 to 2 hours, resulting in a substantial improvement in the reaction time. 2-acetylthiophene oxime can be obtained with the same yield. As the organic acid, lower aliphatic organic acids having 1 to 4 carbon atoms, particularly acetic acid and propionic acid, are preferably used. The amount used is an amount sufficient to adjust the pH of the reaction mixture to 2 to 6, as described above. After completion of the reaction, the desired 2-acetylthiophene oxime can be obtained by, for example, distilling off the solvent or adding a large amount of water to the reaction mixture, cooling it, and filtering off the formed precipitate. I can do it. To O-alkylate 2-acetylthiophene oxime, conventional O-
In the present invention, the alkylating agent used is dimethyl sulfate, diethyl sulfate, di-n-propyl sulfate, diisopropyl sulfate, di-n-butyl sulfate, di-s-butyl sulfate, di- -Dialkyl sulfates such as t-butyl sulfate, methyl iodide, ethyl iodide, iodide-
n-propyl, isopropyl chloride, isopropyl bromide, isopropyl iodide, n-butyl bromide,
n-butyl iodide, s-butyl iodide, t-butyl chloride, t-butyl bromide, t-iodide
Alkyl halides such as butyl can be preferably used. The amount of these alkylating agents to be used is not particularly limited, but is usually in the range of 0.5 to 2 moles, preferably 1.0 to 1.2 moles, relative to the 2-acetylthiophene oxime used. If the amount of alkylating agent used is too small,
This is because the yield of -(α-alkoxyimino)ethylthiophene is low, and on the other hand, even if too much excess is used, no particularly advantageous effects can be obtained. The above O-alkylation reaction of 2-acetylthiophene oxime is usually carried out in the presence of a base. As such bases, hydroxides, hydrides, carbonates, hydrogen carbonates, metal alkoxides, etc. of alkali metals and alkaline earth metals can be preferably used. However, aliphatic, aromatic and heterocyclic tertiary amines such as triethylamine, dimethylaniline, pyridine and the like can also be used if desired. In particular, alkali metal hydroxides,
When a hydride and an alkoxide are used, the desired 2-(α-alkoxyimino)ethylthiophene can be obtained in high yield. The amount of these bases to be used is not particularly limited, but is usually 0.8 to 2 times the mole of 2-acetylthiophene oxime used, preferably 1.0
~1.2 times the molar range. As with the alkylating agent, if too little amount of base is used, the yield of the desired 2-(α-alkoxyimino)ethylthiophene will be low; on the other hand, if too much excess is used, there will be no particularly advantageous effect. can't get it. The above O-alkylation reaction of 2-acetylthiophene oxime is usually carried out in a solvent.
The solvent is not particularly limited as long as it dissolves the 2-acetylthiophene oxime used and is inactive in the reaction.
Preferably, in addition to water, lower aliphatic alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone and methyl ethyl ketone, ethers such as ethyl ether, tetrahydrofuran, and dioxane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene, etc. Halogenated hydrocarbons, aromatic hydrocarbons such as benzene, toluene and xylene, acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethylsulfoxide, and two or more of these. Mention may be made of mixtures of. In particular, in the present invention, N,N-dimethylformamide and its aqueous solution, ie, hydrous N,N-dimethylformamide, are preferred from the viewpoint of obtaining the target product in high yield. The temperature for the alkylation reaction of 2-acetylthiophene oxime is usually in the range of about -10°C to about 50°C, preferably in the range of about 0°C to 35°C. Particularly preferred is a temperature range of about 5°C to about 20°C. When the reaction temperature is higher than about 50°C, the desired 2-(α-alkoxyimino)
This is because the yield of ethylthiophene decreases, and on the other hand, when the reaction temperature is lower than about -10°C, the reaction rate is too slow for practical use. The reaction time may be several hours, and the reaction is usually completed in 1 to 2 hours. After the alkylation reaction of 2-acetylthiophene oxime is completed, the reaction mixture is extracted with, for example, chloroform, washed with water, the chloroform is distilled off, and the residue is further distilled under reduced pressure. , usually the compounds according to the invention can be separated as liquids. The compound according to the present invention can also be separated by directly distilling the reaction mixture under reduced pressure. Furthermore, 2-(α
According to the present invention, -alkoxyimino)ethylthiophene is obtained by adding O-alkylhydroxylamine represented by the general formula RONH ₂ (wherein R represents an alkyl group having 1 to 4 carbon atoms) to 2-acetylthiophene. By direct reaction, it can be obtained more easily and with higher purity. O-alkylhydroxylamine that can be used in the present invention includes O-methylhydroxylamine,
O-ethylhydroxylamine, N-n-propylhydroxylamine, O-isopropylhydroxylamine, O-n-butylhydroxylamine, O-s-butylhydroxylamine or O-
It is t-butylhydroxylamine, and is selected depending on the target 2-(α-alkoxyimino)ethylthiophene. In the O-alkyl oximation reaction of 2-acetylthiophene with O-alkylhydroxylamine, the amount of O-alkylhydroxylamine used is not particularly limited, but it is usually relative to the 2-acetylthiophene used. te 0.5
It is in the range of ~2 times the mole, preferably in the range of 1.0 to 1.5 times the mole. If the amount of O-alkylhydroxylamine used is too small, it will not be possible to obtain the desired 2-(α-alkoxyimino)ethylthiophene in a high yield; on the other hand, if too large a amount is used, a particularly advantageous This is because no effect can be obtained. Since O-alkylhydroxylamine is usually provided as a mineral acid salt such as a hydrochloride or a sulfate salt, when such an O-alkylhydroxylamine salt is used, it is used as a free O-alkylhydroxylamine. For this purpose, 2-acetylthiophene is reacted with an O-alkylhydroxylamine salt in the presence of a base. As the base, hydroxides, hydrides, carbonates, hydrogen carbonates, metal alkoxides, etc. of alkali metals and alkaline earth metals can be preferably used. In particular, when using alkali metal hydroxides or carbonates, the desired 2-
(α-alkoxyimino)ethylthiophene can be obtained. The amount of these bases to be used is not particularly limited, but is usually 0.8 to 2 times the mole of the O-alkylhydroxylamine salt used, preferably
The range is 1.0 to 1.2 times the mole. If the amount of base used is too small, the yield of the desired 2-(α-alkoxyimino)ethylthiophene will be low; on the other hand, if too much is used, no particularly advantageous effect can be obtained. The above O-alkyl oximation reaction of 2-acetylthiophene is usually carried out in a solvent. The solvent is not particularly limited as long as it dissolves the 2-acetylthiophene to be used and is inert in the reaction, but preferable solvents include water and lower aliphatic solvents such as methanol, ethanol, and isopropanol. Alcohols, ethers such as ethyl ether, tetrahydrofuran and dioxane, acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethylsulfoxide,
and mixtures of two or more thereof. The temperature of the O-alkyl oximation reaction of 2-acetylthiophene is usually in the range of about 40 to 120°C, preferably in the range of about 60 to 90°C. When the reaction temperature is higher than about 120°C, the yield of the desired 2-(α-alkoxyimino)ethylthiophene decreases due to side reactions; on the other hand, when the reaction temperature is lower than about 40°C, This is because the reaction rate is too slow for practical use. Although the reaction time is not limited at all, it is usually in the range of 3 to 10 hours. Similarly to the production of 2-acetylthiophene oxime described above, the O-alkyl oximation reaction of 2-acetylthiophene according to the present invention also includes:
Acceleration can be achieved by the presence of an organic acid to bring the pH of the reaction mixture to a range of 2-6. That is, if other reaction conditions are the same, when the pH of the reaction mixture is brought to a range of 2 to 6 by addition of an organic acid, the same yield can usually be obtained by reducing the reaction time by 1 to 2 hours. 2-(α-alkoxyimino)ethylthiophene can be obtained at The organic acid preferably has 1 to 1 carbon atoms.
Lower aliphatic organic acids of No. 4, particularly acetic acid and propionic acid, are preferably used. The amount used is an amount sufficient to adjust the pH of the reaction mixture to 2 to 6, as described above. After the completion of the O-alkyl oximation reaction of 2-acetylthiophene as described above, the reaction mixture is extracted with, for example, chloroform, washed with water, the chloroform is distilled off, and the residue is further extracted under reduced pressure. By distillation, it is usually possible to separate the compounds according to the invention as liquids in high purity and in high yields. 2 obtained in this way
-(α-alkoxyimino)ethylthiophene is
It already has a sufficiently high purity and, as mentioned above, can be used as it is in necessary reactions such as acetylation reactions. However, if necessary, higher purity can be obtained by distilling it under reduced pressure. Further, high purity 2-(α-alkoxyimino)ethylthiophene can also be separated by directly distilling the reaction mixture under reduced pressure. Effects of the Invention The 2-(α-alkoxyimino)ethylthiophene according to the present invention is a new compound, which can be used for pharmaceuticals,
It can be widely used as an important intermediate for the production of agricultural chemicals, etc. Such 2-(α-alkoxyimino)ethylthiophene can be easily obtained in high yield by O-alkylating 2-acetylthiophene oxime, and has been commonly used as a method for identifying organic compounds. The purpose of the present invention is to provide a new method for utilizing oximes, which are known in the art, as industrial raw materials. Moreover, the compound according to the present invention is
It is economically advantageous because it can be produced in high yield from 2-acetylthiophene, which is easily available as an industrial raw material. Furthermore, according to the present invention, 2-(α-alkoxy imino)ethylthiophene can be obtained in high yield, and the 2
Since -(α-alkoxyimino)ethylthiophene has extremely high purity as it is, it is advantageous as an industrial production method. EXAMPLES The present invention will be specifically described below with reference to reference examples and examples. Reference Example Synthesis of 2-acetylthiophene oxime In a 1-volume, 4-necked flask equipped with a stirrer, a dropping funnel, a thermometer, and a condenser, 100 g (0.794 mol) of 2-acetylthiophene, 59.8 g of hydroxylamine hydrochloride, and sodium carbonate were added. 44.3g, methanol
After charging 192 g and 225 g of water and raising the temperature to reflux temperature with stirring, acetic acid was added to this to adjust the pH to 4.
The mixture was refluxed under stirring for 2 hours. After that, part of the methanol was distilled off, and after cooling, the generated precipitate was filtered, washed with water, and dried to produce white 2-acetylthiophene oxime (a mixture of anti-isomer and syn-isomer). 110.2g (yield 98.5%) was obtained. Melting point 82~
93℃. Example 1 Synthesis of 2-(α-methoxyimino)ethylthiophene 141.7 g of N,N-dimethylformamide and 32.9 g of sodium hydroxide were placed in a 2-volume, 4-necked flask equipped with a dropping funnel, thermometer and condenser under stirring.
(0.823 mol) and 35.4 g of water were charged. 2-Acetylthiophene oxime 110.2g
(0.782 mol) of N,N-dimethylformamide solution was added dropwise into the above flask at a temperature of 15 to 20°C over 1 hour, and after cooling to 10°C, 95% Dimethyl sulfate 108.9g
(0.864 l) was added dropwise over a period of 1 hour at a temperature of 10°C. After the dropwise addition was completed, the mixture was stirred at the same temperature for 30 minutes. Thereafter, the reaction mixture was diluted with water, extracted with chloroform, the chloroform extract was washed with water, and then the chloroform was distilled off. By distilling the residue under reduced pressure, 2-(α-methoxyimino)ethylthiophene was converted to a colorless and transparent liquid (70%
~72°C/3mmHg) and 100.6g was obtained. Yield is 2
- It was 83% relative to acetylthiophene oxime. The elemental analysis values, nuclear magnetic resonance absorption spectrum and infrared absorption spectrum data, and molecular weight by mass spectrometry of 2-(α-methoxyimino)ethylthiophene are shown below. Elemental analysis value C H N S Measured value 54.43 5.80 9.00 20.45 Calculated value 54.19 5.81 9.03 20.65 NMR (δppm, CDCl ₃ ) 2.18−2.30 (s, 3H), 3.92−4.00 (s, 3H),
6.90−7.49 (m, 3H). IR (cm ^-1 ) 2960, 2945, 2900, 2825, 1440, 1305,
1240, 1060, 1040, 896, 855, 710. Molecular weight 155 Example 2 Example 1 except that the alkylating agent, base and reaction solvent shown in Table 1 were used.
2-(α-alkoxyimino) shown in Table 1 by performing the same operation as above and using the same molar amount.
Ethylthiophene was obtained. In Table 1, 2-(α-
Ethoxyimino)ethylthiophene, 2-(α-n-butoxyimino)ethylthiophene obtained with number 7, 2-(α-isopropo obtained with number 9), and 2-(α-isopropo) obtained with number 9, and 2 obtained with number 11. - Appearance, boiling point, elemental analysis value of each (α-t-butoxyimino)ethylthiophene,
Spectral data and molecular weight by mass spectrometry are shown. 2- (α -Etoxyimino) ethylchiofen Appearance, colorless and transparent liquid boiling point 77-78 ° C / 2 mmHg elemental analysis value C HN S measured value 56.52 8.72 18.71 Measurement value 56.80 6.51 8.93 NMR (ΔPPM, CDCL ₃ ) 1. 2-1.5 (t, 3H), 2.18−2.29 (s, 3H),
4.05-4.40 (q, 2H), 6.85-7.45 (m, 3H). IR (cm ^-1 ) 2980, 2940, 2880, 1595, 1442, 1380,
1300, 1230, 1095, 1050, 990, 921, 910,
890, 855, 705. Molecular weight 169 2-(α-2-butoxyimino)ethylthiophene Appearance Colorless and transparent liquid Boiling point 94-98℃/3.5mmHg Elemental analysis value C H N S Measured value 60.68 7.50 7.31 16.50 Calculated value 60.91 7.61 7.11 16.24 NMR (δppm, CDCl ₃ ) 0.82-1.10 (t, 3H), 1.20-2.00 (m, 4H),
2.20-2.31 (s, 3H), 4.08-4.32 (t, 2H),
8.9−7.50 (m, 3H). IR (cm ^-1 ) 2970, 2950, 2880, 1600, 1440, 1380,
1300, 1240, 1080, 1040, 1000, 920, 900,
860, 710. Molecular weight 197 2-(α-isopropoxyimino)ethylthiophene Appearance Colorless and transparent liquid Boiling point 83-85℃/3mmHg Elemental analysis value C H N S Measured value 59.28 7.02 7.92 17.42 Calculated value 59.02 7.10 7.62 17.49 NMR (δ ppm , CDCl ₃ ) 1.20−1.42 (d, 6H), 2.18−2.30 (s, 3H),
4.0.-4.42 (s, 1H), 6.90-7.50 (m, 3H). IR (cm ^-1 ) 2970, 2945, 2880, 1595, 1440, 1380,
1300, 1235, 1090, 1050, 990, 900, 870,
710. Molecular weight 183 2- (α -T -butoxyimino) ethylchiofen appearance colorless and transparent liquid boiling point 88 to 92 ° C / 3.5mmHg element analysis value C h N S measured value 60.72 7.49 16.38 calculation value 60.91 7.61 16.24 NMR (16.24 ΔPpm , CDCl ₃ ) 1.20−1.45 (s, 9H), 2.20−2.30 (s, 3H),
6.90−7.48 (m, 3H). IR (cm ^-1 ) 2975, 2950, 2885, 1590, 1440, 1390,
1295, 1240, 1060, 1040, 1000, 920, 910,
860, 720. Molecular weight 197 Example 3 Synthesis of 2-(α-methoxyimino)ethylthiophene In a 2-volume, 4-necked flask equipped with a stirrer, dropping funnel, thermometer and condenser, 141.7 g of N,N-dimethylformamide, Triethylamine 83.0g
(0.823 mol) and 35.4 g of water were charged. 2-Acetylthiophene oxime 110.2g
(0.782 mol) of N,N-dimethylformamide solution was added dropwise into the above flask at a temperature of 15 to 20°C over 1 hour, and after cooling to 10°C, 95% Dimethyl sulfate 108.9g
(0.864 mol) was added dropwise over a period of 1 hour at a temperature of 10°C. After the dropwise addition was completed, the mixture was stirred at the same temperature for 30 minutes. Thereafter, the reaction mixture was diluted with water, extracted with chloroform, the chloroform extract was washed with water, and then the chloroform was distilled off. By distilling the residue under reduced pressure, 2-(α-methoxyimino)ethylthiophene was converted to a colorless and transparent liquid (70%
~72°C/3mmHg), 75.2g was obtained. Yield is 2
-62% relative to acetylthiophene oxime. Example 4 Synthesis of 2-(α-methoxyimino)ethylthiophene 25.2 g of 2-acetylthiophene was placed in a 200 ml four-necked flask equipped with a stirrer, thermometer, and condenser.
(0.2 mol), 18.4 g (0.22 mol) of O-methylhydroxylamine hydrochloride, 11.7 g of sodium carbonate, 20 g of methanol, and 60 g of water, and after adding 2 g of acetic acid with stirring, the mixture was reacted at reflux temperature for 2 hours. . After the reaction was completed, 40 g of water was added to the reaction mixture, cooled to room temperature, extracted with chloroform, the chloroform extract was washed with water, and then the chloroform was distilled off. By distilling the residue under reduced pressure, 29.5 g of 2-(α-methoxyimino)ethylthiophene was obtained as a colorless and transparent liquid (70-72°C/3 mmHg). The yield was 95% based on 2-acetylthiophene. Example 5 The same procedure as in Example 4 was carried out except that the O-alkylhydroxylamine salt, base and organic solvent (and acetic acid or propionic acid in some cases) shown in Table 2 were used. Then, 2-acetylthiophene was converted into O-alkyl oxime under the reaction conditions shown in Table 2 to form the corresponding 2-
(α-alkoxyimino)ethylthiophene was obtained. The boiling points and yields based on 2-acetylthiophene are shown in Table 2.

Claims (1)

[Scope of Claims] 1 2-(α-alkoxyimino)ethylthiophene represented by the general formula [Formula] (wherein R represents an alkyl group having 1 to 4 carbon atoms). 2-(α-alkoxyimino)ethylthiophene according to claim 1, wherein 2R is a methyl group. 2-(α-alkoxyimino)ethylthiophene according to claim 1, wherein 3R is an ethyl group. 2-(α-alkoxyimino)ethylthiophene according to claim 1, wherein 4R is an n-propyl group. 2-(α-alkoxyimino)ethylthiophene according to claim 1, wherein 5R is an isopropyl group. 6 Claim 1 in which R is an n-butyl group
2-(α-alkoxyimino)ethylthiophene as described in 2. 7 Claim 1 in which R is a s-butyl group
2-(α-alkoxyimino)ethylthiophene as described in 2. 8 Claim 1 in which R is a t-butyl group
2-(α-alkoxyimino)ethylthiophene as described in 2. 9 2-acetylthiophene oxime is reacted with an alkylating agent in the presence of a base and is represented by the general formula [Formula] (wherein, R represents an alkyl group having 1 to 4 carbon atoms) A method for producing 2-(α-alkoxyimino)ethylthiophene. 10. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein the alkylating agent is dialkyl sulfuric acid. 11. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein the alkylating agent is an alkyl halide. 12. 2-(α-alkoxyimino) according to claim 9, wherein the base is an alkali metal hydroxide.
A method for producing ethylthiophene. 13. 2-(α-alkoxyimino) according to claim 9, wherein the base is an alkali metal hydride.
A method for producing ethylthiophene. 14. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein the base is an alkali metal alkoxide. 15. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is a methyl group. 16. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is an ethyl group. 17. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is an n-propyl group. 18. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is an isopropyl group. 19. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is an n-butyl group. 20. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is a s-butyl group. 21. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 9, wherein R is a t-butyl group. 22 A general formula characterized by reacting 2-acetylthiophene with an O-alkylhydroxylamine represented by the general formula RONH ₂ (in the formula, R represents an alkyl group having 1 to 4 carbon atoms) [Formula] (In the formula, R is the same as above.) A method for producing 2-(α-alkoxyimino)ethylthiophene represented by: 23 Claim 22 in which R is a methyl group
A method for producing 2-(α-alkoxyimino)ethylthiophene as described in 2. 24 Claim 22 in which R is an ethyl group
A method for producing 2-(α-alkoxyimino)ethylthiophene as described in 2. 25. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 22, wherein R is an n-propyl group. 26. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 22, wherein R is an isopropyl group. 27. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 22, wherein R is an n-butyl group. 28. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 22, wherein R is a s-butyl group. 29. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 22, wherein R is a t-butyl group. 30. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 22, wherein the reaction is carried out in the presence of an organic acid. 31. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 30, wherein the organic acid is acetic acid. 32. The method for producing 2-(α-alkoxyimino)ethylthiophene according to claim 30, wherein the organic acid is propionic acid.