JP2001181234A - Stereoselective o-alkylation reaction of alpha- hydroxymethylenecarbonyl compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stereoselectively producing the E-isomer or Z-isomer of an α-alkoxymethylenecarbonyl compound by O-alkylation of the corresponding α-hydroxymethylenecarbonyl compound. SOLUTION: This method for producing an (E)-α-alkoxymethylenecarbonyl compound (II) comprises O-alkylation of a compound (I) in an amide-based solvent using a base and an alkyl sulfate. Another version of this method comprises producing a (Z)-α-alkoxymethylenecarbonyl compound (III) by O- alkylation of the compound (I) in acetonitrile using a base and an alkylating agent. In the formulas, R1 is a halogen atom, 1-6C alkyl, 1-6C haloalkyl, (substituted) heteroaryloxymethyl or the like; n is an integer of 0, 1, 2, 3, or 4; and R2 is a 1-6C alkyl or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stereoselective O-alkylation reaction of an α-hydroxymethylenecarbonyl compound useful as an intermediate for producing agricultural chemicals or pharmaceuticals.

[0002]

2. Description of the Related Art Compounds having pharmacological activity useful as agricultural chemicals and pharmaceuticals often have a spatially specific configuration. For example, α-alkoxymethylenecarbonyl or α
-Alkoxyiminocarbonyl compounds may have a Z isomer and an E isomer derived from a double bond in the molecule, but a compound useful as an agricultural or horticultural fungicide or an agricultural and horticultural insecticide is an E isomer. Body (see, for example,
No. 136). Here, of the two stereoisomers based on the carbon-carbon double bond of the α-alkoxymethylene compound, the E isomer refers to an isomer in which an alkoxycarbonyl group and an alkoxy group are in a trans relationship, and a Z isomer. The term “body” refers to a compound in which an alkoxycarbonyl group and an alkoxy group have a cis relationship (the same shall apply hereinafter in the present invention).

In order to produce such α-alkoxymethylenecarbonyl compounds and α-alkoxyiminocarbonyl compounds, for example, O-alkylation of the hydroxyl groups of α-hydroxymethylenecarbonyl compounds and α-hydroxyiminocarbonyl compounds is carried out. Can be considered.

However, when alkylation is carried out under ordinary conditions, a mixture of the E isomer and the Z isomer may be obtained, or an undesired isomer may be mainly obtained, and the E isomer or the Z isomer may be obtained. It was difficult to obtain either of the bodies stereoselectively.

As related to the present invention, for example, U
As described below, SP. 4,503,234 discloses 2- (2-aminothiazol-4-yl) -2- (s
yn) -Hydroxyiminoacetic acid ester (A) is reacted with dimethyl sulfate and sodium hydroxide at 0 to 5 ° C in the presence of a phase transfer catalyst to give 2- (2-aminothiazol-4-yl). It is described that -2- (syn) -methoxyiminoacetic acid ester (B) is obtained.

[0006]

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In this reaction, the α-hydroxyiminocarbonyl compound (B) is obtained by methylating the compound (A) which is an α-hydroxyiminocarbonyl compound while maintaining the steric configuration. is there.

[0008]

SUMMARY OF THE INVENTION The present invention provides an O-alkylation of an α-hydroxymethylenecarbonyl compound to stereoselectively convert either the E isomer or the Z isomer of the α-alkoxymethylenecarbonyl compound. It is intended to provide a method of manufacturing.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that α represented by the general formula (I)
The present inventors have found that an α-alkoxymethylenecarbonyl compound can be obtained with high selectivity by selecting a specific solvent when the -hydroxymethylenecarbonyl compound is O-alkylated, and have completed the present invention.

That is, the present invention firstly relates to the general formula (I)

[0011]

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(Wherein R ¹ is a nitro group, a cyano group, a halogen atom, a C _1-6 alkyl group, a C _1-6 haloalkyl group,
C _1-6 alkoxy group, C _1-6 haloalkoxy group, C _1-6 alkoxy C _1-6 alkoxy group, C _1-6 alkylthio C _1-6
An alkoxy group, a C _7-12 aralkyl group which may have a substituent, an aryloxy C _1-4 alkyl group which may have a substituent or a heteroaryloxymethyl group which may have a substituent And n represents 0 or an integer of 1 to 4, and R ² has 1 to 1 carbon atoms which may have a substituent.
6 represents an alkyl group. Wherein the compound represented by the general formula (II) is O-alkylated with a base and an alkylating agent in an amide solvent.

[0013]

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(Wherein, R ¹ , R ² and n have the same meanings as above, and R ³ represents an alkyl group having 1 to 6 carbon atoms).

The present invention also relates to a compound represented by the following general formula (I):

[0016]

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(Wherein R ¹ , R ² and n represent the same meaning as described above) in acetonitrile.
General formula (III), characterized in that O-alkylation is carried out using a base and an alkylating agent.

[0018]

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(Wherein, R ¹ , R ² , R ³ and n have the same meanings as described above).

In the first and second inventions, it is preferable to use an alkali metal hydroxide as the base.

According to the first invention, an α-carbonylhydroxymethylene compound represented by the general formula (I) is O-alkylated with a base and an alkylating agent by using an amide solvent as a solvent. As a result, the (E) -α-carbonylalkoxymethylene compound represented by the general formula (II) can be produced with high yield and high stereoselectivity.

According to the second aspect of the present invention, the α-carbonylhydroxymethylene compound represented by the general formula (I) is O-alkylated by using acetonitrile as a solvent with the action of a base and an alkylating agent. (Z) -α- represented by the general formula (III) with high yield and high stereoselectivity
A carbonylalkoxymethylene compound can be produced.

[0023]

Embodiments of the present invention will be described below. (1) Starting Compound (I) In the present invention, the α-hydroxymethylenecarbonyl compound represented by the general formula (I) is used as a starting compound.

In the compound represented by the above general formula (I), R ¹ is a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl. C _1-6 alkyl groups such as butyl, t-butyl, pentyl and hexyl groups;

C _1-6 haloalkyl groups such as chloromethyl, fluoromethyl, dichloromethyl, bromomethyl, difluoromethyl, trichloromethyl, trifluoromethyl, chlorodifluoromethyl, 2,2,2-trifluoroethyl and pentafluoroethyl groups , Methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-
C _1-6 such as butoxy, t-butoxy and hexyloxy groups
An alkoxy group,

Chloromethoxy, fluoromethoxy, bromomethoxy, dichloromethoxy, difluoromethoxy,
Trichloromethoxy, trifluoromethoxy, 2,2
2 trifluoride Melo ethoxy, C _1-6 haloalkoxy groups such as pentafluoro ethoxy, methoxymethoxy, ethoxymethoxy, propoxy methoxy, iso-propoxy methoxy, butoxymethoxy, t-butoxymethoxy,
C _1-6 alkoxy C _1-6 alkoxy groups such as methoxyethoxy, ethoxyethoxy, propoxyethoxy, isopropoxyethoxy, t-butoxyethoxy,

Methylthiomethoxy, ethylthiomethoxy, propylthiomethoxy, isopropylthiomethoxy, butylthiomethoxy, t-butylthiomethoxy, methylthioethoxy, ethylthioethoxy, propylthioethoxy, isopropylthioethoxy, t-butylthioethoxy, etc. A C _1-6 alkoxy C _1-6 alkoxy group,

A C _7-12 aralkyl group which may have a substituent at any position of the benzene ring, such as benzyloxymethyl, benzyloxyethyl, α-methylbenzyloxymethyl,

An aryloxyalkyl group which may have a substituent at any position of an aromatic carbon ring such as a phenoxymethyl, phenoxyethyl, phenoxypropyl, α-naphthylmethyl, β-naphthylmethyl group; Represents a heteroaryloxymethyl group which may have a group.

Examples of the heterocyclic group of the heteroaryloxymethyl group include 2-furyl, 3-furyl,
2-thienyl, 3-thienyl, 2-pyrrolyl, 3-pyrrolyl, 3-pyrazolyl, 4-pyrazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-
Thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl,
5-isothiazolyl, 1,2,3-triazinyl, 1,
5-membered heterocyclic groups such as 2,4-triazinyl and 1,2,4,5-tetrazinyl;

2-pyridyl, 3-pyridyl, 4-pyridyl, 5-pyridyl, 2-pyranyl, 3-pyranyl, 4-
Pyranyl, 5-pyranyl, 2-thianyl, 3-thianyl, 4-thianyl, 5-thianyl, 3-pyridazinyl,
4-pyridazinyl, 2-pyrimidinyl, 3-pyrimidinyl, 4-pyrimidinyl, 2-dioxanyl, 3-dioxaynyl, morpholin-2-yl, morpholin-3-yl, piperazin-2-yl, piperidin-2-yl and the like A 6-membered heterocyclic group, and

Examples include fused heterocyclic groups such as quinolinyl, isoquinolinyl, quinoxalinyl and benzothienyl groups.

The heteroaryloxymethyl group is more preferably 2-imidazolyloxymethyl,
4-imidazolyloxymethyl, 5-imidazolyloxymethyl, 2-oxazolyloxymethyl, 4-oxazolyloxymethyl, 5-oxazolyloxymethyl,
2-thiazolyloxymethyl, 3-thiazolyloxymethyl, 5-thiazolyloxymethyl, 2-pyridyloxymethyl, 3-pyridyloxymethyl, 4-pyridyloxymethyl, 3-pyridazinyloxyethyl , 4-pyridazinyloxymethyl, 5-pyridazinyloxymethyl, 2-pyrimidyloxymethyl, 4-pyrimidyloxymethyl, 5-pyrimidyloxymethyl group and the like.

Examples of the substituent bonded to the aromatic carbon ring or the hetero ring of the aralkyl group, the aryloxyalkyl group and the heteroaryloxymethyl group include a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, and bromine; C _1-6 alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl group, chloromethyl,
C _1-6 haloalkyl groups such as fluoromethyl, dichloromethyl, bromomethyl, difluoromethyl, trichloromethyl, trifluoromethyl, chlorodifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, methoxy, ethoxy, propoxy , Isopropoxy, butoxy, sec-butoxy, t-butoxy, C _1-6 alkoxy groups such as hexyloxy, chloromethoxy, fluoromethoxy, bromomethoxy, dichloromethoxy, difluoromethoxy, trichloromethoxy, trifluoromethoxy, 2, Examples thereof include C _1-6 haloalkoxy groups such as 2,2-trifluoroacetoxy and pentafluoroethoxy groups.

These aromatic carbocycles and heterocycles may have the same or different substituents.

R ² is methyl, ethyl, propyl,
Isopropyl, butyl, isobutyl, sec-butyl,
represents a C _1-6 alkyl group such as t-butyl, pentyl, hexyl and the like.

In the present invention, in the compound represented by the general formula (I), as R ¹ , a compound bonded to the 2-position of a benzene ring can be preferably used.

As R ¹ , more specifically, 2-
Pyridyloxymethyl, 3-pyridyloxymethyl, 4
-Pyridyloxymethyl, (5-chloropyridine-2-
Yl,) oxymethyl, (4-trifluoromethylpyridin-2-yl) oxymethyl, (5-trifluoromethylpyridin-2-yl) oxymethyl, 3-pyridazinyloxymethyl, 4-pyridazini Ruoxymethyl,
(5-isopropyl-pyridazin-3-yl) oxymethyl, 4-pyrimidyloxymethyl, 2-pyrimidyloxymethyl, (2-isopropoxy-6-trifluoromethyl-pyrimidin-4-yl) oxymethyl Group 5
A compound having a nitrogen-containing heteroyloxymethyl group of 6 to 6 members can be more preferably used.

(2) Production of Starting Compound (I) The starting compound (I) of the present invention can be produced, for example, by the following method.

[0040]

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(Wherein, R ¹ and R ² have the same meanings as described above). That is, the starting compound (I) is prepared by reacting the compound of the general formula (I) in a suitable solvent.
V) in a temperature range from -20 ° C to the boiling point of the solvent used.
Formic acid ester represented by ₂ R 'can be produced by the action.

Solvents that can be used in this reaction include N, N-dimethylformamide (DMF), N, N
-Dimethylacetamide, tetrahydrofuran, diethyl ether, 1,2-dimethoxyethane and the like.

Examples of the base that can be used include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium methylate, sodium ethylate, magnesium ethylate, potassium t-butoxide, sodium hydride, calcium hydride, Triethylamine, diisopropylethylamine, pyridine and the like. The amount of the base to be used is about 1-5 mol per 1 mol of compound (IV).

Examples of the formate represented by HCO ₂ R ′ include methyl formate, ethyl formate, propyl formate, isopropyl formate and the like. The amount of the formate used is about 1 to 3 mol per 1 mol of the compound (IV).

In this case, if a titanium compound is present, the reaction proceeds more smoothly, and the desired compound can be obtained in good yield.
(I) can be obtained. Such titanium compounds include titanium tetrachloride, tetramethoxytitanium,
Examples thereof include tetraethoxytitanium, tetrapropoxytitanium, and tetraisopropoxytitanium.
The amount of the titanium compound to be used is about 0.5-3 mol per 1 mol of the compound (IV).

(3) Production of compound (II)

[0047]

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The compound represented by the general formula (II) is subjected to O-alkylation by using the compound represented by the general formula (I) as a starting material in an amide solvent using a base and an alkylating agent. Can be manufactured.

The amide solvent used in this reaction is
Generally, it refers to a polar solvent having an amide bond (—C (＝ O) N—) in the molecule. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and the like can be mentioned.

The amount of the solvent used is not particularly limited, but generally, the concentration of the compound represented by the general formula (I) is preferably in the range of about 0.1% to 20% by weight. .

Examples of the base used include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkali metal hydroxides such as magnesium hydroxide and calcium hydroxide, sodium methoxide, and the like.
Metal alkoxides such as sodium ethoxide, potassium methoxide, potassium ethoxide, potassium t-butoxide, magnesium methoxide, magnesium ethoxide, sodium carbonate, potassium carbonate, calcium carbonate, carbonates such as magnesium carbonate, sodium hydride,
Examples include hydrides such as potassium hydride and calcium hydride, and organic bases such as triethylamine, diisopropylethylamine, pyridine, piperidine, piperazine, and morpholine.

Of these, in the present invention, the use of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide is preferred in view of the stereoselectivity of the reaction, the reaction yield and the production cost. preferable.

The amount of the base to be used is about 1 to 3 mol per 1 mol of the compound represented by the general formula (I).
In general, when an excessive amount of a base is used, the reaction is slowed down and the amount of by-products increases, so that it is more preferable to use a 1- to 1.5-fold molar amount.

Examples of the alkylating agent include sulfates (alkyl sulfate) such as dimethyl sulfate and diethyl sulfate, methyl iodide, ethyl iodide, ethyl bromide, propyl iodide, propyl bromide, isopropyl iodide, and the like.
And alkyl halides such as isopropyl bromide. In the present invention, use of an alkylsulfuric acid represented by the formula (R ³ O) ₂ SO ₂ is preferred from the viewpoint of stereoselectivity of the reaction, production cost and ease of handling.

The amount of the alkylating agent used is represented by the general formula
The amount is preferably about 1 to 3 mol per 1 mol of the compound represented by (I).

The reaction proceeds smoothly in the temperature range from -10 ° C. to the boiling point of the solvent used. The reaction time is usually about several minutes to 24 hours.

(4) Production of compound (III)

[0058]

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The compound represented by the general formula (III) is prepared by using the compound represented by the general formula (I) as a starting material, acetonitrile as a solvent, and an O-alkylation using a base and an alkylating agent. Can be manufactured.

The amount of the solvent to be used is not particularly limited, but generally, the concentration of the compound represented by the general formula (I) is preferably in the range of about 0.1 to 20% by weight.

The base used in this reaction includes, for example, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; alkali metal hydroxides such as magnesium hydroxide and calcium hydroxide; Metal alkoxides such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, potassium t-butoxide, magnesium methoxide, magnesium ethoxide, carbonates such as sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, hydrogen, etc. Examples include hydrides such as sodium hydride, potassium hydride and calcium hydride, and organic bases such as triethylamine, diisopropylethylamine, pyridine, piperidine, piperazine and morpholine.

Of these, the use of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide is preferred in view of the stereoselectivity of the reaction, the reaction yield and the production cost.

The amount of the base to be used is about 1 to 3 mol per 1 mol of the compound represented by the general formula (I).
In general, when an excessive amount of a base is used, the reaction is slowed down and the amount of by-products increases, so that it is more preferable to use a 1- to 1.5-fold molar amount.

As the alkylating agent, those similar to those listed as the alkylating agent used in producing the compound represented by formula (II) can be preferably exemplified.

The amount of the alkylating agent used is represented by the general formula
The amount is preferably about 1 to 3 mol per 1 mol of the compound represented by (I).

The O-alkylation reaction is carried out in a temperature range from 0 ° C. to the boiling point of the solvent used, preferably from 10 ° C. to 10 ° C.
It proceeds smoothly in the range of 0 ° C. In this case, when the reaction temperature is increased, the Z selectivity (the ratio of obtaining the compound (III)) is improved, but the amount of by-products slightly increases.

In the case of any of the compounds represented by the above general formulas (II) and (III), after the reaction is completed, the desired product can be easily obtained by performing ordinary organic synthetic chemistry post-treatment operations. be able to. The structure of the reaction product can be determined from various spectra such as an NMR spectrum and a mass spectrum.

[0068]

Next, the present invention will be described in more detail by way of examples. Example 1 (E) -Methyl α-methoxymethylene [2
Preparation of-(2'-isopropoxy-6'-trifluoromethylpyrimidin-4-yl) oxymethyl] phenylacetate (VI)

[0069]

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Methyl α-hydroxymethylene [2-
2 g of (2′-isopropoxy-6′-trifluoromethylpyrimidin-4-yl) oxymethyl] phenylacetate (V) was dissolved in 10 ml of DMF, and 0.27 g of lithium hydroxide was added thereto. .
82 g was slowly added at room temperature and stirred at room temperature for 3 hours. The reaction mixture is subjected to high performance liquid column chromatography (eluent: acetonitrile / 1% acetic acid aqueous solution = 7/3)
As a result of analyzing by (1), the (E) isomer (target substance) was 86.
It was found that 5% and the (Z) isomer were obtained in a yield of 10.4%, respectively. This (E) isomer is described in WO96 /
It is a compound described in No. 16047.

Example 2 Preparation of (Z) -methyl α-methoxymethylene [2- (2′-isopropoxy-6′-trifluoromethylpyrimidin-4-yl) oxymethyl] phenylacetate (VII)

[0072]

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Methyl α-hydroxymethylene [2-
2 g of (2′-isopropoxy-6′-trifluoromethylpyrimidin-4-yl) oxymethyl] phenylacetate (V) was dissolved in 10 ml of acetonitrile, and 0.27 g of lithium hydroxide was added thereto. 0.82 g was slowly added at room temperature, and the mixture was stirred at room temperature for 8 hours. The reaction mixture was subjected to high performance liquid column chromatography (eluent: acetonitrile / 1% acetic acid aqueous solution = 7 /
As a result of the analysis in 3), it was found that the (Z) isomer (target substance) was 8
It was found that 4.1% and the (E) isomer were obtained in a yield of 8.7%, respectively.

¹ H-NMR (CDCl ₃ ) of compound (VII)
δ ppm: 1.40 (6H, d), 3.65 (3H,
s), 3.86 (3H, s), 5.28 (1H, m),
5.37 (2H, dd), 6.60 (1H, s), 6.
62 (1H, s), 7.20-7.50 (4H, m)

REFERENCE EXAMPLE Synthesis of methyl α-hydroxymethylene [2- (2′-isopropoxy-6′-trifluoromethylpyrimidin-4-yl) oxymethyl] phenyl acetate (V)

[0076]

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To 1800 ml of methylene chloride, 506.4 g of titanium tetrachloride was added at -5 ° C. to 0 ° C., and 160.2 g of methyl formate was added while stirring at the same temperature. A solution prepared by dissolving 683.9 g of methyl [2- (2'-isopropoxy-6'-trifluoromethylpyrimidin-4-yl) oxymethyl] phenylacetate (VIII) in 890 ml of methylene chloride was added to -5 ml of this solution. 6 ° C at 0 ° C
It was added dropwise over 0 minutes. After completion of the dropwise addition, the mixture was stirred at the same temperature for 30 minutes, and then 540.4 g of triethylamine was added to -5.
Added between 0 ° C and 0 ° C. After stirring at 0 ° C to 2 ° C for 30 minutes, 320.4 g of acetic acid and 710 ml of water were sequentially added to the reaction mixture to stop the reaction. After the organic layer was separated and washed with dilute hydrochloric acid and water, the organic layer was dried over anhydrous magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure and produced by silica gel flash column chromatography to obtain 691.8 g of the desired product. 97.6% yield

¹ H-NMR (CDCl ₃ ) δ of compound (V)
ppm: 1.41 (6H, d), 3.72 (3H,
s), 5.23-5.37 (1H, m), 5.37 (2
H, s), 6.65 (1H, s), 7.20 (1H,
d), 7.17-7.52 (4H, m), 11.92.
(1H, d)

[0079]

As described above, according to the present invention,
When the α-hydroxymethylenecarbonyl compound is O-alkylated using an alkylating agent and a base, either the E-isomer or the Z-isomer of the α-alkoxymethylenecarbonyl compound is selected by appropriately selecting the reaction solvent to be used. Can be produced in a stereoselective and high yield.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Ozaki 345 Takada, Odawara-shi, Kanagawa Foda term in Odawara Research Laboratories, Nippon Soda Co., Ltd. 4H006 AA02 AC43 BA02 BA06 BA10 BA28 BA29 BA32 BA39 BA51 BB20 BB25 BC10 BC19 BC34 BJ50 BP10

Claims (4)

[Claims] 1. A compound of the general formula (I) (Wherein R ¹ is a nitro group, a cyano group, a halogen atom,
C _1-6 alkyl group, C _1-6 haloalkyl group, C _1-6 alkoxy group, C _1-6 haloalkoxy group, C _1-6 alkoxy C
_C1-6 alkoxy group, C _1-6 alkylthio C _1-6 alkoxy group which may have a substituent C _7-12 aralkyl group which may have a substituent aryloxy C _1-4 alkyl represents a group or may have a substituent group heteroaryloxy methyl, n is 0 or 1 to 4 of an integer, R ² is carbon atoms which may have a substituent 1-6 Represents an alkyl group. Wherein the compound of formula (II) is O-alkylated in an amide solvent using a base and an alkylating agent. (Wherein, R ^1, R ² and n are as defined above, R ³
Represents an alkyl group having 1 to 6 carbon atoms. )). 2. A compound of the general formula (I) Wherein R ¹ , R ² and n have the same meanings as described above, wherein the compound is O-alkylated in acetonitrile using a base and an alkylating agent. General formula (III) (Wherein, R ¹ , R ² , R ³ and n represent the same meaning as described above). 3. The method for producing a compound represented by the general formula (II) according to claim 1, wherein an alkali metal hydroxide is used as the base. 4. The method for producing the compound represented by the general formula (III) according to claim 2, wherein an alkali metal hydroxide is used as the base.