Process for the preparation of 5-chloro-pyridine-2-carboxylic acids and carboxylates bearing 3-sulfur-containing substituents

Abstract

Formula I: TIFF2023503989000033.tif4069 (wherein R1 and R2 are as defined herein) A process for the preparation of the compound of formula (I) is provided.

Description

[Technical Field]

[0001] The present invention relates to the preparation of 5-chloropyridine-2-carboxylic acids and carboxylates bearing 3-sulfur-containing substituents, which are useful intermediates in the preparation of pesticides.

[0002] More specifically, the present invention relates to a compound of formula I [ka] (wherein R1 is H or C1-C4 alkyl, and R2 is C1-C4 alkyl) or agrochemically acceptable salts of the compound of formula (I) and a process for the preparation thereof. [Background technology]

[0003] 5-Halo-pyridine-2-carboxylic acids and carboxylates bearing a 3-alkylsulfanyl substituent are useful intermediates in the agrochemical industry for the preparation of biologically active compounds, as previously described, for example, in WO 2016 / 005263, WO 2016 / 023954, WO 2016 / 030229, WO 2016 / 046071, WO 2016 / 059145, WO 2016 / 096584, WO 2016 / 104746 and WO 2019 / 065568.

[0004] The known synthesis of 5-halo-pyridine-2-carboxylic acids and carboxylates (Y) bearing 3-alkylsulfanyl substituents involves many reaction steps. For example, as shown in Scheme 1 (R1 is H, C1-C4 alkyl or alkali metal ion), two routes to obtain 5-bromo compounds (Y) have been reported (Route A: China Patent Application Publication No. 105218437; Route B: US Patent Application Publication No. 2012 / 0165338 or J. Org. Chem. 2009, 74, 4547-4553). [ka]

[0005] As shown in Scheme 2, WO 2016 / 104746 reports the access to the corresponding 5-iodo compound (Y) from commercially available 5,6-dichloronicotinic acid in seven steps. [ka]

[0006] Clearly, such lengthy and laborious syntheses are not suitable for preparing large quantities of material due to low overall yields and the generation of large amounts of waste. It would therefore be advantageous to have available more efficient and more economical routes to these intermediates.

[0007] Furthermore, within the class of 5-halo-3-alkylsulfanyl-pyridine-2-carboxylic acid carboxylates, 5-chloro-3-alkylsulfanyl-pyridine-2-carboxylic acids and corresponding esters have not been disclosed and their preparation routes are difficult to achieve. The unavailability of chlorinated intermediates of formula (I) has previously prompted the synthetic industry to adopt bromo and iodo analogs for the preparation of biologically active pesticides (WO 2016 / 005263, WO 2016 / 096584, WO 2016 / 104746, WO 2016 / 023954, WO 2016 / 046071, WO 2016 / 087265, WO 2016 / 087257, WO 2016 / 030229, WO 2016 / 121997, WO 2016 / 104746). However, the use of building blocks of formula (I) in these syntheses would be significantly advantageous, as it would reduce the formation of bromine- and iodine-containing waste products in subsequent functionalization reactions at the 5-position (such as metal-catalyzed cross-coupling reactions, nucleophilic aromatic substitutions, etc.) in favor of less harmful chlorine-containing waste products. Furthermore, compounds of formula (I) can be considered as convenient alternative intermediates that significantly shorten the synthesis of other agrochemicals originally conceived via laborious and lengthy routes (WO 2019 / 065568, WO 2019 / 124529, WO 2020 / 050212).

[0008] Commercially available 3,5-dichloropyridine-2-carboxylic acid (VIII) and its corresponding ester (IX), where R1 is C1-C4 alkyl, can be convenient starting materials for intermediates of formulae (VI) and (VII). In principle, all that would be required is the selective replacement of the chlorine ortho to the carboxylate group with ethyl thiolate (Scheme 3). [ka] Scheme 3. Possible routes from (VIII) or (IX) to (VI) or (VII)

[0009] However, it is unclear whether such selectivity is achievable, since the 2-carboxylate moiety renders the "ortho" position sterically inaccessible, disfavoring the formation of the desired 3-alkylsulfanyl product. In fact, reaction of compound of formula (IXa) under standard conditions for nucleophilic aromatic substitution reactions preferentially affords the undesired isomer (Xa) in all solvents tested (Scheme 4). [ka] Scheme 4. Selectivity observed in reaction (IXa)

[0010] Ortho-selective thiolation of polychlorinated aromatic compounds bearing free acid moieties is challenging and has been rarely described, usually via copper-mediated, carboxylate-directed Ullmann-type coupling, as shown in Scheme 5 (e.g., as described in Sambiagio C., Marsden SP, Blacker AJ, McGowan PC, Chem. Soc. Rev., 2014, 43, 3525-3550). [ka] Scheme 5. Cu-mediated Ullmann-type coupling to chlorinated benzoic acids

[0011] No examples of this reaction have been reported previously for polychlorinated picolinic acids. Summary of the Invention [Means for solving the problem]

[0012] Therefore, according to the present invention, a compound of formula I: [ka] (wherein R1 is H or C1-C4 alkyl, preferably R1 is methyl, ethyl or t-butyl, more preferably R1 is ethyl, and R2 is C1-C4 alkyl, preferably R2 is ethyl). (Scheme 6) provides a process for the preparation of a compound of the formula (A) Formula II [ka] wherein Xa is fluoro or chloro, preferably Xa is chloro. with a thiol compound R3-S-R2 (wherein R2 is as defined in formula I and R3 is H or an alkali metal ion, preferably R3 is H, sodium, potassium or lithium) in the presence of a suitable base in a suitable solvent (or diluent) having a dielectric constant of less than 15 to give a compound of formula (Ia): [ka] or a salt thereof, and optionally esterifying a compound of formula (Ia) or a salt thereof in the presence of a compound of formula ROH, wherein R is C1-4 alkyl, to produce a compound of formula (I), wherein R is C1-4 alkyl; Includes.

[0013] The present process proves highly useful as it allows the synthesis of key building blocks for the preparation of pesticides in higher yields and under more favorable conditions compared to previously described routes.

[0014] The compounds of formula I prepared by the process of the present invention, which have at least one basic center, can form, for example, acid addition salts with strong inorganic acids, such as mineral acids, for example, perchloric acid, sulfuric acid, nitric acid, nitrous acid, phosphorus-containing acids, hydrohalic acids, and the like; with strong organic carboxylic acids, for example, unsubstituted or halogen-substituted C1-C4 alkane carboxylic acids, such as acetic acid; saturated or unsaturated dicarboxylic acids, for example, oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, phthalic acid, and the like; hydroxycarboxylic acids, for example, ascorbic acid, lactic acid, malic acid, tartaric acid, citric acid, and the like; or with organic sulfonic acids, for example, unsubstituted or halogen-substituted C1-C4 alkane or aryl sulfonic acids, for example, methane or p-toluenesulfonic acid, and the like. Compounds of formula I having at least one acidic group can, for example, form salts with bases, for example mineral salts, for example alkali metal or alkaline earth metal salts, for example sodium, potassium, lithium or magnesium salts, or salts with ammonia or organic amines, for example morpholine, piperidine, pyrrolidine, mono-, di- or tri-lower alkylamines, for example ethyl, diethyl, triethyl or dimethylpropylamine or mono-, di- or trihydroxy-lower alkylamines, for example mono-, di- or triethanolamine.

[0015] In each case, the compounds of formula (I) prepared by the process according to the invention may be in free form or in salt form, for example in an agriculturally acceptable salt form.

[0016] The term "C1-C4 alkyl" as used herein means a saturated linear or branched hydrocarbon group having 1 to 4 carbon atoms bonded via any of the carbon atoms, such as any one of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a t-butyl group.

[0017] Surprisingly, it has been found that high ortho-selectivity in the thiolation of 3,5-dichloropicolinic acid (the compound of formula (II) represented by formula (VIII)) is observed in aprotic, nonpolar solvents without any copper catalyst. In particular, it has been found that the selectivity is significantly affected by the nature of the solvent. That is, in solvents with high dielectric constants (i.e., DMSO [dielectric constant of 46.7]), high selectivity for the "para" isomer (XV) is observed, whereas in solvents with low dielectric constants (i.e., dioxane, toluene, 2-MeTHF... [dielectric constants of 2.25, 2.38, and 6.97]), selective formation of the "ortho" isomer (the compound of formula (Ia) represented by formula (XIV)) is observed. This concept is illustrated in Scheme 6. [ka] Scheme 6. Selectivity observed in the thiolation of (VIII)

[0018] In another embodiment of the present invention, a compound of formula Ia: [ka] Agriculturally acceptable salts of the compounds of formula I or compounds of formula Ia are provided, which are represented by the compounds:

[0019] In a further embodiment of the invention, a compound of formula Ia-1: [ka] (wherein M is sodium, potassium or lithium, preferably sodium or lithium). Compounds of formula I are provided, represented by the compound:

[0020] In yet another embodiment of the present invention, a compound of formula I-2: [ka] (In the formula, R 1a is C 1-4 alkyl, preferably R 1ais methyl, ethyl or t-butyl, more preferably R 1a is ethyl) Agriculturally acceptable salts of the compounds of formula I or I-2 are provided, which are represented by the compounds:

[0021] In a further embodiment of the invention, a compound of formula I-2a: [ka] (In the formula, R 1b is C 1-4 alkyl, preferably R 1b is methyl, ethyl or t-butyl, more preferably R 1b is ethyl, and n is 1 or 2, preferably n is 2. or a pesticidally acceptable salt of a compound of formula I-2a is provided.

[0022] Compounds of formula I-2a can be prepared by oxidation of compounds of formula I-2 by known methods, such as those described in WO 2016 / 005263.

[0023] In the process according to the invention for preparing a compound of formula (I) (Scheme 6), examples of suitable bases are alkali metal hydroxides or alkali metal carbonates. Examples that may be mentioned are sodium hydroxide, sodium carbonate, lithium hydroxide, potassium hydroxide and potassium carbonate, preferably alkali metal carbonates, more preferably sodium carbonate or potassium carbonate, most preferably potassium carbonate.

[0024] In the process according to the invention for making compounds of formula (I) (Scheme 6), examples of suitable solvents (or diluents) are those having a dielectric constant of less than 15, more preferably solvents (or diluents) having a dielectric constant of less than 12, even more preferably solvents (or diluents) having a dielectric constant of less than 10. In other embodiments, suitable solvents (or diluents) have a dielectric constant of less than 6. Examples of suitable solvents (or diluents) are dioxane, methyltetrahydrofuran, toluene, anisole, pyridine, more preferably non-polar organics selected from dioxane, methyltetrahydrofuran or toluene, and most preferably suitable solvents have a dielectric constant in the range of 1.5 to 15.

[0025] In one embodiment, in the process according to the invention for making a compound of formula (I) (Scheme 6), the reaction is advantageously carried out at a temperature ranging from about 0° C. to about +140° C., preferably from about 0° C. to about +100° C., and often from ambient temperature to about +80° C. In a preferred embodiment, the reaction of step a. is carried out at a temperature ranging from 0° C. to the boiling point of the reaction mixture, more preferably from 20° C. to 100° C., and most preferably from 60° C. to 100° C.

[0026] In a preferred embodiment, the present invention provides compounds of formula (Ia) and (Ib) [ka] (In the formula, R4=C 1-4 alkyl) The present invention provides a highly selective thiolation reaction of 3,5-dichloropicolinic acid compound and the corresponding carboxylate salt of formula (II) (wherein R1 is as defined in formula I) with sodium ethanethiolate or ethanethiol and a base in a selected aprotic nonpolar solvent having a dielectric constant of less than 15 under scalable conditions to produce an alkyl 5-chloro-3-ethylsulfanyl-pyridine-2-carboxylate intermediate of formula (II).

[0027] Having thus generally described the invention, reference is now made to the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1] 1 shows the observed selectivity as a function of solvent dielectric constant, and more specifically, the correlation between ortho-para-thiolation selectivity and solvent dielectric constant observed in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] This solvent-dependent phenomenon was further explored, and a correlation was established between the observed selectivity and the dielectric constant of the solvent, as shown in Figure 1 (Lide, D.R., ed. (2005) CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0486-5). [Example]

[0030] Preparation example: Throughout this specification, LC / MS means liquid chromatography mass spectrometry and the following method was used to analyze the compounds.

[0031] Method A: Spectra were recorded on a Waters mass spectrometer (SQD, SQDII single quadrupole mass spectrometer) equipped with an electrospray source (polarity: positive or negative ion, capillary: 3.00 kV, cone range: 30 V, extractor: 2.00 V, source temperature: 150 °C, desolvation temperature: 350 °C, cone gas flow: 50 l / h, desolvation gas flow: 650 l / h, mass range: 100-900 Da) and a Waters Acquity UPLC: binary pump, heated column compartment, diode array detector, and ELSD detector. Column: Waters UPLC HSS T3, 1.8 μm, 30 × 2.1 mm, temperature: 60 °C, DAD wavelength range (nm): 210–500, solvent gradient: A = water + 5% MeOH + 0.05% HCOOH, B = acetonitrile + 0.05% HCOOH, gradient: 10–100% B within 1.2 min, flow (ml / min) 0.85.

[0032] Method B: Spectra were recorded on a Waters mass spectrometer (SQD single quadrupole mass spectrometer) equipped with an electrospray source (polarity: positive or negative ion, full scan, capillary: 3.00 kV, cone range: 41 V, source temperature: 150 °C, desolvation temperature: 500 °C, cone gas flow: 50 L / Hr, desolvation gas flow: 1000 L / Hr, mass range: 110–800 Da) and a Waters H-Class UPLC: binary pump, heated column compartment, and diode array detector. Column: Waters UPLC HSS T3 C18, 1.8 μm, 30 × 2.1 mm; Temperature: 40 °C; DAD wavelength range (nm): 200–400; Solvent gradient: A = water + 5% acetonitrile + 0.1% HCOOH, B = acetonitrile + 0.05% HCOOH; Gradient: 0 min 10% B, 0.0–0.2 min 10–50% B, 0.2–0.7 min 50–100% B, 0.7–1.3 min 100% B, 1.3–1.4 min 100–10% B, 1.4–1.6 min 10% B; Flow (mL / min) 0.6.

[0033] Example 1: Preparation of sodium 3,5-dichloropyridine-2-carboxylate (XIIIa) [ka] A mixture of 3,5-dichloropyridine-2-carboxylic acid (20.0 g, 104 mmol) and sodium hydroxide (1 M in water, 100 mL, 100 mmol, 0.96 equiv) was stirred at room temperature for 2 h. The solution was filtered and the water was concentrated under reduced pressure to give the desired product (94%, 22.0 g, 96.6 mmol, 93% yield), which was used without further purification. 1 H NMR(400MHz,DMSO-d6)δ ppm 8.04(d,J=2.20Hz,1H)8.38(d,J=2.20Hz,1H).

[0034] Example 2: Preparation of 5-chloro-3-ethylsulfanyl-pyridine-2-carboxylic acid (VI) [ka] A round-bottom flask was charged with sodium 3,5-dichloropyridine-2-carboxylate (94%, 4.00 g, 17.2 mmol). The flask was purged with argon, and pre-deoxygenated 2-methyltetrahydrofuran (86 mL) was added under argon. The reaction mixture was heated to 70°C, and sodium ethanethiolate (1.82 g, 20.6 mmol, 1.19 equiv.) was added. It was then stirred at 70°C for 7 hours. The reaction mixture was concentrated under reduced pressure. The resulting residue was dissolved in water (29 mL) and acetonitrile (12 mL). Insoluble particles were filtered off. The filtrate was heated to 80°C, and additional water (10 mL) and acetonitrile (5 mL) were added. Hot 1N hydrochloric acid (45°C, 16 mL) was added dropwise at 80°C, and the mixture was stirred for several minutes. The resulting precipitate was filtered hot and dried under vacuum to give the desired product (94%, 2.30 g, 9.95 mmol, 58% yield). LC-MS (Method A): Retention time 0.77 min, m / z218[M+H + ]. 1H NMR(400MHz,DMSO-d6)δ ppm 1.25(t,J=7.34Hz,3H)3.02(q,J=7.34Hz,2H)7.93(d,J=1.83Hz,1H)8.41(d,J=1.83Hz,1H).

[0035] Example 3: Preparation of 5-chloro-3-ethylsulfanyl-pyridine-2-carboxylic acid (VI) [ka] To a stirred solution of 3,5-dichloropyridine-2-carboxylic acid (1.00 g, 5.21 mmol) and sodium carbonate (0.662 g, 6.25 mmol, 1.20 equiv.) in previously deoxygenated 2-methyltetrahydrofuran (13 mL) was added sodium ethanethiolate (0.920 g, 10.9 mmol, 2.10 equiv.) at room temperature. The reaction mixture was heated to 50 °C and stirred for 3 h. Additional 2-methyltetrahydrofuran (13 mL) was added, and the reaction mixture was stirred at 50 °C for 18 h. After cooling to room temperature, the reaction mixture was diluted with water, and the 2-methyltetrahydrofuran was removed in vacuo. Acetonitrile (6 mL) was added, followed by the dropwise addition of 1 N hydrochloric acid (21 mL). The resulting precipitate was filtered and dried under reduced pressure to give the desired product (71%, 1.00 g, 3.27 mmol, 63% yield).

[0036] Example 4: Preparation of 3-chloro-5-ethylsulfanyl-pyridine-2-carboxylic acid (XVI) [ka] A solution of 3,5-dichloropyridine-2-carboxylic acid (0.500 g, 2.47 mmol) in dimethyl sulfoxide (5.5 mL) was prepared and heated to 100°C. Potassium carbonate (0.378 g, 2.60 mmol, 1.05 equiv.) was added, and the reaction mixture was stirred at 100°C for 1 hour. Sodium ethanethiolate (0.250 g, 2.97 mmol, 1.20 equiv.) was then added, and the reaction mixture was continued to stir at 100°C overnight. After cooling to room temperature, the reaction mixture was diluted with ethyl acetate and water. The aqueous layer was then acidified and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. Purification of the crude material by reverse-phase chromatography afforded the desired product as a white solid (0.536 mmol, 22% yield). LC-MS (Method A): Retention time 0.74 min, m / z218[M+H + ]. 1 H NMR(400MHz,DMSO-d6)δ ppm 1.26(t,J=7.15Hz,3H)3.10-3.18(q,J=7.15Hz,2H)7.95(d,J=2.20Hz,1H)8.44(s,1H).

[0037] Example 5: Preparation of ethyl 5-chloro-3-ethylsulfanyl-pyridine-2-carboxylate [ka] To a suspension of 5-chloro-3-ethylsulfanyl-pyridine-2-carboxylic acid (2.35 g, 10.6 mmol) in ethanol (26 mL) was added sulfuric acid (0.575 mL, 10.6 mmol, 1.00 equiv) slowly at room temperature. The reaction mixture was heated to 70 °C and stirred for 15 h. After cooling to room temperature, the reaction mixture was concentrated under reduced pressure. The resulting residue was diluted with ethyl acetate, washed twice with sodium bicarbonate sat. aq., dried over sodium sulfate, filtered, and concentrated under reduced pressure to give the desired product (90%, 2.55 g, 9.34 mmol, 88% yield), which was used without further purification. LC-MS (Method A): Retention time 0.99 min, m / z246[M+H + ]. 1 H NMR(400MHz,chloroform-d)δ ppm 1.39-1.47(m,6H)2.93(q,J=7.34Hz,2H)4.48(q,J=7.21Hz,2H)7.62(d,J=2.20Hz,1H)8.37(d,J=1.83Hz,1H).

[0038] Example 6: Preparation of ethyl 3-chloro-5-ethylsulfanyl-pyridine-2-carboxylate (VIIa) [ka] To a stirred solution of ethyl 3,5-dichloropyridine-2-carboxylate (96%, 0.200 g, 0.873 mmol) in toluene (2 mL) was added sodium ethanethiolate (0.122 g, 1.31 mmol, 1.50 equiv.) at 0° C. The reaction mixture was allowed to reach room temperature and stirred first at this temperature for 24 h and then at 80° C. for 15 h. After cooling to room temperature, an LC-MS sample was measured to determine the ratio of products VIIa and Xa. The results gave 60% conversion of the starting material and the formation of VIIa:Xa with a ratio of 1:1.9. LC-MS (Method B): Retention time 1.08 min, m / z246[M+H + ]. 1 H NMR(400MHz,chloroform-d)δ ppm 1.36-1.47(m,6H)3.04(q,J=7.42Hz,2H)4.47(q,J=7.09Hz,2H)7.62(d,J=2.08Hz,1H)8.42(d,J=1.96Hz,1H).

[0039] Example 7: Preparation of ethyl 3-chloro-5-ethylsulfanyl-pyridine-2-carboxylate (VIIa) [ka] To a stirred solution of ethyl 3,5-dichloropyridine-2-carboxylate (95%, 0.200 g, 0.863 mmol) in 1-methyl-2-pyrrolidinone (2 mL) was added sodium ethanethiolate (0.099 g, 1.04 mmol, 1.20 equiv.) at 0° C. The reaction mixture was allowed to reach room temperature and stirred for 6 h. An LC-MS sample was run to determine the ratio of the formed products VIIa and Xa. The results gave 70% conversion of the starting material and the formation of VIIa:Xa with a ratio of 1:10.2. LC-MS (Method B): Retention time 1.08 min, m / z246[M+H + ]. 1 H NMR(400MHz,chloroform-d)δ ppm 1.36-1.47(m,6H)3.04(q,J=7.42Hz,2H)4.47(q,J=7.09Hz,2H)7.62(d,J=2.08Hz,1H)8.42(d,J=1.96Hz,1H).

[0040] Example 8: Solvent effect on the thiolation reaction to sodium 3,5-dichloropyridine-2-carboxylate (XIIIa) [ka] A 5 mL microwave vial was charged with sodium 3,5-dichloropyridine-2-carboxylate (94%, 100 mg, 0.422 mmol). The vial was purged with argon, and pre-deoxygenated solvent (2.2 mL) was added under argon. The reaction mixture was heated to 80 °C, and sodium ethanethiolate (42.6 mg, 0.507 mmol, 1.20 equiv.) was added. The reaction mixture was stirred at 80 °C for 3.5 h. After cooling to room temperature, the reaction mixture was stopped and an NMR sample was taken to determine the ratio of products (XIV) and (XV) formed. The results are summarized in the table below.

[0041] [Table 1]

Claims

1. Formula (I): 【Chemistry 1】 (In the formula, R 1 is H or C 1 ~C 4 alkyl, and R 2 is C 1 ~C 4 is alkyl) A process for the preparation of a chloro-pyridine compound of the formula (A) Formula II 【Chemistry 2】 wherein Xa is fluoro or chloro. The compound of formula (I) is reacted with a thiol compound R 3 -S-R 2 (In the formula, R 2 is as defined in formula I, and R 3 is H or an alkali metal ion) in the presence of a suitable base in a suitable solvent (or diluent) having a dielectric constant of less than 15 to give a compound of formula (Ia): 【Chemistry 3】 or a salt thereof, and optionally Formula ROH, where R is C 1-4 esterifying the compound of formula (Ia) or a salt thereof in the presence of a compound of formula (I), 1 is C 1 ~C 4 and forming said compound, A process including.

2. The process of claim 1, wherein R 1 is methyl, ethyl or t-butyl, R 2 is ethyl, Xa is chloro, and R 3 is H or sodium.

3. Xa is chloro; R 1 is ethyl, R 2 is ethyl, and R 3 The process of claim 1 , wherein is sodium.

4. 2. The process of claim 1, wherein the suitable base is selected from alkali metal carbonates and alkali metal hydroxides.

5. The process of claim 1, wherein the suitable base is sodium carbonate or potassium carbonate.

6. The process of claim 1, wherein the suitable solvent (or diluent) is selected from those having a dielectric constant in the range of 1.5 to 15.

7. 7. The process of claim 6, wherein the suitable solvent (or diluent) is selected from dioxane, methyltetrahydrofuran, toluene, anisole, and pyridine.

8. The process of claim 6, wherein the suitable solvent (or diluent) is selected from dioxane, methyltetrahydrofuran, and toluene.

9. 2. The process of claim 1, wherein the reaction of step (A) is carried out at a temperature between 0° C. and the boiling point of the reaction mixture.

10. The process of claim 1, wherein the reaction in step (A) is carried out at a temperature of from 20°C to 100°C.

11. The process of claim 1, wherein the reaction in step (A) is carried out at a temperature of 60 to 100°C.

12. Formula Ia: 【Chemistry 4】 or a pesticidally acceptable salt of a compound of formula Ia.

13. Formula Ia-1: 【Chemistry 5】 (wherein M is sodium, potassium or lithium). Compound.

14. The compound of formula Ia-1 of claim 13, wherein M is sodium or lithium.

15. Formula I-2: 【Chemistry 6】 (In the formula, R 1a is C 1 ~ 4 is alkyl) or a pesticidally acceptable salt of a compound of formula I-2.

16. The compound of formula I-2 or a pesticidally acceptable salt of a compound of formula I-2 according to claim 15, wherein R 1a is methyl, ethyl or t-butyl.

17. Formula I-2a: 【Chemistry 7】 (In the formula, R 1b is C 1-4 alkyl, and n is 1 or 2. or a pesticidally acceptable salt of a compound of formula I-2a.

18. The compound of formula I-2a according to claim 17, or a pesticidally acceptable salt of a compound of formula I-2a, wherein R 1b is methyl, ethyl or t-butyl, and n is 2.

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