Synthesis of 1,1,2-trifluoro-4-(substituted sulfonyl)-but-1-enes

Abstract

The present invention provides a method for producing a compound of formula [I] from a compound of formula [II] using an oxidizing agent and a catalyst, and the method is carried out at low temperature.

Description

[Technical field]

[0001] Throughout this application various publications are cited. The disclosures of these documents in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

[0002] technical field The subject matter has the formula [I]

[0003] [ka]

[0004] wherein R1 is an optionally substituted heterocyclic aromatic ring. The present invention relates to a method for producing the compound of the formula (I). [Background technology]

[0005] 2. Background of the Invention Fluensulfone (5-chloro-2-(3,4,4-trifluorobut-3-enylsulfonyl)-1,3-thiazole; CAS No. 318290-98-1) is a highly effective active ingredient that is highly potent against plant parasitic nematodes. Fluensulfone is a heterocyclic fluoroalkenylsulfone nematicide with significantly reduced environmental impacts that have low toxicity to non-target insects and mammals. The mode of action of Fluensulfone differs from currently available nematicides and therefore represents a promising entry point for crop protection, although the exact mode of action of Fluensulfone is currently unknown.

[0006] Fluensulfone of formula (I) is prepared via oxidation of a compound of formula (II) 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]thiazole. The preparation of formula (II) is described in US Pat. No. 5,399,413, the contents of which are incorporated herein by reference.

[0007] [ka]

[0008] A method for the preparation of fluensulfone by reaction of the corresponding sulfide with an oxidizing agent has been reported.

[0009] US Pat. No. 5,399,433 discloses a method for preparing fluensulfone by reacting the corresponding sulfide with hydrogen peroxide in glacial acetic acid at 55-60° C. for 6 hours.

[0010] Patent Document 2 discloses a method for producing heterocyclic fluoroalkenyl sulfones and fluoroalkenyl sulfoxides from the corresponding fluoroalkenyl thioethers by using oxone. Oxone is expensive and produces a large amount of waste in the form of salts, which is problematic, especially in large-scale production.

[0011] Methods for the preparation of other sulfones by catalytic oxidation of the corresponding sulfides have also been reported.

[0012] Non-Patent Document 1 discloses a method for producing 2-phenylsulfonylethanol by reacting 2-phenylmercaptoethanol with hydrogen peroxide in the presence of sodium tungstate. The disclosed reaction is carried out at 60-75°C.

[0013] Non-Patent Document 2 discloses a method using quaternary ammonium hydrogen sulfate and phenylphosphonic acid in addition to sodium tungstate.

[0014] US Pat. No. 5,399,433 discloses the synthesis of 2-(methylsulfonyl)-5-(trifluoromethyl)-1,3,4-thiadiazole using catalytic oxidation at temperatures from 50°C to 100°C, and preferably from 70°C to 90°C.

[0015] Patent Document 4 discloses a method for producing an alkylsulfone compound using an oxidizing agent in the presence of a tungstate catalyst at a reaction temperature of 0°C to 200°C, and more preferably 10°C to 150°C.

[0016] US Pat. No. 5,399,633 discloses a process for the preparation of sulfone or sulfoxide compounds which comprises reacting a sulfide compound with hydrogen peroxide in the presence of a metal oxide catalyst.

[0017] None of these publications disclose the catalytic oxidation for the preparation of fluenesulfone as disclosed in the present invention. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] International Publication No. 01 / 02378 A1 Brochure [Patent Document 2] US Patent No. 8,901,311 B2 [Patent Document 3] European Patent No. 0926143 A1 [Patent Document 4] European Patent No. 2441751 A1 [Patent Document 5] European Patent No. 1334956 B1 [Non-patent literature]

[0019] [Non-Patent Document 1] J. Org. Chem., 28, 1140 (1963) [Non-Patent Document 2] Tetrahedoron, 57, 2469 (2001) Summary of the Invention

[0020] The present invention relates to a compound represented by formula (I)

[0021] [ka]

[0022] wherein R1 is an optionally substituted heterocyclic aromatic ring. The present invention provides a method for preparing a compound of formula (II):

[0023] [ka]

[0024] The method involves reacting a compound of the formula (I) with an oxidizing agent and a catalyst at low temperature.

[0025] The present invention also provides a method for improving the yield of a compound of formula (I) in a process for the oxidation of a compound of formula (II), which comprises reacting a compound of formula (II) with an oxidizing agent and a catalyst at low temperature.

[0026] The present invention also provides a method for increasing the selectivity of a compound of formula (I) in a process for the oxidation of a compound of formula (II), which comprises reacting a compound of formula (II) with an oxidizing agent and a catalyst at low temperature.

[0027] Detailed Description of the Invention definition Before describing the present subject matter in detail, it may be useful to provide definitions of certain terms to be used herein. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present subject matter pertains. For the sake of clarity, the following definitions are provided:

[0028] The terms "a" or "an" as used herein include singular and plural unless specifically stated otherwise. Thus, the terms "a," "an," or "at least one" may be used interchangeably in this application.

[0029] As used herein, the term "about" when used in conjunction with a numerical value includes ±10% from the recited value. Moreover, all ranges directed to the same component or property herein are inclusive of the endpoints, are independently combinable, and all ranges are inclusive of the endpoints. It is understood that when a parameter range is given, all integers and tenths thereof within that range are also provided by the present invention.

[0030] As used herein, the term "effective", when used, refers to a reaction time of less than 24 hours.

[0031] As used herein, the term "mixture" or "combination" refers to a combination in any physical form, such as, but not limited to, a blend, solution, alloy, and the like.

[0032] The term "heterocyclic aromatic ring" refers to thiophene, thiazole and thiadiazole.

[0033] The term "optionally substituted" refers to H and halogen.

[0034] The present invention is based on the inventors' surprising discovery that the catalytic oxidation of the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole at low temperatures for the synthesis of the compound fluensulfone provides an efficient process with high selectivity, conversion and yield.

[0035] The present invention is advantageous in that it is highly effective. In particular, the process disclosed herein provides a highly selective reaction, exhibiting high conversions, higher yields, reduced production costs and simplified work-up. The present invention is also advantageous in that it is atom efficient and it minimizes the amount of salt waste it generates.

[0036] In the process for the oxidation of sulfides to the corresponding sulfones depicted by Scheme 1, the intermediate sulfoxide (II') is readily generated, however the secondary oxidation to the sulfone is usually relatively slow and requires elevated temperatures.

[0037] [ka]

[0038] Such oxidation methods generally lead to the undesired oxidation of the double bond of the highly reactive halogenated butenyl group of fluensulfone and its oxidative decomposition, resulting in low selectivity of the reaction and, as a result, low yields.

[0039] Scheme 2 shows some examples of such oxidative decomposition and subsequent formation of by-products.

[0040] [ka]

[0041] The purity was confirmed by MS as shown in Figure 1-3.

[0042] In view of the oxidation sensitive double bond of the compound of formula [I], it was an object of the present invention to provide a process for the preparation of sulfones of formula [I] by oxidation of the corresponding sulfides, obtaining high selectivity, conversion and yield while minimizing the amount of waste.

[0043] The inventors have found that catalytic oxidation of the compound of formula [II] at low temperatures gives high selectivity and therefore high conversion and therefore high yield of the corresponding sulfone.

[0044] The present invention provides a process for preparing a compound of formula [I], the process comprising reacting a compound of formula [II] with an oxidant and a catalyst at low temperature.

[0045] [ka]

[0046] wherein R1 is an optionally substituted heterocyclic aromatic ring.

[0047] The present invention provides a process for preparing a compound of formula [I], the process comprising reacting a compound of formula [II] with an oxidant and a catalyst, wherein the process is carried out at a temperature of about -5°C to 25°C.

[0048] [ka]

[0049] wherein R1 is an optionally substituted heterocyclic aromatic ring.

[0050] The present invention provides a method for preparing a compound of formula [I], the method comprising reacting a compound of formula [II] with an oxidizing agent and a catalyst, wherein the method is carried out at a temperature of about -5°C-25°C. In some embodiments, the temperature is between 0°C-20°C. In some embodiments, the temperature is between 5°C-15°C. In a preferred embodiment, the temperature is between 8°C-10°C.

[0051] The oxidizing agent used for the catalytic oxidation can be an agent commonly used for this purpose in organic chemistry, which is known to those skilled in the art and includes, for example, hydrogen peroxide, m-chloroperoxybenzoic acid, peroxyacetic acid, peroxybenzoic acid, magnesium monoperoxyphthalate, potassium peroxymonosulfate, bis(trimethylsilyl)peroxide, methylsilyl peroxide, nickel peroxide, trifluoroperacetic acid, 2,4-dinitroperbenzoic acid, peroxysulfuric acid, carbonoperoxoic acid, sodium perborate monohydrate, tert-butyl hydroperoxide (TBHP), and the like.

[0052] In some embodiments, the oxidizing agent is a peroxide.

[0053] In some embodiments, the oxidizing agent is hydrogen peroxide.

[0054] In some embodiments, the concentration of hydrogen peroxide in the water is at least 10%, 20%, 30%, 40% or 50%.

[0055] In some embodiments, the concentration of hydrogen peroxide in the water is at least 30%. In preferred embodiments, the concentration of hydrogen peroxide in the water is 50%.

[0056] In some embodiments, the oxidizing agent is used as a solution.

[0057] In some embodiments, the catalyst includes TaCl5, Ta(OEt)5, NbCl5, Nb2O5, TiO2 / H3PO4, Ti(OiPr)4, V2O3, V2O5, VO(acac)2, Na2WO4, WO2, WO3, WO, WF6, wrought tungsten and ditungsten-copper pseudoalloys, W metal, W metal in combination with Al2O3, WF6, mixed oxo-fluoro complexes of W(VI), WO5·HMPT·H2O (HMPT=hexamethylphosphoric triamide), mixed oxo-fluoro complexes of W(IV), WO2F2, WOF4, mixed oxo-chloro complexes of W(IV), WO2Cl2, WOCl4, W(CO)6, H2WO4(aq.), MoO3, Na2MoO4, H4PMo 11 VO 40 and combinations thereof. In a preferred embodiment, the catalyst is selected from niobium pentachloride, tantalum pentachloride, sodium tungstate, and sodium molybdate. In a most preferred embodiment, the catalyst is sodium tungstate.

[0058] In some embodiments, the method is carried out in a solvent.

[0059] Solvents include, but are not limited to, polar and non-polar solvents.

[0060] In some embodiments, the solvent is a polar solvent. In some embodiments, the solvent is a non-polar solvent. In some embodiments, the solvent is a mixture of at least one polar solvent and at least one non-polar solvent.

[0061] Polar solvents may include, but are not limited to, nitriles, alcohols, ethers, chlorinated solvents, and combinations thereof.

[0062] In some embodiments, the polar solvent is an alcohol solvent. 1-6 In some embodiments, the alcoholic solvent is methanol. In some embodiments, the alcoholic solvent is ethanol. In some embodiments, the alcoholic solvent is isopropanol. In some embodiments, the alcoholic solvent is butanol. In some embodiments, the alcoholic solvent is pentanol. In some embodiments, the alcoholic solvent is hexanol. In some embodiments, the alcoholic solvent is ethylene glycol.

[0063] In some embodiments, the alcohol solvent is methanol, ethanol, isopropanol, butanol, pentanol, hexanol, ethylene glycol, or a combination thereof.

[0064] In some embodiments, the polar solvent is a nitrile solvent. In some embodiments, the nitrile solvent is a C 1-6 In some embodiments, the nitrile solvent includes, but is not limited to, acetonitrile, isobutyronitrile, propionitrile, acrylonitrile, or a combination thereof. In some embodiments, the nitrile solvent is acetonitrile.

[0065] Non-polar solvents may include, but are not limited to, optionally substituted aliphatic, alicyclic and aromatic solvents such as hexane, cyclohexane, petroleum, ether, ligroin, benzene, toluene, xylene, methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, chlorobenzene, or combinations thereof.

[0066] In some embodiments, the non-polar solvent is an aromatic non-polar solvent, hi some embodiments, the aromatic non-polar solvent is toluene.

[0067] In some embodiments, the non-polar solvent is an aliphatic hydrocarbon non-polar solvent. In some embodiments, the aliphatic hydrocarbon non-polar solvent is hexane.

[0068] In some embodiments, the polar or non-polar solvent is a chlorinated solvent. In some embodiments, the chlorinated solvent may include, but is not limited to, methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, and chlorobenzene.

[0069] In some embodiments, the process is carried out in a solvent selected from methanol, acetonitrile, and toluene, or a combination thereof. In a preferred embodiment, the solvent is methanol.

[0070] In some embodiments, the molar ratio between the compound of formula [II] and the catalyst is 1:1 to 100 :1. In some embodiments, the molar ratio between the compound of formula [II] and the catalyst is from 10:1 to 20:1. In some embodiments, the molar ratio between the compound of formula [II] and the catalyst is about 15:1.

[0071] In some embodiments, the molar ratio between the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole and the catalyst is from 1:1 to 100:1. In some embodiments, the molar ratio between the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole and the catalyst is from 10:1 to 20:1. In some embodiments, the molar ratio between the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole and the catalyst is about 15:1.

[0072] In some embodiments, the molar ratio between the compound of formula [II] and the oxidizing agent is from 1:1 to 1:10. In some embodiments, the molar ratio between the compound of formula [II] and the oxidizing agent is from 1:1 to 1:5. In a preferred embodiment, the molar ratio between the compound of formula [II] and the oxidizing agent is about 1:4.

[0073] In some embodiments, the molar ratio between the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole and the oxidizing agent is from 1:1 to 1:10. In some embodiments, the molar ratio between the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole and the oxidizing agent is from 1:1 to 1:5. In a preferred embodiment, the molar ratio between the compound 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole and the oxidizing agent is about 1:4.

[0074] In some embodiments, the molar ratio between the oxidant and the catalyst is between 1000:1 and 10:1. In some embodiments, the molar ratio between the oxidant and the catalyst is between 100:1 and 20:1. In some embodiments, the molar ratio between the oxidant and the catalyst is 60:1.

[0075] In some embodiments, the method is carried out for less than 24 hours, less than 22 hours, less than 20 hours, less than 18 hours, less than 16 hours, less than 12 hours, less than 10 hours, less than 8 hours, less than 6 hours, or less than 4 hours.

[0076] In some embodiments, the conversion of the compound of formula [II] to the compound of formula [I] is greater than 90%, 95%, 99% or 100%.

[0077] In some embodiments, the conversion of 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole to fluensulfone is greater than 90%, 95%, 99% or 100%.

[0078] In some embodiments, the chemical yield of the compound of formula [I] is greater than 80%, 85%, 90% or 95%.

[0079] In some embodiments, the chemical yield of fluensulfone is greater than 80%, 85%, 90% or 95%.

[0080] Phase separation and crystallization with methylcyclohexane or n-heptane gives excellent purification from impurities.

[0081] Phase separation and crystallization with methylcyclohexane or n-heptane resulted in a complete separation of the impurities. It gives excellent purification of the ene sulfone.

[0082] Recrystallization is carried out by cooling a hot saturated solution of a non-polar solvent such as methylcyclohexane or heptane or a combination thereof to a temperature range of about 0-70°C.

[0083] The compound of formula [I] is obtained in a yield of greater than 80%, 85%, 90% or 95%.

[0084] The yield of purified sulfone product is greater than 80%.

[0085] Fluensulfone is obtained in yields greater than 80%.

[0086] The present invention also provides a method for improving the yield of a compound of formula (I) in a process for the oxidation of a compound of formula (II), comprising reacting a compound of formula (II) with an oxidizing agent and a catalyst at low temperature. In some embodiments, the compound of formula [I] is fluensulfone.

[0087] The present invention also provides a method for improving the selectivity of a compound of formula (I) in a process for the oxidation of a compound of formula (II), comprising reacting a compound of formula (II) with an oxidizing agent and a catalyst at low temperature. In some embodiments, the compound of formula [I] is fluensulfone.

[0088] The present invention also provides a method for improving the yield of a compound of formula (I) in a process for the oxidation of a compound of formula (II), comprising reacting a compound of formula (II) with an oxidizing agent and a catalyst at a temperature of about −5° C. to 25° C. In some embodiments, the compound of formula [I] is fluensulfone.

[0089] The present invention also provides a method for improving the selectivity of a compound of formula (I) in a process for the oxidation of a compound of formula (II), comprising reacting a compound of formula (II) with an oxidizing agent and a catalyst at a temperature of about −5° C. to 25° C. In some embodiments, the compound of formula [I] is fluensulfone.

[0090] In some embodiments, the temperature is between 0° C.-20° C. In some embodiments, the temperature is between 5° C.-15° C. In preferred embodiments, the temperature is between 8° C.-10° C.

[0091] The present invention also provides an improved process for obtaining a compound of formula (I), which comprises reacting a compound of formula (II) with an oxidizing agent and a catalyst at low temperature.

[0092] The present invention also provides an improved process for obtaining a compound of formula (I), which comprises reacting a compound of formula (II) with an oxidizing agent and a catalyst at a temperature of about -5°C to 25°C.

[0093] In some embodiments, the temperature is between 0° C.-20° C. In some embodiments, the temperature is between 5° C.-15° C. In preferred embodiments, the temperature is between 8° C.-10° C.

[0094] In some embodiments, the improvement comprises obtaining at least 90%, or 95%, or 99%, or 100% conversion of the compound of formula (II) to the compound of formula (I). In some embodiments, the improvement comprises obtaining greater than 90%, or 95%, or 99%, or 100% conversion of the compound of formula (II) to the compound of formula (I). In some embodiments, the compound of formula (I) is fluensulfone.

[0095] In some embodiments, the improvement is at least 80%, 85%, 90% or more of the compound of formula (I). % or 95% chemical yield. In some embodiments, the compound of formula (I) is fluensulfone. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0096] Experimental part EXAMPLES

[0097] 20.2 g of 5-chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole (96.8%, 74.55 mmol) and 100 g of methanol were added to a 1 L flask equipped with a mechanical stirrer, a condenser, a thermometer and a dropping funnel. A solution of 1.7 g of Na2WO4*2H2O (5.10 mmol) in 14 mL of water was added to the reaction mixture and the reaction mixture was cooled to 10°C.

[0098] The reaction was stirred at 8-10° C. while 21.0 g of H2O2 (50% in water, 17.5 mL, 308.73 mmol) was added slowly over 6 hours. After complete addition of H2O2, the reaction was stirred for an additional 1 to 4 hours at 8-10° C. Samples were taken for analysis (LC) at the end of the feed and periodically until the sulfoxide (Formula II') was <1% by normalization.

[0099] After the reaction was complete, the reaction mixture was cooled to 5° C. and Na2S2O5 was added slowly while maintaining the temperature at 5-20° C. until the peroxide test was negative. Methanol was removed by vacuum distillation and 40 mL of water was added.

[0100] The pH was slowly corrected to 6-7 using 15% NaOH solution and the reaction mixture was stirred for an additional 15 min.

[0101] 120 g of methylcyclohexane was added, heated to 70° C. and the phases were separated hot. The organic phase was washed with 100 g of water at 70° C. and the phases were separated hot.

[0102] Crystallization was carried out gradually from 70° C. to 0° C. and the reaction mixture was filtered at 0° C. The cake was dried on a sinter and later in vacuum (10 mbar at 25° C.).

[0103] After drying, 85-91% yield of fluensulfone was obtained (assay >97%).

[0104] Discussion The oxidation of sulfides in the presence of alkene groups is challenging and improving the selectivity affects yield and effectiveness. Catalytic oxidation at low temperatures has been found to be effective and gives high selectivity. [Brief description of the drawings]

[0105] [Figure 1] The purity is confirmed by MS. [Diagram 2] The purity is confirmed by MS. [Diagram 3] The purity is confirmed by MS.

Claims

1. The compound of formula [II] is reacted with an oxidizing agent selected from the group consisting of hydrogen peroxide, m-chloroperoxybenzoic acid, peroxyacetic acid, peroxybenzoic acid, magnesium monoperoxyphthalate, potassium peroxymonosulfate, bis(trimethylsilyl)peroxide, methylsilyl peroxide, nickel peroxide, trifluoroperacetic acid, 2,4-dinitroperbenzoic acid, peroxysulfuric acid, carbonoperoxoacid, sodium perborate monohydrate, and tert-butyl hydroperoxide, and NbCl 5 , Na 2 WO 4 , W.O. 2 and Na 2 A method for producing a compound of formula [I], comprising reacting a catalyst selected from the group consisting of MoO 4 , 【Chemistry 1】 [In the formula, R 1 is selected from the group consisting of optionally substituted thiophene, optionally substituted thiazole, and optionally substituted thiadiazole. The above process, wherein the process is carried out at a temperature of about -5°C to 25°C.

2. The method of claim 1, wherein the temperature is about 5°C to 15°C.

3. The method according to claim 1 or 2, wherein the temperature is about 8°C-10°C.

4. 2. The method of claim 1, wherein the oxidizing agent is hydrogen peroxide.

5. 5. The method of claim 4, wherein the concentration of hydrogen peroxide in the water is at least 30%.

6. 6. The method of claim 5, wherein the concentration of hydrogen peroxide in water is 50%.

7. The catalyst is Na 2 WO 4 The method according to claim 1, wherein

8. 8. The process according to any one of claims 1 to 7, wherein the process is carried out in a solvent selected from the group consisting of alcohols, nitriles, ethers, chlorinated solvents, optionally substituted aliphatic, alicyclic and aromatic solvents or combinations thereof.

9. 9. The process of claim 8, wherein the process is carried out in a solvent selected from the group consisting of methanol, acetonitrile, toluene, or combinations thereof.

10. 10. The process according to claim 8 or 9, wherein the solvent is methanol.

11. The process according to any one of claims 1 to 10, wherein the molar ratio between the compound of formula [II] and the catalyst is from 1:1 to 100:

1.

12. The method according to claim 11, wherein the molar ratio between the compound of formula [II] and the catalyst is from 10:1 to 20:

1.

13. 13. The method according to claim 11 or 12, wherein the molar ratio between the compound of formula [II] and the catalyst is 15:

1.

14. The method according to any one of claims 1 to 13, wherein the molar ratio between the compound of formula [II] and the oxidizing agent is from 1:1 to 1:

10.

15. The method according to claim 14, wherein the molar ratio between the compound of formula [II] and the oxidizing agent is from 1:1 to 1:

5.

16. 16. The method according to claim 14 or 15, wherein the molar ratio between the compound of formula [II] and the oxidizing agent is about 1:

4.

17. 17. The method of any one of claims 1-16, wherein the method is carried out for less than 24 hours.

18. 20. The method of claim 17, wherein the method is carried out for less than 12 hours.

19. 20. The method of claim 18, wherein the method is carried out for less than 10 hours.

20. 20. The process according to any one of claims 1 to 19, wherein the conversion of the compound of formula [II] to the compound of formula [I] is greater than 90%.

21. 21. The process of any one of claims 1-20, wherein the chemical yield is greater than 85%.

22. The method according to any one of claims 1 to 21, wherein the compound of formula [I] is further purified by recrystallization.

23. 23. The method of claim 22, wherein the recrystallization is by cooling of a hot saturated solution.

24. 24. A process according to claim 22 or 23, wherein the recrystallisation is by cooling of a hot saturated solution of the non-polar solvent.

25. 25. The method of claim 24, wherein the non-polar solvent is methylcyclohexane or heptane or a combination thereof.

26. 26. The process according to any one of claims 22 to 25, wherein the purification is carried out at a temperature range of about 0-70°C.

27. 27. The method of any one of claims 22-26, wherein the yield of purified product is greater than 80%.

28. The method according to any one of claims 1 to 27, wherein the compound of formula [I] is fluensulfone.

29. The method according to any one of claims 1 to 28, wherein the compound of formula [II] is chloro-2-[(3,4,4-trifluoro-3-buten-1-yl)thio]-thiazole.

30. A process for enhancing the yield of a compound of formula (I) comprising reacting a compound of formula (II) with an oxidizing agent and a catalyst according to the process of any one of claims 1-29.

31. A process for enhancing the selectivity of a compound of formula (I) comprising reacting a compound of formula (II) with an oxidizing agent and a catalyst according to the process of any one of claims 1-29.

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