A pyridyloxazole sulfone compound, a preparation method and application thereof

Abstract

The application discloses a pyridine oxazole sulfone compound and a preparation method and application thereof. The structural general formula of the compound is shown in the specification. RX is any one or more of -H, -CH3, -OCH3, -NO2, -Br, -Cl, -F, -CN and the like. The pyridine oxazole sulfone compound provided by the application has excellent herbicidal activity, especially remarkable effect on Gramineae for controlling annual and perennial weeds, and the total weed control effect reaches at least 98.4% and the fresh weight control effect reaches at least 94.1% on the seventh day after treatment. The compound has good control effect on barnyard grass resistant to cyhalofop-butyl and quinclorac, small residue on late crops and safety to non-target bees. The compound has small dosage, low cost and short residue period, reduces potential threats of pesticides to the environment, and has simple and economical synthesis method, so that the compound can be used as a lead compound to provide a new reference for development of new herbicides with high efficiency and low toxicity.

Description

Technical Field

[0001] This invention belongs to the fields of organic synthesis and pesticide technology, specifically relating to a pyridine oxazole sulfone compound and its preparation method and application. Background Technology

[0002] Herbicides are pesticides that can kill weeds completely or selectively. For a long time, applying chemical herbicides has been the most direct and effective means of controlling weeds in farmland. However, the irrational use of herbicides can cause environmental pollution, lead to weed resistance, and harm non-weed organisms, which is detrimental to ensuring food security and quality in farmland. Furthermore, existing chemical herbicides have relatively high dosages and costs, resulting in relatively high control costs. Developing new targeted herbicides can not only reduce usage costs but also potentially solve the problem of weed resistance, achieving efficient and green farmland production. Summary of the Invention

[0003] One of the objectives of this invention is to provide a pyridine oxazole sulfone compound that has excellent control effect, requires less herbicide dosage, has low cost, and has a simple synthesis process.

[0004] A second objective of this invention is to provide a method for preparing the pyridine oxazole sulfone compounds.

[0005] A third objective of this invention is to provide applications of the aforementioned pyridine oxazole sulfone compounds.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a pyridine oxazole sulfone compound, the general structural formula of which is shown in Formula I:

[0008]

[0009] Wherein, RX is any one or more of -H, -CH3, -OCH3, -NO2, -Br, -Cl, -F, -CN, etc.

[0010] Preferably, the pyridine oxazole sulfone compound has a structural formula as shown in any one of formulas II to XII:

[0011]

[0012]

[0013]

[0014]

[0015] The present invention also provides a method for preparing the pyridine oxazole sulfone compound, comprising the following steps:

[0016] S1. Dissolve compound 1 in a solvent, add compound X and an acid-binding agent, heat and stir to react, then extract, wash, dry, filter and rotary evaporate to obtain compound 2;

[0017] S2. Dissolve compound 2 in an organic solvent, add a catalyst and heat, then add hydrogen peroxide solution dropwise. After the addition is complete, continue to heat the reaction until the preset conditions are reached. Cool to precipitate solid, filter, wash with water and dry to obtain the pyridine oxazole sulfone compound.

[0018] Its synthetic route is as follows:

[0019]

[0020] Further, in step S1, the molar ratio of compound 1 to the acid-binding agent is 1:(1-3); the solvent is at least one selected from N,N-didimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, tetrahydrofuran, and chloroform.

[0021] The general structural formula of compound X is:

[0022]

[0023] Wherein, RX is any one or more of -H, -CH3, -OCH3, -NO2, -Br, -Cl, -F, -CN, etc.; the molar ratio of compound X to compound 1 is 1:1.

[0024] Specifically, the acid-binding agent is at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, and triethylamine; the reaction conditions for the heating and stirring reaction are: stirring rate of 500-600 rpm; heating temperature of 50-60℃; reaction time of 4-8 h; and thin-layer chromatography monitoring of the reaction process.

[0025] Specifically, after the heating and stirring reaction was completed, dichloromethane was used for extraction, followed by washing with brine several times, and finally drying with magnesium sulfate. After filtration and selective evaporation of solvent, compound 2 was obtained.

[0026] Further, step S2 specifically involves: dissolving compound 2 in DMF, adding sodium tungstate as a catalyst, heating to 45-45°C, then adding 30% hydrogen peroxide solution dropwise at a preset rate, finally heating to 60-65°C, monitoring the reaction using thin-layer chromatography until the starting material spot disappears, cooling to room temperature, then pouring into ice water to precipitate the solid, filtering, washing several times with deionized water, and drying to obtain the pyridine oxazole sulfone compound.

[0027] Specifically, the amount of sodium tungstate used is 10% to 20% of compound 1; the amount of 30% hydrogen peroxide solution used is 10 to 20 times that of compound 1.

[0028] The present invention also provides the application of the pyridine oxazole sulfone compound as a herbicidal active substance in suppressing weeds in farmland.

[0029] Furthermore, the farmland weeds include annual weeds and perennial weeds.

[0030] The beneficial effects of this invention are:

[0031] The pyridine oxazolium sulfone compounds provided by this invention exhibit excellent herbicidal activity, particularly effective against annual and perennial grass weeds. Seven days after application, the control efficacy against total weeds reaches at least 98.4% and fresh weight efficacy reaches at least 94.1%. It also shows good control of barnyardgrass resistant to cyhalofop-butyl and quinclorac, and has low residue on later-stage crops and is safe for non-target bees. This compound requires low dosage, is low in cost, and has a short residual period, reducing the potential environmental threat of pesticides. Furthermore, its synthesis method is simple and economical, making it a suitable lead compound for developing highly effective and low-toxicity novel herbicides. Attached Figure Description

[0032] Figure 1 This is the general structural formula of the pyridine oxazole sulfone compounds disclosed in this invention. Detailed Implementation

[0033] The embodiments of the present invention will be described in further detail below with reference to specific examples. These examples are used to illustrate the present invention, but should not be construed as limiting the scope of the invention.

[0034] Example 1

[0035] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((3-methylbenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (3-CH3), the specific steps are as follows:

[0036] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of tetrahydrofuran. After dissolution, 0.555 g of compound A (3 mmol) was added, followed by 0.336 g of sodium bicarbonate (4 mmol) as an acid-binding agent. The mixture was heated to 50 °C and stirred for 8 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was completed, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. After drying, compound 2 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The mixture was heated to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was maintained until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.801 g. The yield was calculated to be 77.3%. The synthetic route is as follows:

[0037]

[0038] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0039] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.30 (d, J=3.6Hz, 1H, Py-H), 7.43 (d, J=3.6Hz, 1H, Py-H), 7.216-7.259 (m,4H,Ar-H),7.11(d,H,J=4.4Hz,Py-H),4.50(s,2H,CH2),3.98(s,3H,OCH3),2.43(s,3H,Ar-CH3). 13 C NMR (100MHz, CDCl3) δ165.41,164.83,164.03,148.25,138.65,135.17,133.11,1 29.85,129.03,128.77,126.21,113.25,107.99,83.88,36.84,21.34.HRMS(ESI)C 16 H 16 N3O4S[M+H]+:calcd.346.0957, found 346.0958.

[0040] Example 2

[0041] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((2,4-dimethylbenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (2,4-CH3), the specific steps are as follows:

[0042] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of dimethyl sulfoxide. After dissolution, 0.594 g of compound B (3 mmol) was added, followed by 0.5 g of potassium bicarbonate (5 mmol) as an acid-binding agent. The mixture was heated to 55 °C and stirred for 6 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried again. Compound 3 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The temperature was raised to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.811 g. The yield was calculated to be 75.3%. The synthetic route is as follows:

[0043]

[0044] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0045] White solid 1 H NMR (400MHz, DMSO-d6) δ8.40(d,J=4.4Hz,1H,Py-H),7.50(d,J=5.2Hz,1H,Py-H),7.29(d,J=8.9Hz,2H,Ar-H),7.04(s, 1H, Ar-H), 6.96 (d, J = 7.7Hz, 1H, Py-H), 4.60 (s, 2H, CH2), 3.94-3.92 (m, 3H, OCH3), 2.37 (s, 3H, CH3), 2.24 (s, 3H, CH3). 13 C NMR(100MHz,DMSO-d6)δ165.07,164.72,164.05,149.15,138.11,137.17,133.37, 131.68,130.96,130.58,127.16,113.84,107.70,84.20,21.08,19.15.HRMS(ESI)C 17 H 18 N3O4S[M+H] + :calcd.360.1180,found 360.1151.

[0046] Example 3

[0047] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((2-chlorobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R...x (For 2-Cl), the specific steps are as follows:

[0048] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of dimethyl sulfoxide. After dissolution, 0.616 g of compound C (3 mmol) was added, followed by 0.606 g of triethylamine (6 mmol) as an acid-binding agent. The mixture was heated to 55 °C and stirred for 5 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was completed, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The solution was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried. Compound 4 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The mixture was heated to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was maintained until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.890 g. The yield was calculated to be 81.1%. The synthetic route is as follows:

[0049]

[0050] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0051] Pale yellow solid, δ 8.30 (d, J=2.8Hz 1H Py-H), 7.63 (d, JJ=6.4Hz, 1H, Ar-H), 7.40-7.43 (m, 2H, Py-H), 7.24 (m, 3H, Ar-H), 4.64 (s, 2H, CH2), 3.98 (s, 3H, OCH3). 13 C NMR (151MHz, CDCl3) δ165.31,164.82,164.20,148.27,134.41,133.47,133.0 4,131.57,129.85,129.78,127.15,113.22,107.98,83.88,34.60.HRMS(ESI)C 15 H 13 ClN3O4S[M+H] + :calcd.366.8411,found 366.8412

[0052] Example 4

[0053] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((3,4-dichlorobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (For 3,4-Cl), the specific steps are as follows:

[0054] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of N,N-dimethylformamide. 0.702 g of compound D (3 mmol) was added, followed by 0.424 g of sodium carbonate (4 mmol) as an acid-binding agent. The mixture was heated to 55 °C and stirred for 7 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. Compound 5 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The temperature was raised to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water, where a solid precipitated. The solid was filtered, washed with water, dried, and weighed to 0.953 g. The yield was calculated to be 79.3%. The synthetic route is as follows:

[0055]

[0056] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0057] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.31 (d, J=5.3Hz, 1H, Py-H), 7.58 (s, 1H, Py-H), 7.43-7.40 (m, 2H ,Ar-H),7.33(d,J=8.3Hz,1H,Ar-H),7.26(s,1H,Py-H),4.47(s,2H,CH2),3.98(s,3H,OCH3). 13 C NMR (100MHz, CDCl3, δppm): δ164.85,164.63,164.35,148.33,135.84,132.93 ,132.49,131.07,130.76,128.57,113.22,108.05,83.92,35.41.HRMS(ESI)C 15 H 12 Cl2N3O4S[M+H] + :calcd.401.0123,found 401.0122.

[0058] Example 5

[0059] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((3-methoxy-4-fluorobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (3-OCH3-4-F), the specific steps are as follows:

[0060] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of acetone. Then, 0.657 g (3 mmol) of compound E was added, followed by 0.816 g (3 mmol) of potassium carbonate as an acid-binding agent. The mixture was heated to 60 °C and stirred for 4 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried again. Compound 6 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The mixture was heated to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.861 g. The yield was calculated to be 75.7%. The synthetic route is as follows:

[0061]

[0062] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0063] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.31 (d, J=5.3Hz, 1H, Py-H), 7.58 (s, 1H, Py-H), 7.43-7.40 (m, 2H, Ar-H), 7 .33(d,J=8.3Hz,1H,Ar-H),7.26(s,1H,Py-H),4.47(s,2H,CH2),4.06(s,3H,OCH3),3.98(s,3H,OCH3). 13 CNMR (100MHz, CDCl3, δppm): δ164.85,164.63,164.35,148.33,135.84,132.93,1 32.49,131.07,130.76,128.57,113.22,108.05,84.36,53.92,35.41.HRMS(ESI)C 16 H 15 FN3O5S[M+H] + :calcd.380.0723,found 380.0722.

[0064] Example 6

[0065] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((2-fluorobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x For 2-F), the specific steps are as follows:

[0066] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of chloroform. Then, 0.567 g of compound F (3 mmol) was added, followed by 0.909 g of triethylamine (9 mmol) as an acid-binding agent. The mixture was heated to 50 °C and stirred for 8 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried again. Compound 7 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The mixture was heated to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.820 g. The yield was calculated to be 78.3%. The synthetic route is as follows:

[0067]

[0068] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0069] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.30 (d, J=5.2Hz, 1H, Py-H), 7.55 (t, J=7.7Hz, 1H, Py-H), 7.43 (d, J=5.1Hz, 1H, Py-H),7.28(d,J=17.0Hz,2H,Ar-H),7.10(t,J=18.4,8.4Hz,2H,Ar-H),4.56(s,2H,CH2),3.98(s,3H,OCH3). 13 C NMR (100MHz, CDCl3, δppm): 13 C NMR(151MHz,Chloroform-d)δ165.15,164.85,164.23,148.27,133.05,131.46,13 0.29,124.39,122.89,115.77,115.63,113.24,108.01,83.90,30.13.HRMS(ESI)C 15 H 13 FN3O4S[M+H] + :calcd.350.3808,found 350.3806.

[0070] Example 7

[0071] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((3,5-difluorobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x For 3,5-F), the specific steps are as follows:

[0072] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of dimethyl sulfoxide. Then, 0.621 g of compound G (3 mmol) was added, followed by 0.8 g of potassium bicarbonate (8 mmol) as an acid-binding agent. The mixture was heated to 60 °C and stirred for 5 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried again. Compound 8 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The mixture was heated to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.882 g. The yield was calculated to be 80.1%. The synthetic route is as follows:

[0073]

[0074] The target compound in this embodiment was characterized by melting point NMR and high-resolution mass spectrometry, and the results are as follows:

[0075] White solid 1 H NMR (400MHz, CDCl3, δppm): 8.30 (d, J=5.6Hz, 1H, Py-H), 7.54 (s, 1H, Ar-H), 7.43 (s, 1H, Ar -H),7.26(s,1H,Ar-H),6.85(d,J=8.3Hz,2H,Py-H),4.52(s,2H,CH2),3.98(s,3H,OCH3). 13 C NMR (100MHz, CDCl3, δppm): δ164.97,164.85,164.30,162.11,160.26,148.30,13 2.98,132.37,118.99,113.21,111.68,108.02,104.08,83.90,29.56.HRMS(ESI)C 15 H 12 F2N3O4S[M+H] + :calcd.368.0613,found 368.0612

[0076] Example 8

[0077] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((2-chloro-5-bromobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (2-Cl-5-Br), the specific steps are as follows:

[0078] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of chloroform. Then, 0.852 g of compound H (3 mmol) was added, followed by 0.69 g of potassium carbonate (5 mmol) as an acid-binding agent. The mixture was heated to 60 °C and stirred for 4 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried again. Compound 9 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The temperature was raised to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 1.08 g. The yield was calculated to be 81.0%. The synthetic route is as follows:

[0079]

[0080] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0081] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.31 (d, J=5.4Hz, 1H, Py-H), 7.58 (d, J=2.0Hz, 1H, Py-H), 7.54 (d, J=8.2Hz, 1H, Ar-H), 7.41-7.42(m,1H,Ar-H),7.36-7.37(m,1H,Ar-H),7.26(d,J=4.2Hz,1H,Py-H),4.58(s,2H,CH2),3.98(s,3H,OCH3). 13 C NMR (100MHz, CDCl3) δ165.02,164.84,164.34,148.31,135.28,132.96,132.68,132.46,130.37,122.72,113.20,108.02,83.91,33.99.HRMS(ESI)C 15 H 12 BrClN3O4S[M+H] + :calcd.443.7817,found443.7817.

[0082] Example 9

[0083] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((2-cyano-4-chlorobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (2-CN-4-Cl), the specific steps are as follows:

[0084] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of N,N-dimethylformamide. After dissolution, 0.692 g of compound I (3 mmol) was added, followed by 0.90 g of potassium bicarbonate (9 mmol) as an acid-binding agent. The mixture was heated to 50 °C and stirred for 8 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. After drying, compound 10 was dissolved in DMF (5 mL). Sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The temperature was raised to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 0.941 g. The yield was calculated to be 80.4%. The synthetic route is as follows:

[0085]

[0086] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0087] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.30 (d, J=5.2Hz, 1H, Py-H), 7.61 (d, J=8.3Hz, 1H, Py-H), 7.42 (d, J=4 .2Hz,2H,Ar-H),7.25(s,1H,Ar-H),7.20-7.22(m,1H,Py-H),4.59(s,2H,CH2),3.98(s,3H,OCH3). 13 C NMR (100MHz, CDCl3) δ165.03,164.83,164.32,148.30,135.09,135.00,132.95,13 2.40,132.17,129.68,127.43,116.90,113.20,108.00,83.90,33.92.HRMS(ESI)C 16 H 12 ClN4O4S[M+H] + :calcd.391.8026,found 390.8025.

[0088] Example 10

[0089] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-((3-nitro-4-bromobenzyl)sulfone)-1,3,4-oxadiazole (wherein, R... x (3-NO2-4-Br), the specific steps are as follows:

[0090] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of chloroform. Then, 0.885 g of compound J (3 mmol) was added, followed by 0.954 g of sodium carbonate (9 mmol) as an acid-binding agent. The mixture was heated to 60 °C and stirred for 5 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The mixture was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The mixture was dried again. Compound 11 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The temperature was raised to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water. The solid precipitated, filtered, washed with water, dried, and weighed 1.13 g. The yield was calculated to be 82.7%. The synthetic route is as follows:

[0091]

[0092] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0093] White solid 1 H NMR (400MHz, CDCl3, δppm): δ8.37(s,1H,Ar-H),8.31(d,J=4.4Hz1H,Ar-H),8.17(d,J=5.6Hz,1H,Py-H),7.87(d,J =5.2Hz,1H,Ar-H),7.43(d,J=3.6Hz,1H,Py-H),7.26(d,J=4.4Hz,1H,Py-H),4.61(s,2H,CH2),3.99(s,3H,OCH3). 13 C NMR (100MHz, CDCl3) δ164.84,164.45,164.40,148.46,148.34,137.89,135.3 5,132.85,129.80,124.07,123.22,113.20,108.05,83.93,35.61.HRMS(ESI)C 15 H 12 BrN4O4S[M+H]+ :calcd.456.2653,found456.2655

[0094] Example 11

[0095] This embodiment prepares a pyridine oxazole sulfone compound: 2-(2-methoxypyridin-4-yl)-5-(benzyl sulfone)-1,3,4-oxadiazole (wherein, R... x For H), the specific steps are as follows:

[0096] 0.627 g (3 mmol) of compound 1 was dissolved in 20 mL of dimethyl sulfoxide. After dissolution, 0.513 g of compound K (3 mmol) was added, followed by 0.900 g of potassium bicarbonate (9 mmol) as an acid-binding agent. The mixture was heated to 60 °C and stirred for 4 h. The reaction progress was monitored by thin-layer chromatography. After the reaction was complete, dichloromethane (2 x 50 mL) was added, and the mixture was washed three times with brine. The solution was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. Compound 12 was dissolved in DMF (5 mL), and sodium tungstate (0.3 mmol, 88 mg) was added as a catalyst. The temperature was raised to 45 °C, and 30% hydrogen peroxide (5 mL) solution was slowly added dropwise. After the addition was complete, the temperature was raised to 65 °C. TLC monitoring was continued until the starting material spot disappeared. The mixture was cooled to room temperature and poured into ice water, where a solid precipitated. The solid was filtered, washed with water, dried, and weighed to 0.761 g. The yield was calculated to be 76.6%. The synthetic route is as follows:

[0097]

[0098] The target compound in this embodiment was characterized by NMR and high-resolution mass spectrometry, and the results are as follows:

[0099] Orange solid, 1 H NMR (400MHz, CDCl3, δppm): δ8.30 (d, J=3.6Hz, 1H, Py-H), 7.46 (d, 2H, J=5.2Hz, Ar-H), 7.43 (d, 1H, J=3.2Hz,Py-H),7.302-7.354(m,3H,Ar-H),7.26(s,H,Py-H),4.53(s,2H,CH2),3.98(s,3H,OCH3). 13 C NMR (100MHz, CDCl3) δ165.31,164.82,164.07,148.26,135.34,133.08,129.18,128.87,128.24,113.24,107.99,83.89,36.82.HRMS(ESI)C 15 H 14 N3O4S[M+H] +:calcd.332.0802,found 332.0802

[0100] Example 12 Indoor Biometrics

[0101] The toxicity of the pyridine oxazole sulfone compounds prepared in Examples 1 to 11 was determined by foliar spraying (NY / T 1155.4-2006) in the laboratory.

[0102] Test reagents: (a) Example 1; (b) Example 2; (c) Example 3; (d) Example 4; (e) Example 5; (f) Example 6; (g) Example 7; (h) Example 8; (i) Example 9; (j) Example 10; (k) Example 11; (l) Water control.

[0103] Test materials: barnyard grass, amaranth retroflexus

[0104] After soaking and germinating barnyard grass and amaranth retroflexus seeds, they were sown in soil covering a cross-sectional area of ​​0.25m². 2 Sow 20 seeds per plastic pot and cultivate them in a greenhouse until they reach the 2-leaf stage before treatment. Apply the pesticide solution using a handheld compressor sprayer (3NY-1.2) according to the designed dosage concentration gradient (15 g / ha, 30 g / ha, 45 g / ha, 60 g / ha, 75 g / ha, 90 g / ha), with a spray volume of 50 mL per treatment. Keep the soil moist after application. Each treatment is repeated 4 times. 20 days after application, weigh the fresh weight of the aboveground parts of each treatment and calculate the fresh weight control efficacy (%) using the following formula:

[0105] E = 100 × (CT) / C

[0106] In the formula, E represents the fresh weight efficacy; C represents the fresh weight of the control aboveground parts; and T represents the fresh weight of the treated aboveground parts.

[0107] The test results are shown in Tables 1 and 2.

[0108] Table 1. Results of indoor toxicity assays of pyridine oxazole sulfone compounds against barnyardgrass.

[0109]

[0110]

[0111] Table 2. Results of indoor toxicity assays of pyridine oxazole sulfone compounds to Amaranthus retroflexus.

[0112]

[0113] As can be seen from Tables 1 and 2, the EC values ​​of the pyridine oxazole sulfone compounds obtained in Examples 1 to 11 are... 90The values ​​were all below 90 g / ha and below 6 g / mu, indicating that the pyridine oxazole sulfone compounds obtained in Examples 1-11 have good herbicidal activity against monocotyledonous weeds barnyardgrass and dicotyledonous reverse branch amaranth.

[0114] Example 13 Bee Safety Test

[0115] The pyridine oxazole sulfone compounds prepared in Examples 1-11 were subjected to crop safety tests using the foliar spray method.

[0116] Test reagents: (a) Example 1; (b) Example 2; (c) Example 3; (d) Example 4; (e) Example 5; (f) Example 6; (g) Example 7; (h) Example 8; (i) Example 9; (j) Example 10; (k) Example 11; (l) Sugar water control.

[0117] Test material: Italian honeybee.

[0118] Healthy and uniformly weighted Italian honeybees, typically worker bees, were selected. Test substances: Reagents a-l were prepared as a 40,000 ppm stock solution using acetone, and then diluted with 50% sucrose solution to six concentrations: 50, 100, 200, 400, 800, and 1600 ppm. The bees' responses were assessed by feeding them sugar solutions containing different concentrations of the test substances. Typically, 20 worker bees were placed in a feeding cage, and the experiment was repeated three times. The medicated sugar solution was provided as the sole food source, and each concentration was repeated three times. The number of deaths was observed after a period of time (72 hours). Temperature, humidity, and light should be kept stable (e.g., 25℃ ± 2℃, relative humidity 50%-70%). Other environmental stressors or sources of pollution should be avoided to prevent interference with the bees. The experimental results were analyzed using Probit analysis to calculate the dose that would kill half of the bees. The results showed the LD50 of Examples 2, 4, 6, 8, and 10 on the Chinese honeybee. 50 The concentration of the median lethal dose (the dose that would kill half of the bees) was greater than 800 ppm, and the rest were all greater than 200 ppm (greater than 200 ppm is considered low toxicity for bees). The tested compounds were all low toxicity to non-target bees.

[0119] Example 14 Field Trial

[0120] The pyridine oxazole sulfone compounds prepared in Examples 1, 3, 5, 7, and 11 were applied to control annual and perennial weeds in cornfields. For Examples 1, 3, 5, 7, and 11, the compounds were diluted with water at a concentration of 75 g / ha and sprayed. Seven days after application, the control efficacy against total weeds was 93.23%, 94.12%, 95.18%, and 97.01%, respectively, and the control efficacy against fresh weight was 95.17%, 96.45%, 96.27%, and 97.55%. Therefore, the pyridine oxazole sulfone compounds provided by this invention have a significant effect on controlling annual and perennial weeds in cornfields, further broadening the weed control spectrum. They not only have the potential to be developed into herbicides but also possess the advantages of low cost and environmental friendliness.

[0121] The above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Although the invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the invention do not depart from the spirit and scope of the invention and should be covered within the scope of the claims of the invention.

Claims

1. A pyridine oxazole sulfone compound, characterized in that, Its general structural formula is shown in Formula I: Wherein, RX is any one or more of -H, -CH3, -OCH3, -NO2, -Br, -Cl, -F, and -CN.

2. The pyridine oxazole sulfone compound according to claim 1, characterized in that, The pyridine oxazole sulfone compounds have structural formulas as shown in any one of formulas II to XII: Formula II Formula III Formula IV Formula V Formula VI Formula VII Formula VIII Formula IX Formula X Formula XI Formula XII.

3. A method for preparing a pyridine oxazole sulfone compound as described in claim 1, characterized in that, Includes the following steps: S1. Dissolve compound 1 in a solvent, add compound X and an acid-binding agent, heat and stir to react, then extract, wash, dry, filter and rotary evaporate to obtain compound 2; S2. Dissolve compound 2 in an organic solvent, add a catalyst and heat, then add hydrogen peroxide solution dropwise. After the addition is complete, continue to heat the reaction until the preset conditions are reached. Cool to precipitate solid, filter, wash with water and dry to obtain the pyridine oxazole sulfone compound. Its synthetic route is as follows: ； In step S1, the general structural formula of compound X is: ； Wherein, RX is any one or more of -H, -CH3, -OCH3, -NO2, -Br, -Cl, -F, and -CN.

4. The preparation method according to claim 3, characterized in that, In step S1, the molar ratio of compound X to compound 1 is 1:

1.

5. The preparation method according to claim 3, characterized in that, In step S1, the molar ratio of compound 1 to the acid-binding agent is 1:(1~3); the solvent is at least one of N,N-didimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, tetrahydrofuran, and chloroform; and the acid-binding agent is at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, and triethylamine.

6. The preparation method according to claim 3, characterized in that, The reaction conditions for the heating and stirring reaction are as follows: stirring rate of 500-600 rpm; heating temperature of 50-60℃; reaction time of 4-8 h; and thin-layer chromatography monitoring of the reaction process.

7. The preparation method according to claim 5, characterized in that, After the heating and stirring reaction was completed, the mixture was extracted with dichloromethane, washed several times with brine, dried with magnesium sulfate, filtered, and the solvent was rotary evaporated to obtain compound 2.

8. The preparation method according to claim 3, characterized in that, Step S2 is as follows: Compound 2 is dissolved in DMF, sodium tungstate is added as a catalyst, the temperature is raised to 45-45°C, and then 30% hydrogen peroxide solution is added dropwise at a preset rate. Finally, the temperature is raised to 60-65°C, and the reaction is monitored by thin-layer chromatography until the starting material spot disappears. The mixture is cooled to room temperature, and then poured into ice water to precipitate the solid. The solid is filtered, washed several times with deionized water, and dried to obtain the pyridine oxazole sulfone compound. The amount of sodium tungstate used is 10% to 20% of compound 1; the amount of 30% hydrogen peroxide solution used is 10 to 20 times that of compound 1.

9. The application of a pyridine oxazole sulfone compound as described in any one of claims 1 or 2, or a pyridine oxazole sulfone compound prepared by any one of claims 3 to 8, as a herbicidal active substance in suppressing weeds in farmland.

10. The application according to claim 9, characterized in that, The farmland weeds include annual weeds and perennial weeds.

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