A N-(substituted phenyl)thiazolephenoxyacetamide compound and its preparation method and application

Abstract

The present invention discloses an N-(substituted phenyl)thiazolephenoxyacetamide compound, its preparation method, and application. The compound has a general structural formula as shown in Formula I: #imgabs0# In Formula I, R1 is a substituted benzene ring, wherein the substituent is selected from any one or two of the following: -OCH3, -NO2, and -COOCH3; R2 is a phenyl group or a substituted benzene ring. When R2 is a substituted benzene ring, the substituent is selected from any one or two of the following: -CH3, -C2H5, -OCH3, -NO2, -Br, -Cl, and -F. The compound has excellent herbicidal activity, particularly effective in controlling annual and perennial weeds in soybean fields. Fifteen days after application, the total weed control efficiency is as high as 90.79% and the fresh weight control efficiency is as high as 95.67%. It is also safe and harmless to soybeans.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and pesticides, and particularly relates to an N-(substituted phenyl)thiazolephenoxyacetamide compound and a preparation method and application thereof. Background Art

[0002] Weeds in my country's farmlands cause direct economic losses exceeding 120 billion yuan annually. Chemical weed control, the primary method of weed control, is effective and time-saving. Herbicides are chemical agents that kill weeds completely or selectively, eliminating or inhibiting plant growth. However, the widespread use of chemical agents has also led to a series of problems. The evolution of weed resistance under herbicide selection pressure is a major challenge that needs to be addressed in weed control. Globally, 1,581 weed biotypes have developed resistance to 167 herbicides. Factors such as the emergence of herbicide-resistant weed plants, environmental pollution caused by herbicide residues, and harm to non-weed organisms hinder farmland weed control. The development of new herbicides with high efficiency and low toxicity is imminent, and heterocyclic compounds have shown excellent effects in the development of pesticides, ushering pesticides into a new era of ultra-high efficiency. Among them, 1,3,4-thiadiazole and substituents in heterocyclic compounds are important physiologically active substances. They have antibacterial, antiviral, insecticidal, weed control and plant growth regulating activities in agriculture, and are a hot topic in green pesticide research. Summary of the Invention

[0003] The present invention aims to provide an N-(substituted phenyl)thiazolephenoxyacetamide compound with excellent control effect, low herbicide dosage, low cost, simple synthesis and environmental protection, as well as a preparation method and application.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] In the first aspect, the general structural formula of the N-(substituted phenyl)thiazolephenoxyacetamide compound provided by the present invention is shown in Formula I:

[0006]

[0007] In Formula I, R1 is a benzene ring containing a substituent; R2 is a phenyl group or a benzene ring containing a substituent.

[0008] Said R1 is a benzene ring containing a substituent, wherein the substituent is selected from any one or any two of the following: -OCH3, -NO2 and -COOCH3;

[0009] The R2 is a phenyl group or a substituted benzene ring. When R2 is a substituted benzene ring, the substituent is selected from any one or any two of the following: -CH3, -C2H5, -OCH3, -NO2, -Br, -Cl and -F.

[0010] The R1 is a benzene ring containing a substituent, and the substituent is selected from any one of the following: 3,5-OCH3, 2-OCH3-5-COOCH3, 4-OCH3, 3,4-COOCH3, 2-COOCH3-4-NO2, 3,5-NO2, 2-NO2, 3-OCH3-5-NO2;

[0011] R2 is a phenyl group or a substituted benzene ring. When R2 is a substituted benzene ring, the substituent is selected from any one of the following: 4-Cl, 2-F, 3-Br-4-Cl, 3-NO2, 3,4-CH3, 3-Cl-4-C2H5, 2-F-4-OCH3;

[0012] The R1 is any one of the following: 3,5-dimethoxyphenyl, 2-methoxy-5-methylformylphenyl, 4-methoxyphenyl, 3,4-dimethyldiformylphenyl, 4-nitro-2-methylformylphenyl, 3,5-dinitrophenyl, 2-nitrophenyl, 3-methoxy-5-nitrophenyl; the R2 is any one of the following: phenyl, 4-chlorophenyl, 2-fluorophenyl, 3-bromo-4-chlorophenyl, 3-nitrophenyl, 3,4-dimethylphenyl, 3-chloro-4-ethylphenyl, 2-fluoro-4-methoxyphenyl.

[0013] In a second aspect, the present invention provides a method for preparing the compound according to the first aspect, comprising the following steps:

[0014] 1) Compound 1 was reacted with thiosemicarbazide in solvent A, stirred and refluxed. After the reaction, the reaction solution was cooled to room temperature and poured into ice water. The pH was adjusted to 8-9, allowed to stand, filtered, washed with water, and dried to obtain compound 3;

[0015] 2) Compound 3 and Compound 4 were dissolved in solvent B, and then an acid-binding agent was added. The reaction was stirred and the reaction progress was monitored until the reaction was completed. The reaction solution was then poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized to obtain the compound;

[0016] Its synthetic route is as follows:

[0017]

[0018] In step 1), the molar ratio of compound 1 to thiosemicarbazide is 1:(1-2), preferably 1:1.5.

[0019] In step 1), the solvent A is a mixed solvent of 1,4-dioxane and phosphorus oxychloride, wherein the volume ratio of 1,4-dioxane to phosphorus oxychloride is 1:(3-6), preferably 1:(4-5).

[0020] In step 1), the stirring and refluxing process has a reflux temperature of 105 to 110° C. and a reflux time of 2 to 6 hours, preferably 4 to 5 hours.

[0021] In step 1), the stirring reflux has a stirring rate of 500 to 600 rpm.

[0022] In step 2), the molar ratio of compound 3 to compound 4 is 1:(1-3), preferably 1:2.

[0023] In step 2), the solvent B is tetrahydrofuran.

[0024] In step 2), the acid binding agent is any one of potassium carbonate, sodium carbonate, triethylamine, potassium bicarbonate and sodium bicarbonate.

[0025] In step 2), the molar ratio of compound 3 to the acid-binding agent is 1:2; the reaction progress is monitored by thin layer chromatography (TLC).

[0026] In step 2), the stirring reaction is carried out at room temperature.

[0027] In step 2), the stirring reaction has a stirring rate of 500 to 600 rpm.

[0028] In the step 2), recrystallization is performed using DMF / methanol.

[0029] In a third aspect, the present invention provides the use of the N-(substituted phenyl)thiazolephenoxyacetamide compound as a herbicidal active substance in inhibiting weeds in soybean fields.

[0030] The weeds are mainly annual and perennial weeds.

[0031] In a fourth aspect, the present invention provides a herbicide, the active ingredient of which is the compound.

[0032] Beneficial effects of the present invention:

[0033] The N-(substituted phenyl)thiazolephenoxyacetamide compounds provided by the present invention have excellent herbicidal activity, especially effective against annual and perennial weeds in soybean fields. Fifteen days after application, the total weed control efficiency reached 90.79% per plant and 95.67% per fresh weight. They are also safe and harmless to soybeans. These compounds can also effectively reduce herbicide usage and costs, minimize residues, and mitigate the potential environmental threat posed by pesticides. Furthermore, their simple and economical synthesis method makes them suitable as lead compounds, providing a new area for the development of safe, efficient, and environmentally friendly new herbicides. DETAILED DESCRIPTION

[0034] The following embodiments of the present invention are described in further detail with reference to specific examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0035] Unless otherwise specified, the materials and reagents used in the following examples can be purchased from commercial sources.

[0036] Example 1

[0037] Compound a (i.e., N-(5-(3,5-dimethoxyphenyl)-1,3,4-thiazol-2-yl)-4-chlorophenoxyacetamide), i.e., the compound represented by formula I provided by the present invention, was prepared by the following method, wherein R1 is 3,5-dimethoxyphenyl and R2 is 4-chlorophenyl.

[0038] The specific steps are as follows:

[0039] 1.82 g (10 mmol) of 3,5-dimethoxybenzoic acid and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 40 mL of phosphorus oxychloride was added. The mixture was refluxed at 105°C for 5 h, cooled to room temperature, and poured into ice water. The pH was adjusted to 8-9, allowed to stand, filtered, washed with water, and dried to obtain 5-(3,5-dimethoxyphenyl)-1,3,4-thiazol-2-amine, weighing 2.01 g. The yield was calculated to be 84.8%.

[0040] 0.71 g (3 mmol) of 5-(3,5-dimethoxyphenyl)-1,3,4-thiazol-2-amine and 0.68 g (3.3 mmol) of 4-chlorophenoxyacetyl chloride were dissolved in 20 mL of tetrahydrofuran, and 0.61 g (6 mmol) of triethylamine was added. The reaction was allowed to react at room temperature. The reaction progress was monitored by thin-layer chromatography until the reaction was completed. The reaction solution was then poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a white solid, i.e., compound a, weighing 0.81 g. The yield was calculated to be 66.4%.

[0041] Its synthetic route is:

[0042]

[0043] The melting point test and NMR characterization of compound a prepared in this example were performed, and the results were as follows:

[0044] Melting point: 171.5~173.2℃, 1H NMR (400MHz, DMSO-d6, δppm): δ: 12.98 (s, 1H, NH), 7.36 ~ 7.37 (d, 1H, J = 4Hz, Ar-H), 7.35 ~ 7.36 (d, 1H, J = 1.2Hz, Ar-H), 7.06 (d, 2H, J = 1.6Hz, A r-H),7.04(d,1H,J=1.2Hz,Ar-H),7.02~7.03(d,1H,J=1.6Hz,Ar-H),6.65~6.66(t,1H,J=3.2Hz,Ar-H),4.96(s,2H,CH2),3.83(s,6H,OCH3). 13 C NMR (100 MHz, DMSO-d6, δ ppm): δ: 167.57, 162.51, 161.42, 158.47, 157.04, 132.25, 129.74, 125.52, 116.96, 105.24, 103.22, 66.83, 56.00 (the structure is symmetrical, and only one group of carbon atom peaks is shown). HRMS (ESI) C 18 H 16 ClN3O4S, [M+H] + :calcd.406.0623,found406.0625.

[0045] Example 2

[0046] Compound b (i.e., N-(5-(2-methoxy-5-benzoic acid methyl ester)-1,3,4-thiazol-2-yl)-2-fluorophenoxyacetamide), i.e., the compound represented by formula I provided by the present invention, was prepared by the following method, wherein R1 is 2-methoxy-5-methylformylphenyl and R2 is 2-fluorophenyl.

[0047] The specific steps are as follows:

[0048] 2.1 g (10 mmol) of 2-methoxy-5-methylbenzoate and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 15 mL of 1,4-dioxane, and 50 mL of phosphorus oxychloride was added. After stirring and reflux at 105°C for 5 h, the reaction solution was cooled to room temperature and then poured into ice water. The pH was adjusted to 8-9. The reaction mixture was allowed to stand, filtered, washed with water, and dried to obtain 5-(2-methoxy-5-methylbenzoate)-1,3,4-thiazol-2-amine, weighing 2.31 g. The yield was calculated to be 87.1%.

[0049] 0.80 g (3 mmol) of 5-(2-methoxy-5-benzoic acid methyl ester)-1,3,4-thiazol-2-amine and 0.62 g (3.3 mmol) of 2-(4-fluorophenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran, and 0.84 g (6 mmol) of potassium carbonate as an acid-binding agent was added. The reaction was allowed to react at room temperature. The reaction progress was monitored by thin-layer chromatography until the reaction was completed. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a white solid, i.e., compound b, weighing 0.93 g. The yield was calculated to be 74.3%.

[0050] Its synthetic route is:

[0051]

[0052] The melting point test and NMR characterization of compound b prepared in this example were performed, and the results were as follows:

[0053] Melting point: 211.5~213.2℃, 1 H NMR (400MHz, DMSO-d6, δppm): 13.03 (s, 1H, NH), 8.74 (s, 1H, Ar-H), 8.12 (d, J = 3.2Hz, 1H, Ar-H), 7.65 (d, J = 3.2 Hz,1H,Ar-H),7.26(m,2H,Ar-H),7.11(m,2H,Ar-H),5.05(s,2H,CH2),3.93(s,3H,COOCH3),3.83(s,3H,OCH3). 13 C NMR (100 MHz, DMSO-d6, δ ppm): 173.11, 162.39, 161.40, 152.95, 151.33, 146.20, 146.13, 132.28, 125.22, 125.19, 122.38, 122.33, 116.77, 116.65, 115.71, 105.19, 104.71, 103.18, 67.25, 55.99, 52.53 (the fluorine atoms on the benzene ring can split the nearby carbon atoms, and the carbon atom peak is more than the theoretical value). HRMS (ESI) C 19 H 16 FN3O5S, [M+H] + :calcd.418.0919,found 418.0919.

[0054] Example 3

[0055] Compound C (i.e., N-(5-(4-methoxyphenyl)-1,3,4-thiazol-2-yl)-3-bromo-4-chlorophenoxyacetamide), which is the compound of formula I provided by the present invention, was prepared by the following method, wherein R1 is 4-methoxyphenyl and R2 is 3-bromo-4-chlorophenyl.

[0056] 1.52 g (10 mmol) of 4-methoxybenzoic acid and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 60 mL of phosphorus oxychloride was added. The mixture was stirred and refluxed at 105° C. for 6 h. The mixture was cooled to room temperature, and the reaction solution was poured into ice water. The pH was adjusted to 8-9. The mixture was allowed to stand, filtered, washed with water, and dried to obtain 5-(4-methoxyphenyl)-1,3,4-thiazol-2-amine, weighing 1.78 g. The yield was calculated to be 85.9%.

[0057] 0.62 g (3 mmol) of 5-(4-methoxyphenyl)-1,3,4-thiazol-2-amine and 0.86 g (3.3 mmol) of 2-(3-bromo-4-chlorophenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran, and 0.60 g (6 mmol) of potassium bicarbonate, an acid-binding agent, was added. The reaction was allowed to react at room temperature. The reaction progress was monitored by thin-layer chromatography until completion. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a white solid, i.e., Compound C, weighing 1.04 g. The yield was calculated to be 76.4%.

[0058] Its synthetic route is:

[0059]

[0060] Melting point: 204.1-206.6℃, 1 H NMR (400MHz, DMSO-d6, δppm): 12.97 (s, 1H, NH), 7.87 (d, 2H, J = 6Hz, Ar-H), 7.35 (d, 1H, J = 1.6Hz, Ar-H),, 7.25 ( d,1H,J=5.6Hz,Ar-H),7.06(d,2H,J=6Hz,Ar-H),6.98~6.99(m,1H,Ar-H),6.65(s,2H,CH2),5.02(s,3H,OCH3). 13 C NMR (100MHz, DMSO-d6, δppm): δ: 161.42, 161.25, 158.30, 134.59, 134.04, 133.23, 132. 24,117.47,116.37,113.16,105.23,104.73,103.23,101.96,67.00,55.89.HRMS(ESI)C 17H 13 BrClN3O3S,[M+H]+:calcd.455.9728,found 455.9728.

[0061] Example 4

[0062] Compound d (i.e., N-(5-(3,4-dimethyl phthalate)-1,3,4-thiazol-2-yl)-3-nitrophenoxyacetamide, i.e., the compound represented by formula I provided by the present invention) was prepared by the following method, wherein R1 is 3,4-dimethyl dicarboxylate phenyl and R2 is 3-nitrophenyl.

[0063] The specific steps are as follows:

[0064] 2.38 g (10 mmol) of dimethyl 3,4-dicarboxylate benzoic acid and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 50 mL of phosphorus oxychloride was added. The mixture was stirred and refluxed at 105°C for 5 h. The mixture was cooled to room temperature, and the reaction solution was poured into ice water. The pH was adjusted to 8-9. The mixture was allowed to stand, filtered, washed with water, and dried to obtain 5-(dimethyl 3,4-phthalate)-1,3,4-thiazole-2-amine, weighing 2.56 g. The yield was calculated to be 87.4%.

[0065] 0.88 g (3 mmol) of 5-(3,4-dimethyl phthalate)-1,3,4-thiazol-2-amine and 0.71 g (3.3 mmol) of 2-(3-nitrophenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran. 0.64 g (6 mmol) of sodium carbonate (acid binder) was added and the reaction was allowed to proceed at room temperature. The reaction progress was monitored by thin-layer chromatography until completion. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a light yellow solid, namely compound d, weighing 1.14 g, with a calculated yield of 80.3%. The synthetic route is as follows:

[0066]

[0067] The melting point test and NMR characterization of compound d prepared in this example were performed, and the results were as follows:

[0068] Melting point: 261.3-262.5℃; 1H NMR (400MHz, DMSO-d6, δppm): 12.98 (s, 1H, NH), 8.83 (d, J=1.6Hz, 1H, Ar-H), 8.56 (d, 1H, J=5.6Hz, Ar-H), 8.48 (d, 2H, J=5.6Hz, Ar-H), 8.11 (d, 1H, J=5.6Hz, Ar-H), 7.70 (d, 2H, J=6.0Hz, Ar-H), 5.11 (s, 2H, CH2), 3.93 (s, 6H, OCH3). 13 C NMR(100MHz,DMSO-d6,δppm):167.49,164.14,162.53,161.42,159.65,159.58,158.49,132.26,131.26,1 31.20,111.37,111.35,108.54,108.40,105.23,103.23,103.03,102.86,66.82,56.00,52.64.HRMS(ESI)C 20 H 16 N4O8S,[M+H]+:calcd.473.4219,found 473.4219.

[0069] Example 5

[0070] Compound e (i.e., N-(5-(4-nitro-2-benzoic acid methyl ester)-1,3,4-thiazol-2-yl)-3,4-dimethylphenoxyacetamide), i.e., the compound represented by formula I provided by the present invention, was prepared by the following method, wherein R1 is 4-nitro-2-methylformate phenyl and R2 is 3,4-dimethylphenyl.

[0071] The specific steps are as follows:

[0072] 2.25 g (10 mmol) of methyl 4-nitro-2-benzoate and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 45 mL of phosphorus oxychloride was added. The mixture was stirred and refluxed at 105° C. for 4 h. After cooling to room temperature, the reaction solution was poured into ice water and the pH was adjusted to 8-9. The reaction mixture was allowed to stand, filtered, washed with water, and dried to obtain 5-(methyl 4-nitro-2-benzoate)-1,3,4-thiazole-2-amine, weighing 2.26 g. The yield was calculated to be 80.7%.

[0073] 0.84 g (3 mmol) of 5-(4-nitro-2-benzoic acid methyl ester)-1,3,4-thiazol-2-amine and 0.65 g (3.3 mmol) of 2-(3,4-dimethylphenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran, and 0.59 g (6 mmol) of sodium bicarbonate, an acid-binding agent, was added. The reaction was allowed to react at room temperature. The reaction progress was monitored by thin-layer chromatography until the reaction was completed. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a light yellow solid, i.e., compound e, weighing 1.02 g. The yield was calculated to be 76.7%.

[0074] Its synthetic route is:

[0075]

[0076] The melting point test and NMR characterization of compound e prepared in this example were performed, and the results were as follows:

[0077] Melting point: 251.3~253.9℃; 1 H NMR (400MHz, DMSO-d6, δppm): 12.90 (s, 1H, NH), 8.66 (d, 1H, J = 1.2Hz, Ar-H), 8.54 (d, 1H, J = 5.6Hz, Ar-H), 8.01 (d, 1H, J = 5.6Hz, Ar-H), 7.21 (d, 1H, J=6.8Hz,Ar-H),7.13(d,1H,J=6.8Hz,Ar-H),6.95(d,1H,J=1.6Hz,Ar-H),4.88(s,2H,CH2),3.83(s,3H,OCH3),2.19(s,3H,CH3),2.14(s,3H,CH3). 13 C NMR (100MHz, DMSO-d6, δppm): δ:167.99,166.45,161.42,158.50,156.25,137.83,132.28, 130.64,129.35,116.56,111.92,105.24,103.19,66.68,56.00,20.09,18.88.HRMS(ESI)C 20 H 18 N4O6S, [M+H] + :calcd.443.4215found 443.4212.Example 6

[0078] Compound f (i.e., N-(5-(3,5-dinitrophenyl)-1,3,4-thiazol-2-yl)-phenoxyacetamide), i.e., the compound represented by formula I provided by the present invention, was prepared by the following method, wherein R1 is 3,5-dinitrophenyl and R2 is phenyl.

[0079] The specific steps are as follows:

[0080] 2.12 g (10 mmol) of 3,5-dinitrobenzoic acid and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 55 mL of phosphorus oxychloride was added. The mixture was stirred and refluxed at 105°C for 5 h. After cooling to room temperature, the reaction solution was poured into ice water and the pH was adjusted to 8-9. The reaction mixture was allowed to stand, filtered, washed with water, and dried to obtain 5-(3,5-dinitrobenzene)-1,3,4-thiazole-2-amine, weighing 2.24 g. The yield was calculated to be 83.9%.

[0081] 0.70 g (3 mmol) of 5-(3,5-dinitrobenzene)-1,3,4-thiazol-2-amine and 0.65 g (3.3 mmol) of 2-(phenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran. 0.61 g (6 mmol) of triethylamine (acid binder) was added and the reaction was allowed to proceed at room temperature. The reaction progress was monitored by thin-layer chromatography until completion. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a yellow solid, namely compound f, weighing 0.95 g, with a calculated yield of 79.1%. The synthetic route is as follows:

[0082]

[0083] The melting point test and NMR characterization of compound f prepared in this example were performed, and the results were as follows:

[0084] Melting point: 222.3~224.1℃; 1 H NMR (400MHz, DMSO-d6, δppm): 13.22 (s, 1H, NH), 9.03 (d, J = 1.2Hz, 2H, Ar-H), 8.90 (d, J =1.6Hz,1H,Ar-H),7.31-7.34(m,2H,Ar-H),6.98-7.01(m,3H,Ar-H),4.98(s,2H,CH2). 13 C NMR (100MHz, DMSO-d6, δppm):168.27,160.20,158.97,158.08,149.13,133.32,130.02,127.44,127.15,121.85,120.04,115.09,66.61.HRMS(ESI)C 16 H 11 N5O6S, [M+H] + :calcd.402.3508,found 402.3507.

[0085] Example 7

[0086] Compound g (i.e., N-(5-(2-nitrophenyl)-1,3,4-thiazol-2-yl)-3-chloro-4-ethylphenoxyacetamide), which is the compound of formula I provided by the present invention, was prepared by the following method, wherein R1 is 2-nitrophenyl and R2 is 3-chloro-4-ethylphenyl.

[0087] The specific steps are as follows:

[0088] 1.67 g (10 mmol) of 2-nitrobenzoic acid and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 60 mL of phosphorus oxychloride was added. The mixture was stirred and refluxed at 105°C for 5 h. The mixture was cooled to room temperature, and the reaction solution was poured into ice water. The pH was adjusted to 8-9. The reaction mixture was allowed to stand, filtered, washed with water, and dried to obtain 5-(2-nitrophenyl)-1,3,4-thiazol-2-amine, weighing 1.89 g. The yield was calculated to be 85.1%.

[0089] 0.66 g (3 mmol) of 5-(2-nitrophenyl)-1,3,4-thiazol-2-amine and 0.77 g (3.3 mmol) of 2-(3-chloro-4-ethylphenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran. 0.61 g (6 mmol) of triethylamine (acid binder) was added and the reaction was allowed to proceed at room temperature. The reaction progress was monitored by thin-layer chromatography until completion. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a light yellow solid, namely compound g, weighing 1.02 g, with a calculated yield of 76.7%. The synthetic route is as follows:

[0090]

[0091] The melting point test and NMR characterization of compound g prepared in this example were performed, and the results were as follows:

[0092] Melting point: 199.3~201.7℃; 1 H NMR (400MHz, DMSO-d6, δppm): 12.92 (s, 1H, NH), 8.53 (d, J = 5.2Hz, 1H, Ar-H), 8.41 (d, J = 5.6Hz, 1H, Ar-H), 8.13 (m, 2H, Ar-H), 7.61 (d, J=6.0,1H,Ar-H),7.31(d,J=5.6,1H,Ar-H),6.95(d,J=1.6,1H,Ar-H),4.98(s,2H,CH2),2.38(m,2H,CH2),1.52(t,J=5.2Hz,3H,CH3). 13C NMR(100MHz,DMSO-d6,δppm):168.17,161.42,153.66,144.99,140.51,132.2 4,120.76,117.68,110.04,105.22,103.26,68.22,20.12,13.23.HRMS(ESI)C 18 H 15 ClN4O4S,[M+H]+:calcd.418.8571,found 418.8575.

[0093] Example 8

[0094] Compound h (i.e., N-(5-(3-methoxy-5-nitrophenyl)-1,3,4-thiazol-2-yl)-2-fluoro-4-methoxyphenoxyacetamide), i.e., the compound represented by formula I provided by the present invention, was prepared by the following method, wherein R1 is 3-methoxy-5-nitrophenyl and R2 is 2-fluoro-4-methoxyphenyl.

[0095] The specific steps are as follows:

[0096] 1.97 g (10 mmol) of 3-methoxy-5-nitrobenzoic acid and 0.91 g (10 mmol) of thiosemicarbazide were dissolved in 10 mL of 1,4-dioxane, and 60 mL of phosphorus oxychloride was added. The mixture was stirred and refluxed at 105° C. for 4.5 h, cooled to room temperature, and the reaction solution was poured into ice water. The pH was adjusted to 8-9, allowed to stand, filtered, washed with water, and dried to obtain 5-(3-methoxy-5-nitrophenyl)-1,3,4-thiazole-2-amine, weighing 2.10 g. The yield was calculated to be 83.3%.

[0097] 0.76 g (3 mmol) of 5-(3-methoxy-5-nitrophenyl)-1,3,4-thiazol-2-amine and 0.65 g (3.3 mmol) of 2-(2-fluoro-4-methoxyphenoxy)acetyl chloride were dissolved in 25 mL of tetrahydrofuran. 0.61 g (6 mmol) of triethylamine, an acid-binding agent, was added and allowed to react at room temperature. The reaction progress was monitored by thin-layer chromatography until completion. The reaction solution was poured into ice water to precipitate a solid, which was filtered, washed with water, and recrystallized from DMF / methanol to obtain a white solid, namely compound h, weighing 1.02 g, with a calculated yield of 76.7%. The synthetic route is as follows:

[0098]

[0099] The melting point test and NMR characterization of compound h prepared in this example were performed, and the results were as follows:

[0100] Melting point: 239.5~241.3℃; 1H NMR (400MHz, DMSO-d6, δppm): 13.0 (s, 1H, NH), 7.62~7.65 (t, J=5.6Hz, 1H, Ar-H), 7.28~7.32 (m, 2H, Ar-H), 7.16 (s, 1H ,Ar-H),7.00~7.03(t,J=6.4Hz,1H,Ar-H),6.86(s,1H,Ar-H),5.04(s,2H,CH2),3.83(s,3H,OCH3),3.80(s,3H,OCH3). 13 C NMR (100MHz, DMSO-d6, δppm): δ: 167.36, 161.40, 158.46, 155.73, 152.76, 152.68, 151.12, 143.01, 142.92, 141.85,132.24,116.73,111.38,111.20,105.58,105.19,103.41,103.20,67.81,55.98,55.86.HRMS(ESI)C 18 H 15 FN4O6S,[M+H]+:calcd.435.4071,found 435.4075.

[0101] Example 9 Indoor bioassay

[0102] The compounds a to h prepared in Examples 1 to 8 were subjected to indoor toxicity tests using the stem-leaf spray method (NY / T 1155.4-2006).

[0103] 1) Test agents: 8 compounds a-h obtained in Examples 1-8, acetochlor, 2,4-D butyl ester, and water.

[0104] 2) Test materials: Erigeron candidum and lettuce seeds.

[0105] 3) Test method: After soaking and germinating the seeds of Erigeron candidum and lettuce, they were sown in a soil-filled area with a cross-sectional area of 0.25 m 2 Plants were sown in plastic pots, 20 seeds per pot. After incubation in a greenhouse until the two-leaf stage, the plants were treated with 5 mg / L, 10 mg / L, 20 mg / L, 50 mg / L, 80 mg / L, 120 mg / L, 200 mg / L, and 300 mg / L of the eight compounds a-h obtained in Examples 1-8, respectively. Acetochlor and 2,4-D butyl ester and water served as controls. The solution was sprayed with a handheld compression sprayer (3NY-1.2) at a rate of 50 mL per treatment. The soil was kept moist after application. Each treatment was repeated four times. Twenty days after application, the fresh weight of the aboveground portion of each treatment was weighed, and the fresh weight control efficacy (%) for each treatment was calculated according to the following formula:

[0106] E=100×(CT) / C

[0107] Where, E is the fresh weight of the control; C is the fresh weight of the aboveground part of the control; T is the fresh weight of the aboveground part of the treatment.

[0108] The test results are shown in Tables 1 and 2.

[0109] Table 1 Toxicity test results of compounds a-h, acetochlor and 2,4-D butyl ester to Erigeron candidum

[0110]

[0111] As can be seen from Table 1, the EC values of compound a, compound b and compound f are 50 The values were lower than those of the control examples acetochlor (28.77 mg / L) and 2,4-D butyl ester (24.78 mg / L), indicating that compared with compound a and compound b and compound f, acetochlor and 2,4-D butyl ester were more toxic to Erigeron canina and had higher herbicidal activity.

[0112] Table 2 Toxicity test results of compounds a-h, acetochlor and 2,4-D butyl ester to lettuce

[0113]

[0114] As can be seen from Table 2, the EC values of compound b, compound c, compound f and compound h are 50 The values were lower than those of the control example acetochlor (33.08 mg / L). The EC values of compound c and compound f were 50 The values were comparable to those of the control 2,4-D butyl ester (17.41 mg / L), indicating that they had comparable herbicidal activity against lettuce.

[0115] Example 10 Crop Safety Test

[0116] The crop safety test of compounds a, b, c, f and h prepared in the examples was carried out using the stem and leaf spray method.

[0117] 1) Test agents: Compounds a, b, c, f, and h, as well as acetochlor, 2,4-D butyl ester, and water.

[0118] 2) Test material: soybean.

[0119] 3) Test method: Soybean seeds were soaked and germinated, and then sown in a soil-filled area with a cross-sectional area of 0.25m 2Ten seeds were sown per pot in plastic pots. After incubation in the greenhouse until the two-leaf stage, plants were treated with compounds a, b, c, f, and h, respectively, as well as acetochlor and 2,4-D butyl ester as controls. Each treatment was applied at a rate of 50 g of active ingredient per mu (approximately 50 mL) using a handheld compression sprayer (3NY-1.2). The soil was kept moist after application. Each treatment was replicated four times. Twenty days after application, the fresh weight of the aboveground portion of each treatment was weighed, and the fresh weight efficacy (%) of each treatment was calculated using the following formula:

[0120] E=100×(CT) / C

[0121] Where: E is the fresh weight of the control; C is the fresh weight of the aboveground part of the control; T is the fresh weight of the aboveground part of the treatment.

[0122] The test results are shown in Table 3.

[0123] Table 3 Test results of the safety of compounds a, b, c, f and h on soybeans

[0124]

[0125] As can be seen from Table 3, the weight loss ratios of compounds b and f are not much different from that of acetochlor, indicating that the safety of compounds b and f for soybeans is comparable to that of acetochlor; the weight loss ratios of compounds a, b, c, f and h are all lower than that of 2,4-D butyl ester, indicating that compounds a, b, c, f and h are safer for soybeans than 2,4-D butyl ester.

[0126] Example 11 Field test

[0127] Compounds b and f, prepared in Examples 2 and 6, respectively, were applied to soybean fields for controlling annual and perennial weeds. Compounds b and f, diluted and sprayed at 750 g ai / ha, achieved plant-to-plant efficacy of 90.76% and 90.79% against total weeds, and 93.17% and 95.67% against fresh weight weeds, respectively, 15 days after application. A control agent, acetochlor, diluted and sprayed at a concentration of 750 g ai / ha, achieved plant-to-plant efficacy of 81.21% and 83.34%, respectively, against total weeds, 15 days after application. This demonstrates that the N-(substituted phenyl)thiazolylphenoxyacetamide compounds provided by the present invention are significantly effective in controlling annual and perennial weeds in soybean fields, further broadening their spectrum of weed control. These compounds not only have the potential for development as herbicides, but also offer the advantages of low cost and environmental friendliness.

[0128] The above embodiments are intended to illustrate the present invention only and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention, such as replacing the benzene ring with an aromatic heterocycle or a condensed ring, do not depart from the spirit and scope of the technical solutions of the present invention and should be encompassed by the scope of the claims of the present invention.

Claims

1. An N-(substituted phenyl)thiazolephenoxyacetamide compound, characterized in that: The general structural formula of the compound is shown in Formula I: In formula I, R1 is any one of the following: 3,5-dimethoxyphenyl, 2-methoxy-5-methylformylphenyl, 3,4-dimethyldiformylphenyl, 4-nitro-2-methylformylphenyl, 3,5-dinitrophenyl, 2-nitrophenyl, 3-methoxy-5-nitrophenyl; R2 is any one of the following: phenyl, 4-chlorophenyl, 2-fluorophenyl, 3-bromo-4-chlorophenyl, 3-nitrophenyl, 3,4-dimethylphenyl, 3-chloro-4-ethylphenyl, 2-fluoro-4-methoxyphenyl.

2. A method for preparing the compound according to claim 1, comprising the following steps: 1) Compound 1 was reacted with thiosemicarbazide in solvent A, stirred and refluxed. After the reaction, the reaction solution was cooled to room temperature and poured into ice water. The pH was adjusted to 8-9. The solution was allowed to stand, filtered, washed with water, and dried to obtain compound 3. 2) Compound 3 and Compound 4 are dissolved in solvent B, an acid-binding agent is added, the reaction is stirred, and the reaction progress is monitored until the reaction is complete. The reaction solution is then poured into ice water to precipitate a solid, which is filtered, washed with water, and recrystallized to obtain the compound; Its synthetic route is as follows: 。 3. The preparation method according to claim 2, characterized in that In step 1), the molar ratio of compound 1 to thiosemicarbazide is 1:(1-2); the solvent A is a mixed solvent of 1,4-dioxane and phosphorus oxychloride, wherein the volume ratio of 1,4-dioxane to phosphorus oxychloride is 1:(3-6).

4. The preparation method according to claim 2, characterized in that In step 1), the stirring and refluxing process has a stirring rate of 500-600 rpm, a reflux temperature of 105-110° C., and a reflux time of 2-6 h.

5. The preparation method according to claim 2, characterized in that In step 2), the molar ratio of compound 3 to compound 4 is 1:(1-3); the solvent B is tetrahydrofuran; the acid binding agent is any one of potassium carbonate, sodium carbonate, triethylamine, potassium bicarbonate and sodium bicarbonate; the molar ratio of compound 3 to the acid binding agent is 1:

2.

6. The preparation method according to claim 2, characterized in that In step 2), the stirring reaction is carried out at room temperature and a stirring rate of 500-600 rpm; the reaction progress is monitored by thin layer chromatography; and the recrystallization is carried out using DMF / methanol.

7. Use of the compound according to claim 1 as a herbicidal active substance in suppressing weeds in soybean fields.

8. The use according to claim 7, characterized in that The weeds are annual and perennial weeds.

9. A herbicide, the active ingredient of which is the compound according to claim 1.

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