A phenylaminothiazole derivative and its application as a bactericide

Abstract

This invention discloses a phenylaminothiazole derivative as shown in Formula I and its application in the control of plant diseases. The phenylaminothiazole derivative uses readily available raw materials, has a simple preparation method, convenient post-processing, and a high product yield. Furthermore, the compound shown in Formula I exhibits broad-spectrum and highly effective antifungal activity against plant fungi, particularly showing excellent bactericidal effects against rice sheath blight, rapeseed sclerotinia sclerotinia, tomato early blight, grape bud blight, apple black rot, wheat sheath blight, wheat scab, and colloidal anthracnose.

Description

Technical Field

[0001] This invention belongs to the field of fungicides and relates to a phenylaminothiazole derivative, specifically to the application of this type of compound in resisting common plant pathogens such as rice sheath blight, rapeseed sclerotinia rot, and tomato early blight. Background Technology

[0002] In agricultural production, chemical pesticides remain the primary means of controlling crop diseases, holding a significant position in the industry due to their high efficiency, convenience, economy, and wide applicability (J. Agric. Food Chem. 2024, 72, 3342-3353). However, the overuse of pesticides has led to the development of pesticide resistance, environmental pollution, and negative impacts on non-target organisms. Therefore, a core task for pesticide researchers is to develop pesticides with novel structures and targets to continuously meet the growing market demand.

[0003] Thiazole heterocycles possess abundant electrons, enabling them to interact effectively with a wide range of biological targets, thereby enhancing biological activity. In particular, 2-aminothiazole derivatives are generally of interest due to their broad range of biological activities (J. Agric. Food Chem. 2022, 70, 10100-10110).

[0004] Prior art, Bioorganic & Medicinal Chemistry Letters 29(2019)938–9, has identified a novel strigolactone (SL) agonist 113D10, along with compounds 8 and 9, through a series of biological and biochemical assays. These novel SL agonists could be used to increase crop yield by controlling branching number without stimulating seed germination in root parasites.

[0005]

[0006] The prior art CN 118239903 A reports a method for preparing a 2-amino-4-trifluoromethylthiazole derivative.

[0007] The phenylaminothiazole derivatives described in this invention and their applications in the field of bactericides are not found in the prior art. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a class of phenylaminothiazole derivatives with anti-plant pathogenic activity. To obtain thiazole compounds with simple structures, lower production costs, and broader and higher activity, the applicant has been dedicated to the research of thiazole compounds. Through research in recent years, the applicant has discovered a class of novel thiazole compounds with high antibacterial activity. Although existing technologies share structural similarities with the compounds of this invention, no reports have been found regarding the bactericidal activity of such compounds. Furthermore, the applicant discovered that introducing a fluorine atom at the meta position of the benzene ring results in compounds with unexpected antibacterial effects.

[0009] This invention provides a phenylaminothiazole derivative of Formula I with activity against plant pathogens, the compound being shown in general Formula I:

[0010]

[0011] Wherein, R is selected from hydrogen and alkyl groups respectively; R 1 Selected from fluorine, chlorine, bromine, iodine, trifluoromethyl, trifluoromethoxy, difluoromethyl, and difluoromethoxy, respectively; R 2 X is selected from hydrogen, fluorine, chlorine, and bromine respectively; X is selected from hydrogen, fluorine, chlorine, bromine, and iodine respectively.

[0012] The preferred embodiment of this invention is that the compound of formula I is:

[0013] N-(3,5-Difluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine;

[0014] N-(3-chloro-5-fluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine;

[0015] N-(3-bromo-5-fluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine;

[0016] N-(3-fluoro-5-(trifluoromethyl)phenyl)-4-(trifluoromethyl)thiazolyl-2-amine;

[0017] N-(3,5-difluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0018] N-(3-chloro-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0019] N-(3-bromo-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0020] N-(3-fluoro-5-(trifluoromethyl)phenyl)-N-methyl-4-(trifluoromethane)thiazolyl-2-amine;

[0021] N-(3,5-difluorophenyl)-5-fluoro-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0022] 5-Chloro-N-(3,5-difluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0023] 5-Bromo-N-(3,5-difluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0024] 5-Bromo-N-(3-chloro-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0025] 5-Bromo-N-(3-Bromo-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0026] 5-Bromo-N-(3-fluoro-5-(trifluoromethyl)phenyl)-N-methyl-4-(trifluoromethane)thiazolyl-2-amine;

[0027] N-(3-(difluoromethyl)-5-fluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine;

[0028] N-(3-(difluoromethyl)-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0029] 5-Chloro-N-(3-(difluoromethyl)-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0030] 5-Bromo-N-(3-(difluoromethyl)-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine;

[0031] 4-(difluoromethyl)-N-(3,5-difluorophenyl)thiazol-2-amine;

[0032] N-(3-chloro-5-fluorophenyl)-4-(difluoromethyl)thiazolyl-2-amine;

[0033] N-(3-bromo-5-fluorophenyl)-4-(difluoromethyl)thiazolyl-2-amine;

[0034] 4-(difluoromethyl)-N-(3-fluoro-5-(trifluoromethyl)phenyl)thiazol-2-amine.

[0035] On the other hand, the present invention provides the application of the phenylaminothiazole derivative in the preparation of reagents against plant pathogens, wherein the pathogen is at least one of the following: rice rhizoctonia solani, rapeseed sclerotinia, tomato early blight, grape bud blight, apple black rot, wheat rhizoctonia solani, wheat scab, strawberry gray mold, tobacco red spot, collodion anthracnose, wheat powdery mildew pathogen, soybean rust pathogen, and corn rust pathogen.

[0036] The present invention also includes a bactericidal composition having a compound of general formula I as the active ingredient. The bactericidal composition contains, by weight, a compound of general formula I as the active ingredient in a percentage between 1% and 99%. The bactericidal composition also includes an agriculturally or forestry-acceptable carrier.

[0037] Beneficial effects of this invention:

[0038] The compounds described in this invention are not only simple to synthesize and use readily available and low-cost raw materials, but also have a very broad-spectrum bactericidal activity. They exhibit excellent antibacterial effects against plant pathogens such as rice sheath blight, rapeseed sclerotinia rot, tomato early blight, grape bud blight, apple black rot, wheat sheath blight, wheat scab, strawberry gray mold, and collodion. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0040] Figure 1 The diagram shows the in vivo control efficacy of compound I-1 and the positive controls pyrimethanil and carbendazim at a concentration of 100 mg / L against Sclerotinia sclerotinia in rapeseed and early blight of tomato, respectively, in the embodiments of the present invention. Detailed Implementation

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0042] Synthesis Example

[0043] Example 1: Preparation of N-(3,5-difluorophenyl)-4-(trifluoromethyl)thiazole-2-amine (I-1)

[0044]

[0045] 0.52 g (6.83 mmol) of ammonium thiocyanate and 15 mL of acetone were added to a reaction flask and dissolved thoroughly. 0.96 g (6.83 mol) of benzoyl chloride was slowly added dropwise under magnetic stirring at room temperature. After the addition was complete, the temperature was raised to 60 °C and stirred for 30 minutes. Then, 15 mL of an acetone solution containing 0.83 g (6.44 mmol) of 3,5-difluoroaniline was slowly added dropwise using a constant-pressure dropping funnel. After the addition was complete, the reaction was continued at 60 °C for 5 hours. Acetone was recovered by vacuum distillation, and the residue was mixed with 50 mL of water, stirred thoroughly, ground, filtered, and dried to obtain 1.59 g of the intermediate N-(3,5-difluorophenyl)carbamoyl)benzamide, with a yield of 85%.

[0046] 1.50 g (5.14 mmol) of N-(3,5-difluorophenyl)carbamoyl)benzamide, 15 mL of methanol, and 15 mL of ammonia were added sequentially to a reaction flask, and the mixture was refluxed at 70 °C for 1 hour. After removing most of the solvent by vacuum distillation, the mixture was extracted with ethyl acetate (30 × 3), and the organic layers were combined, dried over anhydrous sodium sulfate, and the ethyl acetate was recovered by vacuum distillation. The solid residue was slurried with petroleum ether, filtered, and the filter cake was dried to give 0.96 g of intermediate 1-(3,5-difluorophenyl)thiourea, with a yield of 97%.

[0047] 0.80 g (4.25 mmol) of 1-(3,5-difluorophenyl)thiourea was dissolved in 20 mL of anhydrous ethanol in a reaction flask. 1.22 g (6.38 mmol) of 3-bromo-1,1,1-trifluoro-2-propanone was added dropwise, and the mixture was refluxed for 19 hours. The solvent was removed by vacuum distillation, and the mixture was extracted with ethyl acetate (30 mL × 3). The organic layers were combined, dried over anhydrous sodium sulfate, and the ethyl acetate was recovered by vacuum distillation. The residue was subjected to rapid column chromatography to give 0.89 g of the target compound I-1, in 75% yield.

[0048] The preparation of N-(3-fluoro-5-(trifluoromethyl)phenyl)-4-(trifluoromethyl)thiazole-2-amine (I-2) and the preparation methods of comparative compounds 1-12 are the same as those of compound I-1.

[0049] NMR data for compound I-1: white solid, melting point 125.8–127.4 °C. 1 H NMR (400MHz, DMSO-d6) δ10.98(s,1H),7.76(s,1H),7.30(d,J=9.8Hz,1H),6.80(td,J=9.4,2.1Hz,1H). 13C NMR (101MHz, DMSO-d6) δ 164.43, 162.80 (dd, J = 243.1, 15.7Hz), 142.63 (t, J = 14.0Hz), 138. 47(q,J=36.2Hz), 120.47(q,J=269.7Hz), 113.22, 100.42–99.65(m), 96.86(t,J=26.3Hz).

[0050] NMR data for compound I-2: pale yellow solid, melting point 109.4–111.2 °C. 1 H NMR (400MHz, Chloroform-d) δ8.05 (s, 1H), 7.55 (d, J = 10.2Hz, 1H), 7.35 (s, 1H), 7.19 (s, 1H), 7.05 (d, J = 8.2Hz, 1H). 13 CNMR(101MHz,Chloroform-d)δ165.06,163.34(d,J=248.6Hz),141.84(d,J=10.9Hz),141.19(q,J=37.5Hz),133.58(q,J=33.6Hz),133.48( q, J=33.7Hz), 123.13 (q, J=272.7Hz), 120.24 (q, J=270.2Hz), 111.25–110.91 (m), 108.95 (d, J=26.1Hz), 107.76 (ddd, J=25.0, 7.5, 3.7Hz).

[0051] The structures of compounds 1–12 are compared below:

[0052]

[0053]

[0054] Examples of bioactivity assays

[0055] Example 2: In vitro plate antibacterial activity test

[0056] This embodiment is used to determine the in vitro antibacterial activity of the compounds prepared in Example 1 and the comparative compounds against a variety of plant pathogenic fungi.

[0057] The tested plant pathogenic fungi were: Rhizoctonia solani (rice sheath blight), Sclerotonia sclerotiorum (rapeseed sclerotium), Alternaria solani (tomato early blight), Botryosphaeria dothidea (grape bud rot), Valsa mali (apple black rot), Rhizoctonia cerealis (wheat sheath blight), Gibberella zeae (wheat scab), and Colletotrichum gloeosporioides (wheat anthracnose).

[0058] 1. Experimental Methods

[0059] The mycelial growth rate method was used. The target compound was weighed using a 1 / 100,000 analytical balance and dissolved in DMSO to prepare a stock solution with a concentration of 10 g / L. The stock solution was added to PDA medium. The initial screening concentration of the target compound was 20 mg / L. Pure DMSO without the test compound was added to the PDA culture medium as a blank control. Commercial fungicides pyrimethanil, thifluzamide, and carbendazim were used as positive controls. Fresh mycelial discs with a diameter of 5 mm were taken from the edge of the fungal colonies in the PDA culture and inoculated onto the above PDA medium. Three identical mycelial discs were evenly inoculated into each plate in an equilateral triangle pattern. The diameter (mm) of the mycelial discs was measured using calipers using the cross-cross method, and the average value was calculated. The relative inhibition rate (%) was calculated according to the following formula:

[0060]

[0061] 2. Experimental Results

[0062] The results of the antibacterial activity test are shown in Table 1, where Rs represents *Rhizoctonia solani* (rice sheath blight), Ss represents *Sclerotinia sclerotiorum* (rapeseed sclerotinia), As represents *Early blight* (tomato wilt), Bd represents *Gnaphalium affine* (grape bud blight), Vm represents *Agropyron cristatum* (apple black rot), Rc represents *Rhizoctonia solani* (wheat sheath blight), Gz represents *Fusarium graminearum* (wheat scab), and Cg represents *Colletotrichum gloeosporioides* (colloidal anthracnose). Table 1 clearly shows that compounds I-1 and I-2 in the examples possess very broad-spectrum and highly efficient antibacterial activity. Their antibacterial activity at a concentration of 20 mg / L is significantly superior to the commercial fungicides pyrimethanil and thifluzamide, and comparable to carbendazim. Structure-activity relationship studies with comparative compounds reveal that the fluorine atom at the 3-position of the benzene ring plays a crucial role in enhancing activity, and the introduction of substituents at the 5-position of the benzene ring yields unexpected antibacterial effects.

[0063] Table 1

[0064]

[0065] Example 3: Inoculation Test of Isolated Leaves and Fruits

[0066] This embodiment is used to verify the antibacterial effects of compound I-1 prepared in Example 1 and commercial fungicides pyrimethanil and carbendazim against Sclerotinia sclerotiorum var. sclerotiorum and early blight pathogens of tomato.

[0067] The test method was as follows: Compound I-1 and the fungicides pyrimethanil and carbendazim were dissolved in DMSO and diluted to 100 mg / L with an aqueous solution containing 0.1% Tween-80. Several uniformly sized, smooth, and healthy rapeseed leaves and tomato fruits were selected and washed sequentially with sterile water and 75% ethanol aqueous solution. After air-drying at room temperature, the above-mentioned agents were sprayed onto the rapeseed leaves and tomato fruits using a small sprayer, and then allowed to air dry naturally. Next, the cuticle layer on the surface of the rapeseed leaves and tomato fruits was pierced with a sterilized needle, and mycelial cakes with a diameter of 5 mm of *Sclerotinia sclerotiorum* and *Early blight* causal agent of tomato were inoculated onto the rapeseed leaves and tomato fruits, respectively. The mixtures were incubated in a light incubator at 25℃ and 95% relative humidity. When the control group showed obvious disease, the diameter of the lesions was measured with calipers, and the control efficacy was calculated according to the corresponding formula.

[0068] The test results are as follows Figure 1 As shown in Table 2, from Figure 1 As can be clearly seen from Table 2, compound I-1 exhibits excellent control efficacy against sclerotinia stem rot in rapeseed and early blight in tomato. The control efficacy of compound I-1 against sclerotinia stem rot in rapeseed and early blight in tomato is better than that of pyrimethanil. Although the control efficacy of compound I-1 against sclerotinia stem rot in rapeseed is not as good as that of carbendazim, its control efficacy against early blight in tomato is significantly better than that of carbendazim.

[0069] Table 2

[0070]

[0071] Example 4 Cytotoxicity Test

[0072] This test case was used to determine the cytotoxicity of compound I-1 from the examples and thifluzamide, which is also a thiazole fungicide.

[0073] The test method was as follows: Transformed human liver epithelial cells (THLE-2) and normal human lung epithelial cells (BEAS-2B) were cultured in 1640 complete medium at 37°C and 5% CO2 incubator until the logarithmic growth phase. Then, the cells were seeded into 96-well plates and incubated overnight. The old medium was discarded, and medium containing the compound to be tested was added (for the control group, DMSO solvent was added at a proportional dilution). The plates were then incubated in a CO2 incubator for 24 h. The medium in the 96-well plates was then discarded, and 90 μL of fresh medium and 10 μL of CCK8 working solution were added to each well. The plates were incubated for another 2 h and then shaken in the dark for 15 min. The absorbance of the solution was measured at 490 nm using a microplate reader.

[0074] The cytotoxicity data of the compounds to THLE-2 and BEAS-2B cells are shown in Table 3 below.

[0075] Table 3

[0076]

[0077] As can be seen from Table 3, both compound I-1 and the commercially available bactericide thifluzamide are thiazole compounds, and both have very low toxicity to both THLE-2 and BEAS-2B cells. Therefore, the compound of the present invention, as a thiazole derivative, has a predictable advantage of low toxicity, demonstrating its high safety to non-target cells.

[0078] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A class of phenylaminothiazole derivatives with activity against plant pathogens, characterized in that: The structure of the phenylaminothiazole derivative is shown in general formula I: Wherein, R is selected from hydrogen and alkyl groups respectively; R 1 Selected from fluorine, chlorine, bromine, iodine, trifluoromethyl, trifluoromethoxy, difluoromethyl, and difluoromethoxy, respectively; R 2 X is selected from hydrogen, fluorine, chlorine, and bromine respectively; X is selected from hydrogen, fluorine, chlorine, bromine, and iodine respectively.

2. The phenylaminothiazole derivative according to claim 1, characterized in that... The compound represented by general formula I is: N-(3,5-Difluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-chloro-5-fluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-bromo-5-fluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-fluoro-5-(trifluoromethyl)phenyl)-4-(trifluoromethyl)thiazolyl-2-amine; N-(3,5-difluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-chloro-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-bromo-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-fluoro-5-(trifluoromethyl)phenyl)-N-methyl-4-(trifluoromethane)thiazolyl-2-amine; N-(3,5-difluorophenyl)-5-fluoro-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Chloro-N-(3,5-difluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Bromo-N-(3,5-difluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Bromo-N-(3-chloro-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Bromo-N-(3-Bromo-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Bromo-N-(3-fluoro-5-(trifluoromethyl)phenyl)-N-methyl-4-(trifluoromethane)thiazolyl-2-amine; N-(3-(difluoromethyl)-5-fluorophenyl)-4-(trifluoromethyl)thiazolyl-2-amine; N-(3-(difluoromethyl)-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Chloro-N-(3-(difluoromethyl)-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 5-Bromo-N-(3-(difluoromethyl)-5-fluorophenyl)-N-methyl-4-(trifluoromethyl)thiazolyl-2-amine; 4-(difluoromethyl)-N-(3,5-difluorophenyl)thiazol-2-amine; N-(3-chloro-5-fluorophenyl)-4-(difluoromethyl)thiazolyl-2-amine; N-(3-bromo-5-fluorophenyl)-4-(difluoromethyl)thiazolyl-2-amine; 4-(difluoromethyl)-N-(3-fluoro-5-(trifluoromethyl)phenyl)thiazol-2-amine.

3. The application of the phenylaminothiazole derivative according to claim 1 in the preparation of reagents against plant pathogens, wherein, The pathogen is at least one of the following: rice sheath blight fungus, rapeseed sclerotinia rot fungus, tomato early blight fungus, grape bud blight fungus, apple black rot fungus, wheat sheath blight fungus, wheat scab fungus, strawberry gray mold fungus, tobacco red spot fungus, collodion anthracnose fungus, wheat powdery mildew pathogen, soybean rust pathogen, and corn rust pathogen.

4. A bactericide comprising an active ingredient and excipients, wherein the active ingredient comprises at least one of the compounds of claim 1.

5. The bactericide according to claim 4, wherein, The content of the active ingredient is 1-99.9% by weight.

6. The bactericide according to claim 4 or 5, wherein, The formulation of this bactericide is selected from at least one of emulsifiable concentrate, suspension concentrate, powder, granule, and aqueous solution.

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