Application of benzaldehyde thiosemicarbazone compound and bactericide

Abstract

The present invention relates to the field of pesticides, and discloses an application of a benzaldehyde thiosemicarbazone compound and a bactericide, the benzaldehyde thiosemicarbazone compound has a structure represented by a formula (I), in the formula (I), A is CH or N; r1 is selected from halogen; and R2 and R3 are respectively and independently selected from alkyl groups of C2-C6. The benzaldehyde thiosemicarbazone compound provided by the invention can effectively prevent and treat plant fungal diseases, has an excellent prevention and treatment effect on plant diseases caused by fungi such as magnaporthe oryzae, ustilaginoidea virens, rhizoctonia solani, fusarium graminearum and fusarium pseudograminearum, and has a very good market development prospect. Formula (I)

Description

Technical Field

[0001] This invention relates to the field of pesticides, specifically to the application of a benzaldehyde thiourea compound and its use as a fungicide. Background Technology

[0002] Rice and wheat are my country's two major staple crops. However, in recent years, fungal diseases (such as rice blast, rice false smut, wheat scab, and stem rot) have become increasingly prevalent, seriously threatening the stable, high, and high yields of rice and wheat through single or combined infections. Therefore, there is an urgent need to construct a three-pronged solution encompassing "mechanism research – technological innovation – product development," including elucidating pathogenic mechanisms at the molecular interaction level, establishing a genetic improvement system for crop disease resistance, developing highly efficient and low-toxicity fungicides, and establishing integrated management models based on multi-target synergistic effects. However, current fungicide development faces severe bottlenecks; approximately 60% of commercially available products focus on C-14 demethylases. Drug Resis Update 1999, 2 , 390-402], succinate dehydrogenase [ Annu. Rev. Biochem. 2003, 72 , 77-109.]、Cytochrome bc1 complex[ Mol. Biol. 2004, 341, [281-302.] These three major energy metabolism targets lead to severe homogenization competition and a prominent risk of drug resistance. Against this backdrop, using multi-omics technologies to deeply analyze novel targets and mechanisms of action, and establishing a rational design platform based on structural biology, holds promise for finding a key breakthrough in the creation of novel fungicides. This is of great significance for achieving green control of fungal diseases.

[0003] Existing pesticides reported for controlling rice or wheat diseases include pyraclostrobin, tebuconazole, and benzimidazole compounds such as carbendazim. However, due to years of continuous use of these single pesticides, resistance has developed rapidly, the detection rate of resistant strains has increased dramatically, and the control efficacy has declined year by year. Therefore, it is necessary to develop new alternative pesticides. Summary of the Invention

[0004] The purpose of this invention is to provide a novel fungicide that can effectively prevent and control plant diseases, especially fungal diseases of rice and / or wheat.

[0005] To achieve the above objectives, a first aspect of the present invention provides the application of a benzaldehyde thiourea compound or its agrochemically acceptable salts, hydrates, and solvates in the control of plant fungal diseases, the benzaldehyde thiourea compound having the structure shown in formula (I). Formula (I), In equation (I), A is either CH or N; R1 is selected from halogens; R2 and R3 are each independently selected from C2-C6 alkyl groups.

[0006] A second aspect of the present invention provides a bactericide containing excipients and an active ingredient, wherein the active ingredient is a compound used in the application described in the first aspect above.

[0007] The third aspect of the present invention provides the application of the fungicide described in the second aspect above in the prevention and control of rice blast, rice false smut, rice sheath blight, wheat scab, and wheat stem rot.

[0008] The benzaldehyde thiourea compound or its agrochemically acceptable salts, hydrates and solvates provided by this invention can effectively control plant fungal diseases. It has excellent control effects on plant diseases caused by fungi such as rice blast fungus, rice false smut fungus, rice sheath blight fungus, Fusarium graminearum and Fusarium pseudograminearum. It is comparable to the currently commercially available fungal disease control agent pyraclostrobin, and its structure is completely different from existing commercial agents. It overcomes the defect of the current commercial agents that have developed resistance due to continuous single use for many years, and has a very good market development prospect. Attached Figure Description

[0009] Figure 1 This is the mycelial growth curve of rice blast fungus P131; Figure 2 The effect of compound 1 on mycelial growth and sporulation of rice blast fungus P131; Figure 3 The experiment was conducted on barley leaves to evaluate the effect of compound 1 on the pathogenicity of P131 strain spores. Figure 4 Compound 1 inhibits the infection of rice C039 leaves by rice blast fungus 16-117; Figure 5 Compound 1 inhibits the infection of rice xwx11 leaves by rice blast fungus 16-117; Figure 6 Compound 1 inhibits the infection of rice leaves by the rice blast fungus Guy11; Figure 7 This is a test of the inhibitory activity of BT-CN against P131, the virigation pathogen of rice blast fungus; Figure 8 The leaf spot coverage rate of rice varieties C039 and xwx11 after co-inoculation with BT-CN and rice blast strain spores; Figure 9 This is the growth curve of HPB-1, the rice sheath blight pathogen; Figure 10 The assay showed that compound 1 inhibited the growth of HPB-1, the causal agent of rice sheath blight. Figure 11 This is the growth curve of rice false smut fungus Us43; Figure 12 The assay showed that compound 1 had inhibitory activity against rice false smut fungus Us43. Figure 13 The assay was performed to detect the inhibitory activity of compound 1 against Fusarium graminearum. Figure 14 The assay was performed to detect the inhibitory activity of compound 1 against Fusarium graminearum. Figure 15 The experiment involved a field study on the inhibition of rice false smut by compound 1. Detailed Implementation

[0010] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0011] In this invention, "C2-C6 alkyl" refers to alkyl groups with a total number of carbon atoms of 2-6, including straight-chain alkyl and branched-chain alkyl. For example, it can be a straight-chain alkyl or a branched-chain alkyl group with a total number of carbon atoms of 2, 3, 4, 5, or 6, such as ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, etc. A similar interpretation applies to "C2-C4 alkyl," the only difference being the total number of carbon atoms.

[0012] As previously stated, a first aspect of the present invention provides the use of a benzaldehyde thiourea compound or its agrochemically acceptable salts, hydrates, and solvates in the control of plant fungal diseases, the benzaldehyde thiourea compound having the structure shown in formula (I). Formula (I), In equation (I), A is either CH or N; R1 is selected from halogens; R2 and R3 are each independently selected from C2-C6 alkyl groups.

[0013] In a preferred embodiment, A is CH or N in equation (I); R1 is selected from F, Cl, and Br; R2 and R3 are each independently selected from C2-C4 alkyl groups.

[0014] According to a preferred embodiment, in formula (I), A is CH; R1 is Br; and R2 and R3 are each independently selected from C2-C4 alkyl groups.

[0015] Particularly preferred, the compound represented by formula (I) is compound 1; Compound 1: .

[0016] In some preferred embodiments, the compound represented by formula (I) is compound 1, and the pathogen causing the plant fungal disease is selected from at least one of rice blast fungus, rice false smut fungus, rice sheath blight fungus, Fusarium graminearum, and Fusarium pseudograminearum.

[0017] As previously stated, a second aspect of the present invention provides a bactericide containing excipients and an active ingredient, wherein the active ingredient is a compound used in the application described in the first aspect.

[0018] Preferably, the active ingredient in the bactericidal composition has a mass content of ≥5 ppm, more preferably ≥50 ppm.

[0019] In a preferred embodiment, the auxiliary material is selected from at least one of clay, silicate, solid fertilizer, water, alcohol, ketone, aromatic hydrocarbon, and dimethyl sulfoxide.

[0020] In a preferred embodiment, the formulation of the bactericide is selected from at least one of emulsifiable concentrates, suspension concentrates, powders, granules, aqueous solutions, and poison baits.

[0021] As previously stated, the third aspect of the present invention provides the application of the fungicide described in the second aspect in the prevention and control of rice blast, rice false smut, rice sheath blight, wheat scab, and wheat stem rot.

[0022] This invention does not specifically limit the method for obtaining the above-mentioned benzaldehyde thiourea compound. Those skilled in the art can obtain a suitable method for preparing the benzaldehyde thiourea compound by combining the specific structure of the benzaldehyde thiourea compound provided by this invention with synthetic methods in the field of organic synthesis. However, in order to obtain compounds with better yield and purity, this invention provides a preferred method for preparing the compound described in the first aspect.

[0023] In a preferred embodiment, the method for preparing the benzaldehyde thiourea compound includes: In the presence of a solvent, the compound shown in formula (II) and the compound shown in formula (III) are reacted to obtain the compound shown in formula (I); Formula (I), Equation (II), Formula (III) The definitions of A, R1, R2, and R3 correspond to the positions of the compound groups in the first aspect mentioned above.

[0024] Preferably, the conditions for the contact reaction are: temperature 75-100℃ and time 10-15h.

[0025] Preferably, the solvent is selected from at least one of acetonitrile, ethanol, and N,N-dimethylformamide.

[0026] Those skilled in the art should understand that the method described in this invention may also include a step of purifying the obtained product. There are no special requirements for the purification method, and various purification methods commonly used by those skilled in the art can be adopted. For example, extraction with an extractant, drying with a drying agent, and removal of impurities by column chromatography or other methods can be used.

[0027] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials are commercially available. The room temperature mentioned in this invention refers to 25±2℃.

[0028] The structural formulas of commercial reagents PYR (pyraclostrobin), tebuconazole, and BT-CN are as follows: PYR Tebuconazole

[0029] BT-CN Preparation Example 1: Preparation of Compound 1

[0030] Step 1: Preparation of intermediate 3-bromo-4-(diethylamino)benzaldehyde.

[0031] NBS was added to a mixture of 4-(diethylamino)benzaldehyde and a catalytic amount of NH4OAc in MeCN, and the mixture was stirred at room temperature. After the reaction was complete as detected by TLC, the mixture was concentrated under vacuum and extracted with EtOAc-H2O (1:1) (3 × 5 ml). The organic fraction was separated from the extract, dried, and concentrated. The product was purified by column chromatography (silica gel, hexane-ethyl acetate, v / v = 10:1) to give the pure intermediate 3-bromo-4-(diethylamino)benzaldehyde.

[0032] Step 2: Preparation of target product compound 1 A dry 50 mL round-bottom flask was filled with 1.95 mmol of 3-bromo-4-(diethylamino)benzaldehyde, 10 mL of ethanol, and 1.95 mmol of thioaminourea. The mixture was then refluxed overnight. After the reaction was completed, the mixture was cooled to 25 °C and filtered. The product was dried to give the desired product compound 1 (385.2 mg, 60%) as a pale yellow solid.

[0033] Preparation Example 2: Preparation of Compound 1

[0034] Reaction conditions: i) K₂CO₃, DMF, 80℃, 8 h; ii) EtOH reflux, 6 h. The yield of the compound is indicated in parentheses.

[0035] Step 1: Preparation of 3-bromo-4-(diethylamino)benzaldehyde (Intermediate 1). 4.00 mmol of 3-bromo-4-fluorobenzaldehyde was placed in a 50 mL round-bottom flask, and diethylamine (8.00 mmol) and potassium carbonate (12.00 mmol) were added. DMF (10 mL) was added to dissolve the product. The mixture was stirred at 80 °C and reacted for 8 h. The reaction was monitored by thin-layer chromatography (TLC, eluent: petroleum ether (PE) / ethyl acetate (EA) = 10:1, v / v). After the reaction was complete, the mixture was concentrated and extracted with ethyl acetate. The organic phases were combined, dried, and concentrated to obtain the crude product. This crude product was then purified by silica gel column chromatography (eluent: PE:EA = 10:1, v / v) to obtain Intermediate 1 (yield 60%).

[0036] Step 2: Preparation of target product compound 1. Intermediate 1 (2.00 mmol) and thioaminourea (2.00 mmol) were added sequentially to a dry 50 mL round-bottom flask, followed by the addition of anhydrous ethanol (10 mL) and stirring to dissolve. The mixture was heated to reflux and stirred continuously for 6 h. The reaction progress was monitored by TLC (PE:EA = 20:1, v / v). After the reaction was complete, the system turned orange-yellow. The mixture was cooled to room temperature, filtered, and the solid was collected and dried to obtain a pale yellow solid, compound 1 (526.8 mg, yield 80%).

[0037] Comparative Preparation Example 1: Preparation of BT-CN

[0038]

[0039] Step 1: Preparation of intermediate 3-cyano-4-(diethylamino)benzaldehyde Diethylamine was added to a mixture of 3-cyano-4-fluorobenzaldehyde and a catalytic amount of K₂CO₃ in DMF, and the mixture was refluxed at 110°C. After the reaction was completed by TLC, the mixture was washed with ethyl acetate and saturated brine for extraction. The organic phase was separated, dried, and concentrated. The product was purified by column chromatography (silica gel, hexane-ethyl acetate, v / v = 5:1) to give the pure intermediate 3-cyano-4-(diethylamino)benzaldehyde.

[0040] Step 2: Preparation of the target product BT-CN 3-Cyano-4-(diethylamino)benzaldehyde (5.6 mmol), ethanol (10 mL), and thioaminourea (6.7 mmol) were added to a dry 50 mL round-bottom flask and refluxed. After the reaction was completed as detected by TLC, the product was dried and concentrated. The product was then purified by column chromatography (silica gel, hexane-ethyl acetate, v / v = 5:1) to obtain the desired product BT-CN (821 mg, 56%) as a yellow solid.

[0041] The characterization data of the compounds provided by this invention are shown in Table 1.

[0042] Table 1

[0043] Test Example 1: Rice blast fungus 1. Control of rice blast disease by compound 1 (1) Experimental method of solid culture of rice blast fungus: After the rice blast fungus P131 was activated for 7 days, a fungal cake with a diameter of 5 mm was punched at the edge of the colony and inoculated into potato dextrose agar (PDA) medium containing different concentrations of compound 1 and cultured upside down in the dark at 28°C for 6 days.

[0044] The results are as follows Figure 1 and Figure 2 As shown, compound 1 significantly inhibited mycelial growth after 6 days of treatment with rice blast fungus strain P131; at concentrations of 4.32 ppm, 8.98 ppm and 18.68 ppm, the sporulation inhibition rates of spores treated with compound 1 for 10 days reached 60.00%, 72.71% and 81.71%, respectively.

[0045] (2) Barley leaf experiment to evaluate the effect of compound 1 on the pathogenicity of P131 strain spores. Test method: Select barley seedlings with fully expanded first true leaves and uniform growth, and cut the leaves to a uniform length. Collect spores with sterile distilled water containing 0.025% Tween-20, centrifuge at 5000 rpm at room temperature for 5 min, discard the supernatant, resuspend the spores in sterile water containing 0.025% Tween-20, count with a hemocytometer, and adjust the spore concentration to 1×10⁻¹⁰ per milliliter of 0.025% Tween-20 sterile water. 5 1 spore. Barley leaves were laid flat on a damp paper towel. 15 µL of spore solution was mixed with 15 µL of compound 1 at different concentrations prepared using 0.025% Tween-20 as a solvent. 10 µL of each compound 1 was then dropped evenly onto the veins of the barley leaves. The mixture was incubated in the dark at 28°C for 24 h, then transferred to a light incubator, maintaining a relative humidity of 90%, a temperature of 28°C, and a light intensity of 150 μmol / m².2 / s, record the leaf disease status 3 days later.

[0046] The results are as follows Figure 3 As shown, (a) represents the percentage of leaf patch area, and (b) represents the relative incidence rate with Tween-20 as a reference. PYR is the commercially available fungicide pyraclostrobin. Pathogenicity studies have shown that compound 1 can effectively reduce the pathogenicity of rice blast fungus. After barley leaves were co-treated with compound 1 and P131 spores for 3 days, the percentage of leaf patch area and the incidence rate decreased significantly.

[0047] (3) Pot experiment (Hunan Hybrid Rice Research Center) Compound 1 was co-inoculated with spores of rice blast fungus strain (rice blast fungus strain 16-117) (fully dissolved in dimethyl sulfoxide and diluted with water) on rice varieties C039 and xwx11. Rice blast fungus spores infected rice leaves. The disease level was determined according to the "Technical Specification for Field Monitoring of Rice Blast Resistance" (NY / T3685-2020). 5-7 days after inoculation, the sprayed rice was photographed and the disease level was assessed. The specific disease levels are shown in Table 2.

[0048] Table 2

[0049] The results are as follows Figure 4 , Figure 5 , and as shown in Table 3.

[0050] Pot experiments confirmed that compound 1 was effective against rice blast in rice varieties C039 / xwx11. The 6.25 ppm treatment reduced leaf lesions in xwx11 by 95%, with an effect comparable to the commercial fungicide PYR (pyraclostrobin).

[0051] (4) Pot experiment (Zhejiang Agriculture and Forestry University) Compound 1 was co-inoculated with spores of rice blast fungus (Guy11) (dissolved in acetone and diluted with water) in rice varieties C039 and TP309, and the rice blast fungus spores infected the rice leaves.

[0052] The results are as follows Figure 6 As shown.

[0053] Pot experiments confirmed that compound 1 was effective against rice blast in rice varieties C039 and TP309. When the concentration of compound 1 was 50 ppm, the diseased area was less than 10%, and the effect was comparable to that of the commercial fungicide PYR (pyraclostrobin).

[0054] 2. BT-CN for the prevention and control of rice blast The inhibitory effects of BT-CN on rice blast fungus are as follows: Figure 7 , Figure 8 As shown, BT-CN exhibits significantly poor inhibitory effects against rice blast fungus. EC 50 >25 ppm.

[0055] Table 3

[0056] Test Example 2: Rice Sheath Blight Method for testing the inhibitory activity of compound 1 against rice sheath blight pathogen: After activating rice sheath blight pathogen HPB-1 for 2 days, 5 mm diameter mycelial cakes were punched at the edge of the colony using a puncher and inoculated into PDA medium containing different concentrations of compound 1. The mycelial cakes were then incubated upside down in the dark at 28°C for 2 days.

[0057] The results are as follows Figure 9 and Figure 10 As shown, it can be seen that compound 1 showed significant inhibitory activity against HPB-1 strain of sheath blight after 2 days of treatment.

[0058] Test Example 3: Rice blast disease Method for testing the inhibitory activity of compound 1 against rice false smut: After activating rice false smut for 10 days, mycelial cakes with a diameter of 5 mm were punched at the edge of the colony using a puncher and inoculated into PDA medium containing different concentrations of compound 1. The cakes were then incubated upside down in the dark at 28°C for 15 days. BT-CN and tebuconazole were used as control groups.

[0059] The inhibitory effect of compound 1 on rice false smut is as follows: Figure 11 , Figure 12 As shown, it can be seen that the mycelial growth of rice false smut was significantly inhibited after 15 days of treatment with compound 1. The test data (Jiangsu Zhongqi) showed that the control efficacy of 6.25 ppm and 25 ppm treatments against rice false smut reached 68% and 100%, respectively.

[0060] The method for calculating the control effect is as follows: Mycelial growth inhibition rate (%) = (Corona diameter of control group - Corona diameter of experimental group) / (Corona diameter of control group - Diameter of mycelial cake) × 100.

[0061] The results are shown in Table 4.

[0062] Table 4

[0063] Test Example 4: Fusarium pseudograss Method for testing the inhibitory activity of compound 1 against Fusarium oxysporum: After activating Fusarium oxysporum for 5 days, 5 mm diameter mycelial cakes were punched at the edge of the colony using a puncher and inoculated into PDA medium containing different concentrations of compound 1. The mycelial cakes were then incubated upside down in the dark at 28°C for 6 days.

[0064] The results are as follows Figure 13 As shown, compound 1 also exhibits excellent inhibitory activity against Fusarium pseudograss.

[0065] Test Example 5: Fusarium graminearum Method for testing the inhibitory activity of compound 1 against Fusarium graminearum: After activating Fusarium graminearum for 5 days, 5 mm diameter mycelial cakes were punched at the edge of the colony using a puncher and inoculated into PDA medium containing different concentrations of compound 1. The mycelial cakes were then incubated upside down in the dark at 28°C for 6 days.

[0066] The results are as follows Figure 14 As shown, compound 1 also exhibits excellent inhibitory activity against Fusarium graminearum.

[0067] Compound 1 inhibits the growth of different fungi ( EC 50 The summary is shown in Table 5.

[0068] Table 5

[0069] Test Example 6 Field tests of compound 1 against rice false smut 1. Experimental location: Jinzhong Group, Jinzhongqiao Village, Daweishan Town, Liuyang City, 113°56′52.778″E, 28°25′47.788″N.

[0070] 2. Rice variety and planting area: Shuangliangyou 138, planting density 6*8 inches, no fungicide used in field management, other management according to local conditions. A total of 18 plots were tested, each plot 40m². 2 .

[0071] 3. Operation timeline: Sowing date: May 23, 2025; First spraying date: August 15, 2025; Second spraying date: August 29, 2025. Survey date: September 26, 2025.

[0072] 4. Gradient Setup: For the efficacy experiment of compound 1, four concentration gradients were set up. First, the compound was completely dissolved in acetone, then diluted with 1% Tween water to four mass concentrations: 100 ppm, 200 ppm, 400 ppm, and 800 ppm. A total of six treatments were also included: fluazinam (pesticide control) and a water control. Each treatment had three replicates, resulting in a total of 18 plots. Three rows of isolation were used between plots, and two outer protective rows were used for further isolation.

[0073] 5. Spraying method: The agent was sprayed in each experimental plot using a spray bottle, with a solution volume of 1.6 L per plot.

[0074] 6. Disease Survey: A disease survey was conducted during the yellow ripening stage of rice. Each plot was surveyed based on the actual disease incidence, recording the total number of panicles, the number of diseased panicles, and the number of diseased grains per panicle. The results were statistically analyzed according to the disease panicle grading standards in Table 6 below, as shown in Table 7. Figure 15 As shown.

[0075] Table 6

[0076] Table 7

[0077] Note that “(1), (2) and (3)” in the table refer to the groups of parallel repeated trials.

[0078] From Table 7 and Figure 15 It can be seen that when the concentration of compound 1 reaches 200 ppm, it has a significant control effect on rice false smut.

[0079] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of benzaldehyde thiourea compounds or their agrochemically acceptable salts, hydrates, and solvates in the control of plant fungal diseases, characterized in that, The benzaldehyde thiourea compound has the structure shown in formula (I). Formula (I), In equation (I), A is either CH or N; R1 is selected from halogens; R2 and R3 are each independently selected from C2-C6 alkyl groups.

2. The application according to claim 1, characterized in that, In equation (I), A is either CH or N; R1 is selected from F, Cl, and Br; R2 and R3 are each independently selected from C2-C4 alkyl groups.

3. The application according to claim 1 or 2, characterized in that, In equation (I), A is CH; R1 is Br; R2 and R3 are each independently selected from C2-C4 alkyl groups.

4. The application according to claim 3, characterized in that, The compound shown in formula (I) is compound 1; Compound 1: .

5. The application according to claim 4, characterized in that, The compound shown in formula (I) is compound 1, and the pathogen causing the plant fungal disease is selected from at least one of rice blast fungus, rice false smut fungus, rice sheath blight fungus, Fusarium graminearum and Fusarium pseudograminearum.

6. A bactericide, characterized in that, The bactericide contains excipients and active ingredients, wherein the active ingredients are compounds used in any one of claims 1-5.

7. The bactericide according to claim 6, characterized in that, The active ingredient in the bactericide contains ≥5 ppm by mass, preferably ≥50 ppm.

8. The bactericide according to claim 6 or 7, characterized in that, The auxiliary materials are selected from at least one of clay, silicates, solid fertilizers, water, alcohols, ketones, aromatics, and dimethyl sulfoxide.

9. The bactericide according to claim 6 or 7, characterized in that, The formulation of the bactericide is selected from at least one of emulsifiable concentrate, suspension concentrate, powder, granule, aqueous solution, and poison bait.

10. The application of the fungicide according to any one of claims 6-9 in the prevention and control of rice blast, rice false smut, rice sheath blight, wheat scab, and wheat stem rot.

Images