Pyrrolinedione compound, and preparation method therefor and use thereof as microbicide

Abstract

Provided in the present application are a pyrrolinedione compound, and a preparation method therefor and the use thereof as a microbicide. The pyrrolinedione compound is 1-(2,6-diethyl-4-methylphenyl)-1H-pyrrole-2,5-dione. The pyrrolinedione compound and an agricultural microbicide using the pyrrolinedione compound as an active ingredient are used for controlling a variety of plant diseases caused by phytopathogenic fungi, oomycetes and bacteria. The pyrrolonedione compound has a novel structure and action mechanism, a convenient synthesis method and good safety, exhibits a broad-spectrum and high-efficiency antimicrobial activity, shows no cross resistance with other existing microbicides, can be used for controlling plant diseases in vegetables, fruits, grain crops, oil crops, economic crops, landscape crops and Chinese medicinal materials, and has a particularly good chemical protective effect and systemic therapeutic effect on diseases in drug-resistant crops.

Description

A pyrrolidone compound, its preparation method, and its application as a bactericide.

[0001] This application claims priority to Chinese Patent Application No. CN202411535350.8, filed on October 22, 2024, entitled "A pyrrolinoline dione compound and its preparation method and application as a bactericide", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of agricultural chemistry, specifically to a pyrrolidone compound, its preparation method, and its application as a fungicide. Background Technology

[0003] Safe and efficient selective pesticides are indispensable production materials in modern agriculture. However, due to their single site of action, selective pesticides easily lead to resistance problems caused by genetic variations in pests. Many existing pesticides are known to have the same mode of action, resulting in cross-resistance. Plant pathogens with high reproduction rates and rapid mutation are particularly prone to resistance under pesticide selection pressure, leading to crop disease control failures, and there are few alternative pesticides available. Therefore, discovering new pesticide targets and developing selective pesticides with novel modes of action is a crucial need for controlling pesticide resistance and ensuring sustainable pest control.

[0004] Through decades of fundamental research on the toxicology and resistance of bactericides, the inventors of this patented technology have gained a profound understanding of the specificity and precision of the interaction between ligand small molecule compounds and receptor proteins. That is, small molecule compounds can only bind to specific sites on the structure of specific protein molecules, and the binding force at these sites depends on the fine structure of both the ligand and the receptor. Differences in individual amino acids at the drug sensitivity sites of target proteins in different species determine the selectivity of the ligand small molecule compound, and subtle changes or optimizations in the structure of the small molecule compound determine its binding mode and binding force with the receptor protein, as well as the rate of cellular absorption. Therefore, the fine structure of the small molecule compound determines its antibiotic spectrum and biological activity. Summary of the Invention

[0005] The purpose of this application is to provide a pyrrolidone compound that can be used as an active ingredient in pesticides.

[0006] Another objective of this application is to provide a method for preparing one of the aforementioned pyrrolidone compounds.

[0007] Another objective of this application is to provide an agricultural fungicide with the aforementioned pyrrolidone compound as the active ingredient.

[0008] Another objective of this application is to provide the application of the above-mentioned pyrrolidone compound or an agricultural fungicide with the above-mentioned pyrrolidone compound as the active ingredient in the prevention and control of plant diseases.

[0009] To achieve the above-mentioned objectives, this application provides the following technical solution:

[0010] This application provides a pyrrolidone compound having the structure shown in Formula I:

[0011] This application provides a method for preparing a pyrrolidone compound as described in the above technical solution, characterized by comprising the following steps:

[0012] Compound II, maleic anhydride, a catalyst, and an organic solvent were mixed and reacted to yield a pyrrolidone compound having the structure shown in Formula I, wherein compound II has the structure shown in Formula II.

[0013] Preferably, the molar ratio of compound II to maleic anhydride is 1:0.95 to 1.20; the catalyst is selected from one or more of methanesulfonic acid, p-toluenesulfonic acid, and benzenesulfonic acid; and the organic solvent is selected from one or more of benzene, toluene, xylene, and cyclohexane.

[0014] The above-described technical solution involves mixing compound II, maleic anhydride, a catalyst, and an organic solvent, followed by a reaction. Specifically, this reaction is carried out by heating under reflux to achieve a dehydration reaction. The reaction is complete when the amount of dehydrated material reaches the theoretical value. The product system is then cooled, followed by washing and drying to obtain a crude product. In this application, the washing solution is preferably a saturated NaHCO3 solution followed by distilled water. The washing with saturated NaHCO3 solution is preferably performed 2-4 times, primarily to remove residual dehydrating catalyst. The washing with distilled water is preferably performed until the solution reaches neutrality. In this application, the drying agent is anhydrous Na2SO4 or anhydrous MgSO4, preferably anhydrous Na2SO4. This invention removes moisture through drying. After drying, the obtained material is preferably filtered, and the collected liquid is subjected to vacuum distillation to remove the organic solvent, yielding the crude product.

[0015] After obtaining the crude product, this application further purifies the crude product by recrystallization or column chromatography to obtain a pyrrolinolinedione compound having the structure shown in Formula I. Specifically, the crude product in this application is a solid crude product, which can be recrystallized or separated by column chromatography. In this application, the recrystallization reagent is preferably a mixture of petroleum ether and ethyl acetate prepared in a volume ratio of 100:0 to 100; preferably, the recrystallization process also includes filtration, collecting the filter cake, and drying it to obtain a pyrrolinolinedione compound with the structure shown in Formula I. In this application, the eluent used for column chromatography is preferably a mixture of petroleum ether and ethyl acetate prepared in a volume ratio of 100:0 to 100. In this application, the column chromatography separation preferably further includes: removing the solvent from the resulting eluent by vacuum distillation to obtain a pyrrolinolinedione compound having the structure shown in Formula I; the pyrrolinolinedione compound provided in this application is a yellow, light yellow, or white solid.

[0016] This application provides an agricultural fungicide composed of an active ingredient and excipients; the active ingredient refers to a pyrrolidone compound as described in the above technical solution. The excipients are preferably agriculturally acceptable excipients, and more preferably include one or more of the following: carrier, solvent, co-solvent, surfactant, dispersant, emulsifier, wetting agent, suspending agent, thickener, stabilizer, defoamer, antifreeze agent, and synergist.

[0017] The content range of the active ingredient in the agricultural fungicide described in the above technical solution is 3-95% (by weight).

[0018] The agricultural fungicide described in the above technical solution is formulated from at least one of the following: emulsifiable concentrate, suspension concentrate, suspension emulsion, aqueous solution, water-in-oil emulsion, microemulsion, powder, wettable powder, soluble powder, granules, water-dispersible granules, oil suspension, fumigant, and bait. The formulation of the agricultural fungicide described in the above technical solution is prepared according to the methods described in *Pesticide Formulation Processing and Management*, edited by Shen Jinliang, China Agricultural Press, Beijing (2002), and *Pesticide Formulation Science*, edited by Wang Kaiyun, China Agricultural Press, Beijing (2002).

[0019] This application provides the application of a pyrrolidone compound or an agricultural fungicide as described in the above technical solution in the prevention and control of plant diseases.

[0020] Preferably, the plant diseases include those caused by one or more of pathogenic fungi, pathogenic oomycetes, and pathogenic bacteria.

[0021] Preferably, the plant disease is caused by pathogenic fungi such as *Fusarium*, *Magnaporthe*, *Rhizoctonia*, *Setosphaeria*, *Bipolaris*, *Botrytis*, *Glomerella*, *Alternaria*, *Sclerotinia*, *Didymella*, *Cercospora*, *Puccinia*, *Uromyces*, and *Phakopsora*; or by pathogenic fungi such as *Phytophthora*. Diseases caused by oomycetes such as *Phytophthora*, *Sclerophthora*, *Sclerospora*, *Plasmopara*, *Peronophythora*, *Pseudoperonospora*, *Peronospora*, *Bremia*, *Paraperonospora*, *Albugo*, and *Pythium*; and plant diseases caused by pathogenic bacteria such as *Xanthomonas*, *Pseudomonas*, and *Erwinia*. Examples include, but are not limited to, wheat scab, wheat rust, wheat powdery mildew, wheat stem base rot, rice blast, rice bakanae disease, rice sheath blight, seedling bacterial wilt, rice bacterial leaf blight, rice bacterial stripe, corn large leaf spot, corn small leaf spot, corn rust, corn stem base rot, citrus and kiwifruit canker, fruit and vegetable gray mold, cruciferous crop sclerotinia rot, peanut brown spot, watermelon vine blight, potato and tomato late / early blight, pepper blight, Chinese cabbage soft rot, soybean blight, soybean rust, lychee blight, cucumber downy mildew, cucumber angular leaf spot, vegetable downy mildew, grape downy mildew, and various fruit and vegetable crops anthracnose and powdery mildew.

[0022] Preferably, the plants include one or more of the following: vegetables, fruits, grain crops, oil crops, garden crops, medicinal herbs, lawns, and other plants.

[0023] This application provides a technical solution for determining the antibacterial spectrum and antibacterial activity of a pyrrolidone compound or an agricultural fungicide as described above.

[0024] Specifically, using plant pathogen materials preserved and temporarily collected in this laboratory, the effects of the aforementioned pyrrolidone compound or agricultural fungicide on *Fusarium graminearum* (wheat scab), *Magnaporthe grisea* (rice blast fungus), *F. moniliforme* (rice bakanae disease pathogen), *Setosphaeria turcica* (corn leaf spot pathogen), *Bipolaris madis* (corn leaf spot pathogen), *Botrytis cinerea* (gray mold pathogen), *Glomerella cingulata* (anthracnose pathogen), *Alternaria solani* (early blight pathogen), *Sclerotinia sclerotiorum* (sclerotinia sclerotiorum), *Didymella bryoniae* (watermelon vine blight pathogen), and *Cercospora* (peanut brown spot pathogen) were determined. The inhibitory activity of the pyrrolidone compound or an agricultural fungicide on the germination of conidia of 11 pathogenic fungi, including Phytophthora infestans (potato and tomato wilt), Phytophthora soja (soybean wilt), Phytophthora capsici (pepper wilt), Phytophthora parasitica (tobacco black shank wilt), Peronophthora litchii (lychee wilt), Plasmopara viticola (grape wilt), Pseudoperonospora cubensis (cucumber wilt), and Pythium sp. (rice seedling blight) was determined. The inhibitory activity of the pyrrolidone compound or an agricultural fungicide on the sporangium germination of 8 plant pathogenic oomycetes, including Psytophthora infestans (potato and tomato wilt), Psytophthora soja (soybean wilt), Psytophthora capsici (pepper wilt), Phytophthora parasitica (tobacco black shank wilt), Peronophthora litchii (lychee wilt), Plasmopara viticola (grape wilt), Pseudoperonospora cubensis (cucumber wilt), and Pythium sp. (rice seedling blight wilt) was also determined. The study investigated the inhibitory activity of seven plant pathogenic bacteria, including *X. oryzicola* (bacterial leaf streak of rice), *Pseudomonas solanacearum* (bacterial wilt of tomato), *X. citri* (bacterial canker of citrus), *Erwinia carotovora* (bacterial soft rot of Chinese cabbage), *Erwinia amylovora* (bacterial fire blight of pear), and *Acidovorax citrulli* (bacterial fruit spot).

[0025] Specifically, the bioactivity of the pyrrolidone compound or agricultural fungicide against plant pathogenic fungi and oomycetes was determined using the classic spore germination method. The pyrrolidone compound or agricultural fungicide was dissolved in dimethyl sulfoxide (DMSO) or methanol to obtain a stock solution with a concentration of 10 mg / mL or 20 mg / mL, which was then stored for a short period at 4°C. Before use, it was diluted with tap water containing 1% orange juice to a concentration of 20.0, 6.0, 2.0, 0.6, 0.2, 0.06, or 0 (CK) μg / mL. The prepared solution was then mixed 1:1 with a fungal conidia suspension or an oomycete sporangium suspension to achieve a final concentration of 10.0, 3.0, 1.0, 0.3, 0.1, 0.03, or 0 (CK) μg / mL. (Per petri dish) Add 10 mL of the drug solution and spore mixture, and culture statically for 5–8 hours at the appropriate temperature for spore germination of different pathogens. When the spore germination rate of the control treatment reaches 95%, investigate the minimum drug concentration (MIC) that completely inhibits spore / sporangium germination under a microscope.

[0026] The bioactivity of the pyrrolidone compound or agricultural fungicide against plant pathogenic bacteria was determined using a turbidimetric method. The prepared drug solution was mixed 1:1 with a bacterial suspension with a turbidity of 50 to final concentrations of 10.0, 3.0, 1.0, 0.3, 0.1, 0.03, and 0 (CK) μg / mL, and the initial turbidity was measured. Subsequently, the mixture was incubated at 28°C for 72 hours, and the minimum inhibitory concentration (MIC) of the agent that completely inhibited bacterial growth was determined using a turbidimeter.

[0027] The preparation of pathogen inoculum involved culturing the pathogenic fungus on PDA solid medium plates or liquid medium, collecting conidia, and preparing them into 1×10⁻⁶ inoculum, referring to relevant plant pathology literature. 5 A spore suspension of / mL was used for spore germination inhibition activity assays and inoculation experiments on plants.

[0028] The preparation of pathogenic oomycete inoculum involves rinsing collected downy mildew-infected grape or cucumber leaves with tap water, placing them on moist filter paper in a 15cm diameter glass petri dish, covering them, and incubating them overnight at 18℃. The sporangia are then washed off with 4℃ tap water and prepared into 10... 5 A sporangium suspension of 1 × 10⁶ mL can be prepared; alternatively, *Phytophthora indicum* and *Phytophthora capsici* can be cultured separately on CMA medium at 20°C for 3 days. After 3 days, mycelia are picked from the edge of the colony and inoculated into Petri liquid culture medium. The mixture is then shaken for 2–3 days, filtered through gauze, and centrifuged at 1000 rpm for 5 minutes to collect the sporangia. The sporangia are then resuspended in sterile water, and the sporangium concentration is adjusted to 1 × 10⁶ mL. 5 A sporangium suspension of 1 sporangium / mL was used to determine sporangium germination inhibition activity and inoculation experiments on plants.

[0029] The preparation of pathogenic bacterial inoculum involves streaking bacteria on NA (beef broth agar) slants, washing off the bacterial pus with sterile water, and preparing a bacterial suspension with a turbidity of 50 for growth inhibition activity determination.

[0030] The determination of the antibacterial activity of a pyrrolidone compound or an agricultural fungicide described in the above technical solution refers to literature such as "Biological Determination of Pesticides" edited by Shen Jinliang (China Agriculture Press, 2013, Beijing). The antibacterial activity against other plant pathogens can also be determined according to these literatures.

[0031] This application provides an evaluation scheme for the application effect of the agricultural fungicide described in the above-mentioned technical solution in the control of plant diseases. Using 15-1000g of the active ingredient of the agricultural fungicide per hectare, and employing seed treatment, soil treatment, and spraying methods, the control effect of the agricultural fungicide on rice bakanae disease, rice seedling wilt, rice blast, rice bacterial leaf streak, potato late blight, pepper blight, and grape downy mildew was determined.

[0032] Specifically, the control of rice bakanae disease involved diluting an agricultural fungicide suspension containing one of the aforementioned pyrrolidone compounds with water to a concentration of 100, 200, and 400 mg / L. Infected rice seeds were soaked in 150 L of the solution per hectare, with water soaking serving as a control. After stirring, the seeds were soaked for 48 hours under natural conditions at 20–30°C. The seeds were then removed, sown in plastic basins, and cultured in a greenhouse for 21 days. The disease incidence and control efficacy of each treatment were then investigated.

[0033] Specifically, to prevent and control bacterial wilt of rice seedlings, a water-dispersible granule fungicide containing one of the aforementioned pyrrolidone compounds is mixed with 225 kg of fine soil at a rate of 1000, 750, or 500 g of active ingredient per hectare. The mixture is then applied when the seedlings have two leaves and one bud. Ten days later, the mortality rate of each treatment seedbed is investigated, and the control efficacy is calculated.

[0034] Specifically, to control rice blast, a water-dispersible granule fungicide containing one of the aforementioned pyrrolidone compounds is diluted with water to a concentration of 100, 200, or 400 mg / L. 750 L of the solution is sprayed per hectare onto 3-leaf stage seedlings. 24 hours later, a suspension of rice blast fungal spores is sprayed on the seedlings. After overnight in darkness and humidity, the seedlings are transferred to a greenhouse for cultivation. The efficacy is assessed after 10 days.

[0035] Specifically, to control bacterial leaf streak in rice, the emulsifiable concentrate containing one of the aforementioned pyrrolidone compounds is diluted with water to a concentration of 250, 500, or 800 mg / L. The solution is then sprayed at a rate of 750 L per hectare during the booting stage. A second spray is applied 7 days later, and the efficacy is assessed 10 days after each application.

[0036] Specifically, to control grape downy mildew, a suspension of a pyrrolidone compound is diluted with water to 3.125, 6.25, 12.5, 25, and 50 mg / L. The solution is sprayed onto the underside of grape leaves until the solution begins to run off (750–1000 L of solution per hectare). After drying, a suspension of downy mildew sporangia is sprayed on the leaves 24 hours later. The leaves are then placed in a humidified environment at 20–25°C and cultured under alternating light and dark conditions (12 hours each). The control efficacy is assessed after 7 days.

[0037] Specifically, to control late blight of potatoes and blight of peppers, the water-dispersible granules of the aforementioned pyrrolidone compound are diluted with water to a concentration of 125, 250, or 500 mg / L. The solution is sprayed until the leaves begin to run off, then dried. After 24 hours, a suspension of fungal sporangia is dripped onto the leaves. The mixture is kept moist overnight and then transferred to a greenhouse (20–30°C) for cultivation. The efficacy is assessed after 7 days.

[0038] This application can also be used to determine the control or treatment effects on other plant diseases using known chemical treatments and pathogen inoculation methods.

[0039] This application provides a method for determining the cross-resistance between a pyrrolidone compound or an agricultural fungicide and existing fungicides, as described in the above technical solution.

[0040] Specifically, wild-type susceptible strains of *Botrytis cinerea* and polyresistant strains resistant to benzimidazoles, dicarboximides, aminopyrimidines, benzylpyrroles, QoIs, and SDHIs are inoculated and cultured on a culture medium plate containing 20 μg / mL of a pyrrolidone compound or an active ingredient of an agricultural fungicide as described in the above technical solution; or wild-type susceptible strains of *Phytophthora capsici* and strains resistant to benzimidazoles, dimethomorphs, QoIs, and oxosteroside-binding protein inhibitors are inoculated and cultured; the presence or absence of drug resistance is determined based on whether the strain can grow.

[0041] The beneficial effects of this application are as follows: The pyrrolidone compound or an agricultural fungicide with it as an active ingredient described in this application has ideal broad-spectrum antibacterial activity against plant pathogenic fungi, oomycetes, and bacteria. It is also safe for plants, selective, and environmentally adaptable, conforming to the development direction of original fungicides that are safe, efficient, low-toxic, low-residue, and environmentally compatible, and meeting the requirements for ensuring environmental and ecological safety. It does not exhibit cross-resistance with existing fungicides and can be used in combination with multiple fungicides to control drug-resistant diseases, especially solving the problem of having no effective treatment for multidrug-resistant diseases. Its advantages include high antibacterial activity, long-lasting effect, low dosage per unit area, low cost, long suitable application period, high input-output ratio, and good economic benefits, which align with the requirements for promoting high-quality green development in agriculture, rural areas, and farmers. Detailed Implementation

[0042] The inventors of this patented technology, through toxicological studies of drug-target protein interactions, discovered a transmembrane motor protein with vital life functions in an important plant pathogenic fungus (Fusarium graminearum). Furthermore, the key amino acids at the binding sites to small molecules show significant differentiation in animals, plants, and microorganisms, providing patentability for the creation of safe, highly effective, and selectively targeted inhibitors. Based on the structural characteristics of the drug sensitivity sites of proteins from different plant pathogenic fungi, the inventors used computer simulation screening to discover that pyrrolidone small molecule compounds can interact with the functional sites of proteins. By substituting the H at the 1, 3, and 4 positions of pyrrole with phenyl, alkyl, and halogen compounds, either alone or in different combinations, they found that introducing a phenyl group at the 1 position enhances antibacterial activity. Further, groups such as -Cl, -Br, -F, -CF3, -CH3, -C2H5, -n-C3H7, -i-C3H7, -NH2, -NO2, and -CN were introduced onto the benzene ring. Structural optimization and antibacterial spectrum and bioactivity assays were performed. Compounds with ethyl groups introduced at positions 2 and 6 and a methyl group introduced at position 4 on the benzene ring were discovered. Their lipophilic nature facilitates absorption by fungi, oomycetes, and bacteria, maximizing the antibacterial spectrum and significantly increasing antibacterial activity compared to other derivatives. A novel pyrrololinide dione compound, 1-(2,6-diethyl-4-methylbenzene)-1H-pyrrole-2,5-dione (hereinafter referred to as "a pyrrololinide dione compound"), with strong broad-spectrum bactericidal activity against plant pathogenic bacteria, fungi, and oomycetes, was invented.

[0043] The inventor of this patented technology uses *Fusarium graminearum*, the pathogen causing Fusarium head blight in wheat and other crops; *Magnaporthegrisea*, the pathogen causing rice blast; *F. moniliforme*, the pathogen causing rice seedling blight; *Setosphaeria turcica*, the pathogen causing corn leaf blight; *Bipolaris madis*, the pathogen causing corn leaf spot; *Botrytis cinerea*, the pathogen causing gray mold in fruits and vegetables; *Glomerella cingulata*, the pathogen causing anthracnose; *Alternaria solani*, the pathogen causing early blight; *Sclerotinia sclerotiorum*, the pathogen causing sclerotinia rot; *Didymella bryoniae*, the pathogen causing watermelon vine blight; and *Cercospora*, the pathogen causing peanut brown spot. Eleven pathogenic fungi, including *Phytophthora infestans* (causing late blight in potatoes and tomatoes), eight plant pathogenic oomycetes, including *Phytophthora soja* (causing blight in soybeans), *Phytophthora capsici* (causing blight in peppers), *Phytophthora parasitica* (causing black shank in tobacco), *Peronophthora litchii* (causing blight in litchis), *Plasmopara viticola* (causing downy mildew in grapes), *Pseudoperonospora cubensis* (causing downy mildew in cucumbers), and *Pythium sp.* (causing rice seedling blight), are included in the list of pathogenic fungi that cause late blight in potatoes and tomatoes. *Xanthomonas* (causing bacterial blight in rice) is also included in the list of pathogenic oomycetes that cause bacterial blight in rice. Using seven plant pathogenic bacteria as materials, including *X. oryzicola* (bacterial leaf streak of rice), *Pseudomonassolanacearum* (bacterial wilt of tomato), *X. citri* (bacterial canker of citrus), *Erwinia carotovora* (bacterial rot of Chinese cabbage), *Erwinia amylovora* (bacterial blight of pear), and *Acidovorax citrulli* (bacterial spot of fruit blight), the antibacterial spectrum and antibacterial activity of the above-mentioned pyrrolidone compounds were determined. These compounds were then processed into fungicide formulations such as suspension concentrates, water-dispersible granules, and emulsifiable concentrates, and used in control experiments against different plant diseases, thus completing this invention.

[0044] The following examples will provide a better understanding of this application, but they should not be construed as limiting the scope of protection of this application.

[0045] Example 1: Preparation of a pyrrolidone compound (Formula I)

[0046] The implementation steps of this embodiment are as follows:

[0047] 0.02 mol of compound II, 0.0202 mol of maleic anhydride, and 0.0005 mol of methanesulfonic acid were mixed thoroughly in 40 mL of toluene. The mixture was then heated under reflux with stirring to separate the water. The reaction was stopped when 0.02 mol of water was separated. The resulting reaction solution was cooled, and saturated NaHCO3 solution was added to the reaction solution at a volume ratio of 1:1.2 for washing. The washing was repeated twice, followed by washing with distilled water in the same manner. Wash until neutral, dry the resulting neutral combined reaction solution with anhydrous Na2SO4, filter, collect the filtrate, and distill under reduced pressure using a rotary evaporator to obtain a crude solid product. Recrystallize the crude solid product in a mixed solution of petroleum ether and ethyl acetate in a volume ratio of 100:10, filter, and dry in an oven at 50°C to obtain a pale yellow solid pyrrolidone compound as shown in Formula I, with a melting point of 126.0–127.5°C and a yield of 98%. Its NMR and high-resolution mass spectrometry data are as follows:

[0048] 1 H-NMR (400MHz, CDCl3) δ: 7.01 (s, 2H, ArH), 6.87 (s, 2H, COCH=CHCO), 2.36 (q, J=7.6Hz, 4H, 2CH2), 2.35 (s, 3H, ArCH3), 1.12 (t, J=7.6Hz, 6H, 2CH3); HRMS (ESI): m / z calcd for C 15 H 18 NO2([M+H] + ): 244.1332, found: 244.1332.

[0049] Example 2: Preparation of a pyrrolidone compound (Formula I)

[0050] The implementation steps of this embodiment are as follows:

[0051] 0.10 mol of compound II, 0.10 mol of maleic anhydride, and 0.002 mol of p-toluenesulfonic acid were mixed thoroughly in 100 mL of benzene. The mixture was then heated under reflux with stirring to separate the water. The reaction was stopped when 0.10 mol of water was separated. The resulting reaction solution was cooled, and saturated NaHCO3 solution was added to the reaction solution at a volume ratio of 1:1 for washing. The mixture was washed three times, followed by washing with distilled water in the same manner. The mixture was washed until neutral, and the resulting neutral combined reaction solution was dried with anhydrous Na2SO4. After filtration, the filtrate was collected and distilled under reduced pressure using a rotary evaporator to obtain a solid crude product. The solid crude product was recrystallized in a mixed solution of petroleum ether and ethyl acetate in a volume ratio of 100:8, then filtered and dried in an oven at 55°C to obtain a white solid pyrrolidone compound with a melting point of 126.2–127.1°C and a yield of 99%. Its nuclear magnetic resonance and high-resolution mass spectrometry data were the same as those determined in Example 1.

[0052] Example 3: Determination of the antibacterial spectrum and bactericidal activity of a pyrrolidone compound.

[0053] According to the above technical solution, the bioactivity of a pyrrolinodinone compound against plant pathogenic fungi and oomycetes was determined using the classic spore germination method. A pyrrolinodinone compound provided in this application was dissolved in dimethyl sulfoxide (DMSO) or methanol to obtain a stock solution with a concentration of 10 mg / mL or 20 mg / mL. This stock solution was then diluted with tap water containing 1% orange juice to concentrations of 20.0, 6.0, 2.0, 0.6, 0.2, 0.06, and 0 (CK) μg / mL. The prepared stock solution was then mixed 1:1 with a suspension of fungal conidia or oomycete sporangia to achieve final concentrations of 10.0, 3.0, 1.0, 0.3, 0.1, 0.03, and 0 (CK) μg / mL. (Per culture dish) Add 10 mL of the drug solution and spore mixture, and culture statically for 5–8 hours at the appropriate temperature for spore germination of different pathogens. When the spore germination rate of the control treatment reaches 95%, investigate the minimum drug concentration (MIC) that completely inhibits spore / sporangium germination under a microscope.

[0054] The results showed that the lowest concentration (MIC) of the pyrrolidone compound that inhibited the germination of conidia of *Fusarium graminearum* (wheat scab), *F. moniliforme* (rice blast fungus), *Magnaporthegrisea* (rice blast fungus), *Botrytis cinerea* (gray mold), *Glomerella cingulata* (anthracnose causal agent), *Sclerotinia sclerotiorum* (sclerotinia sclerotiorum), and *Didymella bryoniae* (watermelon vine blight) was 1.0 μg / mL, and the germination of sporangia of *Phytophthora infestans* (potato and tomato late blight), *Phytophthora capsici* (pepper blight causal agent), *Phytophthora parasitica* (tobacco black shank causal agent), *Peronophthora litchii* (lychee blight causal agent), and *Plasmopara viticola* (grape downy mildew) was 1.0 μg / mL. The MIC for *Cercospora* (peanut brown spot causal agent) was also 1.0 μg / mL. The MIC (micron activity) for the germination of conidia of *Phytophthora soja*, *Pythium sp.*, and *Pseudoperonospora cubensis* sporangia was 3.0 μg / mL; the MIC for the germination of conidia of *Setosphaeria turcica*, *Bipolaris madis*, and *Alternaria solani* was 10.0 μg / mL. At a concentration of 0.03 μg / mL, except for *Setosphaeria turcica*, *Bipolaris madis*, and *Alternaria solani*, where the conidia germination rate was above 50%, the germination rates of conidia of other fungi and sporangia of oomycetes were all below 50%. This indicates that the LD50 of this compound against most pathogenic fungi and oomycetes is low. 50 Less than 0.03 μg / mL.

[0055] A bacterial suspension with a turbidity of 50 was mixed with drug solutions of different concentrations at a 1:1 ratio to achieve final drug concentrations of 10.0, 3.0, 1.0, 0.3, 0.1, 0.03, and 0 (CK) μg / mL. The mixture was incubated on a shaker (180 r / min) for 3 days, and the minimum inhibitory concentration (MIC) was determined by turbidity. The results showed that the pyrrolidone compound described in this application exhibited a MIC of 1 μg / mL against the growth of seven plant pathogenic bacteria, including *Xanthomonas oryzae* (bacterial leaf blight of rice), *X. oryzicola* (bacterial leaf streak of rice), *Pseudomonas solanacearum* (bacterial wilt of tomato), *X. citri* (citrus canker), *Erwinia carotovora* (soft rot of Chinese cabbage), *Erwinia amylovora* (fire blight of pear), and *Acidovorax citrulli* (fruit spot disease), demonstrating strong bactericidal activity.

[0056] The antibacterial activity assay results of the pyrrolinolinedione compound described in this application show that the compound exhibits strong broad-spectrum fungicidal activity against 26 representative plant pathogenic fungi, oomycetes, and bacteria tested, indicating that the target of the compound is conserved among different pathogenic microorganisms. The pyrrolinolinedione compound described in this application, when processed into a fungicide formulation according to the method described in this specification, yields an agricultural fungicide with the pyrrolinolinedione compound as the active ingredient. Further efficacy tests against some common diseases were conducted on plant tissues or seedlings, or field efficacy trials were performed, comparing the results with currently commonly used fungicides, and simultaneously determining its safety to plants.

[0057] Example 4: Preparation of bactericide suspension (20% SC or 50% SC)

[0058] Based on the effective content of the formulation to be processed, weigh 20% of a pyrrolidone compound (300 mesh particle size), 1% of a wetting agent (specifically sodium dodecyl sulfonate), 3% of a dispersing and suspending agent (specifically NNO), 0.2% of a thickener (specifically xanthan gum), 5% of a stabilizer (specifically bentonite), 3% of an antifreeze agent (specifically polyethylene glycol 400), and 0.1% of an antifoaming agent (specifically lauric acid) according to the weight of the effective ingredient; add water to 100% to obtain a suspension with an effective ingredient content of 20%, i.e., a mixture of 20 wt% SC.

[0059] Weigh out 50% of a pyrrolidone compound (300 mesh particle size), 1.5% of a water-soluble wetting agent (specifically, agricultural emulsion 100), 5% of a dispersing and suspending agent (specifically, sodium ethylenediaminetetraacetate), 0.5% of a thickener (specifically, gum arabic), 15% of a stabilizer (specifically, bentonite), 8% of an antifreeze agent (specifically, urea), and 0.2% of an antifoaming agent (specifically, sulfonamide), and add water to 100% to obtain a suspension with an effective ingredient content of 50%, i.e., a mixture of 50 wt% SC.

[0060] The two mixtures were mixed and formulated into slurries, then ground 3 to 4 times in a sand mill. Finally, the pH value, fluidity and wettability were adjusted to obtain bactericide formulations with an effective ingredient content of 20wt%SC or 50wt%SC.

[0061] The sample quality was tested according to the standard method of NY / T 4014-2021. The results showed that the relative error of the effective ingredient content was ±0.1 to 0.5%, there was no stratification or sedimentation after 30 days of indoor storage, and it could maintain a stable suspension state when diluted with water. The effective suspension rate was greater than 90% after standing for 1 hour.

[0062] Example 5: Preparation of water-dispersible granules of bactericide (10% WG or 25% WG)

[0063] Based on the effective content of the formulation to be processed, weigh out 10% of a pyrrolidone compound, 10% of an adjuvant (specifically, a disintegrant), 10% of a disintegrant (specifically, 4:1 ammonium sulfate + sodium chloride), and 70% of a carrier (specifically, silica) to obtain a water-dispersible granule with an effective content of 10%, i.e., a mixture of 10 wt% WG.

[0064] Weigh out 25% of a pyrrolidone compound, 10% of an adjuvant (a mixture of 5% naphthalene sulfonate dispersant GY-D10, 2% sodium butylbenzene sulfonate, and 3% urea), 20% of a disintegrant (specifically, ammonium sulfate and sucrose in a mass ratio of 3:1), and 45% of a carrier (specifically, silica) to prepare a water-dispersible granule with an effective ingredient content of 25%, i.e., a mixture of 25 wt% WG.

[0065] The two mixtures were respectively subjected to air jet milling, and the mixtures with a particle size of less than 10 μm were collected and then extruded, granulated and dried to obtain bactericide formulations with an active ingredient content of 10 wt% WG or 25 wt% WG, respectively.

[0066] The sample quality was tested according to the HG / T 4463-2012 standard method, and the results showed that the above two types of 10wt% WG and 25wt% WG met the quality requirements.

[0067] Example 6: Preparation of bactericide emulsifiable concentrate (10% EC w / v)

[0068] Weigh out 10% of a pyrrolidone compound by volume and dissolve it in about 2 / 3 of the total volume of No. 100 solvent oil. Add 10% w / v of emulsifier (a mixture of 5% agricultural emulsion 600 and 5% Tween 40), and then add No. 100 solvent oil to make up to the set volume to obtain a fungicide formulation with 10% EC (w / v).

[0069] The sample quality was tested according to the standard method of GB / T 1540-2002, and the results showed that the above-mentioned 10% EC w / v met the quality requirements.

[0070] Example 7: Experiment on the control of rice bakanae disease (Fusarium fujikuroi) with agricultural fungicides

[0071] The implementation method of this experimental example is as follows:

[0072] The pyrrolidone compound described in this application is processed into 20% SC; the control agent cyazofamid 25% SC (provided by Jiangsu Pesticide Research Institute Co., Ltd.)

[0073] Experimental conditions: Greenhouse pot experiment;

[0074] Experimental method: The above-mentioned test preparation samples were diluted with tap water to obtain solutions with effective ingredient contents of 100 mg ai / L, 200 mg ai / L and 400 mg ai / L respectively. Infected rice seeds were soaked in 150 L of solution (15-60 g ai / ha) per hectare. After soaking at room temperature (20-30℃) for 48 hours, the seeds were germinated at 25-30℃ for 48 hours, sown in plastic pots, and then placed in a greenhouse for 21 days before checking the disease incidence of the seedlings.

[0075] Prevention efficacy % = [1 - (disease incidence of treated seedlings ÷ disease incidence of blank control seedlings)] × 100.

[0076] Experimental Results: Twenty-one days after sowing, the cumulative incidence of bakanae disease in seedlings soaked in clean water reached 16.4%. Seed soaking in 100, 200, and 400 mg / L solutions of an agricultural fungicide (20% SC) containing a pyrrolidone compound as the active ingredient showed control efficacy of 86.7%, 93.9%, and 98.8% against bakanae disease, respectively, significantly higher than the control efficacy of 80.4%, 84.8%, and 88.1% at the same concentration. Furthermore, all soaking treatments resulted in normal seed germination and emergence, with no observed phytotoxicity.

[0077] Example 8: Experiment on the control of bacterial wilt in rice seedlings with agricultural fungicides

[0078] The implementation method of this experimental example is as follows:

[0079] The pyrrolidone compound described in this application is processed into 10% WG; the control agent is 4% metalaxyl-methyl-fludioxonil-pyraclostrobin SC (produced by Anhui Fengle Agricultural Chemical Co., Ltd., purchased online).

[0080] Experimental conditions: Field seedbed experiment; Rice variety "Yinliangyou 836".

[0081] Experimental Method: The above-mentioned 10% WG test agent was prepared by mixing 1000, 750, and 500 g of active ingredient per hectare (ai) with 450 kg of fine soil to prepare "toxic soil". When the seedlings had two leaves and one bud, 45 g of the toxic soil was applied per square meter of seedbed. The seedling mortality rate was investigated and the control efficacy was calculated after 10 days.

[0082] The efficacy percentage is calculated as follows: [1 - (seedling mortality rate of treated seedlings ÷ seedling mortality rate of blank control seedlings)] × 100.

[0083] Experimental results: The seedling mortality rate of the control group treated with untreated fine soil was 14.34%. Soil treatments using 10% WG agricultural fungicide (containing a pyrrolidone compound as the active ingredient) at concentrations of 1000, 750, and 500 g ai / ha showed control efficacy against bacterial wilt of 96.4%, 89.6%, and 80.3%, respectively, all significantly higher than the 73.3% control efficacy of the control treatment (750 g ai / ha). Seedlings in all soil treatments grew normally, with no observed phytotoxicity.

[0084] Example 9: Experiment on the control of rice blast by agricultural fungicides

[0085] The implementation method of this experimental example is as follows:

[0086] The experiment used 10% and 25% water-dispersible granules of a fungicide with a pyrrolidone compound as the active ingredient as described in this application, and the control agent was 40% isoprothiolane emulsifiable concentrate produced by Shandong Tianrong Biotechnology Co., Ltd. (purchased online) for rice blast control.

[0087] Experimental conditions: Greenhouse pot experiment;

[0088] Experimental Methods: The tested fungicide samples were weighed and diluted with water to concentrations of 400 mg / L, 200 mg / L, and 100 mg / L, respectively, based on their effective content. The control fungicide, isoprothiolane, was diluted with water to concentrations of 500 mg / L and 250 mg / L. Four pots of 3-leaf stage rice seedlings (Sujing 4699, a moderately susceptible rice variety to rice blast) were sprayed with these solutions. After 24 hours, the leaves were inoculated with conidial solution of Magnaphalthegrisea. The plants were then placed at 25°C, kept moist, and in darkness for 12 hours before being transferred to a greenhouse (20–30°C) for cultivation. The efficacy of the compounds in controlling rice blast was determined. Ten days after inoculation, the number of rice blast lesions on the second and third leaves from the bottom was counted, and the control efficacy was calculated by comparing the results with the control.

[0089] Control efficacy % = [1 - (average number of lesions on treated leaves ÷ average number of lesions on blank control leaves)] × 100.

[0090] Experimental results: The results are shown in Table 1.

[0091] Table 1: Control efficacy of agricultural fungicides against rice blast during the seedling stage

[0092] The results showed that the agricultural fungicide using a pyrrolidone compound as the active ingredient described in this application had a superior preventive effect against rice blast compared to the control agent, and its effect was positively correlated with the effective dose of the treatment, but independent of the formulation content. No adverse effects were observed on seedling growth in any of the treatments.

[0093] Example 10: Experiment on the control of bacterial leaf streak of rice with agricultural fungicides

[0094] The implementation method of this experimental example is as follows:

[0095] One of the pyrrolidone compounds of this application was processed into a 10% emulsifiable concentrate (EC) according to this specification, with a control agent of 20% thiazolyl zinc SC (provided by Zhejiang Xinong Co., Ltd.).

[0096] Experimental conditions: Field; Rice variety: Yinliangyou 836; Growth period: Booting stage

[0097] Experimental Method: The above-mentioned test formulation samples were diluted with tap water to obtain solutions with active ingredient concentrations of 250 mg ai / L, 500 mg ai / L, and 800 mg ai / L, respectively. 750 L of solution was sprayed per hectare (187.5–600 g ai / ha). The control was sprayed with water. A second application was made after a 7-day interval. The disease incidence rate on the flag leaf and the second leaf from the top was examined after 10 days. The control effect was calculated as follows:

[0098] Control efficacy % = [1 - (incidence rate of treated leaves ÷ incidence rate of blank control leaves)] × 100.

[0099] The experimental results showed that 7 days after the first application, approximately 15% of the leaves in the control group began to show signs of disease. Ten days after the second application, the disease incidence rate in the control group reached 78.54%. The disease incidence rates in the treatment areas with the agricultural fungicide of this application at 250 mg ai / L, 500 mg ai / L, and 800 mg ai / L were 7.68%, 2.45%, and 0.24%, respectively. The control efficacy was 90.2%, 96.9%, and 99.7%, respectively. It was also noted that the number of lesions on the leaves in the pesticide-treated areas was significantly less than that in the control group.

[0100] Example 11: Experiment on the control of grape downy mildew by agricultural fungicides

[0101] The implementation method of this experimental example is as follows:

[0102] A. Test compound:

[0103] The 20% pyrrolidone compound bactericide suspension (SC) prepared in Example 3 of this application was diluted with water to concentrations of 3.125, 6.25, 12.5, 25.0, 50.0, and 500 mg / L.

[0104] The control reagent was 10% Zengweiying Green OD (manufactured by DuPont). It was diluted with water to concentrations of 3.125, 6.25, 12.5, and 25.0 mg / L.

[0105] 50% dimethomorph WP (produced by Tianjin Hanbang Plant Protection Agent Co., Ltd., available online), 25.0, 50.0, 100.0, and 200.0 mg / L solutions.

[0106] B. Experimental methods and conditions:

[0107] Take the 3rd to 7th healthy leaves from the bottom of a greenhouse potted grape vine (variety: Muscat), rinse with tap water and let dry. Spray different concentrations of the test solution onto the underside or front side of the leaves until the entire leaf surface is wet (equivalent to spraying 1500 kg of solution per hectare or 4.69 g ai to 750 g ai / ha). 24 hours later, spray the underside of the leaves with a suspension of grape downy mildew sporangia. After culturing for 7 days in an artificial climate chamber under light / dark (12 h) conditions, a temperature of 20–25℃, and a relative humidity of RH of 90%–95%, investigate the disease incidence and calculate the control efficacy based on the percentage of leaf area affected (spongina production area).

[0108] Efficacy % = [1 - (average lesion area percentage of the treated area ÷ average lesion area percentage of the blank control area)] × 100.

[0109] C. Experimental Results:

[0110] The test results are listed in Table 2.

[0111] Table 2: Experimental results of agricultural fungicides for the control of grape downy mildew

[0112] The results showed that the agricultural fungicide with pyrrolidone compounds as the active ingredient in this application has a good preventive effect against grape downy mildew. No disease was observed in any leaves treated with solutions of 25, 50, and 500 mg / L. Furthermore, treatment on the upper leaf surface also showed high control efficacy against inoculation on the lower leaf surface, indicating that it has transdermal activity from the upper to the lower leaf surface.

[0113] Example 12: Experiment on the control of potato late blight and pepper blight by agricultural fungicides

[0114] The implementation method of this experimental example is as follows:

[0115] A. Test reagents

[0116] The 20% and 50% pyrrolidone compound suspension (SC) bactericide formulations prepared in Example 3 of this application.

[0117] The control agent is 50% dimethomorph WP (produced by Tianjin Hanbang Plant Protection Agent Co., Ltd., purchased online).

[0118] B. Greenhouse pot experiment conditions

[0119] Potato and chili seedlings at the 5-leaf stage, 2 seedlings per pot; cultivated in a glass greenhouse at a temperature of 20-30℃.

[0120] C. Test Methods

[0121] I. Preparation of test solution:

[0122] Weigh out the above-mentioned compound suspensions and dilute them with water to the effective ingredient concentrations of 500 mg / L, 250 mg / L and 125 mg / L respectively to prepare drug solutions of three treatment concentrations.

[0123] II. Test Procedure:

[0124] Three pots of potato and pepper seedlings were sprayed with three different treatment concentrations of each compound using a throat sprayer until the solution began to drip from the leaves. Twenty-four hours later, 10 μl of the prepared sporangium suspensions of *Phytophthora infestans* (potato late blight causal agent) and *P. capsici* (pepper causal agent) were drip-inoculated at each inoculation point, for a total of 24 leaflets (8 leaves per pot of seedlings). After drying, the pots were placed in a greenhouse and covered with black plastic sheeting for overnight incubation to maintain humidity. The plastic sheeting was then removed, and the plants were incubated for another 7 days. The number and length of lesions were assessed, and the control efficacy was calculated using the following formula:

[0125] Efficacy % = [1 - (average lesion length of the treated ÷ average lesion length of the blank control)] × 100.

[0126] D. Test Results:

[0127] The test results are listed in Table 3.

[0128] Table 3: Experimental results of agricultural fungicides for the control of potato late blight and pepper blight

[0129] The experimental results show that the agricultural fungicide of this application has ideal preventive effects against potato late blight and pepper blight. The control effect is directly proportional to the dosage of the active ingredient tested, and is independent of the content of the processed formulation. An agricultural fungicide of this application, with a pyrrolidone compound as the active ingredient, shows significantly better control effects against both blight and the control agent than the control agent.

[0130] Example 13: Determination of cross-resistance between a pyrrolidone compound and existing fungicides

[0131] Test reagent samples: a pyrrolidone compound of this application, and fungicides with different mechanisms of action such as boscalid, carbendazim, pyrimethanil, iprodione, pyraclostrobin, fludioxonil, metalaxyl, dimethomorph, and fluthiazopyr acetone technical grade, preserved in the laboratory.

[0132] Test method: A pyrrolidone compound of this application and a commonly used fungicide technical were dissolved in methanol and carbendazim was dissolved in 0.1 mol hydrochloric acid to prepare a 10 mg / mL stock solution. The stock solution was then diluted with sterile water to 200 μg / mL and then diluted with PDA medium to prepare a drug-containing medium plate with a final concentration of 20 μg / mL.

[0133] The strains used for testing were laboratory-preserved *Botrytis cinerea* multi-resistant strain B5 and wild-type sensitive strain B1, resistant to boscalid, carbendazim, pyrimethanil, iprodione, azoxystrobin, and fludioxonil; and *Phytophthora capsici* multi-resistant strain PcR and wild-type sensitive strain PcS, resistant to azoxystrobin, metalaxyl, dimethomorph, and fluthiazopyrone. *Botrytis cinerea* and *Phytophthora capsici* were cultured on drug-free PDA and lima bean agar plates, respectively. 5mm diameter mycelial discs were prepared near the edge of the colonies and inoculated onto drug-containing plates. The discs were incubated at 25°C for 5 days. Growth was recorded as "+", non-growth as "-", and no test as " / ". The results are shown in Table 4. The results of growth on drug-containing media indicate that one of the pyrrolinoline dione compounds in this application does not exhibit cross-resistance with existing fungicides, suggesting a novel mechanism of action.

[0134] Table 4. Cross-resistance patterns between a pyrrolidone compound and existing bactericides with different modes of action.

[0135] The above description is merely a preferred embodiment of this application and does not constitute any limitation on this application. Any simple modifications, equivalent changes, or alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall fall within the scope of the technical solution of this application.

Claims

1. A pyrrolidone compound, characterized in that, It has the structure shown in Equation I:

2. The method for preparing a pyrrolidone compound according to claim 1, characterized in that, Includes the following steps: Compound II, having the structure shown in Formula II, maleic anhydride, a dehydration catalyst, and an organic solvent are mixed and subjected to a dehydration reaction to obtain pyrrolidone compounds having the structure shown in Formula I.

3. The method for preparing a pyrrolidone compound according to claim 2, characterized in that, The molar ratio of compound II to maleic anhydride is 1:0.95 to 1.20; The dehydration catalyst is selected from one or more of methanesulfonic acid, p-toluenesulfonic acid and benzenesulfonic acid; The organic solvent is selected from one or more of benzene, toluene, xylene, and cyclohexane.

4. The method for preparing a pyrrolidone compound according to claim 2 or 3, characterized in that, The dehydration reaction is carried out under heating and reflux conditions.

5. The method for preparing a pyrrolidone compound according to claim 2, characterized in that, The dehydration reaction further includes: cooling the resulting product system, then washing and drying it sequentially to obtain a crude product; and then recrystallizing or purifying the crude product by column chromatography to obtain a pyrrolidone compound having the structure shown in Formula I.

6. The method for preparing a pyrrolidone compound according to claim 5, characterized in that, The washing solution used is a saturated NaHCO3 solution followed by distilled water, and the washing is performed 2 to 4 times with the saturated NaHCO3 solution. The drying agent used is anhydrous Na2SO4 or anhydrous MgSO4. After drying, the process further includes filtering the obtained material, collecting the liquid, and removing the organic solvent by vacuum distillation to obtain the crude product.

7. The method for preparing a pyrrolidone compound according to claim 5, characterized in that, The recrystallization reagent used for recrystallization is a mixed reagent prepared by petroleum ether and ethyl acetate in a volume ratio of 100:0 to 100; the recrystallization process further includes: filtering the obtained material, collecting the filter cake and drying it to obtain a pyrrolidone compound with the structure shown in Formula I. The eluent used in the column chromatography separation is a mixed reagent prepared by mixing petroleum ether and ethyl acetate in a volume ratio of 100:0 to 100; the column chromatography separation further includes: removing the solvent by vacuum distillation of the obtained eluent to obtain a pyrrolidone compound having the structure shown in Formula I.

8. An agricultural fungicide, characterized in that, It is composed of an active ingredient and excipients, wherein the active ingredient is a pyrrolidone compound as described in claim 1.

9. The agricultural fungicide according to claim 8, characterized in that, The excipients include one or more of the following: carrier, solvent, cosolvent, surfactant, dispersant, emulsifier, wetting agent, suspending agent, thickener, stabilizer, defoamer, antifreeze agent, and synergist.

10. The agricultural fungicide according to claim 8 or 9, characterized in that, The active ingredient content in the agricultural fungicide is 3-95% by mass.

11. The agricultural fungicide according to claim 8 or 9, characterized in that, The formulation of the agricultural fungicide is selected from emulsifiable concentrates, suspension concentrates, suspension emulsions, aqueous solutions, water-in-oil emulsions, microemulsions, powders, wettable powders, soluble powders, granules, water-dispersible granules, oil suspensions, fumigants, or baits.

12. The application of a pyrrolidone compound as described in claim 1 or an agricultural fungicide as described in any one of claims 8 to 11 in the prevention and control of plant diseases.

13. The application according to claim 12, characterized in that, The plant diseases mentioned include those caused by one or more of the following: pathogenic fungi, pathogenic oomycetes, and pathogenic bacteria.

14. The application according to claim 13, characterized in that, The pathogenic fungi include one or more of the genera Fusarium, Pyrrosia, Rhizoctonia, Cercozoella, Helicobacter, Botrytis, Microcystis, Alternaria, Sclerotium, Subsp., Cercozoella, Styloides, Unicellular rust, and Layer rust.

15. The application according to claim 13 or 14, characterized in that, The pathogenic fungi include one or more of the following: wheat scab, rice blast fungus, rice bakanae disease fungus, maize large leaf spot fungus, maize small leaf spot fungus, gray mold fungus, anthracnose fungus, early blight fungus, sclerotinia sclerotinia, watermelon vine blight fungus, and peanut brown spot fungus.

16. The application according to claim 13, characterized in that, The pathogenic oomycetes include one or more of the genera *Phytophthora*, *Phytophthora*, *Peronospora*, *Peronospora*, *Phytophthora*, *Pseudomonas*, *Peronospora ...Pythium*, and *Pythium*.

17. The application according to claim 13 or 16, characterized in that, The pathogenic oomycetes include one or more of the following: Potato and tomato late blight fungus, soybean blight fungus, pepper blight fungus, tobacco black shank fungus, litchi blight fungus, grape downy mildew fungus, cucumber downy mildew fungus, and rice seedling rot fungus.

18. The application according to claim 13, characterized in that, The pathogenic bacteria include one or more of the genera Xanthomonas, Pseudomonas, and Erwinia.

19. The application according to claim 13 or 18, characterized in that, The pathogenic bacteria include one or more of the following: rice bacterial blight pathogen, rice bacterial leaf streak pathogen, tomato bacterial wilt pathogen, citrus canker pathogen, Chinese cabbage soft rot pathogen, pear fire blight pathogen, and fruit spot pathogen.

20. The application according to claim 12 or 13, characterized in that, The plant diseases mentioned include one or more of the following: wheat scab, wheat rust, wheat powdery mildew, wheat stem base rot, rice blast, rice bakanae disease, rice sheath blight, seedling bacterial wilt, rice bacterial leaf blight, rice bacterial streak, corn large leaf spot, corn small leaf spot, corn rust, corn stem base rot, citrus canker, kiwifruit canker, fruit and vegetable gray mold, cruciferous crop sclerotinia rot, peanut brown spot, watermelon vine blight, potato and tomato late blight, potato and tomato early blight, pepper blight, Chinese cabbage soft rot, soybean blight, soybean rust, lychee blight, cucumber downy mildew, cucumber angular leaf spot, vegetable downy mildew, grape downy mildew, fruit and vegetable crop anthracnose, and fruit and vegetable crop powdery mildew.

21. The application according to claim 12 or 13, characterized in that, The plants include one or more of the following: vegetables, fruits, grain crops, oil crops, garden crops, medicinal herbs, and lawns.

22. The application according to claim 12 or 13, characterized in that, Use 15-1000g of the active ingredient of a pyrrolidone compound as described in claim 1 or an agricultural fungicide as described in any one of claims 8-11 per hectare.

23. The application according to claim 12 or 13, characterized in that, The method of applying a pyrrolidone compound as described in claim 1 or an agricultural fungicide as described in any one of claims 8 to 11 to seed and soil treatment or spraying.

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