Bromopyrrole nitrile-beta-aminobutyric acid derivative as well as preparation method and application thereof

Abstract

The invention provides a bromo-pyrrole nitrile-beta-aminobutyric acid derivative as well as a preparation method and application thereof, and belongs to the technical field of preparation of pesticide compounds. The bromopyrrole nitrile-beta-aminobutyric acid derivative disclosed by the invention is a derivative of 3-(2-(3-bromo-5-(4-chlorphenyl)-4-cyano-2-(trifluoromethyl)-1H-pyrrole-1-yl) acetamido)-2-methyl propionic acid and ester of 3-(2-(3-bromo-5-(4-chlorphenyl)-4-cyano-2-(trifluoromethyl)-1H-pyrrole-1-yl) acetamido)-2-methyl propionic According to the invention, bromo-pyrrolo-nitrile is used as a parent structure and is subjected to active substructure splicing with different substituted beta-aminobutyric acid derivatives to synthesize a series of novel compounds, the chemical structure is novel, and the compounds can be used for preventing and treating plant parasitic nematodes such as root-knot nematodes and cyst nematodes; a biological assay result shows that the prevention effect of bromo-pyrrolecarbonitrile-beta-aminobutyric acid on tomato root-knot nematodes is obviously superior to that of a commercial medicament fluopyram and is equivalent to that of a novel nematicide trifluoropyridylamine, and the bromo-pyrrolecarbonitrile-beta-aminobutyric acid has a relatively high commercial prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide compound preparation, and in particular to a bromopyrrolecarbonitrile-β-aminobutyric acid derivative and a preparation method and application thereof. Background Art

[0002] Plant nematodes are one of the most important plant infectious pathogens. Due to their wide distribution, small size, hiding underground, and severe damage to plant roots, they can cause a reduction of about 12.3% in the yield of major crops, and in severe cases, the loss can reach 60%. According to incomplete statistics, the annual loss caused by plant nematodes to agriculture worldwide exceeds 150 billion US dollars. Plant root-knot nematodes (Meloidogyn spp.) are the nematodes with the largest variety, the widest distribution, and the most serious damage. In addition to root-knot nematodes, other serious plant nematodes in China include soybean and beet cyst nematodes, wheat grain nematodes, sweet potato stem nematodes, rice stem tip nematodes, millet nematodes, pine wood nematodes, etc. At present, the prevention and control of plant nematodes is mainly chemical control. Traditional nematicides are mainly avermectins, emamectin benzoate, thiamethoxam, carbofuran, but they are seriously resistant and the control effect is not ideal; in recent years, the resistance of the newly developed nematicides fluopyram and trifluopyram has also developed rapidly, and they are expensive.

[0003] Bromopyrrole nitrile is an aromatic pyrrole compound synthesized by modifying the natural antibiotic dioxazolidinone. It has excellent insecticidal, acaricidal, fungicidal and nematicidal activities, but its application in agriculture is limited by its certain phytotoxicity to some crops. Bromopyrrole nitrile is now mainly used as a pesticide intermediate for the synthesis of the insecticide cypermethrin. Amino acids, as endogenous substances in plants, are widely used in the research and development of new pesticides because of their advantages such as crop safety, environmental friendliness and unique chemical structure. The most common in organisms are α-amino acids, in addition to β-amino acids and γ-amino acids. β-Aminobutyric acid (BABA) is a 4-carbon non-protein amino acid present in plants. It was first detected in the root secretions of tomatoes that were overexposed to the sun. As an inducible elicitor, BABA can induce plants to acquire systemic disease resistance to diseases caused by a variety of pathogenic fungi, bacteria, viruses and pathogenic microorganisms such as plant nematodes. BABA is a broad-spectrum plant immune inducer that can not only induce systemic resistance of various plants to pathogenic microorganisms, but also induce plants to resist abiotic stresses such as drought, high salt, and extreme temperature. Therefore, the introduction of β-aminobutyric acid into the structure of brominated pyrrole nitrile to obtain compounds that can prevent and control plant nematodes and induce disease resistance has broad application prospects. Summary of the invention

[0004] The purpose of the present invention is to provide a bromopyrrolecarbonitrile-β-aminobutyric acid derivative and a preparation method and application thereof, so as to solve the technical problems that the existing nematicides are expensive and have unsatisfactory control effects.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a bromopyrrolecarbonitrile-β-aminobutyric acid derivative, wherein the bromopyrrolecarbonitrile-β-aminobutyric acid derivative has the following structural formula:

[0007]

[0008] Wherein, R is one of H, a C1-C4 straight-chain alkyl group, a C1-C4 branched-chain alkyl group, a phenyl group and a trifluoromethyl group, and n is an integer of 1-8.

[0009] The present invention provides a method for preparing a bromopyrrolecarbonitrile-β-aminobutyric acid derivative, comprising the following steps:

[0010] (1) dissolving bromopyrrolecarbonitrile, cesium carbonate and potassium iodide in a solvent, and then adding ethyl bromoacetate to carry out a substitution reaction to obtain ethyl bromopyrrolecarbonitrile;

[0011] (2) mixing ethyl bromopyrrolecarbonitrile acetate and lithium hydroxide monohydrate in a solvent for reaction to obtain bromopyrrolecarbonitrile acetic acid;

[0012] (3) dissolving bromopyrrole nitrile acetic acid in a solvent, and then adding oxalyl chloride to react to obtain bromopyrrole nitrile acetyl chloride;

[0013] (4) dissolving ethyl β-aminobutyrate in a solvent, and then adding bromopyrrolecarbonitrile acetyl chloride to react to obtain bromopyrrolecarbonitrile-β-aminobutyrate ethyl ester;

[0014] (5) ethyl bromopyrrolecarbonitrile-β-aminobutyrate and lithium hydroxide monohydrate are mixed in a solvent for reaction to obtain bromopyrrolecarbonitrile-β-aminobutyric acid.

[0015] Furthermore, in the step (1), the molar ratio of bromopyrrolecarbonitrile, cesium carbonate, potassium iodide and ethyl bromoacetate is 1:0.5 to 1:1:1 to 1.5, and the amount ratio of bromopyrrolecarbonitrile to solvent is 25 mmol:80 to 120 mL;

[0016] In the step (1), the temperature of the substitution reaction is 35 to 135° C., and the time of the substitution reaction is 6 to 10 hours.

[0017] Furthermore, in the step (2), the amount ratio of ethyl bromopyrrolecarbonitrile, lithium hydroxide monohydrate and solvent is 20-25 mmol: 30-35 mmol: 80-120 mL;

[0018] The reaction temperature is 20-40° C., and the reaction time is 2-5 hours.

[0019] Furthermore, in the step (3), the ratio of bromopyrrole nitrile acetic acid, oxalyl chloride and solvent is 5-10 mmol: 5-10 mmol: 80-120 mL;

[0020] The reaction temperature is 35-135° C., and the reaction time is 1-5 hours.

[0021] Furthermore, in the step (4), the ratio of β-aminobutyric acid ethyl ester, bromopyrrole nitrile acetyl chloride and solvent is 5-10 mmol: 5-10 mmol: 80-120 mL;

[0022] The temperature for adding bromopyrrolecarbonitrile acetyl chloride is -5 to 5°C;

[0023] The reaction temperature is 20-40° C., and the reaction time is 1-5 hours.

[0024] Furthermore, in the step (5), the usage ratio of bromopyrrolecarbonitrile-β-aminobutyric acid ethyl ester, lithium hydroxide monohydrate and solvent is 3 mmol: 8-10 mmol: 40-60 mL.

[0025] Furthermore, in the step (5), the reaction temperature is 20 to 40° C., and the reaction time is 1 to 5 hours.

[0026] Furthermore, in steps (1), (2), (3), (4) and (5), the solvent independently comprises one or more of dichloromethane, chloroform, ethanol, methanol, n-propanol, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, ether, petroleum ether, benzene, toluene and acetone.

[0027] The present invention also provides a use of a brominated pyrrole carbonitrile-β-aminobutyric acid derivative as a nematicide in preventing and controlling nematode diseases, wherein the nematode diseases include root knot nematode disease, soybean cyst nematode disease, beet cyst nematode disease, sweet potato stem nematode disease and pine wood nematode disease.

[0028] Beneficial effects of the present invention:

[0029] The invention uses bromopyrrole nitrile as a parent structure and splices an active substructure with beta-aminobutyric acid ester to synthesize a series of new compounds with novel chemical structures, and can be used to prevent and treat root knot nematode disease, soybean cyst nematode disease, beet cyst nematode disease, sweet potato stem nematode disease and pine wood nematode disease. The bioassay results show that the control effect of 3-(2-(3-bromo-5-(4-chlorophenyl)-4-cyano-2-(trifluoromethyl)-1H-pyrrol-1-yl)acetylamino)-2-methylpropionic acid on tomato root knot nematode disease is significantly better than that of novel commercial nematicides fluopyram and trifluopyram, and the compound has a high commercial prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a graph showing the control effect of the compound of Example 1 on tomato root-knot nematodes. DETAILED DESCRIPTION

[0031] The present invention provides a bromopyrrolecarbonitrile-β-aminobutyric acid derivative, wherein the bromopyrrolecarbonitrile-β-aminobutyric acid derivative has the following structural formula:

[0032]

[0033] Wherein, R is one of H, a C1-C4 straight-chain alkyl group, a C1-C4 branched-chain alkyl group, a phenyl group and a trifluoromethyl group, and n is an integer of 1-8.

[0034] In the present invention, the bromopyrrolecarbonitrile-β-aminobutyric acid derivative is a derivative of 3-(2-(3-bromo-5-(4-chlorophenyl)-4-cyano-2-(trifluoromethyl)-1H-pyrrol-1-yl)acetylamino)-2-methylpropionic acid and ester, preferably having the following structural formula:

[0035]

[0036] The present invention provides a method for preparing a bromopyrrolecarbonitrile-β-aminobutyric acid derivative, comprising the following steps:

[0037] (1) dissolving bromopyrrolecarbonitrile, cesium carbonate and potassium iodide in a solvent, and then adding ethyl bromoacetate to carry out a substitution reaction to obtain ethyl bromopyrrolecarbonitrile;

[0038] (2) mixing ethyl bromopyrrolecarbonitrile acetate and lithium hydroxide monohydrate in a solvent for reaction to obtain bromopyrrolecarbonitrile acetic acid;

[0039] (3) dissolving bromopyrrole nitrile acetic acid in a solvent, and then adding oxalyl chloride to react to obtain bromopyrrole nitrile acetyl chloride;

[0040] (4) dissolving ethyl β-aminobutyrate in a solvent, and then adding bromopyrrolecarbonitrile acetyl chloride to react to obtain bromopyrrolecarbonitrile-β-aminobutyrate ethyl ester;

[0041] (5) ethyl bromopyrrolecarbonitrile-β-aminobutyrate and lithium hydroxide monohydrate are mixed in a solvent for reaction to obtain bromopyrrolecarbonitrile-β-aminobutyric acid.

[0042] In the present invention, in the step (1), the molar ratio of bromopyrrolecarbonitrile, cesium carbonate, potassium iodide and ethyl bromoacetate is 1:0.5-1:1:1-1.5, preferably 1:0.9:1:1.2; the amount ratio of bromopyrrolecarbonitrile and solvent is 25mmol:80-120mL, preferably 25mmol:100mL.

[0043] In the present invention, in step (1), the temperature of the substitution reaction is 35 to 135° C., preferably 60 to 110° C.; the time of the substitution reaction is 6 to 10 h, preferably 8 h.

[0044] In the present invention, in the step (2), the usage ratio of ethyl bromopyrrolecarbonitrile, lithium hydroxide monohydrate and solvent is 20-25 mmol: 30-35 mmol: 80-120 mL, preferably 22.5 mmol: 33.9 mmol: 100 mL.

[0045] In the present invention, in the step (2), the reaction temperature is 20 to 40° C., preferably 25 to 35° C.; the reaction time is 2 to 5 hours, preferably 4 hours.

[0046] In the present invention, in the step (3), the usage ratio of bromopyrrole nitrile acetic acid, oxalyl chloride and solvent is 5-10 mmol: 5-10 mmol: 80-120 mL, preferably 6-8 mmol: 6-9 mmol: 80-100 mL, and more preferably 7.36 mmol: 8.83 mmol: 80-90 mL.

[0047] In the present invention, in the step (3), the reaction temperature is 35 to 135° C., preferably 60 to 110° C.; the reaction time is 1 to 5 hours, preferably 3 hours.

[0048] In the present invention, in the step (4), the usage ratio of β-aminobutyric acid ethyl ester, bromopyrrolecarbonitrile acetyl chloride and solvent is 5-10 mmol: 5-10 mmol: 80-120 mL, preferably 6-9 mmol: 6-8 mmol: 100 mL, and more preferably 8 mmol: 7.3 mmol: 100 mL.

[0049] The temperature for adding bromopyrrolecarbonitrile acetyl chloride is -5 to 5°C, preferably -2 to 2°C, and more preferably 0°C.

[0050] The reaction temperature is 20-40°C, preferably 25-35°C, and more preferably 30°C; the reaction time is 1-5h, and preferably 3h.

[0051] In the present invention, in the step (5), the usage ratio of bromopyrrolecarbonitrile-β-aminobutyric acid ethyl ester, lithium hydroxide monohydrate and solvent is 3mmol:8-10mmol:40-60mL, preferably 3mmol:9mmol:50mL.

[0052] In the present invention, in the step (5), the reaction temperature is 20 to 40°C, preferably 25 to 35°C, and more preferably 30°C; the reaction time is 1 to 5 hours, and preferably 3 hours.

[0053] In the present invention, in the steps (1), (2), (3), (4) and (5), the solvent independently comprises one or more of dichloromethane, chloroform, ethanol, methanol, n-propanol, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, ether, petroleum ether, benzene, toluene and acetone, preferably one or more of dichloromethane, chloroform, ethanol, methanol, n-propanol, ethyl acetate and tetrahydrofuran.

[0054] The present invention also provides a use of a brominated pyrrole carbonitrile-β-aminobutyric acid derivative as a nematicide in preventing and controlling nematode diseases, wherein the nematode diseases include root knot nematode disease, soybean cyst nematode disease, beet cyst nematode disease, sweet potato stem nematode disease and pine wood nematode disease.

[0055] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0056] Example 1

[0057] A bromopyrrole nitrile-β-aminobutyric acid derivative, wherein the bromopyrrole nitrile-β-aminobutyric acid derivative is compounds 3a and 3b in Table 1 and Table 2, and is prepared by the following steps:

[0058] Synthesis of Ethyl Bromopyrrole Carbonitrile

[0059] Weigh 5.35g (25mmol) of bromopyrrole nitrile, 7.33g (22.5mmol) of cesium carbonate, and 2.49g (25mmol) of potassium iodide in a 250mL round-bottom flask, add 100mL of acetonitrile, stir at room temperature until bromopyrrole nitrile is completely dissolved, slowly add 3.33mL (30mmol) of ethyl bromoacetate, after the addition is completed, heat to 85°C and reflux, react for about 8h, and monitor the reaction by thin layer chromatography (TLC, V (petroleum ether): V (ethyl acetate) = 6:1) until the reaction is complete. Concentrate to dryness under reduced pressure, add 50mL of dichloromethane to dissolve and extract 3 times with saturated brine, dry the organic layer with anhydrous sodium sulfate, concentrate to dryness under reduced pressure, separate and purify by column chromatography (V (petroleum ether): V (ethyl acetate) = 12:1), and dry to obtain 5.88g of bromopyrrole nitrile ethyl acetate.

[0060] Synthesis of Bromopyrrole Nitrile Acetic Acid

[0061] Weigh 9.8 g (22.5 mmol) of ethyl bromopyrrole nitrile and 1.42 g (33.9 mmol) of lithium hydroxide monohydrate in a 250 mL round-bottom flask, add 100 mL of tetrahydrofuran, react at room temperature for 4 h, and monitor the reaction by thin layer chromatography (TLC, V (petroleum ether): V (ethyl acetate) = 6:1) until the reaction is complete. Concentrate to dryness under reduced pressure, pour the reaction solution into water, add dilute hydrochloric acid dropwise to adjust the pH to 2 under ice bath conditions, and a white precipitate appears, which is filtered and dried to obtain 8.71 g of bromopyrrole nitrile acetic acid.

[0062] Synthesis of Bromopyrrole Carbonitrile Acetyl Chloride

[0063] Weigh 3.00g (7.36mmol) of bromopyrrole nitrile acetic acid in a 250mL round-bottom flask, add 80mL of dichloromethane and 1 drop of DMF, stir at room temperature until completely dissolved, slowly add 1.12g (8.83mmol) of oxalyl chloride, after the addition is complete, heat to 120°C and reflux for 3h, monitor with thin layer chromatography (TLC, V (petroleum ether): V (ethyl acetate) = 2:1) until the reaction is complete. Concentrate to dryness under reduced pressure, add dichloromethane (25mL) and continue to spin dry the solvent, repeat 2 times to ensure that the excess oxalyl chloride is completely spun off, and obtain the compound bromopyrrole nitrile acetyl chloride, which is sealed and dried for later use.

[0064] Synthesis of ethyl brominated pyrrolecarbonitrile-β-aminobutyrate 3a

[0065] Weigh β-aminobutyric acid ethyl ester (8 mmol) in a 250 mL round-bottom flask, add 100 mL of dichloromethane, take bromopyrrole nitrile acetyl chloride (7.3 mmol) and dissolve it in dichloromethane. In an ice bath, drop bromopyrrole nitrile acetyl chloride into the reaction system at a uniform rate. After the titration is completed, remove the ice bath, react at room temperature for 3 h, and monitor the reaction by thin layer chromatography (TLC, V (petroleum ether): V (ethyl acetate) = 2: 1) until the reaction is complete. Extract with saturated brine three times, dry the organic layer with anhydrous sodium sulfate, and concentrate to dryness under reduced pressure. Separate and purify with column chromatography (V (petroleum ether): V (ethyl acetate) = 6: 1), and dry to obtain bromopyrrole nitrile-β-aminobutyric acid ethyl ester 3a, with a yield of 84%.

[0066] Synthesis of Bromopyrrole Carbonitrile-β-Aminobutyric Acid 3b

[0067] Weigh 3 mmol of bromopyrrolecarbonitrile-β-aminobutyric acid ethyl ester and 0.38 g (9 mmol) of lithium hydroxide monohydrate in a 100 mL round-bottom flask, add 50 mL of tetrahydrofuran, react at room temperature for 3 h, and monitor the reaction by thin layer chromatography (TLC, V (petroleum ether): V (ethyl acetate) = 3:1) until the reaction is complete. Concentrate to dryness under reduced pressure, pour the reaction system into water, add dilute hydrochloric acid dropwise to adjust the pH to 2 under ice bath conditions, precipitate, filter and dry to obtain bromopyrrolecarbonitrile-β-aminobutyric acid 3b, yield: 91%.

[0068] Table 1 Molecular structures and physicochemical properties of compounds 3a and 3b

[0069]

[0070]

[0071] Table 2 H NMR data of compounds 3a and 3b

[0072]

[0073]

[0074] Experimental example

[0075] Nematicidal activity pot test, test method:

[0076] Root-knot nematodes were collected from vegetable greenhouses in Shouguang, Shandong, and subcultured indoors. Root-knot nematodes and egg suspension were inoculated 4 hours before application, and the pesticide was applied 4 hours after inoculation.

[0077] Survey method, time and frequency:

[0078] 35 days after inoculation, the damage caused by tomato root-knot nematodes was investigated.

[0079] Grading standards: Grade 0: healthy root system, no root knots;

[0080] Level 1: The root system has a small number of root knots, accounting for 1-25% of the total root system;

[0081] Level 3: The number of root-knot nematodes in the root system is moderate, accounting for 26-50% of the entire root system;

[0082] Level 5: There are a large number of root-knot nematodes in the root system, accounting for 51-75% of the entire root system;

[0083] Level 7: The number of root-knot nematodes in the root system is extremely large, accounting for 76-100% of the entire root system.

[0084] The dosage of the nematicide potted plant efficacy test is shown in Table 3. The control effect of the target compounds on tomato root-knot nematodes is shown in Table 4.

[0085] Table 3 Treatment of test compounds in potted plant experiments

[0086]

[0087] Table 4 Control effect of target compounds on root-knot nematodes

[0088]

[0089]

[0090] The results of the efficacy test showed that the two target compounds with an active ingredient dosage of 10 mg / plant had significantly higher efficacy against tomato root-knot nematodes (3a: 76.47%, 3b: 88.23%) than the commercial control agent fluopyram (active ingredient dosage of 15 mg / plant, 29.41%), and the control effect of the target compound 3b was slightly higher than that of the new nematicide trifluopyramide (active ingredient dosage of 5.4 mg / plant, 82.35%), and the control effects of 3a and 3b against tomato root-knot nematodes were lower than that of avermectin (active ingredient dosage of 3 mg / plant, 91.18%). At the same dosage, the control effect of compound 3b against tomato root-knot nematodes was significantly higher than that of 3a.

[0091] As can be seen from the above embodiments, the present invention provides a bromopyrrole nitrile-β-aminobutyric acid derivative and its preparation method and application. The present invention uses bromopyrrole nitrile as the parent structure and splices the active substructure with different substituted β-aminobutyric acid derivatives to synthesize a series of new compounds with novel chemical structures, which can be used to prevent and control plant parasitic nematodes such as root-knot nematodes and cyst nematodes; the bioassay results show that the control effect of bromopyrrole nitrile-β-aminobutyric acid on tomato root-knot nematodes is significantly better than that of the commercial agent fluopyram, and is equivalent to the control effect of the new nematicide trifluopyram. The compound 3b of the present invention exhibits excellent nematicidal activity, is easy to prepare, has low cost, and has a high commercialization prospect.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bromopyrrolecarbonitrile-β-aminobutyric acid derivative, characterized in that: The bromopyrrole nitrile-β-aminobutyric acid derivative has the following structural formula: Wherein, R is one of H, a C1-C4 straight-chain alkyl group, a C1-C4 branched-chain alkyl group, a phenyl group and a trifluoromethyl group, and n is an integer of 1-8.

2. The method for preparing the bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 1, characterized in that: The following steps are involved: (1) dissolving bromopyrrolecarbonitrile, cesium carbonate and potassium iodide in a solvent, and then adding ethyl bromoacetate to carry out a substitution reaction to obtain ethyl bromopyrrolecarbonitrile; (2) mixing ethyl bromopyrrolecarbonitrile acetate and lithium hydroxide monohydrate in a solvent for reaction to obtain bromopyrrolecarbonitrile acetic acid; (3) dissolving bromopyrrole nitrile acetic acid in a solvent, and then adding oxalyl chloride to react to obtain bromopyrrole nitrile acetyl chloride; (4) dissolving ethyl β-aminobutyrate in a solvent, and then adding bromopyrrolecarbonitrile acetyl chloride to react to obtain bromopyrrolecarbonitrile-β-aminobutyrate ethyl ester; (5) Bromopyrrolecarbonitrile-β-aminobutyric acid ethyl ester and lithium hydroxide monohydrate are mixed in a solvent for reaction to obtain bromopyrrolecarbonitrile-β-aminobutyric acid.

3. The method for preparing the bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 2, characterized in that: In the step (1), the molar ratio of bromopyrrolecarbonitrile, cesium carbonate, potassium iodide and ethyl bromoacetate is 1:0.5 to 1:1:1 to 1.5, and the amount ratio of bromopyrrolecarbonitrile to solvent is 25 mmol:80 to 120 mL; In the step (1), the temperature of the substitution reaction is 35 to 135° C., and the time of the substitution reaction is 6 to 10 hours.

4. The method for preparing a bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 2 or 3, characterized in that: In the step (2), the amount ratio of ethyl bromopyrrolecarbonitrile, lithium hydroxide monohydrate and solvent is 20-25 mmol: 30-35 mmol: 80-120 mL; The reaction temperature is 20-40° C., and the reaction time is 2-5 hours.

5. The method for preparing the bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 4, characterized in that: In the step (3), the ratio of bromopyrrole nitrile acetic acid, oxalyl chloride and solvent is 5-10 mmol: 5-10 mmol: 80-120 mL; The reaction temperature is 35-135° C., and the reaction time is 1-5 hours.

6. The method for preparing the bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 2 or 5, characterized in that: In the step (4), the ratio of β-aminobutyric acid ethyl ester, bromopyrrole nitrile acetyl chloride and solvent is 5-10 mmol: 5-10 mmol: 80-120 mL; The temperature for adding bromopyrrolecarbonitrile acetyl chloride is -5 to 5°C; The reaction temperature is 20-40° C., and the reaction time is 1-5 hours.

7. The method for preparing the bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 6, characterized in that: In the step (5), the amount ratio of bromopyrrolecarbonitrile-β-aminobutyric acid ethyl ester, lithium hydroxide monohydrate and solvent is 3 mmol: 8-10 mmol: 40-60 mL.

8. The method for preparing the bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 2, 5 or 7, characterized in that: In the step (5), the reaction temperature is 20 to 40° C., and the reaction time is 1 to 5 hours.

9. The method for preparing a bromopyrrolecarbonitrile-β-aminobutyric acid derivative according to claim 2, characterized in that: In the steps (1), (2), (3), (4) and (5), the solvent independently comprises one or more of dichloromethane, chloroform, ethanol, methanol, n-propanol, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, ether, petroleum ether, benzene, toluene and acetone.

10. Use of the brominated pyrrole carbonitrile-β-aminobutyric acid derivative according to claim 1 as a nematicide in the prevention and treatment of nematode diseases, characterized in that: The nematode diseases include root knot nematode disease, soybean cyst nematode disease, beet cyst nematode disease, sweet potato stem nematode disease and pine wood nematode disease.

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