5-acyl barbituric acid compound containing pyrrole-2, 5-diketone structure, preparation method and herbicide application of 5-acyl barbituric acid compound

Abstract

The invention relates to a 5-acyl barbituric acid compound containing a pyrrole-2, 5-diketone structure, which is characterized in that a nitrophenol compound is used as a raw material, and the nitrophenol compound is subjected to nucleophilic reaction, hydrolysis reaction, hydrogenation reduction reaction, condensation reaction and acylating chlorination reaction to obtain a phenoxyalkanoyl chloride compound containing the pyrrole-2, 5-diketone structure. The 5-acyl barbituric acid compound containing the pyrrole-2, 5-diketone structure is obtained through a condensation reaction between the pyrrole-2, 5-diketone structure and a barbituric acid compound, and the compound has an excellent growth inhibition rate on plants such as oilseed rape, piemarker, amaranthus retroflexus, Chinese velvet, barnyard grass, digitaria sanguinalis, eleusine indica and green bristlegrass and can be used as a candidate variety of efficient herbicides.

Description

Technical Field

[0001] The invention belongs to the technical field of herbicides, and specifically relates to a 5-acylbarbituric acid compound containing a pyrrole-2,5-dione structure, a preparation method and herbicide application thereof. Background Art

[0002] Farmland weeds are one of the main factors threatening food security. Herbicides have played a huge role in controlling farmland weeds and ensuring food security. However, with the long-term and large-scale use of herbicides, environmental pollution, food quality and safety, and weed resistance have become increasingly prominent. Creating new herbicides with high efficiency, low toxicity, and unique mode of action is an effective way to solve these problems.

[0003] One of the key points and difficulties in the creation of new herbicides is to discover highly active lead compounds with novel structures. The present invention uses the 5-acylbarbituric acid with good herbicidal activity discovered in the early stage as the lead structure, and introduces the active structural fragment of phthalimide herbicides-pyrrole-2,5-dione structure into the benzene ring part of 5-acylbarbituric acid through the active substructure splicing method, and designs and synthesizes 5-acylbarbituric acid compounds containing pyrrole-2,5-dione structure for the first time. The herbicidal activity test found that some compounds showed herbicidal activity comparable to or even better than that of the control drug fluazifop-butyl. This result has important guiding significance for the development of new 5-acylbarbituric acid candidate herbicide molecules containing pyrrole-2,5-dione structure, and provides a new prevention and control strategy for solving the increasingly serious drug resistance of farmland weeds. At present, there are no reports on the synthesis of 5-acylbarbituric acid compounds containing pyrrole-2,5-dione structure and their use in agricultural herbicides. Summary of the invention

[0004] The purpose of the present invention is to provide a 5-acylbarbituric acid compound containing a pyrrole-2,5-dione structure and application thereof, and specifically involves the following parts.

[0005] The first part of the present invention provides a compound represented by formula V, or a stereoisomer thereof, or an agrochemically acceptable salt thereof:

[0006]

[0007] Among them, R 1 , R 2 , R 3 , R 4 Independently selected from the following groups: any one of hydrogen, halogen, C1-C6 straight chain or branched chain alkyl, halogen-substituted C1-C6 straight chain or branched chain alkyl, and C1-C6 alkoxy;

[0008] R 5 , R 6Independently selected from the following groups: hydrogen, C1-C6 straight chain or branched chain alkyl or halogen-substituted C1-C6 straight chain or branched chain alkyl;

[0009] R 7 , R 8 are independently selected from the following groups: hydrogen, C1-C6 straight chain or branched chain alkyl or halogen-substituted C1-C6 straight chain or branched chain alkyl; or R 7 , R 8 The atoms directly connected to it form a 4-6 membered cycloalkane or a 5-10 membered aromatic ring;

[0010] n is selected from 1, 2, 3 or 4.

[0011] Further, wherein the halogen is selected from fluorine, chlorine, bromine or iodine;

[0012] The C1-C6 straight or branched alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl;

[0013] The C1-C6 alkoxy group is selected from methoxy, ethoxy, n-propoxy, isopropoxy or n-butoxy;

[0014] The 4-6 membered cycloalkyl group is selected from cyclohexane or cyclopentane;

[0015] The 5-10 membered aromatic group is selected from a phenyl group or a naphthyl ring group;

[0016] n is selected from 1, 2 or 3.

[0017] Furthermore, the compound of formula V is selected from the structure shown in formula I, formula II or formula III:

[0018]

[0019] Among them, R 1 , R 2 , R 3 , R 4 Independently selected from the following groups: any one of hydrogen, fluorine, chlorine, bromine, iodine, methyl, ethyl or n-propyl;

[0020] R 5 , R 6 Independently selected from the following groups: any one of hydrogen, methyl, ethyl or n-propyl;

[0021] n is selected from 1, 2 or 3.

[0022] Preferably, the compound described in Formula I specifically has the following structure

[0023]

[0024]

[0025]

[0026] The second aspect of the present invention relates to a method for preparing the compound of formula V, or its stereoisomers, or its agrochemically acceptable salts, which comprises the following steps:

[0027] Step a: dissolving the compound of formula 1 and the compound of formula 2 in a solvent, and preparing a compound of formula 3 under alkaline conditions;

[0028]

[0029] Step b: dissolving the compound of formula 3 in a solvent and preparing the compound of formula 4 under alkaline conditions;

[0030] Step c: dissolving the compound of formula 4 in a solvent and preparing the compound of formula 5 under reducing conditions;

[0031]

[0032] Step d: Compound 5 and compound 6 are reacted in an acidic solvent under heating conditions to obtain compound 7;

[0033]

[0034] Step e: dissolving the compound of formula 7 in a solvent, and adding a chlorination agent to obtain a compound of formula 8;

[0035] Step f: dissolving the compound of formula 8 and the compound of formula 9 in a solvent, and preparing the compound of formula V under alkaline conditions;

[0036]

[0037] Wherein the substituent R in Formulas 1 to 9 and V 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , the definition of n is the same as the above structure.

[0038] The compound of formula 6 can be further selected from one of the following three structures:

[0039]

[0040] Furthermore, the solvents in step a, step b, step c, step e and step f are selected from one or two of N,N-dimethylformamide, methanol, ethanol, ethyl acetate, dichloromethane, toluene, DMSO, acetone, acetonitrile, methyl tert-butyl ether, diethyl ether and water;

[0041] Preferably, the solvent in step a is selected from N,N-dimethylformamide;

[0042] In step b, the solvent is selected from methanol and water;

[0043] In the step c, the solvent is selected from ethyl acetate;

[0044] In the step e, the solvent is selected from dichloromethane;

[0045] In the step f, the solvent is selected from dichloromethane;

[0046] And / or, the alkaline conditions of step a, step b, and step f are selected from sodium hydrogen, sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, N,N-diisopropylethylamine, triethylamine, lithium diisopropylamide, n-(C 1-6 One or both of lithium (alkyl), potassium butoxide or potassium pentoxide;

[0047] Preferably, the alkaline condition in step a is selected from potassium carbonate;

[0048] The alkaline condition in step b is selected from lithium hydroxide;

[0049] The alkaline condition in step f is selected from triethylamine;

[0050] And / or, the reduction conditions of step c are palladium / carbon and hydrogen, iron powder and hydrochloric acid, zinc powder and hydrochloric acid, lithium aluminum tetrahydride or sodium borohydride,

[0051] Preferably, the reduction conditions in step c are palladium / carbon and hydrogen;

[0052] And / or, the acidic solvent in step d is hydrochloric acid, acetic acid or sulfuric acid:

[0053] Preferably, the acidic condition in step d is acetic acid;

[0054] And / or, the chlorination agent in step e is thionyl chloride.

[0055] The third aspect of the present invention relates to a pesticide composition, which comprises at least one compound of formula I-1 as described in any one of claims 1 to 4, or its stereoisomer, or its agrochemically acceptable salt and a carrier; the carrier is in liquid or solid form.

[0056] The fourth aspect of the present invention relates to the use of the above-mentioned compound, or its stereoisomer, or its agrochemically acceptable salt or the aforementioned pesticide composition in an agricultural herbicide. Preferably, the agricultural herbicide is used to kill weeds, and the weeds are dicotyledons or monocotyledons.

[0057] Furthermore, the weeds are rapeseed, velvetleaf, Amaranthus retroflexus, Leonurus japonicus, Echinochloa crusgalli, Digitaria sanguinea, Goosegrass or Setaria viridis.

[0058] A fifth aspect of the invention relates to a method for controlling or preventing the growth of unwanted plants, wherein a herbicidally effective amount of a compound as defined above, or its stereoisomers, or its agrochemically acceptable salts or the aforementioned pesticide composition is applied to these plants, their parts or their loci.

[0059] The following is an explanation and description of the terms of the present invention:

[0060] The compounds and derivatives provided in the present invention can be named according to the IUPAC (International Union of Pure and Applied Chemistry) or CAS (Chemical Abstracts Service, Columbus, OH) nomenclature system.

[0061] "Substitution" refers to the replacement of a hydrogen atom in a molecule by another different atom or molecule.

[0062] The minimum and maximum carbon atom content of a hydrocarbon group is indicated by a prefix, for example, the prefix C1-b alkyl indicates any alkyl group containing from "a" to "b" carbon atoms. Thus, for example, "C1-4 alkyl" refers to an alkyl group containing 1 to 4 carbon atoms.

[0063] The term "alkyl" refers to a saturated hydrocarbon chain with a specified number of member atoms. For example, C1-6 alkyl refers to an alkyl group with 1 to 6 member atoms, such as 1 to 4 member atoms. The alkyl group can be straight or branched. Representative branched alkyl groups have one, two or three branches. The alkyl group may be optionally substituted with one or more substituents as defined herein. Alkyl includes methyl, ethyl, propyl (n-propyl and isopropyl), butyl (n-butyl, isobutyl and tert-butyl), pentyl (n-pentyl, isopentyl and neopentyl) and hexyl, 2,2-dimethylbutyl and 2,3-dimethylbutyl, etc. The term "C1-C3 alkyl" refers to a straight or branched saturated hydrocarbon group with 1-3 carbon atoms. The alkyl group may also be part of other groups, such as C1-C6 alkoxy.

[0064] The term "alkoxy" refers to an O-alkyl group. The term "C1-C8 alkoxy" refers to an O-C1-C8 alkyl group.

[0065] The term "C6-C 10"Aryl" refers to an all-carbon monocyclic or fused polycyclic group of 6 to 10 carbon atoms, with a completely conjugated π electron system. Typical examples include, but are not limited to, phenyl and naphthyl rings.

[0066] The term "cycloalkyl", "cycloalkane" refers to a saturated or partially saturated cyclic group having carbon atoms and no ring heteroatoms and having a single ring or multiple rings (including condensed, combined and). For polycyclic systems with aromatic and non-aromatic rings without ring heteroatoms, when the point of attachment is located at a non-aromatic carbon atom, the term "cycloalkyl" (e.g., 5,6,7,8,-tetrahydronaphthalene-5-yl) is applicable. The term "cycloalkyl" includes cycloalkenyl groups, such as cyclohexenyl. Examples of cycloalkyl groups include, for example, adamantyl, cyclopropyl, cyclobutyl, cyclohexyl, cyclopentyl, cyclooctyl, cyclopentenyl and cyclohexenyl.

[0067] The term "halogen" refers to fluorine, chlorine, bromine or iodine.

[0068] The term "halogen-substituted alkyl" or "halogen-substituted C1-C6 straight or branched alkyl" means that the hydrogen atoms in the alkyl group may be substituted by one or more halogen atoms. For example, C1-4 halogen alkyl refers to an alkyl group containing 1 to 4 carbon atoms in which the hydrogen atoms are substituted by one or more halogen atoms, such as: -CFH2, -CF2H, -CF3, -CH3CFH2, -CH3CF2H or -CH3CF 3。

[0069] The term "agronomically acceptable salt" refers to the above-mentioned compound or its stereoisomer, acidic and / or basic salts formed with inorganic and / or organic acids and bases, also including zwitterionic salts (inner salts), and also including quaternary ammonium salts, such as alkylammonium salts. These salts can be directly obtained in the final separation and purification of the compound. It can also be obtained by mixing the above-mentioned compound, or its stereoisomer, with a certain amount of acid or base appropriately (such as equivalent). These salts may form precipitation in the solution and be collected by filtering, or be recovered after solvent evaporation, or be obtained by freeze drying after reaction in an aqueous medium. The salt described in the present invention can be the hydrochloride, sulfate, citrate, benzenesulfonate, hydrobromide, hydrofluoride, phosphate, acetate, propionate, succinate, oxalate, malate, succinate, fumarate, maleate, tartrate or trifluoroacetate of the compound.

[0070] Compounds according to the present invention can be used as herbicides in unmodified forms, but they are usually formulated into compositions using formulation adjuvants (such as carriers, solvents and surfactants) in a variety of ways. These formulations can be in different physical forms, for example, in the following forms: dusting agents, gels, wettable powders, water dispersible granules, water dispersible tablets, effervescent compressed tablets, emulsifiable concentrates, micro-emulsifiable concentrates, oil-in-water emulsions, flowable oils, aqueous dispersions, oily dispersions, suspoemulsions, capsule suspensions, emulsifiable granules, soluble liquids, water-soluble concentrates, impregnated polymer films or in known other forms. For water-soluble compounds, preferably soluble liquids, water-soluble concentrates or water-soluble granules. Such formulations can be used directly or can be diluted before use. Can be diluted with, for example, water, liquid fertilizers, micronutrients, biological organisms, oil or solvents.

[0071] These formulations can be prepared, for example, by mixing the active ingredients with formulation adjuvants so as to obtain compositions in the form of finely divided solids, granules, solutions, dispersions or emulsions. The active ingredients can also be formulated together with other adjuvants.

[0072] Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

[0073] Beneficial technical effects of the present invention:

[0074] 1. The present invention provides a 5-acylbarbituric acid compound containing a pyrrole-2,5-dione structure. The 5-acylbarbituric acid with good herbicidal activity found in previous work is used as a lead structure. The active structural fragment of the phthalimide herbicide is introduced into the benzene ring part of the 5-acylbarbituric acid through the active substructure splicing method. For the first time, a 5-acylbarbituric acid compound containing a pyrrole-2,5-dione structure is designed and synthesized.

[0075] 2. The 5-acylbarbituric acid compounds containing pyrrole-2,5-dione structure provided by the present invention have excellent inhibitory effects on the growth of weeds such as rape, velvetleaf, Amaranthus retroflexus and Leonurus japonicus at a dosage of 75 g / hectare after post-emergence treatment, and some compounds show herbicidal activity comparable to or even superior to that of the control drug fluazifop-butyl. The present invention has important guiding significance for developing new candidate 5-acylbarbituric acid herbicide molecules containing pyrrole-2,5-dione structure, and provides a new prevention and control strategy for solving the increasingly serious drug resistance of farmland weeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 : Target compound I-31 HNMR;

[0077] Figure 2 : Target compound I-3 13 CNMR. DETAILED DESCRIPTION

[0078] The present invention is further illustrated by the following examples, but are not intended to limit the present invention.

[0079] Intermediate Preparation Example 1: Synthesis of ethyl 3-nitro-4-fluorophenoxyacetate

[0080]

[0081] 3-Nitro-4-fluorophenol (15.7 g, 100 mmol) was dissolved in 150 mL of N, N-dimethylformamide (DMF), and potassium carbonate (20.7 g, 150 mmol) and ethyl chloroacetate (12.2 g, 100 mmol) were added in sequence, and the reaction system was stirred at room temperature for 12 h. 300 mL of water was added to the reaction system, and the mixture was extracted twice with ethyl acetate, and the ethyl acetate was combined. The organic phase was washed three times with saturated brine and dried over anhydrous sodium sulfate. After the solvent was dried under reduced pressure, 22.8 g of brown oil was obtained with a yield of 93.8%.

[0082] Intermediate Preparation Example 2: Synthesis of 3-nitro-4-fluorophenoxyacetic acid

[0083]

[0084] Dissolve ethyl 3-nitro-4-fluorophenoxyacetate (22.8 g, 93.8 mmol) in 200 mL of methanol, add lithium hydroxide (4.5 g, 187.6 mmol) and 10 mL of water, and stir the reaction system at room temperature for 12 h. The solvent in the reaction system was dried under reduced pressure, and the residue was dissolved in 200 mL of water, and the pH was adjusted to 1 with 1 M hydrochloric acid, and then the aqueous phase was extracted with ethyl acetate twice, and the ethyl acetate was combined. The organic phase was washed with water once, washed with saturated brine three times, and then dried over anhydrous sodium sulfate. After the solvent was dried under reduced pressure, 19.4 g of brown solid was obtained, with a yield of 96.0%.

[0085] Intermediate Preparation Example 3: Synthesis of 3-amino-4-fluorophenoxyacetic acid

[0086]

[0087] 3-Nitro-4-fluorophenoxyacetic acid (4.3 g, 20 mmol) was dissolved in 50 mL of ethyl acetate, 5% palladium / carbon (0.43 g) was added, and then hydrogen was introduced, and the reaction system was stirred at room temperature for 24 h. The reaction system was filtered, the filtrate was collected, the solvent was dried under reduced pressure, and the residue was purified by column chromatography to obtain 3.0 g of a white solid, the eluent was dichloromethane:methanol, the volume ratio was 15:1, and the yield was 81.0%.

[0088] Intermediate Preparation Example 4: Synthesis of 2-(3-(1,3-dihydroisoindolin-2-yl)-4-fluorophenoxy)acetic acid

[0089]

[0090] 3-Amino-4-fluorophenoxyacetic acid (1.85 g, 10 mmol) and phthalic anhydride (1.48 g, 10 mmol) were dissolved in 20 mL of glacial acetic acid, and the reaction system was heated to 120°C and stirred for 12 h. The reaction system was cooled to 0°C, and a white solid precipitated. It was filtered, washed with water, and vacuum dried to obtain 2.4 g of a white solid with a yield of 76.2%.

[0091] Example 1: Synthesis of 5-(2-(3-(1,3-dioxoisoindolin-2-yl)-4-fluorophenoxy)-1-hydroxyethylidene)-1,3-dimethylpyrimidine-2,4,6-(1H,3H,5H)-trione

[0092]

[0093] 2-(3-(1,3-dioxoisoindolin-2-yl)-4-fluorophenoxy)acetic acid (2.4 g, 7.6 mmol) was dissolved in 30 mL of dichloromethane (DCM), and then 10 mL of dichlorothionyl (SOCl2) and a drop of DMF were added, and the reaction system was stirred at room temperature for 12 h. After the solvent in the reaction system was dried under reduced pressure, the residue was redissolved in 30 mL of dichloromethane, and triethylamine (1.5 g, 15.2 mmol) was added, and the reaction system was stirred at room temperature for 48 h. The reaction system was dried under reduced pressure, and the residue was purified by column chromatography to obtain 1.2 g of a white solid, the eluent was petroleum ether: ethyl acetate, the volume ratio was 2: 1, and the yield was 34.9%. The derivatives of this type prepared using different raw materials according to the preparation methods of intermediate preparation examples 1-4 and Example 1 are listed in Table 1, and the yields of some derivatives are shown in Table 1. 1 H NMR, 13 C NMR (Bruker AV-500 spectrometer using tetramethylsilane as the internal standard) and melting point data are shown in Table 2. 1HNMR and 13 CNMR see the attached figure in the specification Figure 1 and Figure 2 .

[0094] Table 1 Structures of target compounds

[0095]

[0096]

[0097] Table 2 NMR and melting point data of compounds of formula I, formula II and formula III

[0098]

[0099]

[0100]

[0101]

[0102]

[0103] Effect embodiment 1:

[0104] The compounds provided by the present invention were used to test the herbicidal activity in greenhouse potted plants. The test subjects were dicotyledonous plants (rapeseed, velvetleaf, Amaranthus retroflexus, Chenopodium album) and monocotyledonous plants (barnyard grass, crabgrass, goosegrass, Setaria viridis), and the test method was the fresh weight inhibition method. The test method is as follows:

[0105] Place 150g of sandy clay in a small plastic cup with a diameter of 8cm and moisten it with water. Then plant 15 germinated seeds to a depth of 1-2cm and place them in a greenhouse. When the seedlings grow to the two-leaf and one-heart stage, spray the stems and leaves. Spray the solution of the compound on the stems and leaves of the plants at a dosage of 150g / hectare at a dosage of 1000 liters of water / hectare, and use the untreated seedlings as the control group. Set up three parallels for each experimental group. After 3 weeks, weigh the fresh weight of the aboveground part of each potted plant after cutting it from the boundary between the root and seedling, and express the efficacy as the percentage of fresh weight inhibition. The inhibition rate calculation formula is: Inhibition rate (%) = (fresh weight of blank control grass - fresh weight of treated pot grass) / fresh weight of blank control grass × 100%.

[0106] The test results of the above greenhouse potted herbicidal activity are shown in Table 3:

[0107] Table 3 Inhibition rate of greenhouse potted herbicidal activity of some target compounds (%)

[0108]

[0109]

[0110] The results of greenhouse potted herbicidal activity showed that some target compounds showed good herbicidal activity, and most compounds had higher inhibitory effects on dicotyledons than on monocotyledons. For example, the inhibition rates of compound II-1 on dicotyledonous plants rape, velvetleaf, Amaranthus retroflexus and Chenopodium album were 84%, 90%, 100% and 97%, respectively, while the inhibition rates on monocotyledonous plants barnyard grass, crabgrass, goosegrass and foxtail grass were 67%, 11%, 37% and 40%, respectively; the inhibition rates of compound II-6 on rape, velvetleaf, Amaranthus retroflexus and Chenopodium album were all 100%, while the inhibition rates on monocotyledonous plants barnyard grass, crabgrass, goosegrass and foxtail grass were 50%, 60%, 67% and 53%, respectively. In addition, the structure-activity relationship study found that the number of side chain carbons of the target compound had a certain effect on the herbicidal activity. When n=3, the herbicidal activity of the compound was generally higher than that of compound n=1. The substituents on the benzene ring of the target compound also have a great influence on the herbicidal activity of the compound. When R2 of the compound is a fluorine atom and R4 is a chlorine atom, the herbicidal activity of compound II-6 is the best.

[0111] The above results indicate that the compounds provided so far have application potential in the selective control of dicotyledonous weeds in farmland.

[0112] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A compound of formula V, or a stereoisomer thereof, or an agrochemically acceptable salt thereof: in, R 1 , R 2 , R 3 , R 4 Independently selected from the following groups: any one of hydrogen, halogen, C1-C6 straight chain or branched chain alkyl, halogen-substituted C1-C6 straight chain or branched chain alkyl, and C1-C6 alkoxy; R 5 , R 6 Independently selected from the following groups: hydrogen, C1-C6 straight chain or branched chain alkyl or halogen-substituted C1-C6 straight chain or branched chain alkyl; R 7 , R 8 are independently selected from the following groups: hydrogen, C1-C6 straight chain or branched chain alkyl or halogen-substituted C1-C6 straight chain or branched chain alkyl; or R 7 , R 8 The atoms directly connected to it form a 4-6 membered cycloalkane or a 5-10 membered aromatic ring; n is selected from 1, 2, 3 or 4.

2. The compound according to claim 1, or its stereoisomer, or its agrochemically acceptable salt, characterized in that: in, The halogen is selected from fluorine, chlorine, bromine or iodine; The C1-C6 straight or branched alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl; The C1-C6 alkoxy group is selected from methoxy, ethoxy, n-propoxy, isopropoxy or n-butoxy; The 4-6 membered cycloalkyl group is selected from cyclohexane or cyclopentane; The 5-10 membered aromatic group is selected from a phenyl group or a naphthyl ring group; n is selected from 1, 2 or 3.

3. The compound according to any one of claims 1 to 2, or its stereoisomer, or its agrochemically acceptable salt, characterized in that: The compound of formula V is selected from the structure shown in formula I, formula II or formula III: Among them, R 1 , R 2 , R 3 , R 4 Independently selected from the following groups: any one of hydrogen, fluorine, chlorine, bromine, iodine, methyl, ethyl or n-propyl; R 5 , R 6 Independently selected from the following groups: any one of hydrogen, methyl, ethyl or n-propyl; n is selected from 1, 2 or 3.

4. The compound according to any one of claims 1 to 3, or its stereoisomer, or its agrochemically acceptable salt, characterized in that: The specific structure of the compound is:

5. A method for preparing the compound of formula V according to any one of claims 1 to 4, or its stereoisomers, or its agrochemically acceptable salts, characterized in that: It includes the following steps: Step a: dissolving the compound of formula 1 and the compound of formula 2 in a solvent, and preparing a compound of formula 3 under alkaline conditions; Step b: dissolving the compound of formula 3 in a solvent and preparing the compound of formula 4 under alkaline conditions; Step c: dissolving the compound of formula 4 in a solvent and preparing the compound of formula 5 under reducing conditions; Step d: Compound 5 and compound 6 are reacted in an acidic solvent under heating conditions to obtain compound 7; Step e: dissolving the compound of formula 7 in a solvent, and adding a chlorination agent to obtain a compound of formula 8; Step f: dissolving the compound of formula 8 and the compound of formula 9 in a solvent, and preparing the compound of formula V under alkaline conditions; Wherein the substituent R in Formulas 1 to 9 and V 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , n is defined as in any one of claims 1 to 4.

6. The preparation method according to claim 5, characterized in that: The solvent in step a, step b, step c, step e and step f is selected from one or two of N,N-dimethylformamide, methanol, ethanol, ethyl acetate, dichloromethane, toluene, DMSO, acetone, acetonitrile, methyl tert-butyl ether, diethyl ether and water; Preferably, the solvent in step a is selected from N,N-dimethylformamide; In step b, the solvent is selected from methanol and water; In the step c, the solvent is selected from ethyl acetate; In the step e, the solvent is selected from dichloromethane; In the step f, the solvent is selected from dichloromethane; And / or, the alkaline conditions of step a, step b, and step f are selected from sodium hydrogen, sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, N,N-diisopropylethylamine, triethylamine, lithium diisopropylamide, n-(C 1-6 One or both of lithium (alkyl), potassium butoxide or potassium pentoxide; Preferably, the alkaline condition in step a is selected from potassium carbonate; The alkaline condition in step b is selected from lithium hydroxide; The alkaline condition in step f is selected from triethylamine; And / or, the reduction conditions of step c are palladium / carbon and hydrogen, iron powder and hydrochloric acid, zinc powder and hydrochloric acid, lithium aluminum tetrahydride or sodium borohydride, Preferably, the reduction conditions in step c are palladium / carbon and hydrogen; And / or, the acidic solvent in step d is hydrochloric acid, acetic acid or sulfuric acid: Preferably, the acidic condition in step d is acetic acid; And / or, the chlorination agent in step e is thionyl chloride.

7. A pesticide composition comprising at least one compound of formula I-1 according to any one of claims 1 to 4, or a stereoisomer thereof, or an agrochemically acceptable salt thereof and a carrier; the carrier is in liquid or solid form.

8. Use of the compound according to any one of claims 1 to 4, or its stereoisomer, or its agrochemically acceptable salt, or the pesticide composition according to claim 7 in an agricultural herbicide, preferably, the agricultural herbicide is used to kill weeds, and the weeds are dicotyledons or monocotyledons.

9. The use according to claim 8, wherein the weeds are rape, velvetleaf, Amaranthus retroflexus, Leonurus japonicus, Echinochloa crusgalli, Digitaria sanguinea, Goosegrass or Setaria viridis.

10. A method for controlling or preventing unwanted plant growth, wherein a herbicidally effective amount of a compound as defined in any one of claims 1 to 4, or a stereoisomer thereof, or an agrochemically acceptable salt thereof, or a pesticidal composition as claimed in claim 7 is applied to these plants, parts thereof or the locus thereof.

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