Acetohydroxyacid synthase inhibitor, preparation method therefor, and use thereof as herbicide

Abstract

The present invention relates to inhibitor compounds and aims to provide an acetohydroxyacid synthase inhibitor, a preparation method therefor, and a use thereof as an herbicide. The structure of the compound is shown in formula (I), and said compound specifically inhibits the activity of acetohydroxyacid synthase or a mutant thereof W574L in plants. The present invention further provides a method for applying said compound as an agrochemical herbicide. The described compound exhibits good enzyme inhibitory activity against wild-type acetohydroxyacid synthase and / or a mutant thereof W574L, and therefore can be used as an agrochemical herbicide for the control of various weeds in the agricultural field. Moreover, the compound can be used as both a pre-emergence and post-emergence herbicide, targeting various field weeds, and is particularly effective in controlling the malignant weed Leptochloa chinensis. The described compound features low dosage, excellent herbicidal activity, broad weed control spectrum, good translocation, wide application window, and safety to rice.

Description

Acetohydroxy acid synthase inhibitor, preparation method thereof and use as herbicide Technical Field

[0001] The present invention relates to an inhibitor compound, particularly an acetohydroxyacid synthase inhibitor, its preparation method, and its use as a herbicide. The compound targets acetohydroxyacid synthase or its mutant W574L and can be used as a herbicide for weed control in the agricultural sector. The product is particularly effective against the malignant weed Leptochloa chinensis and is superior to the commonly used commercial herbicides cyhalofop-butyl and penoxsulam in controlling resistant Leptochloa chinensis. Background Art

[0002] Leptochloa chinensis (L.) Nees. belongs to the grass family and is a malignant weed worldwide. Leptochloa chinensis has a large number of seeds (an average of 45,000 seeds per plant) and a strong tillering ability (the number of tillers can be as high as 48.2). In addition, the drought-tolerant and moisture-loving characteristics of Leptochloa chinensis are very suitable for its occurrence and rapid spread in rice fields, evolving into the main weed population in rice fields, competing with rice and causing serious rice yield reductions. With the promotion and development of direct seeding technology and no-tillage technology in rice fields, the damage caused by Leptochloa chinensis is becoming increasingly serious. Studies have shown that the density of Leptochloa chinensis reaches 21 plants / m 2 When the amount of water is increased, the rice yield can be reduced by 44.36%.

[0003] In the prevention and control of Leptochloa chinensis, it is difficult to control it by time difference because Leptochloa chinensis and rice seedlings emerge almost simultaneously. In terms of chemical control, there are few herbicide options for Leptochloa chinensis. Currently, aryloxyphenoxypropionate (APP) herbicides such as cyhalofop-butyl, fenoxaprop-butyl and methoprene-butyl are mainly used for farmland weed control. This type of herbicide is an acetyl-coenzyme A carboxylase (ACCase) inhibitor and can only be used for post-emergence control of Leptochloa chinensis.

[0004] Cyhalofop-butyl is most widely used in rice fields, but the long-term, excessive, and frequent use of the same herbicide has also led to the rapid development of resistant Leptochloa chinensis. Some Leptochloa chinensis populations resistant to cyhalofop-butyl have a resistance coefficient of up to 191.6 times that of the herbicide. Furthermore, in Southeast Asia and China, Leptochloa chinensis resistant to ACCase inhibitor herbicides has also been found to develop cross-resistance to inhibitors of other targets, such as propanil (a photosynthetic system II inhibitor) and quinclorac (a growth hormone herbicide).

[0005] The mechanisms of insecticide resistance in Leptochloa chinensis include target resistance and non-target resistance. Currently reported target resistance in Leptochloa chinensis primarily arises from amino acid mutations at positions 1781, 1999, and 2027. Non-target resistance may be related to increased activity of glutathione S-transferases (GSTs), which can increase the rate of herbicide metabolism and decomposition in weeds, leading to insecticide resistance in Leptochloa chinensis.

[0006] Acetohydroxyacid synthase (AHAS) is a key enzyme that catalyzes the first stage of the biosynthesis pathway for the branched-chain amino acids leucine, valine, and isoleucine. AHAS catalyzes the conversion of two molecules of pyruvate to α-acetolactate, or one molecule of pyruvate and α-ketobutyrate to 2-acetyl-2-hydroxybutyrate. AHAS inhibitors inhibit the catalytic activity of AHAS in plants, hindering the synthesis of branched-chain amino acids, affecting protein synthesis and further inhibiting cell division. This leads to chlorosis and yellowing of plant tissues, inhibited plant growth, and ultimately, plant death. Furthermore, AHAS is found only in plants, fungi, and bacteria, not in animals. Therefore, inhibitors designed as a target for AHAS are highly biosafe for mammals. Furthermore, these herbicides offer low application doses, broad-spectrum herbicidal activity, and high crop safety, making them currently the most important class of herbicides.

[0007] However, existing commercial herbicides targeting acetohydroxyacid synthase are ineffective in controlling resistant Leptochloa chinensis at recommended field doses due to the specific structural properties of their compounds. Furthermore, there is no cross-resistance between herbicides targeting AHAS and ACCase inhibitors.

[0008] Based on the above reasons, it is urgent and of great significance to construct herbicides with skeleton structures different from existing acetohydroxyacid synthase inhibitors and use them to control resistant Leptochloa chinensis. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide an acetohydroxyacid synthase inhibitor and a preparation method thereof and application thereof as a herbicide.

[0010] To achieve the above object, the solution of the present invention is:

[0011] Provided is an acetohydroxyacid synthase inhibitor, the structural formula of the compound is shown in formula (I):

[0012] The compound specifically inhibits the activity of acetohydroxy acid synthase or its mutant W574L in plants.

[0013] The present invention further provides a method for preparing the acetohydroxyacid synthase inhibitor, and the synthetic route of the preparation method is shown in the following formula:

[0014] As a preferred embodiment of the present invention, the preparation method specifically comprises the following steps:

[0015] (1) using methanol or ethanol as the solvent of the reaction system, reacting 4-(4-chlorophenoxy)aniline with salicylaldehyde to prepare the corresponding Schiff base; controlling the molar ratio of 4-(4-chlorophenoxy)aniline to salicylaldehyde to be 1:1.2, the reaction temperature to be room temperature, and the reaction time to be 2 hours;

[0016] (2) using sodium borohydride or potassium borohydride as a reducing agent and methanol or ethanol as a solvent for the reaction system to reduce a Schiff base to obtain a benzylamine compound; controlling the molar ratio of the Schiff base to the reducing agent to be 1:1.5, the reaction temperature to be room temperature, and the reaction time to be 0.5 hours;

[0017] (3) The target product, an acetohydroxyacid synthase inhibitor, is prepared by reacting a benzylamine compound with 2-methylsulfonyl-4,6-dimethoxypyrimidine; potassium carbonate or cesium carbonate is used as a base, and 1,4-dioxane is used as a reaction solvent; the molar ratio of the benzylamine compound, 2-methylsulfonyl-4,6-dimethoxypyrimidine and the base is controlled to be 1:1.2:1.2, the reaction temperature is the boiling point of the solvent, and the reaction time is 1 hour; the target product is finally obtained and purified by silica gel chromatography or recrystallization.

[0018] The present invention further provides a herbicidal composition comprising a herbicidally active amount of the acetohydroxyacid synthase inhibitor according to claim 1 and at least one formulation adjuvant.

[0019] The present invention further provides a method for preparing a herbicidally active composition, comprising mixing a herbicidally active amount of the acetohydroxyacid synthase inhibitor according to claim 1 and at least one formulation adjuvant.

[0020] The present invention further provides the use of the aforementioned acetohydroxyacid synthase inhibitor as an agricultural chemical herbicide, wherein the compound specifically inhibits the activity of acetohydroxyacid synthase or its mutant W574L in plants.

[0021] The present invention further provides a method for using the aforementioned acetohydroxy acid synthase inhibitor as an agricultural chemical herbicide to control resistant Leptochloa chinensis, which comprises applying a herbicidally active amount of the acetohydroxy acid synthase inhibitor to the leaves of the resistant Leptochloa chinensis in the pre-bud or late-bud stage, and the compound specifically inhibits the activity of acetohydroxy acid synthase or its mutant W574L in the resistant Leptochloa chinensis plant.

[0022] The present invention further provides a method for using the aforementioned acetohydroxyacid synthase inhibitor as an agricultural chemical herbicide, comprising applying a herbicidally active amount of the acetohydroxyacid synthase inhibitor to the leaves of weeds, wherein the compound specifically inhibits the activity of acetohydroxyacid synthase or its mutant W574L in the weed plant body; the weed is any one of the following: Leptochloa chinensis, Echinochloa crus-galli, Digitaria sanguinalis, Amaranthus retroflexus, Goosegrass, Setaria viridis, Poa annua, Chenopodium album, Purslane, Setaria officinalis, Herba Revolutae, Brassica juncea, Polygonum sylvestris, Cyperus dimorphus, Achyranthes bidentata, Dalbergia vaginalis, or Cyperus rotundus.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The acetohydroxyacid synthase inhibitor provided by the present invention has good enzyme inhibitory activity against wild-type acetohydroxyacid synthase and / or its mutant W574L. Therefore, it can be used as an agricultural chemical herbicide for controlling various weeds in the agricultural field.

[0025] 2. The acetohydroxyacid synthase inhibitor provided by the present invention can be used as a pre-emergence and post-emergence herbicide, and the objects of control include barnyard grass, crabgrass, Amaranthus retroflexus, Goosegrass, Setaria viridis, Poa annua, Chenopodium album, Purslane, Setaria officinalis, revolutionary grass, mustard, Polygonum multiflorum, Cyperus dimorphus, Amaranthus chinensis, Dalbergia tongue, Cyperus rotundus, etc.

[0026] 3. The acetohydroxyacid synthase inhibitor provided by the present invention is particularly effective in preventing and controlling the malignant weed Leptochloa chinensis, and its control effect on resistant Leptochloa chinensis is better than the commercial herbicides cyhalofop-butyl and penoxsulam.

[0027] 4. The acetohydroxyacid synthase inhibitors provided by this invention are used as agricultural chemical herbicides for weed control in the agricultural sector. They offer advantages such as low dosage, excellent herbicidal activity, a broad spectrum of weed control, good conductivity, a wide window of use, and safety for rice. They are particularly effective in controlling Leptochloa chinensis, particularly resistant Leptochloa chinensis, and have great potential. DETAILED DESCRIPTION

[0028] The following specific examples are used to further illustrate the present invention, but the present invention is by no means limited to these examples.

[0029] Example 1: This example is used to illustrate the synthesis of the acetohydroxyacid synthase inhibitor (I) provided by the present invention.

[0030] The synthetic route of this preparation method is shown below:

[0031] Salicylaldehyde (4.44 g, 36 mmol) was added dropwise to a solution of 4-(4-chlorophenoxy)aniline (6.61 g, 30 mmol) in anhydrous methanol (150 mL). The reaction was stirred at room temperature for 2 hours, and the starting material disappeared by TLC to obtain the corresponding Schiff base. Sodium borohydride (1.71 g, 45 mmol) was added to the above reaction system in three portions, and the reaction was allowed to proceed at room temperature for 0.5 hours. The solvent was removed under reduced pressure to obtain the crude product of the benzylamine compound. The crude product of the benzylamine compound was dissolved in 1,4-dioxane (150 mL), and anhydrous cesium carbonate (11.73 g, 36 mmol) and 2-methylsulfonyl-4,6-dimethoxypyrimidine (7.86 g, 36 mmol) were added. The reaction was heated at reflux for 1 hour, and the starting material disappeared by TLC. The solvent 1,4-dioxane was removed under reduced pressure. Water was added to the crude residue, and the mixture was extracted with ethyl acetate (150 mL x 3). The combined organic phases were washed with brine, dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain a crude product of Compound (I). The crude product was recrystallized from ethyl acetate to obtain a white solid product, ie, an acetohydroxyacid synthase inhibitor (9.81 g, 70.3%).

[0032] The physicochemical properties of inhibitor (I) are as follows:

[0033] Solid; melting point: 127.8-128.9℃; 1 H NMR (400MHz, DMSO-d6) δ7.43(dd,J=7.5Hz,1.4,1H),7.31(td,J=6.4Hz,5.9,2.3,3H),7.23(td,J=7.4Hz,1.2,1H),7.17(dd,J=7. 9Hz,1.2,1H),6.87-6.81(m,2H),6.80-6.75(m,2H),6.57-6.49(m,2H),6.18(s,1H),6.00(s,1H),4.15(s,2H),3.76(s,6H).HRMS m / z(ESI-TOF):calcd.for C 25 H 23 ClN3O4[M+H] + :464.1372,found 464.1372.

[0034] Example 2: This example is used to illustrate the inhibitory activity of the acetohydroxyacid synthase inhibitor (I) provided by the present invention on wild-type acetohydroxyacidase and its mutant W7574L.

[0035] The enzyme activity test was carried out according to the method described in the literature "Anal Biochem 1988, 171, 173-179", and it was found that the inhibitor (I) provided by the present invention had an activity against the wild type acetohydroxyacid synthase (IC 50 and K i : μM) and its mutant W574L (IC 50 : μM) inhibitory activity. IC 50 : Half inhibitory concentration. K i : Inhibition constant, specific results are shown in Table 1.

[0036] The binding ability of inhibitor (I) to wild-type acetohydroxyacid synthase (K D : μM). K D : Equilibrium dissociation constant of inhibitor (I) and protein. Specific results are shown in Table 1.

[0037] Table 1

[0038] As shown in Table 1, inhibitor (I) exhibits good inhibitory activity against wild-type AHAS, reaching micromolar activity, indicating that it is an acetohydroxyacid synthase inhibitor. Inhibitor (I) exhibits comparable enzyme inhibitory activity against wild-type AHAS and its W574L mutant, indicating that the inhibitor also exhibits good adaptability to the mutant.

[0039] Because the molecular skeleton structure of inhibitor (I) is different from all existing commercial acetohydroxyacid synthase inhibitors, it is a novel inhibitor with good adaptability to acetohydroxyacid synthase. Importantly, Example 2 lays the molecular foundation for the development of inhibitor (I) into a new herbicide.

[0040] Example 3: This example is used to illustrate the post-emergence herbicidal activity test of the acetohydroxyacid synthase inhibitor (I) provided by the present invention against resistant Leptochloa chinensis.

[0041] Test agent: inhibitor (I).

[0042] Control agent: cyhalofop-butyl.

[0043] Test target: ACCase-resistant Leptochloa chinensis.

[0044] Planting method: The soil used in the experiment is sandy soil, silt soil and clay, which are prepared in a mass ratio of 1:1:1. After mixing and stirring evenly, they are used as special soil for the experiment. Take a flower pot with a diameter of 8 cm, fill the soil to 3 / 4 of the flower pot, and place the flower pot in a large stainless steel basin filled with 5 cm deep water until the soil is completely moistened. Sow 10-15 target weed seeds mentioned above in the flower pot. After sowing, cover with 0.2-0.5 cm of soil, and then place it in a greenhouse for cultivation. Replenish water every day to keep the soil moisture at about 80% (relative humidity). The greenhouse temperature is 28±2°C and the relative humidity is 60-80%.

[0045] Application method: Using the greenhouse potting method, spray the stems and leaves of weeds until they reach the two-leaf stage. Each treatment is repeated twice, with a blank control (distilled water) provided. The treatment doses are shown in Table 2. After spraying, the weeds are allowed to stand still indoors until the weed leaves have absorbed the spray solution. They are then transferred to the greenhouse for cultivation at a growth temperature of 28±2°C.

[0046] Investigation Method: Regularly observe the growth and symptoms of treated weeds. Twenty-one days after treatment, cut the aboveground portion of the target weeds and weigh their fresh weight. The fresh weight inhibition rate was calculated using the following formula. See Table 2 for detailed test results.

[0047] F=(CT) / C×100

[0048] Where: F: fresh weight inhibition rate (%); C: fresh weight of the aboveground part of the blank control plant (g); T: fresh weight of the aboveground part of the treated plant (g).

[0049] Table 2

[0050] As shown in Table 2, cyhalofop-butyl at the recommended field dose (75 g ai / ha) had a control efficacy of only 17.3% against resistant Leptochloa chinensis, while at a high dose (300 g ai / ha), the efficacy was only 59.5%. Inhibitor (I) had a control efficacy of 86.2% at the same dose (75 g ai / ha), and even at a lower dose of 37.5 g ai / ha, it still maintained an efficacy of 83.4%.

[0051] The results showed that inhibitor (I) was significantly more active than cyhalofop-butyl against ACCase-resistant Leptochloa chinensis. Cyhalofop-butyl was no longer effective against ACCase-resistant Leptochloa chinensis at the recommended field dose. Therefore, inhibitor (I) targeting acetohydroxyacid synthase could replace cyhalofop-butyl for the control of ACCase-resistant Leptochloa chinensis.

[0052] Example 4: This example is used to illustrate the effect of the leaf age of Leptochloa chinensis on the herbicidal activity of the acetohydroxyacid synthase inhibitor (I) provided by the present invention.

[0053] Test agent: inhibitor (I).

[0054] Control agent: cyhalofop-butyl.

[0055] Test target: Sensitive Leptochloa chinensis.

[0056] Planting method: Same as Example 3. Growth temperature: 25±2°C.

[0057] Application method: Using the greenhouse potting method, weeds were sprayed on their stems and leaves when they reached the 0, 1, 2, 3, and 4 leaf stages, with three replicates per treatment. A blank control (distilled water) was used as the blank control. Treatment dosages are shown in Table 3.

[0058] After spraying, let it stand still indoors until the weed leaves absorb the liquid, then move it into the greenhouse for cultivation at a growth temperature of 25±2℃.

[0059] Investigation Method: Regularly observe the growth and symptoms of treated weeds. Twenty-one days after treatment, cut the aboveground portion of the target weeds, weigh the fresh weight, and calculate the fresh weight inhibition rate. The fresh weight inhibition rate was calculated using the following formula. Specific test results are shown in Table 3.

[0060] F=(CT) / C×100

[0061] Where: F: fresh weight inhibition rate (%); C: fresh weight of the aboveground part of the blank control plant (g); T: fresh weight of the aboveground part of the treated plant (g).

[0062] Table 3

[0063] As shown in Table 3, at the same dosage (75 g ai / ha), inhibitor (I) had a control effect of 96.2-99.7% on the fresh weight of sensitive Leptochloa chinensis at the 0-1 leaf stage, which was better than the control agent cyhalofop-butyl.

[0064] For weeds in the 2-4 leaf stage, at a dosage of 75g ai / ha, the fresh weight control effect of inhibitor (I) was 71.3-82.9%; when the dosage was increased to 300g ai / h, the fresh weight control effect on weeds in the 2-4 leaf stage was 84.1-97.1%. Therefore, the dosage can be appropriately increased for older Leptochloa chinensis.

[0065] The results of Example 4 demonstrate that inhibitor (I) exhibits good herbicidal activity against weeds in the 0-4 leaf stage and can be used both as a pre-emergence herbicide (sprayed at the 0-1 leaf stage) and a post-emergence herbicide (sprayed at the 2-3 leaf stage). Therefore, inhibitor (I) is both a pre-emergence and post-emergence herbicide with a wider window of efficacy than cyhalofop-butyl.

[0066] Example 5: This example is used to illustrate the effect of application temperature on the post-emergence herbicidal activity of the acetohydroxyacid synthase inhibitor (I) provided by the present invention.

[0067] Test agent: inhibitor (I).

[0068] Control agent: cyhalofop-butyl.

[0069] Test target: Sensitive Leptochloa chinensis.

[0070] Planting method: Example 3.

[0071] Application method: Using the greenhouse potting method, spray the stems and leaves of weeds until they reach the 3-4 leaf stage. Each treatment is repeated three times, with a blank control (distilled water) provided. Treatment dosages are shown in Table 4.

[0072] After spraying, the plants were immediately placed in an artificial climate chamber for cultivation. The cultivation temperature (L / D) was set at: 35°C / 30°C, 25°C / 20°C, 15°C / 10°C, relative humidity at 60-80%, and light intensity (L / D) at 12 / 12 hours.

[0073] Investigation Method: Regularly observe the growth and symptoms of treated weeds. Twenty-one days after treatment, cut the aboveground portion of the target weeds and weigh their fresh weight. The fresh weight inhibition rate was calculated using the same formula as in Example 3. Specific test results are shown in Table 4.

[0074] Table 4

[0075] As shown in Table 4, at a dose of 75 g ai / ha at 30-35°C, inhibitor (I) achieved a 95.4% herbicidal efficacy against Leptochloa chinensis at the 3- to 4-leaf stage, demonstrating extremely high herbicidal activity. At the same dose, inhibitor (I) exhibited a higher inhibition rate against Leptochloa chinensis fresh weight with increasing temperature, demonstrating a positive correlation between its herbicidal activity and temperature. This suggests that inhibitor (I) is well-suited to the rice growth period.

[0076] Example 6: This example is used to illustrate the absorption of the acetohydroxyacid synthase inhibitor (I) provided by the present invention by plants.

[0077] Test agent: inhibitor (I).

[0078] Control agent: cyhalofop-butyl.

[0079] Test target: Sensitive Leptochloa chinensis.

[0080] Planting method: same as Example 3.

[0081] Application method: Using the greenhouse potting method, when weeds reached the 3-4 leaf stage, we applied the pesticide using both foliar spray and root irrigation. Each treatment was replicated three times, with a blank control (distilled water) provided. Treatment dosages are shown in Table 5.

[0082] After the treatment, the plants were placed in a greenhouse for cultivation. During the test, the temperature in the greenhouse was 25°C ± 2°C and the relative humidity was 60% to 80%.

[0083] Investigation Method: Regularly observe the growth and symptoms of treated weeds. Twenty-one days after treatment, cut the aboveground portion of the target weeds and weigh their fresh weight. The fresh weight inhibition rate was calculated using the same formula as in Example 3. Specific test results are shown in Table 5.

[0084] Table 5

[0085] Tests using both foliar spray and root irrigation showed that inhibitor (I) and the control agent, cyhalofop-butyl, significantly inhibited the fresh weight of both the aboveground and underground parts of Leptochloa chinensis. At the same dose, inhibitor (I) had a slightly higher inhibition rate on the fresh weight of the underground parts than on the aboveground parts. These results suggest that inhibitor (I) can be absorbed by the plant through its roots, stems, and leaves.

[0086] Example 7: This example is used to illustrate the safety test of the acetohydroxyacid synthase inhibitor provided by the present invention on rice treated with stems and leaves after germination.

[0087] Test agent: inhibitor (I).

[0088] Test target: Rice (Japonica 9746).

[0089] Planting method: same as Example 3.

[0090] Application method: Same as Example 3. After the rice has grown to 3-4 leaves, the stems and leaves are sprayed. Each treatment is repeated 3 times. A blank control (distilled water) is set. The treatment dosage is shown in Table 6.

[0091] After spraying, the rice plants were left to stand in the room until the liquid on the rice leaves dried, and then moved into the greenhouse for cultivation. The growth temperature was 25±8°C and the relative humidity was 60-80%.

[0092] Investigation Method: Crop growth and symptoms were regularly observed after treatment. Thirty days after treatment, plant height and fresh weight were measured, and plant height and fresh weight inhibition rates were calculated. Fresh weight inhibition rate was calculated as in Example 3, while plant height inhibition rate was calculated using the following formula. Specific test results are shown in Table 6.

[0093] H=(CT) / C×100

[0094] Where: H: plant height inhibition rate (%); C: blank control plant height (cm); T: treated plant height (cm).

[0095] Table 6

[0096] As shown in Table 6, within the dosage range of 150 g ai / ha, the inhibitor (I) had an inhibition rate of less than 10% on the plant height and fresh weight of rice. This dosage was safe for rice seedlings at the 3-4 leaf stage. 10 At low doses (≤60 g ai / ha), inhibitor (I) promoted rice growth.

[0097] Example 8: This example is used to illustrate the field test of controlling Leptochloa chinensis with the acetohydroxyacid synthase inhibitor (I) provided by the present invention.

[0098] Test agent: inhibitor (I).

[0099] Control agents: penoxsulam and cyhalofop-butyl.

[0100] Application method: Spray the pesticide in the evening after rice plants have grown to 3-4 leaves and Leptochloa chinensis has grown to 2-3 leaves. Each treatment plot was 27.5 square meters in size, with three replicates per treatment. A blank control (distilled water) was used as the blank control. Treatment dosages are shown in Table 7.

[0101] Survey Methods: Weed growth and symptoms were regularly observed after treatment. Plant and fresh weight efficacy was assessed 40 days after application. Samples were collected at three locations per plot, each covering 0.10 square meters, for a total of 0.30 square meters. The number of Leptochloa chinensis plants and fresh weight within each location were recorded, and plant and fresh weight efficacy were calculated. These efficacy were calculated using the following formulas. See Table 7 for detailed test results.

[0102] Plant protection effect (%) = (N C –N T ) / N C ×100

[0103] Fresh weight prevention effect (%) = (W C –W T ) / W C ×100

[0104] Where: N C : Number of weeds in the blank control area; N T : the number of weeds in the treatment area; W C W: fresh weight of weeds in blank control area; T : Fresh weight of weeds in treatment areas.

[0105] Table 7

[0106] As shown in Table 7, 40 days after application, inhibitor (I) demonstrated extremely high efficacy against Leptochloa chinensis at both doses, significantly outperforming penoxsulam. When cyhalofop-butyl was used to control resistant Leptochloa chinensis in the field, the dosage required was as high as 750 g ai / ha, approximately 10 times the recommended dosage in the registration. However, inhibitor (I) achieved 100% plant and fresh weight efficacy 40 days after application at a dose of 150 g ai / ha, effectively controlling resistant Leptochloa chinensis.

[0107] The above results showed that inhibitor (I) could effectively control resistant Leptochloa chinensis, and its efficacy was better than cyhalofop-butyl and penoxsulam.

[0108] Example 9: This example is used to illustrate the post-emergence weed control spectrum test of the acetohydroxyacid synthase inhibitor (I) provided by the present invention.

[0109] Test agent: inhibitor (I).

[0110] Test targets: grass weeds, broadleaf weeds, and sedges.

[0111] Planting method: Same as in Example 3. Sow each weed seed in a pot, ensuring 20-30 seeds per pot, and then cultivate in a greenhouse. Water daily to maintain soil moisture at approximately 80% (relative humidity). The growth temperature is 25±2°C and the relative humidity is 60-80%.

[0112] Application Method: Using a greenhouse potting method, spray the stems and leaves of grasses and sedges until they reach the 1-1.5 leaf stage, and broadleaf weeds until they reach the true leaf stage. Three replicates are used for each weed species, with a blank control (distilled water) serving as a blank. The treatment dose is 75 g ai / ha. After spraying, allow the plants to stand still indoors until the weed leaves have absorbed the solution. Then, transfer them to the greenhouse for incubation at a temperature of 25 ± 2°C.

[0113] Investigation Method: Regularly observe the growth and symptoms of treated weeds. Twenty days after application, visually assess the herbicidal activity of inhibitor (I) against each target weed. The visual phytotoxicity evaluation criteria are shown in Table 8, and the specific test results are shown in Table 9.

[0114] Table 8

[0115] Table 9

[0116] As shown in Table 9, at a dose of 75 g ai / ha, six weed species—Poa annua, Goosegrass, Chenopodium album, Amaranthus retroflexus, Cyperus diversiformis, and Brassica juncea—were highly sensitive to inhibitor (I) (90-95%). Seven weed species—Purslane, Digitaria sanguinalis, Setaria officinalis, Grass of Revolution, Cyperus rotundus, Echinochloa crusgalli, and Setaria viridis—were moderately sensitive (80-85%). However, Echinops striata, Abutilon venetum, and Cassia tora were less sensitive. These results indicate that inhibitor (I) has a broad spectrum of herbicidal activity and exhibits good activity against major weeds in rice fields.

[0117] The acetohydroxyacid synthase inhibitor of the present invention can be used as the active ingredient of a herbicide, and can be prepared into various emulsions, granules, etc. by using a pesticide preparation processing method and adding various adjuvants such as organic solvents, surfactants, and carriers for weed control on crops.

[0118] Example 10: Emulsion

[0119] Heat and stir 5% of inhibitor (I), 5% of Nongru No. 500 (calcium salt), 5% of Nongru No. 602, 5% of N-methyl-2-pyrrolidone and 80% of solvent oil 330# to obtain an emulsion.

[0120] When applied in the field, spraying operation is performed with reference to the dosage of the acetohydroxyacid synthase inhibitor in each example.

[0121] Example 11: Wettable powder

[0122] 10% of inhibitor (I), 5% of lignin sulfonate (Mg), 1% of lauryl alcohol polyoxyethylene ether (JFC), 40% of diatomaceous earth and 44% of light calcium carbonate are uniformly mixed and crushed to obtain a wettable powder.

[0123] When applied in the field, the sowing operation is carried out according to the dosage of the acetohydroxyacid synthase inhibitor in each example.

Claims

1. An acetohydroxyacid synthase inhibitor, characterized in that The structural formula of the compound is shown in formula (I): The compound specifically inhibits the activity of acetohydroxy acid synthase or its mutant W574L in plants.

2. The method for preparing the acetohydroxyacid synthase inhibitor according to claim 1, characterized in that: The synthetic route of this preparation method is shown below:

3. The method according to claim 2, characterized in that The specific steps include: (1) using methanol or ethanol as the solvent of the reaction system, reacting 4-(4-chlorophenoxy)aniline with salicylaldehyde to prepare the corresponding Schiff base; controlling the molar ratio of 4-(4-chlorophenoxy)aniline to salicylaldehyde to be 1:1.2, the reaction temperature to be room temperature, and the reaction time to be 2 hours; (2) using sodium borohydride or potassium borohydride as a reducing agent and methanol or ethanol as a solvent for the reaction system to reduce a Schiff base to obtain a benzylamine compound; controlling the molar ratio of the Schiff base to the reducing agent to be 1:1.5, the reaction temperature to be room temperature, and the reaction time to be 0.5 hours; (3) The target product, an acetohydroxyacid synthase inhibitor, is prepared by reacting a benzylamine compound with 2-methylsulfonyl-4,6-dimethoxypyrimidine; potassium carbonate or cesium carbonate is used as a base, and 1,4-dioxane is used as a reaction solvent; the molar ratio of the benzylamine compound, 2-methylsulfonyl-4,6-dimethoxypyrimidine and the base is controlled to be 1:1.2:1.2, the reaction temperature is the boiling point of the solvent, and the reaction time is 1 hour; the target product is finally obtained and purified by silica gel chromatography or recrystallization.

4. A herbicidal composition, characterized in that The method comprises a herbicidally active amount of the acetohydroxyacid synthase inhibitor according to claim 1 and at least one formulation adjuvant.

5. A method for preparing a herbicidally active composition, characterized in that: The method comprises mixing a herbicidally active amount of the acetohydroxyacid synthase inhibitor according to claim 1 and at least one formulation auxiliary.

6. Use of the acetohydroxyacid synthase inhibitor according to claim 1 as an agricultural chemical herbicide, characterized in that: The compound specifically inhibits the activity of acetohydroxy acid synthase or its mutant W574L in plants.

7. The method for using the acetohydroxyacid synthase inhibitor according to claim 1 as an agricultural chemical herbicide for controlling resistant Leptochloa chinensis, characterized in that: The invention relates to a method for treating a herbicidal amount of an acetohydroxy acid synthase inhibitor on leaves of a resistant Leptochloa chinensis at the pre-bud or late-bud stage, wherein the compound specifically inhibits the activity of the acetohydroxy acid synthase or its mutant W574L in the resistant Leptochloa chinensis plant.

8. The method for using the acetohydroxyacid synthase inhibitor as an agricultural chemical herbicide according to claim 1, characterized in that: The method comprises applying a herbicidally active amount of an acetohydroxyacid synthase inhibitor to the leaves of weeds, wherein the compound specifically inhibits the activity of the acetohydroxyacid synthase or its mutant W574L in the weed plant body; The weeds are any one of the following: Leptochloa chinensis, Echinochloa crus-galli, Digitaria sanguinalis, Amaranthus retroflexus, Goosegrass, Setaria viridis, Poa annua, Chenopodium album, Purslane, Setaria officinalis, Grass of Revolution, Brassica juncea, Polygonum sylvestris, Cyperus difformis, Herba Lycopodii, Dalbergia tongue, or Cyperus rotundus.