Acetohydroxy acid synthase inhibitors, processes for their preparation and their use as herbicides

Abstract

The present application relates to an inhibitor compound, and aims to provide an acetohydroxy acid synthase inhibitor and a preparation method and application as a herbicide thereof. The structural formula of the compound is shown as formula (I), and the compound specifically inhibits the activity of acetohydroxy acid synthase or its mutant W574L in plants. The present application further provides a method for applying the compound as an agricultural chemical herbicide. The compound has good enzyme inhibition activity on wild-type acetohydroxy acid synthase and / or its mutant W574L, and thus can be used as an agricultural chemical herbicide for the prevention and treatment of various weeds in the agricultural field; can be used as a pre-emergence and post-emergence herbicide, and the prevention and treatment objects include various field weeds, and has a special effect on the prevention and treatment of the malignant weed Euphorbia lathyris L.; has the characteristics of low dosage, excellent herbicidal activity, wide weed spectrum, good transmission, wide application window period, safety to rice and the like.

Description

Technical Field

[0001] This invention relates to an inhibitor compound, particularly to an acetylhydroxy acid synthase inhibitor, its preparation method, and its application as a herbicide. The compound targets acetylhydroxy acid synthase or its mutant W574L and can be used as a herbicide for weed control in agriculture. This product is highly effective against the noxious weed *Clerodendrum trichotomum*, and is superior to commonly used commercial herbicides such as cyhalofop-butyl and penoxsulam in controlling resistant *Clerodendrum trichotomum*. Background Technology

[0002] *Leptochloa chinensis* (L.) Nees., a grass belonging to the Poaceae family, is a globally prevalent and noxious weed. It produces an enormous number of seeds (an average of 45,000 seeds per plant) and exhibits extremely high tillering ability (up to 48.2 tillers per plant). Combined with its drought-tolerant and moisture-loving characteristics, it is ideally suited for occurrence and rapid spread in paddy fields, quickly becoming a major weed species and competing with rice for nutrients, leading to severe yield reductions. With the promotion and development of direct seeding and no-till techniques in paddy fields, the damage caused by *Leptochloa chinensis* has become increasingly serious. Studies have shown that *Leptochloa chinensis* density can reach 21 plants / m². 2 At times, this can reduce rice yield by up to 44.36%.

[0003] For the control of Echinochloa crus-galli, since it emerges almost simultaneously with rice, it is difficult to control it by exploiting a time difference. In terms of chemical control, there are few herbicides available specifically for Echinochloa crus-galli. Currently, aryloxyphenoxypropionate (APP) herbicides are mainly used for weed control in farmland, such as cyhalofop-butyl, quizalofop-p-ethyl, and oxadiazon. These herbicides are acetyl-coenzyme A carboxylase (ACCase) inhibitors and can only be used for post-emergence control of Echinochloa crus-galli.

[0004] Cyhalofop-butyl is the most widely used herbicide in rice paddies, but long-term, excessive, and frequent use of the same type of herbicide has led to the rapid development of resistant *Echinochloa crus-galli*. Some *Echinochloa crus-galli* populations resistant to cyhalofop-butyl have a resistance coefficient of 191.6 times. Furthermore, in Southeast Asia and China, *Echinochloa crus-galli* species resistant to ACCase inhibitors have also developed cross-resistance with inhibitors of other target herbicides, such as propargite (a photosynthetic system II inhibitor herbicide) and quinclorac (a growth hormone herbicide).

[0005] The mechanisms by which *Echinochloa crus-galli* develops herbicide resistance include both target resistance and non-target resistance. Currently reported target resistance in *Echinochloa crus-galli* mainly originates from amino acid mutations at positions 1781, 1999, and 2027. Non-target resistance may be related to enhanced glutathione S-transferase (GST) activity, which increases the rate of herbicide metabolism in weeds, thus leading to herbicide resistance in *Echinochloa crus-galli*.

[0006] Acetylhydroxyacid synthase (AHAS) is a key enzyme in the first stage of the biosynthesis pathway of branched-chain amino acids—leucine, valine, and isoleucine. AHAS can catalyze the formation of α-acetolactate from two molecules of pyruvate, or the formation of 2-acetyl-2-hydroxybutyrate from one molecule of pyruvate and α-butanolate. Acetylhydroxyacid synthase inhibitors inhibit the catalytic activity of AHAS in plants, thereby hindering the synthesis of branched-chain amino acids, affecting protein synthesis, and further inhibiting cell division. This leads to chlorosis, yellowing, and inhibited plant growth, ultimately causing plant death. Furthermore, acetylhydroxyacid synthase is only found in plants, fungi, and bacteria, not in animals; therefore, inhibitors designed targeting this enzyme have extremely high biosafety in mammals. Simultaneously, these herbicides require low dosages, have broad-spectrum herbicidal activity, and are highly safe for crops, making them one of the most important classes of herbicides currently available.

[0007] However, existing commercially available herbicides targeting acetylhydroxy acid synthase (AHAs) are ineffective in controlling resistant Echinochloa crus-galli when applied at recommended field dosages due to the unique structure of their compound skeletons. Furthermore, there is no cross-resistance between AHAs-targeting herbicides and ACCase inhibitor herbicides.

[0008] For the reasons mentioned above, it is urgent and of great significance to construct herbicides with a framework structure different from existing acetylhydroxy acid synthase inhibitors and use them to control resistant Echinochloa crus-galli. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an acetylhydroxy acid synthase inhibitor, its preparation method and its application as a herbicide.

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

[0011] An acetylhydroxy acid synthase inhibitor is provided, the structural formula of which is shown in formula (I):

[0012]

[0013] This compound specifically inhibits the activity of acetylhydroxy acid synthase or its mutant W574L in plants.

[0014] This invention further provides a method for preparing the acetylhydroxy acid synthase inhibitor, the synthetic route of which is shown in the following formula:

[0015]

[0016]

[0017] As a preferred embodiment of the present invention, the preparation method specifically includes the following steps:

[0018] (1) Using methanol or ethanol as the solvent of the reaction system, the corresponding Schiff base is prepared by reacting 4-(4-chlorophenoxy)aniline with salicylaldehyde; the molar ratio of 4-(4-chlorophenoxy)aniline to salicylaldehyde is controlled to be 1:1.2, the reaction temperature is room temperature, and the reaction time is 2 hours.

[0019] (2) Using sodium borohydride or potassium borohydride as a reducing agent and methanol or ethanol as a solvent in the reaction system, benzylamine compound is prepared by reducing Schiff base; the molar ratio of Schiff base to reducing agent is controlled to be 1:1.5, the reaction temperature is room temperature, and the reaction time is 0.5 hours.

[0020] (3) The target product, an acetylhydroxy acid synthase inhibitor, was prepared by reacting benzylamine compound with 2-methylsulfonyl-4,6-dimethoxypyrimidine. Potassium carbonate or cesium carbonate was used as the base in the reaction, and 1,4-dioxane was used as the reaction solvent. The molar ratio of benzylamine compound, 2-methylsulfonyl-4,6-dimethoxypyrimidine and base was controlled to be 1:1.2:1.2, the reaction temperature was the boiling point of the solvent, and the reaction time was 1 hour. The target product was finally purified by silica gel chromatography or recrystallization.

[0021] The present invention further provides a herbicidal composition comprising a herbicidal active amount of the acetylhydroxy acid synthase inhibitor as described in claim 1 and at least one formulation adjuvant.

[0022] The present invention further provides a method for preparing a herbicidal active composition, which involves mixing a herbicidal active amount of the acetylhydroxy acid synthase inhibitor as described in claim 1 and at least one formulation adjuvant.

[0023] The present invention further provides the use of the aforementioned acetylhydroxy acid synthase inhibitor as an agricultural chemical herbicide, wherein the compound specifically inhibits the activity of acetylhydroxy acid synthase or its mutant W574L in plants.

[0024] The present invention further provides a method for using the aforementioned acetylhydroxyl synthase inhibitor as an agricultural chemical herbicide to control resistant Echinochloa crus-galli. The method involves applying a herbicidal active amount of the acetylhydroxyl synthase inhibitor to the leaves of resistant Echinochloa crus-galli before or after budding. The compound specifically inhibits the activity of acetylhydroxyl synthase or its mutant W574L in resistant Echinochloa crus-galli plants.

[0025] The present invention further provides a method for applying the aforementioned acetylhydroxyl synthase inhibitor as an agricultural chemical herbicide, which involves applying a herbicidal active amount of the acetylhydroxyl synthase inhibitor to the leaves of weeds. This compound specifically inhibits the activity of acetylhydroxyl synthase or its mutant W574L in the weed plant. The weeds are any of the following: barnyard grass, barnyard grass, crabgrass, amaranth, goosegrass, foxtail, Kentucky bluegrass, lambsquarters, purslane, golden foxtail, sedge, mustard greens, clove, sedge, jointed grass, duckweed, or nutgrass.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. The acetylhydroxy acid synthase inhibitor provided by this invention exhibits good enzyme inhibitory activity against wild-type acetylhydroxy acid synthase and / or its mutant W574L. Therefore, it can be used as an agricultural chemical herbicide for the control of various weeds in the agricultural field.

[0028] 2. The acetylhydroxy acid synthase inhibitor provided by this invention can be used as a pre-emergence and post-emergence herbicide, controlling pests including barnyard grass, crabgrass, amaranth, goosegrass, foxtail, Kentucky bluegrass, lambsquarters, purslane, golden foxtail, sedge, mustard greens, clove knotweed, sedge, jointed greens, duckweed, and nutgrass.

[0029] 3. The acetylhydroxy acid synthase inhibitor provided by this invention is highly effective in controlling the noxious weed *Echinochloa crus-galli*, and its control effect on resistant *Echinochloa crus-galli* is superior to that of commercial herbicides cyhalofop-butyl and penoxsulam.

[0030] 4. The acetylhydroxy acid synthase inhibitor provided by this invention, as an agricultural chemical herbicide for weed control in the agricultural field, has the characteristics of low dosage, excellent herbicidal activity, broad spectrum of weed control, good systemic properties, wide application window, and safety for rice. In particular, it is highly effective in controlling Echinochloa crus-galli, and has good efficacy and great potential in controlling resistant Echinochloa crus-galli. Detailed Implementation

[0031] The following specific embodiments are used to further illustrate the present invention, but the present invention is by no means limited to these examples.

[0032] Example 1: This example illustrates the synthesis of the acetylhydroxy acid synthase inhibitor (I) provided by the present invention.

[0033] The synthetic route of this preparation method is shown in the following formula:

[0034]

[0035] Salicylic aldehyde (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 TLC was used to detect the disappearance of the starting material, yielding the corresponding Schiff base. Sodium borohydride (1.71 g, 45 mmol) was added three times to the above reaction system, and the reaction was carried out at room temperature for 0.5 hours. The solvent was removed under reduced pressure to obtain a crude benzylamine compound. The crude 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 under reflux for 1 hour, and TLC was used to detect the disappearance of the starting material. 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 × 3). The combined organic phases were washed with brine, dried with anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain the crude product of compound (I). The crude product was recrystallized from ethyl acetate to give a white solid product, namely the acetylhydroxy acid synthase inhibitor (9.81 g, 70.3%).

[0036] The physicochemical properties of inhibitor (I) are as follows:

[0037] 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.

[0038] Example 2: This example illustrates the inhibitory activity of the acetylhydroxyl synthase inhibitor (I) provided by the present invention on wild-type acetylhydroxylase and its mutant W7574L.

[0039] Enzyme activity was tested according to the method described in the literature "Anal Biochem 1988, 171, 173–179", and the inhibitor (I) provided by this invention was found to be effective against wild-type acetylhydroxy acid synthase (IC). 50 and K i (μM) and its mutant W574L (IC 50 Inhibitory activity (μM): IC 50 Half-inhibitory concentration. K i : Suppression constant, the specific results are shown in Table 1.

[0040] The binding affinity (K) of the inhibitor (I) to wild-type acetylhydroxyl synthase was tested using surface plasmon resonance (SPR) technology. D :μM). K D : The equilibrium dissociation constant between the inhibitor (I) and the protein. Specific results are shown in Table 1.

[0041] Table 1

[0042] AHAS <![CDATA[IC 50 (μM)]]> <![CDATA[K i -Wild type (μM)]]> <![CDATA[K D -Wild type (μM)]]> wild type 75.4 39.4 3.8 W574L 72.8 - -

[0043] As shown in Table 1, inhibitor (I) exhibits good inhibitory activity compared to wild-type AHAS, reaching the micromolar level, indicating that it is an acetylhydroxy acid synthase inhibitor. Inhibitor (I) shows comparable inhibitory activity against both wild-type AHAS and its W574L mutant, suggesting that the inhibitor also exhibits good adaptability to its mutants.

[0044] Because the molecular backbone of inhibitor (I) differs from all existing commercially available acetylhydroxyl synthase inhibitors, it is a novel inhibitor with good adaptability to acetylhydroxyl synthase. Importantly, Example 2 lays the molecular foundation for the development of inhibitor (I) into a novel herbicide.

[0045] Example 3: This example illustrates the post-emergence weed control activity of the acetylhydroxy acid synthase inhibitor (I) provided by the present invention against Echinochloa crus-galli.

[0046] Test agent: Inhibitor (I).

[0047] Reference agent: Cyhalofop-butyl.

[0048] Test target: ACCase-resistant strychnos nux-vomica.

[0049] Planting Method: The experimental soil consisted of sandy soil, silty sand, and clay, mixed in a 1:1:1 mass ratio. The mixture was thoroughly stirred before use as the experimental soil. An 8cm diameter flowerpot was filled to 3 / 4 full with the soil. The flowerpot was then placed in a large stainless steel basin containing 5cm of water until the soil was completely moistened. 10-15 of the target weed seeds were sown in the flowerpot. After sowing, the seeds were covered with 0.2-0.5cm of soil and then placed in a greenhouse for cultivation. Watering was done daily to maintain soil moisture at approximately 80% (relative humidity). The greenhouse temperature was 28±2℃, and the relative humidity was 60-80%.

[0050] Application method: Using the greenhouse pot method, when the weeds reach the 2-leaf stage, perform foliar spraying. Each treatment is repeated twice, with a blank control (distilled water as the blank control). The treatment dosage is shown in Table 2. After spraying, the plants are left to stand indoors until the pesticide is absorbed by the weed leaves, then transferred to the greenhouse for cultivation at a growth temperature of 28±2℃.

[0051] Investigation Methods: The growth and reaction symptoms of the weeds were observed regularly after treatment. 21 days after application, the above-ground portion of the target weeds was harvested and weighed to calculate the fresh weight inhibition rate, which was calculated using the formula below. Specific experimental results are shown in Table 2.

[0052] F = (CT) / C × 100

[0053] In the formula: F: fresh weight inhibition rate (%); C: fresh weight of the aboveground parts of the blank control plant (g); T: fresh weight of the aboveground parts of the treated plant (g).

[0054] Table 2

[0055]

[0056] Table 2 shows that cyhalofop-butyl showed only 17.3% control efficacy against resistant Echinochloa crus-galli at the recommended field dose (75 g ai / ha), and only 59.5% at a higher dose (300 g ai / ha). Inhibitor (I) showed 86.2% control efficacy at the same dose (75 g ai / ha), and even at a lower dose of 37.5 g ai / ha, it still maintained 83.4% control efficacy.

[0057] The results showed that inhibitor (I) was significantly more effective than cyhalofop-butyl cyanide against ACCase-resistant barnyardgrass, and cyhalofop-butyl was no longer effective at the recommended field dosage for controlling resistant barnyardgrass. Therefore, inhibitor (I) targeting acetylhydroxy acid synthase can replace cyhalofop-butyl for the control of ACCase-resistant barnyardgrass.

[0058] Example 4: This example illustrates the effect of leaf age on the herbicidal activity of the acetylhydroxy acid synthase inhibitor (I) provided by this invention.

[0059] Test agent: Inhibitor (I).

[0060] Reference agent: Cyhalofop-butyl.

[0061] Test target: Sensitive Echinopsis.

[0062] Planting method: Same as in Example 3. Growth temperature: 25±2℃.

[0063] Application method: Greenhouse potted plants were used. Foliar spraying was applied when the weeds reached the 0, 1, 2, 3, and 4-leaf stages, with each treatment repeated 3 times. A blank control (distilled water was used as the blank control) was included. The treatment dosages are shown in Table 3.

[0064] After spraying, the plants were left to stand indoors until the pesticide was absorbed by the leaves of the weeds. Then they were moved into a greenhouse for cultivation at a temperature of 25±2℃.

[0065] Investigation Methods: Weed growth and reaction symptoms were observed regularly after treatment. 21 days after application, the above-ground portion of the target weeds was harvested and weighed to calculate the fresh weight inhibition rate. The fresh weight inhibition rate was calculated using the formula below. Specific experimental results are shown in Table 3.

[0066] F = (CT) / C × 100

[0067] In the formula: F: fresh weight inhibition rate (%); C: fresh weight of the aboveground parts of the blank control plant (g); T: fresh weight of the aboveground parts of the treated plant (g).

[0068] Table 3

[0069]

[0070] As shown in Table 3, at the same dosage (75g ai / ha), the inhibitor (I) achieved a control efficacy of 96.2-99.7% on the fresh weight of sensitive Echinochloa crus-galli at the 0-1 leaf stage, which was superior to the control agent cyhalofop-butyl.

[0071] For weeds in the 2-4 leaf stage, the fresh weight control efficacy of inhibitor (I) at a dose of 75 g ai / ha is 71.3-82.9%; when the dose is increased to 300 g ai / h, the fresh weight control efficacy against weeds in the 2-4 leaf stage is 84.1-97.1%. Therefore, the dosage can be appropriately increased for older Echinochloa crus-galli.

[0072] The results of Example 4 show that inhibitor (I) exhibits good herbicidal activity against weeds at the 0-4 leaf stage and can be used as a pre-emergence herbicide (spraying at the 0-1 leaf stage) or a post-emergence herbicide (spraying at the 2-3 leaf stage). Therefore, inhibitor (I) is a pre-emergence and post-emergence herbicide with a wider application window than cyhalofop-butyl.

[0073] Example 5: This example illustrates the effect of application temperature on the post-emergence herbicidal activity of the acetylhydroxy acid synthase inhibitor (I) provided by the present invention.

[0074] Test agent: Inhibitor (I).

[0075] Reference agent: Cyhalofop-butyl.

[0076] Test target: Sensitive Echinopsis.

[0077] Planting method: Example 3.

[0078] Application method: Using greenhouse pot cultivation, when the weeds have grown to the 3-4 leaf stage, perform foliar spraying. Each treatment is repeated 3 times, with a blank control (distilled water as the blank control). The treatment dosage is shown in Table 4.

[0079] Immediately after spray treatment, the samples were placed in an artificial climate chamber for incubation. The incubation temperature (L / D) was set to 35℃ / 30℃, 25℃ / 20℃, and 15℃ / 10℃, with a relative humidity of 60-80% and a light intensity (L / D) of 12 / 12 hours.

[0080] Investigation methods: The growth and reaction symptoms of the weeds were observed regularly after treatment. 21 days after application, the above-ground portion of the target weeds was harvested and weighed to calculate the fresh weight inhibition rate. The formula for calculating the fresh weight inhibition rate was the same as in Example 3. Specific experimental results are shown in Table 4.

[0081] Table 4

[0082]

[0083] Table 4 shows that at 30-35℃, inhibitor (I) at a dosage of 75g ai / ha achieved a control efficacy of 95.4% against *Echinochloa crus-galli* at the 3-4 leaf stage, exhibiting extremely high herbicidal activity. At the same dosage, the fresh weight inhibition rate of inhibitor (I) against *Echinochloa crus-galli* increased with increasing temperature, indicating a positive correlation between the herbicidal activity and temperature. This demonstrates that inhibitor (I) is a herbicide well-suited to the rice's growth stage.

[0084] Example 6: This example illustrates the absorption of the acetylhydroxy acid synthase inhibitor (I) provided by the present invention by the plant.

[0085] Test agent: Inhibitor (I).

[0086] Reference agent: Cyhalofop-butyl.

[0087] Test target: Sensitive Echinopsis.

[0088] Planting method: Same as in Example 3.

[0089] Application methods: Using greenhouse pot cultivation, when the weeds reach the 3-4 leaf stage, apply the pesticide using both foliar spraying and root irrigation. Each treatment is repeated 3 times, with a blank control (distilled water as the blank control). Treatment dosages are shown in Table 5.

[0090] After treatment with the pesticide, the plants were placed in a greenhouse for cultivation. During the experiment, the greenhouse temperature was 25℃±2℃ and the relative humidity was 60%~80%.

[0091] Investigation methods: The growth and reaction symptoms of the weeds were observed regularly after treatment. 21 days after application, the above-ground portion of the target weeds was harvested and weighed to calculate the fresh weight inhibition rate. The formula for calculating the fresh weight inhibition rate was the same as in Example 3. Specific experimental results are shown in Table 5.

[0092] Table 5

[0093]

[0094] The results of tests using two application methods—foliar spraying and root irrigation—showed that both the inhibitor (I) and the control herbicide cyhalofop-butyl severely inhibited the fresh weight of both the aboveground and underground parts of *Erigeron breviscapus*. At the same dosage, the inhibition rate of inhibitor (I) on the fresh weight of the underground parts of *Erigeron breviscapus* was slightly higher than that on the aboveground parts. These results indicate that inhibitor (I) can be absorbed by plants through roots, stems, and leaves.

[0095] Example 7: This example illustrates the safety test of rice treated with the acetylhydroxy acid synthase inhibitor provided by the present invention after budding and foliar application.

[0096] Test agent: Inhibitor (I).

[0097] Experimental target: Rice (Japonica rice 9746).

[0098] Planting method: Same as in Example 3.

[0099] Application method: Same as in Example 3. After the rice has grown to the 3-4 leaf stage, perform foliar spraying treatment, with each treatment repeated 3 times. A blank control (using distilled water as the blank control) was set up. The treatment dosage is shown in Table 6.

[0100] After spraying, the rice leaves were left to stand indoors until the pesticide solution dried. Then, the leaves were moved into a greenhouse for cultivation at a temperature of 25±8℃ and a relative humidity of 60-80%.

[0101] Investigation methods: Crop growth and reaction symptoms were observed regularly after treatment. Thirty days after application, rice plant height and fresh weight were measured, and the inhibition rates for plant height and fresh weight were calculated. The fresh weight inhibition rate was calculated as in Example 3, and the plant height inhibition rate was calculated using the formula below. Specific experimental results are shown in Table 6.

[0102] H = (CT) / C × 100

[0103] In the formula: H: plant height inhibition rate (%); C: height of blank control plants (cm); T: height of treated plants (cm).

[0104] Table 6

[0105] Dosage (g ai / ha) Plant height inhibition rate (%) Fresh weight inhibition rate (%) 180 6.89 22.37 150 6.36 5.95 120 7.78 3.06 90 6.33 4.15 60 5.71 -19.49 30 -2.25 -38.42

[0106] Table 6 shows that within a dosage range of 150 g ai / ha, the inhibitor (I) inhibited plant height and fresh weight of rice by less than 10%, indicating that this dosage was safe for rice seedlings at the 3-4 leaf stage. 10 The value was ≤150 g ai / ha. At low doses (≤60 g ai / ha), the inhibitor (I) promoted rice growth.

[0107] Example 8: This example illustrates the field test of the acetylhydroxy acid synthase inhibitor (I) provided by the present invention for controlling Echinochloa crus-galli.

[0108] Test agent: Inhibitor (I).

[0109] Comparison agents: penoxsulam and cyhalofop-butyl.

[0110] Application method: Spray the pesticide in the evening after the rice has grown to the 3-4 leaf stage and the goosegrass has grown to the 2-3 leaf stage. The area of ​​each treatment plot is 27.5 square meters, and each treatment is replicated 3 times. A blank control (distilled water is used as the blank control) is set up. The treatment dosage is shown in Table 7.

[0111] Investigation Methods: Weed growth and response symptoms were observed regularly after treatment. Forty days after application, the control efficacy per plant and the control efficacy per fresh weight were investigated. Three sampling points were taken from each plot, each covering 0.10 square meters, for a total of 0.30 square meters. The number of *Echinochloa crus-galli* plants and their fresh weight were recorded at each point. The control efficacy per plant and the control efficacy per fresh weight were calculated using the formulas below. Specific experimental results are shown in Table 7.

[0112] Control efficacy (%) = (N) C –N T ) / N C ×100

[0113] Fresh weight efficacy (%) = (W C –W T ) / W C ×100

[0114] Where: N C : Number of weeds in the blank control area; N T : Number of weeds in the treatment area; W C : Fresh weight of weeds in the blank control area; W T Fresh weight of weeds in the treatment area.

[0115] Table 7

[0116]

[0117] Table 7 shows that a 40-day post-application survey revealed that inhibitor (I) exhibited extremely high efficacy against *Echinochloa crus-galli* at both different dosages, significantly superior to penoxsulam. When using cyhalofop-butyl to control resistant *Echinochloa crus-galli* in the field, the dosage must be as high as 750 g ai.i. / ha, which is approximately 10 times the registered recommended dosage. However, using inhibitor (I) at a dosage of 150 g ai / ha, the control efficacy per plant and fresh weight was 100% 40 days post-application, effectively controlling resistant *Echinochloa crus-galli*.

[0118] The above results indicate that inhibitor (I) can effectively control resistant Echinochloa crus-galli, and its efficacy is superior to that of cyhalofop-butyl and penoxsulam.

[0119] Example 9: This example illustrates the post-emergence weed control spectrum of the acetylhydroxy acid synthase inhibitor (I) provided by the present invention.

[0120] Test agent: Inhibitor (I).

[0121] Test targets: grass weeds, broadleaf weeds, and sedges.

[0122] Planting method: Same as in Example 3. Sow the seeds of each weed in flowerpots, ensuring 20-30 seeds per pot, and then place them in a greenhouse for cultivation. Water daily to maintain soil moisture at around 80% (relative humidity), with a growth temperature of 25±2℃ and a relative humidity of 60-80%.

[0123] Application method: Using a greenhouse pot cultivation method, when grasses and sedges reach the 1-1.5 leaf stage, and broadleaf weeds reach the true leaf stage, perform foliar spraying. Each weed species is treated in triplicate, with a blank control (distilled water as the blank control). The treatment dosage is 75 g ai / ha. After spraying, allow the plants to stand indoors until the herbicide is absorbed by the leaves, then transfer them to a greenhouse for cultivation at a growth temperature of 25±2℃.

[0124] Investigation methods: The growth and reaction symptoms of weeds were observed regularly after treatment. Twenty days after application, the herbicidal activity of the inhibitor (I) against each target weed was assessed visually. The evaluation criteria for phytotoxicity using visual methods are shown in Table 8, and the specific test results are shown in Table 9.

[0125] Table 8

[0126]

[0127] Table 9

[0128]

[0129] Table 9 shows that at a dosage of 75 g ai / ha, six weeds—Poa annua, Goosegrass, Lamb's quarters, Amaranthus retroflexus, Cyperus difformis, and Mustard greens—were highly sensitive to inhibitor (I) (90–95%); seven weeds—Portulaca oleracea, Digitaria sanguinalis, Setaria viridis, Cyperus rotundus, Cyperus rotundus, Barnyardgrass, and Setaria viridis—were moderately sensitive (80–85%); while Eclipta prostrata, Abutilon theophrasti, and Cassia tora showed poor sensitivity. These results indicate that inhibitor (I) has a broad spectrum of weed control and good herbicidal activity against major weeds in paddy fields.

[0130] The acetylhydroxy acid synthase inhibitor of the present invention can be used as the active component of herbicides. It can be formulated into various emulsions, granules and other formulations for weed control of crops by adding organic solvents, surfactants, carriers and other adjuvants using pesticide formulation processing methods.

[0131] Example 10: Emulsion

[0132] The emulsion is obtained by heating and stirring 5% inhibitor (I), 5% agricultural emulsion No. 500 (calcium salt), 5% agricultural emulsion No. 602, 5% N-methyl-2-pyrrolidone and 80% solvent oil No. 330 until homogeneous.

[0133] When applying in the field, spray according to the dosage of acetylhydroxy acid synthase inhibitor in each example.

[0134] Example 11: Wettable Powder

[0135] Mix 10% inhibitor (I), 5% lignin sulfonate (Mg), 1% lauryl alcohol polyoxyethylene ether (JFC), 40% diatomaceous earth and 44% light calcium carbonate evenly, and pulverize to obtain a wettable powder.

[0136] When applying in the field, refer to the dosage of acetylhydroxy acid synthase inhibitor in each example for the sowing operation.

Claims

1. An acetylhydroxy acid synthase inhibitor used as an agricultural chemical herbicide to control resistant Echinochloa crus-galli, characterized in that, The inhibitor is a compound of formula (I): ； This compound specifically inhibits the activity of acetylhydroxy acid synthase or its mutant W574L in plants.

2. The method for preparing the acetylhydroxy acid synthase inhibitor according to claim 1, characterized in that, The synthetic route of this preparation method is shown in the following formula: 。 3. The method according to claim 2, characterized in that, Specifically, the following steps are included: (1) Using methanol or ethanol as the solvent of the reaction system, the corresponding Schiff base is prepared by reacting 4-(4-chlorophenoxy)aniline with salicylaldehyde; the molar ratio of 4-(4-chlorophenoxy)aniline and salicylaldehyde is controlled to be 1:1.2, the reaction temperature is room temperature, and the reaction time is 2 hours. (2) Using sodium borohydride or potassium borohydride as a reducing agent and methanol or ethanol as a solvent in the reaction system, benzylamine compound is prepared by reducing Schiff base; the molar ratio of Schiff base to reducing agent is controlled to be 1:1.5, the reaction temperature is room temperature, and the reaction time is 0.5 hours. (3) The target product, an acetylhydroxy acid synthase inhibitor, was prepared by reacting benzylamine compound with 2-methylsulfonyl-4,6-dimethoxypyrimidine. Potassium carbonate or cesium carbonate was used as the base in the reaction, and 1,4-dioxane was used as the reaction solvent. The molar ratio of benzylamine compound, 2-methylsulfonyl-4,6-dimethoxypyrimidine and base was controlled to be 1:1.2:1.2, the reaction temperature was the boiling point of the solvent, and the reaction time was 1 hour. The target product was finally purified by silica gel chromatography or recrystallization.

4. A herbicidal composition, characterized in that, The herbicide contains an amount of the acetylhydroxy acid synthase inhibitor as described in claim 1 and at least one formulation adjuvant.

5. A method for preparing a herbicidal active composition, characterized in that, It involves mixing a herbicidal active amount of the acetylhydroxy acid synthase inhibitor as described in claim 1 with at least one formulation adjuvant.

6. The use of the acetylhydroxy acid synthase inhibitor as described in claim 1 as an agricultural chemical herbicide, characterized in that, This compound specifically inhibits the activity of acetylhydroxy acid synthase or its mutant W574L in plants.

7. The method of using the acetylhydroxy acid synthase inhibitor of claim 1 as an agricultural chemical herbicide to control resistant Echinochloa crus-galli, characterized in that, This involves applying a herbicidal amount of acetylhydroxy acid synthase inhibitor to the leaves of resistant Echinochloa crus-galli before or after budding. The compound specifically inhibits the activity of acetylhydroxy acid synthase or its mutant W574L in resistant Echinochloa crus-galli plants.

8. The method of applying the acetylhydroxy acid synthase inhibitor of claim 1 as an agricultural chemical herbicide with broad-spectrum herbicidal activity, characterized in that, The compound acts on the leaves of weeds with a herbicidal active amount of acetylhydroxy acid synthase inhibitor. This compound specifically inhibits the activity of acetylhydroxy acid synthase or its mutant W574L in the weed plant. The weeds are any of the following: barnyard grass, barnyard grass, crabgrass, amaranth, goosegrass, foxtail grass, bluegrass, lambsquarters, purslane, golden foxtail grass, dandelion, mustard greens, sedge, and nutgrass.

Images