A class of imidazo[1,2-a]pyridine compounds containing hydrazone structures, their preparation methods and applications

Abstract

This invention discloses a class of imidazo[1,2-]azoline containing a hydrazone structure. a Preparation methods and applications of pyridine derivatives, this invention uses imidazo[1,2- a Using the pyridine skeleton as the parent structure, a series of imidazo[1,2-] hydrazone fragments were introduced to design and synthesize a series of imidazo[1,2-] hydrazone-containing structures. a Pyridine derivatives. In vitro activity results showed that these compounds had excellent inhibitory activity against plant pathogenic fungi (such as *Botrytis cinerea*, *Colletotrichum gloeosporioides*, *Colletotrichum sorghum*, *Colletotrichum tea*, *Alternaria alternata*, and *Rhizoctonia solani*), and some of the target compounds also showed good inhibitory activity against plant pathogenic bacteria.

Description

Technical Field

[0001] This invention belongs to the field of pesticide chemistry, specifically relating to imidazo[1,2-]azoline containing a hydrazone structure. a The application of pyridine compounds in the prevention and control of plant diseases, their effective inhibition of plant pathogenic fungi or bacteria, and their use in the prevention and control of agricultural plant diseases. Background Technology

[0002] Plant fungal or bacterial diseases not only reduce crop yields, but toxins can also accumulate in food, affecting food security and ultimately endangering human and animal health. Diseases caused by plant pathogenic fungi account for approximately 70-80% of all plant diseases. Most importantly, plant pathogenic fungi and the plant diseases they cause significantly reduce crop yields and quality, thereby hindering social and economic development.

[0003] Pesticides, as substances with special biological activity, can control and regulate the growth and reproduction of various agricultural pests, thereby playing a role in disease prevention and control. This ensures the yield and safety of global food and cash crops, making them an indispensable production material in modern agriculture. According to relevant data, ceasing pesticide use would lead to a 30% reduction in crop yields and a 50-70% increase in agricultural product prices, while using pesticides can mitigate unnecessary losses. However, due to the ban on highly toxic pesticides and the development of resistance, we are forced to continuously research and develop new, highly efficient, low-toxicity, and low-residue green pesticides. Biopesticides, with their characteristics of low toxicity, low pollution, low cost, easy degradation, and unique modes of action that are less likely to induce resistance, provide many ideal molecules for pesticide development.

[0004] In recent years, fused heterocyclic compounds have gradually become a highlight in new drug development. Heterocyclic compounds are important molecular structural units with diverse applications, including agriculture, medicine, and veterinary medicine. These substances are also found in disinfectants, antioxidants, copolymers, corrosion inhibitors, dyes, etc., and vitamins, hormones, and antibiotics are only a small fraction of the many heterocyclic compounds present in organisms. In medicinal chemistry, nitrogen-containing heterocyclic analogs hold a unique position in therapeutic drugs, currently accounting for over 75% of FDA-authorized drugs. Quinoline, imidazole, pyrrole, indole, pyridine, and pyrrolidine are among these nitrogen-containing heterocyclic compounds, playing a significant role in various research fields, including chemical synthesis and medicine. Due to the diversity of applications, heterocyclic compound synthesis has gained a prominent position in organic synthesis. Imidazolidine exists in isomer forms, such as imidazol[4,5- c Pyridine, imidazo[4,5-] b Pyridine, imidazo[1,5-] a Pyridine and imidazo[1,2-] aPyridine. In the isomers of imidazopyridine, imidazo[1,2-] a Pyridine has gained a lot of attention, imidazole [1, 2- a Pyridine derivatives possess biological activities such as antibacterial, analgesic, antiviral, anticancer, anti-inflammatory, antituberculosis, and antitumor effects, making them a popular research subject in the pharmaceutical field.

[0005] In 2023, Li Ding et al. mainly focused on imidazo[1, 2- a The 2-position of pyridine was structurally modified using benzaldehyde and imidazo[1,2-] with different substituents. a The reaction of pyridine-2-formylhydrazide synthesized several novel imidazo[1,2-]azohydrazide containing acylhydrazone structures. a The invention mainly focuses on imidazo[1,2-]pyridine derivatives and evaluates their in vitro antifungal activity against potato dry rot, tomato gray mold, wheat scab, apple rot, apple anthracnose, and rice blast fungus. a The structure of pyridine was modified at positions 2, 3, 6, 7, and 8 using phenylhydrazine hydrochloride with different substituents and imidazo[1,2-] substituted with different substituents. a Thirty-seven novel imidazo[1,2-] compounds containing hydrazone structures were synthesized by the reaction of pyridine-3-carboxaldehyde. a Pyridine derivatives were investigated, and their in vitro activity against plant pathogenic fungi (Botrytis cinerea, Colletotrichum gloeosporioides, Colletotrichum sorghum, Colletotrichum gloeosporioides, Alternaria alternata, and Rhizoctonia solani) and bacteria (Bacteroides oryzae of rice, Bacteroides citrus canker, and Bacteroides kiwifruit canker) was evaluated. Summary of the Invention

[0006] To address the shortcomings mentioned above, the purpose of this invention is to explore a novel class of heterocyclic imidazo[1,2-] hydrazone-containing structures. a Pyridine fungicides provide heterocyclic imidazo[1,2-] which are effective against plant pathogenic fungi or bacterial diseases. a ]Pyridine derivatives. This compound has a structure as shown in general formula (I): (I) R1 is selected from: hydrogen, carboxyl, halogen, trifluoromethyl, trifluoromethoxy, methoxy, methyl, any substituted or unsubstituted alkyl, any substituted or unsubstituted alkoxy. Y is selected from one or more of hydrazones, imines, and acylhydrazones; R2 is selected from one or more of hydrogen, alkyl (either substituted or unsubstituted), alkenyl (either substituted or unsubstituted), cycloalkyl (either substituted or unsubstituted), aryl (either substituted or unsubstituted), amino or heterocyclic amino (either substituted or unsubstituted), and heteroaryl (either substituted or unsubstituted). R3 is selected from hydrogen, halogen, alkyl group (either substituted or unsubstituted), alkynyl group (either substituted or unsubstituted), alkoxy group (either substituted or unsubstituted), and aryl group (either substituted or unsubstituted). The aforementioned substitutions refer to one or more of the following: hydrogen, hydroxyl, halogen, methyl, methoxy, cyclopropane, cyclohexane, thienyl, furanyl, tolyl, alkyl, aryl, trifluoromethyl, trifluoromethoxy, hydrazone, imine, and acylhydrazone.

[0007] Preferably, R1 is selected from one or more of hydrogen, halogen, methyl, methoxy, trifluoromethyl, and trifluoromethoxy; Y is selected from one or more of hydrazone, imine, and acylhydrazone; R2 is selected from hydrogen, halogen, methyl, phenyl, substituted phenyl, cyclopropane, and heteroaryl; and R3 is selected from hydrogen and halogen.

[0008] A class of imidazo[1,2-] containing a hydrazone structure a Pyridine derivatives, preferably all compounds with the following structural formulas: .

[0009] The specific synthesis steps include the following: (1) Weigh the corresponding substituted 2-aminopyridine and the corresponding substituted bromoacetyl group into a round-bottom flask; weigh sodium bicarbonate into the flask; measure 5 mL of anhydrous ethanol into the round-bottom flask, fix it on an iron stand, add a magnetic stir bar and stir; stir at room temperature for 12 h, monitor the reaction with TCL, and after confirming that the reaction is complete, filter the mixture after the reaction, distill the filtrate under reduced pressure, and purify it by column chromatography (from petroleum ether: ethyl acetate = 10:1~1:1) to obtain intermediate 1.

[0010] (2) Weigh the corresponding substituted intermediate 1 and phosphorus oxychloride into a round-bottom flask, add 6 mL of DMF to the flask, stir at 0 °C for 30 minutes, then heat to 60 °C and stir under reflux for 6 h, monitoring the reaction with TCL. After confirming that the reaction is complete, after the reaction solution cools, add ice water to quench it, then add an appropriate amount of ethyl acetate and an appropriate amount of saturated ammonium chloride solution for extraction (repeat the operation 3-4 times), evaporate the solvent of the organic phase to obtain the residue, and purify by column chromatography (from petroleum ether: ethyl acetate = 15:1-1:1) to obtain the corresponding intermediate 2.

[0011] (3) Weigh the corresponding substituted intermediate 2 and the corresponding substituted hydrazine hydrochloride into a round-bottom flask, add 5 mL of ethanol into the flask, heat to 80°C, stir under reflux for 6 h, monitor the reaction with TCL, filter, wash with ethanol 2-3 times, dry, weigh, and obtain the target compound.

[0012] The specific synthetic chemical equation is as follows: Accordingly, the composition contains imidazo[1,2-]hydrazone. a Pyridine compounds or their stereoisomers, their salts or their solvates.

[0013] Preferably, the dosage form of the required composition is selected from: emulsifiable concentrate, powder, wettable powder, granules, aqueous solution, suspension concentrate, ultra-low volume spray, soluble powder, microcapsule, fumigant, water emulsion or water-dispersible granules.

[0014] Accordingly, the use of the compound shown in Formula I above, or its stereoisomer, or its salt or solvate, or the composition of claim 5 or 6, in the prevention and control of agricultural pests and diseases.

[0015] Preferably, the agricultural pests and diseases are plant fungal or bacterial diseases.

[0016] Preferably, the bacterial disease is any one of rice bacterial blight fungus, citrus canker fungus, kiwifruit canker fungus, and tobacco bacterial wilt fungus.

[0017] Preferably, the fungal disease is any one of the following: *Botrytis cinerea*, *Fusarium oxysporum*, *Colletotrichum gloeosporioides*, *Anthracnose fungus*, *Colletotrichum sacchariformis*, *Alternaria alternata*, *Verticillium wilt*, *Fusarium wilt*, *Fusarium oxysporum*, *Fusarium oxysporum*, *Alternaria alternata*, and *Rhizoctonia solani*. Compared with the prior art, the present invention has the following beneficial effects: With imidazo[1, 2-] containing the corresponding substitutions a A series of imidazo[1,2-]hydrazine-3-carboxaldehyde and corresponding substituted hydrazine hydrochlorides were synthesized from pyridine-3-carboxaldehyde and their substituted hydrochlorides. a Pyridine derivatives, these compounds exhibit excellent inhibitory effects against plant pathogenic fungi (such as *Botrytis cinerea*, *Colletotrichum gloeosporioides*, *Colletotrichum sorghum*, *Colletotrichum tea*, *Alternaria alternata*, and *Rhizoctonia solani*), providing an important scientific basis for the research and development of new pesticides. In vitro experiments showed that the target compounds possessed excellent inhibitory activity against plant pathogenic fungi (such as *Botrytis cinerea*, *Colletotrichum gloeosporioides*, *Colletotrichum sorghum*, *Colletotrichum tea*, *Alternaria alternata*, and *Rhizoctonia solani*). Among them, compounds 30, 32, and 34 showed significant inhibitory activity against *Botrytis cinerea*, with EC50 values ​​exceeding 100%. 50The values ​​were 1.709, 1.694, and 1.517 μg / mL, respectively, which were superior to the control drug, Mai Sui Ning (EC). 50 =3.538 μg / mL) and pyraclostrobin (EC) 50 >100 μg / mL). In addition, compounds 1, 2, 3, 4, 29, 31, 33, 35, 36, and 37 showed EC50 activity against Staphylococcus aureus. 50 The values ​​ranged from 3.870 to 21.565 μg / mL, which was superior to the control drug pyraclostrobin (EC). 50 >100 μg / mL); compounds 1, 2, 3, 5, 9, 12, 25, 29, 31, 33, 34, 35 and 37 showed EC50 values ​​against *Colletotrichum sacchariformis*. 50 The effective value ranged from 7.308 to 21.660 μg / mL, which was superior to the control agent pyraclostrobin (EC). 50 =22.364 μg / mL); compounds 31, 32, 33, 34, 35, 36, and 37 showed good inhibitory effects against rice sheath blight pathogen (EC). 50 The effective value ranged from 8.456 to 30.220 μg / mL, which was superior to the control drug carbendazim (EC). 50 >100 μg / mL), Maisuning (EC) 50 >100 μg / mL) and pyraclostrobin (EC) 50 >100 μg / mL). Notably, compounds 32, 34, 35, 36, and 37 showed good antibacterial effects against Alternaria solanacearum (EC). 50 The effective value ranged from 6.295 to 19.758 μg / mL, which was superior to the control drug carbendazim (EC). 50 >100 μg / mL), Maisuning (EC) 50 >100 μg / mL) and pyraclostrobin (EC) 50 =9.930 μg / mL); compounds 31, 32, 33, 34, 35, 36 and 37 showed good antibacterial effects against *Colletotrichum gloeosporioides* (EC). 50 The effective concentration ranged from 3.048 to 18.789 μg / mL, which was superior to the control agent pyraclostrobin (EC). 50 >100 μg / mL); compounds 31, 32, 33, 34, 35, 36 and 37 showed significant antibacterial effects against *Anthracnose teosinte* (EC). 50 The effective value ranged from 3.805 to 12.350 μg / mL, which was superior to the control drug pyraclostrobin (EC). 50 >100 μg / mL).

[0018] In addition, some of the target compounds showed good inhibitory activity against plant pathogenic bacteria (such as *Bacillus oryzae*, *Actinidia kiwifruit*, and *Citrus canker*). At a concentration of 50 μg / mL, compounds 33, 34, and 37 showed good inhibitory activity against *Bacillus oryzae*, with initial screening activities of 15.77–85.69 μg / mL, which was superior to the control drug thiabendazole copper (14.46 μg / mL). Compounds 34 and 36 showed good inhibitory activity against *Citrus canker*, with initial screening activities of 35.74–68.29 μg / mL, which was superior to the control drug thiabendazole copper (18.60 μg / mL). Compounds 31 and 34 showed good inhibitory activity against *Actinidia kiwifruit*, with initial screening activities of 29.63–97.17 μg / mL, which was superior to the control drug thiabendazole copper (23.03 μg / mL). In summary, some of the target compounds have potential applications in combating fungal or bacterial diseases in plants. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0020] Example 1 Example 1: Intermediate 1: 2-Phenylidene imidazo[1,2-] a Preparation of pyridine.

[0021] The preparation route is as follows: The preparation process is as follows: Weigh 243 mg (1.00 mmol) of 2-aminopyridine and 170.22 mg (1.81 mmol) of 2-bromoacetophenone into a round-bottom flask; weigh 101.29 mg (1.21 mmol) of sodium bicarbonate into the flask; add 5 mL of anhydrous ethanol to the round-bottom flask, fix it on an iron stand, and add a magnetic stir bar for stirring; stir at room temperature for 12 h, and monitor the reaction with TCL. Filter the reaction mixture, and purify the filtrate by vacuum distillation and column chromatography (using petroleum ether:ethyl acetate = 10:1~1:1) to obtain intermediate 1.

[0022] Example 2 Intermediate 2: 2-Phenylidene[1,2-] a Preparation of pyridine-3-carboxaldehyde.

[0023] The preparation route is as follows: The preparation process is as follows: Weigh intermediate 1 (800.00 mg, 4.12 mmol) and phosphorus oxychloride (1.58 g, 10.30 mmol) into a round-bottom flask. Add 6 mL of DMF to the flask and stir at 0 °C for 30 minutes. Then heat to 60 °C and stir under reflux for 6 h. Monitor the reaction with TCL. After confirming that the reaction is complete, quench the reaction solution with ice water after cooling. Then add an appropriate amount of ethyl acetate and an appropriate amount of saturated ammonium chloride solution for extraction (repeat the operation 3-4 times). Evaporate the solvent of the organic phase to obtain the residue. Purify the residue by column chromatography (petroleum ether:ethyl acetate = 15:1-1:1) to obtain intermediate 2.

[0024] Example 3: Target compound: ( E )-3-((2-(4-fluorophenyl)hydrazone)aldehyde)-2-phenylimidazolium[1,2- a Preparation of pyridine.

[0025] The preparation route is as follows: The preparation process is as follows: Intermediate 2 (250 mg, 1.12 mmol) and 4-fluorophenylhydrazine hydrochloride (196.43 mg, 1.12 mmol) were weighed and added to a round-bottom flask. 5 mL of ethanol was added to the flask, and the mixture was heated to 80 °C and stirred under reflux for 6 h. The reaction was monitored by TCL, filtered, washed with ethanol, dried, and weighed to obtain the target compound.

[0026] All compounds in this invention can be prepared by the methods described above or similar to those described above. Appropriate raw materials can be selected according to the different substituents and their positions.

[0027] The structure, 1H NMR spectrum, and 1C NMR high-resolution mass spectrometry data of the synthesized target compound are shown in Table 1, and the physicochemical properties are shown in Table 2.

[0028] Table 1: 1H NMR, 1C NMR, and high-resolution mass spectrometry data of the compounds

[0029] Table 2: Physicochemical properties of the target compound

[0030] Example 4 Application of target compounds This embodiment is used to verify the application activity of the compound prepared in this invention in the prevention and control of agricultural pests and diseases.

[0031] EC 50 Median effective concentration (MEC) is an important indicator for evaluating the sensitivity of plant pathogens to compounds, and it is also a crucial parameter for setting compound concentrations when studying the mechanism of action of compounds. In concentration gradient experiments, five appropriate concentrations were set using the two-fold dilution method. Finally, the inhibition rate of the agent against the plant pathogen and the agent concentration were converted into logarithmic values, and the toxicity curve was obtained through regression analysis using SPSS software to calculate the EC50. 5 0 value.

[0032] The effective medium concentration (EC) of the target compound against plant pathogens was determined using the mycelial growth inhibition method. 50 The test subjects were *Gnaphalium affine*, *Colletotrichum gloeosporioides*, *Colletotrichum sorghum*, *Colletotrichum tea*, *Rhizoctonia solani*, and *Alternaria alternata*. All the strains used were newly activated young strains one week in advance. Weigh the target compound using a 0.01 g / mL balance. Dissolve it in 20 times its volume of DMSO until the concentration of the stock solution is 50 μg / mL. Take the corresponding volume of the stock solution at the desired concentration and transfer it to a 2 mL centrifuge tube. Add DMSO to balance the volume to 1 mL. Transfer the solution to a 15 mL sterile centrifuge tube in a sterile operating table. Add 9 mL of Tween-20 water to a final volume of 10 mL. Shake well and pour the solution into the culture medium. Mix well and distribute evenly into 9 culture media. Cool and set aside. In a sterile operating table, using a sterile 5 mm punch, place the mycelial cake upside down in the center of the culture medium with an inoculation loop. Incubate at 28°C for 4-6 days. When the control group colonies reach a diameter of 5.0-7.0 cm, measure the colony diameter twice using a ruler in a cross-hatching method. Calculate the colony diameter using the average value. Calculate the mycelial growth inhibition rate using the following formula: Inhibition rate % = (C1 - C2) / (C1 - 0.5) × 100 Where: C1 is the diameter of the control colony, i.e., the diameter of the colony treated with DMSO (i.e., CK); C2 is the diameter of the treated colony, i.e., the diameter of the colony treated with the drug; 0.5 is the diameter of the mother mycelium cake; The target compound with the structural formula shown above was tested for EC50 against plant pathogenic fungi using the method described above. 5 0 The values ​​and experimental results are shown in Table 3.

[0033] Table 3 shows the EC50 of some compounds against Staphylococcus aureus, Colletotrichum gloeosporioides, Colletotrichum sorghum, Anthracnose of tea, and Alternaria alternata. 5 0 value.

[0034] Table 3 shows that compounds 30, 32, and 34 have significant inhibitory activity against Staphylococcus aureus, and their EC50 values ​​are [missing data]. 50 The values ​​were 1.709, 1.694, and 1.517 μg / mL, respectively, which were superior to the control drug, Mai Sui Ning (EC). 50 =3.538 μg / mL) and pyraclostrobin (EC) 50 >100 μg / mL). In addition, compounds 1, 2, 3, 4, 29, 31, 33, 35, 36, and 37 showed EC50 activity against Staphylococcus aureus. 50 The values ​​ranged from 3.870 to 21.565 μg / mL, which was superior to the control drug pyraclostrobin (EC). 50 >100 μg / mL); compounds 1, 2, 3, 5, 9, 12, 25, 29, 31, 33, 34, 35 and 37 showed EC50 values ​​against *Colletotrichum sacchariformis*. 50The effective value ranged from 7.308 to 21.660 μg / mL, which was superior to the control agent pyraclostrobin (EC). 50 =22.364 μg / mL); compounds 31, 32, 33, 34, 35, 36, and 37 showed good inhibitory effects against rice sheath blight pathogen (EC). 50 The effective value ranged from 8.456 to 30.220 μg / mL, which was superior to the control drug carbendazim (EC). 50 >100 μg / mL), Maisuning (EC) 50 >100 μg / mL) and pyraclostrobin (EC) 50 >100 μg / mL). Notably, compounds 32, 34, 35, 36, and 37 showed good antibacterial effects against Alternaria solanacearum (EC). 50 The effective value ranged from 6.295 to 19.758 μg / mL, which was superior to the control drug carbendazim (EC). 50 >100 μg / mL), Maisuning (EC) 50 >100 μg / mL) and pyraclostrobin (EC) 50 =9.930 μg / mL); compounds 31, 32, 33, 34, 35, 36 and 37 showed good antibacterial effects against *Colletotrichum gloeosporioides* (EC). 50 The effective concentration ranged from 3.048 to 18.789 μg / mL, which was superior to the control agent pyraclostrobin (EC). 50 >100 μg / mL); compounds 31, 32, 33, 34, 35, 36 and 37 showed significant antibacterial effects against *Anthracnose teosinte* (EC). 50 The effective value ranged from 3.805 to 12.350 μg / mL, which was superior to the control drug pyraclostrobin (EC). 50 >100 μg / mL).

[0035] In summary, compounds 30, 32, and 34 exhibit excellent inhibitory effects against *Botrytis cinerea*, the fungus causing grape canker, and can control fungal diseases caused by *Botrytis cinerea*. Compounds 35 and 37 show significant inhibitory effects against *Rhizoctonia solani*, the pathogen causing rice sheath blight, and *Alternaria alternata*, the pathogen causing early blight in tomatoes, and can control fungal diseases caused by these fungi. Therefore, compounds 30, 32, 34, 35, and 37 have potential antifungal applications.

[0036] Example 5 Imidazolo[1,2-] containing a hydrazone structure a The application of pyridine derivatives against plant pathogenic bacteria is discussed below, focusing on their resistance to rice bacterial blight (…). Xoo ), Citrus canker pathogen ( Right ) and kiwifruit canker pathogen ( PsFor example, the activity of ).

[0037] Turbidimetric assay was used to determine the hydrazone-containing imidazo[1,2-] a Antimicrobial activity of pyridine compounds against *Bacillus oryzae*, *Citrus canker*, and *Actinidia kiwifruit* causal agents. *Bacillus oryzae*, *Citrus canker*, and *Actinidia kiwifruit* causal agents were activated using NA solid medium (10 g glucose, 5 g peptone, 1 g yeast, 3 g beef extract, 15 g agar, and 1000 mL deionized water) and incubated at 28 °C until single colonies appeared. A suitable number of yellow single colonies were selected using an inoculation loop and placed in an Erlenmeyer flask containing NB medium (10 g glucose, 5 g peptone, 1 g yeast, 3 g beef extract, and 1000 mL deionized water). The flasks were then incubated in a shaker until the logarithmic growth phase.

[0038] Prepare the required drug to the specified concentration, and add 1 mL of each to a test tube containing 4 mL of NB medium. Then, add 40 µL of NB medium containing *Bacillus oryzae*, *Citrus canker*, and *Actinidia kiwifruit* to the test tubes. Incubate at 26-28 °C and 180 r / min using a constant temperature shaker. Observe the OD value of the blank control group's NB liquid medium. 595 The values ​​ranged from 0.6 to 0.8. The OD values ​​of the bacterial solutions at various concentrations were measured using a spectrophotometer. 595 value.

[0039] Correcting OD 595 Value = OD of bacterial culture medium 595 - Sterile culture medium OD 595 Inhibition rate (%) = (OD of bacterial culture medium after correction) 595 - Correcting the OD of drug-containing culture media 595 ) / OD value of bacterial suspension in the control culture medium after correction × 100%.

[0040] Table 4 shows the effects of some target compounds on plant pathogens at a concentration of 50 µg / mL. Xoo , Right and Ps In vitro antibacterial activity

[0041] As shown in Table 4, in the in vitro experiments, some target compounds exhibited good antibacterial activity against *Bacillus oryzae*, *Citrus canker*, and *Actinidia chinensis*. At a concentration of 50 μg / mL, compounds 33, 34, and 37 showed good inhibitory activity against *Bacillus oryzae*, with initial screening activities ranging from 15.77 to 85.69 μg / mL, which was superior to the control drug thiabendazole (14.46 μg / mL). Compounds 34 and 36 showed good inhibitory activity against *Citrus canker*, with initial screening activities ranging from 35.74 to 68.29 μg / mL, which was superior to the control drug thiabendazole (18.60 μg / mL). Compounds 31 and 34 showed good inhibitory activity against *Actinidia chinensis*, with initial screening activities ranging from 29.63 to 97.17 μg / mL, which was superior to the control drug thiabendazole (23.03 μg / mL). As can be seen from the above, some of the target compounds have good antibacterial activity.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention. All such modifications or substitutions should be covered by the scope of the claims of the present invention, and the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A class of imidazo[1,2-] containing a hydrazone structure a ]Pyridine derivatives, characterized in that: The compound has the structure shown in general formula (I): （Ⅰ） R1 is selected from: hydrogen, carboxyl, halogen, trifluoromethyl, trifluoromethoxy, methoxy, methyl, any substituted or unsubstituted alkyl, any substituted or unsubstituted alkoxy. Y is selected from one or more of hydrazones, imines, and acylhydrazones; R2 is selected from one or more of hydrogen, alkyl (either substituted or unsubstituted), alkenyl (either substituted or unsubstituted), cycloalkyl (either substituted or unsubstituted), aryl (either substituted or unsubstituted), amino or heterocyclic amino (either substituted or unsubstituted), and heteroaryl (either substituted or unsubstituted). R3 is selected from hydrogen, halogen, alkyl group (either substituted or unsubstituted), alkynyl group (either substituted or unsubstituted), alkoxy group (either substituted or unsubstituted), and aryl group (either substituted or unsubstituted). The aforementioned substitutions refer to one or more of the following: hydrogen, hydroxyl, halogen, methyl, methoxy, cyclopropane, cyclohexane, thienyl, furanyl, tolyl, alkyl, aryl, trifluoromethyl, trifluoromethoxy, hydrazone, imine, and acylhydrazone.

2. The imidazo[1, 2-] hydrazone-containing structure according to claim 1. a ]Pyridine derivatives, characterized in that: R1 is selected from one or more of hydrogen, halogen, methyl, methoxy, trifluoromethyl, and trifluoromethoxy; Y is selected from one or more of hydrazone, imine, and acylhydrazone; R2 is selected from hydrogen, halogen, methyl, phenyl, substituted phenyl, cyclopropane, and heteroaryl; R3 is selected from hydrogen and halogen.

3. The imidazo[1,2-] hydrazone-containing structure according to claim 1 a ]Pyridine derivatives, characterized in that: The structural formulas of all compounds are shown below: 。 4. The imidazo[1, 2-] hydrazone-containing structure as described in any one of claims 1 to 3 a A method for preparing pyridine derivatives, characterized in that: The chemical reaction equation is as follows: 。 5. A composition, characterized in that, The composition contains an imidazo[1,2-] hydrazone-containing structure as described in any one of claims 1-4. a Pyridine derivatives or their stereoisomers, their salts or their solvates.

6. The dosage form of the composition according to claim 5 is selected from: emulsifiable concentrate, powder, wettable powder, granules, aqueous solution, suspension concentrate, ultra-low volume spray, soluble powder, microcapsule, fumigant, water emulsion or water-dispersible granules.

7. The use of the compound of formula (I) as claimed in claim 1 or 2, or its stereoisomer or its salt or its solvate, or the composition as claimed in claim 5 or 6, in the prevention and control of agricultural pests and diseases.

8. The application according to claim 7, characterized in that: The agricultural pests and diseases mentioned are bacterial or fungal plant diseases.

9. The application according to claim 8, characterized in that: The fungal diseases mentioned are any one of the following: *Botrytis cinerea*, *Fusarium oxysporum*, *Colletotrichum gloeosporioides*, *Anthracnose fungus*, *Colletotrichum sacchariformis*, *Tobacco scab*, *Verticillium wilt*, *Fusarium wilt*, *Fusarium wilt*, *Fusarium rot*, *Alternaria alternata*, and *Rhizoctonia solani*.

10. The application according to claim 8, characterized in that: The bacterial diseases mentioned are any one of the following: rice bacterial blight fungus, citrus canker fungus, kiwifruit canker fungus, and tobacco bacterial wilt fungus.

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