8-Substituted aniline-chloroquinoline compounds, their preparation methods and applications

Abstract

This invention discloses an 8-substituted aniline-chloroquinoline compound, its preparation method, and its application. The preparation method of the 8-substituted aniline-chloroquinoline compound includes the following steps: mixing compound III, compound IV, alkali, and ethanol to obtain a reaction solution, refluxing at 70-80℃ for 5-10 hours, extracting the organic phase after the reaction is completed, drying, rotary evaporating, and purifying by column chromatography to obtain the 8-substituted aniline-chloroquinoline compound. All of these 8-substituted aniline-chloroquinoline compounds exhibit certain antibacterial activity, with an inhibition rate of over 80% against *Sclerotinia sclerotiorum* causal agent of rapeseed and an inhibition rate of over 70% against *Rhizoctonia solani* var. *rhizoma*. Specifically, compound I-15 shows an inhibition rate of 92.0% against *Sclerotinia sclerotiorum* causal agent, while compounds I-11 and I-15 show inhibition rates of 78.8% and 78.5% against *Rhizoctonia solani* var. *rhizoma*, respectively.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis and pharmaceutical application technology, specifically relating to an 8-substituted aniline chloroquinoline compound, its preparation method, and its application. Background Technology

[0002] In the development of heterocyclic pesticides, quinoline compounds, as a class of nitrogen-containing heterocyclic compounds with a quinoline skeleton, play an important role in the research and development of novel pesticides. They are widely found in synthetic and natural products. Quinoline, the parent compound of quinoline compounds, was first extracted from coal tar by Runge in 1834; it was a hygroscopic liquid with a strong odor. Later, quinine, an alkaloid belonging to the cinchona tree (Rubia cordifolia family), was isolated from it. This alkaloid is a diastereomer of quinoline compounds and was one of the earliest effective antimalarial drugs.

[0003] Currently, many new varieties of insecticides, fungicides, and herbicides containing quinoline heterocycles have been developed both domestically and internationally. In 1989, the Shanghai Institute of Pesticides successfully developed dichloroquinoline acid, commercially known as chlorpyrifos, which is mainly used to control post-emergence barnyard grass. It is particularly effective against older barnyard grass, has low soil moisture requirements, is highly safe for rice, and can be mixed with other herbicides for single treatment. It boasts advantages such as low dosage, high efficiency, convenient and odorless application, safety for direct-seeded and transplanted rice, and certain growth-promoting effects. In 2011, Meiji Pharmaceutical Co., Ltd. and Nippon Kayaku Co., Ltd. jointly developed a new quinoline insecticide (Flometoquin). This insecticide has excellent control effects on thrips, whiteflies, gall mites, and small lepidopteran pests, with rapid killing speed and long-lasting effect. In 1989, Dow AgroSciences developed quinoxyfen, a commercially available systemic fungicide, which is highly effective in controlling powdery mildew. Suitable for barley, watermelon, and sugar beets, it is environmentally safe and does not cause phytotoxicity to crops, making it an ideal control agent. However, in 2013, the European Union designated quinoxyfen as a priority hazardous substance posing a significant risk to surface water, and ceased renewing its registration in 2019. Furthermore, due to long-term use of quinoline fungicides, many fungal species have developed resistance, necessitating the development of novel quinoline fungicides. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an 8-substituted aniline chloroquinoline compound.

[0005] Another object of the present invention is to provide a method for preparing 8-substituted aniline chloroquinoline compounds.

[0006] Another object of the present invention is to provide the use of 8-substituted aniline chloroquinoline compounds as pesticides in antibacterial applications.

[0007] The objective of this invention is achieved through the following technical solutions.

[0008] An 8-substituted aniline-chloroquinoline compound has the following general structural formula:

[0009]

[0010] Wherein, R is a phenyl or a substituted phenyl, and the substituent on the substituted phenyl is an alkyl, alkoxy, nitro, halogen or haloalkyl.

[0011] In the above technical solution, when R is a substituted phenyl group, the substituent on the substituted phenyl group is 2-fluoro, 2,4-difluoro, 4-chloro, 4-methyl, 3-chloro, 3,4-dichloro, 2-bromo, 3-fluoro, 2-methyl-3-chloro, 2,6-difluoro, 4-bromo, 2-bromo-4-fluoro, 2-bromo-5-fluoro, 4-fluoro, or 3-methyl.

[0012] A method for preparing an 8-substituted aniline-chloroquinoline compound includes the following steps: mixing compound III, compound IV, a base, and ethanol uniformly to obtain a reaction solution, refluxing at 70–80°C for 5–10 h, extracting the organic phase after the reaction is complete, drying, rotary evaporating, and purifying by column chromatography to obtain an 8-substituted aniline-chloroquinoline compound, wherein the molar ratio of compound III, compound IV, and base is 1:(1–1.2):(1–1.1), the general structural formula of compound IV is RNH2, where R is phenyl or a substituted phenyl group, and the substituent on the substituted phenyl group is alkyl, alkoxy, nitro, halogen, or haloalkyl; the structural formula of compound III is... The base is potassium carbonate, triethylamine, pyridine, or sodium hydroxide.

[0013] In the above technical solution, the ratio of the molar amount of compound III to the volume amount of ethanol is 1.16:(8-15), where the molar amount is in mmol and the volume amount is in mL.

[0014] In the above technical solution, the extraction includes: sequential extraction with water, ethyl acetate and saturated brine.

[0015] In the above technical solution, when R is a substituted phenyl group, the substituent on the substituted phenyl group is 2-fluoro, 3-chloro, 2,4-difluoro, 4-chloro, 4-methyl, 3,4-dichloro, 2-bromo, 3-fluoro, 2-methyl-3-chloro, 2,6-difluoro, 4-bromo, 2-bromo-4-fluoro, 2-bromo-5-fluoro, 4-fluoro, or 3-methyl.

[0016] In the above technical solution, the method for obtaining compound III includes: adding phosphorus oxychloride to compound II, refluxing at 140–160°C for 8–12 h, monitoring the reaction until completion by thin-layer chromatography, cooling to room temperature, precipitating the solid in an ice-water mixture, filtering, and drying to obtain compound III. The mass ratio of compound II to phosphorus oxychloride is 1.05:(10–100), where mass parts are in g and molar amounts are in mmol. The structural formula of compound II is [insert structural formula here].

[0017] In the above technical solution, the method for obtaining compound II includes: mixing o-fluoroaniline, ethyl 2-methylacetoacetate, and a cyclizing agent, reacting at 140–160°C, monitoring the reaction until completion by thin-layer chromatography (TLC), cooling to -10–0°C, adjusting the pH to 7–8 at -10–0°C to precipitate the solid, filtering, and drying to obtain compound II. The structural formula of the o-fluoroaniline is as follows: The structural formula of the ethyl 2-methylacetoacetate is as follows: The cyclizing agent is polyphosphoric acid (PPA), and the ratio of o-fluoroaniline, ethyl 2-methylacetoacetate and cyclizing agent by molar amount is 1:(1-1.5):1.5.

[0018] In the method for obtaining compound II, the reaction time is 4.5–5.5 h.

[0019] In the method for obtaining compound II, the pH is adjusted to 7-8 with sodium hydroxide solution to cause the solid to precipitate.

[0020] In the above technical solution, the sodium hydroxide solution is a mixture of sodium hydroxide and water, and the sodium hydroxide content in the sodium hydroxide solution is 9-11 wt%.

[0021] In the above technical solution, the drying process involves irradiating the product under an infrared lamp for 4 to 6 hours.

[0022] The above-mentioned 8-substituted aniline chloroquinoline compounds are used as pesticides for antibacterial purposes.

[0023] The above technical solutions inhibit one or more of the following pathogens: Alternaria solani (tomato early blight), Gibberella zeae (wheat scab), Pyricularia oryae (rice blast fungus), Phytophthora capsici (pepper causal agent), Sclerotinia sclerotiorum (rapeseed sclerotinia), Botrytiscinerea (cucumber gray mold), Riziocotinia solani (rice sheath blight), Fusarium oxysporum (cucumber wilt), and Botryosphaeria berengriana (apple ring rot).

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The preparation method of the 8-substituted aniline-chloroquinoline compounds of the present invention is simple and convenient. All 8-substituted aniline-chloroquinoline compounds have certain antibacterial activity. At a concentration of 10 mg / L, the 8-substituted aniline-chloroquinoline compounds have an inhibition rate of more than 80% against Sclerotinia sclerotiorum var. sclerotiorum and an inhibition rate of more than 70% against Rhizoctonia solani. Among them, compound I-15 showed an inhibition rate of 92.0% against Sclerotinia sclerotiorum var. sclerotiorum, while compounds I-11 and I-15 achieved inhibition rates of 78.8% and 78.5% against Rhizoctonia solani, respectively. Attached Figure Description

[0026] Figure 1 The 1H NMR spectrum is shown for the 8-substituted aniline chloroquinoline compound prepared in Example 15. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] The method for obtaining PDA culture medium in the following examples includes: boiling 200g of peeled potatoes in 1L of water for 30 minutes, filtering the solution with gauze after boiling for 30 minutes, collecting the supernatant, making up to 1L, adding 20g of glucose and 20g of agar, and heating at 50°C while stirring continuously to ensure that the agar is completely dissolved. After dissolving, the solution is placed in an autoclave for sterilization and then set aside for later use.

[0029] In the following examples, the bactericide Tebufloquin has the chemical formula 6-tert-butyl-8-fluoro-2,3-dimethyl-4-quinolinyl acetate.

[0030] In the following examples, compounds IV-1, IV-2, IV-3, IV-4, IV-5, IV-6, IV-7, IV-8, IV-9, IV-10, IV-11, IV-12, IV-13, IV-14 and IV-15 are respectively referred to as compounds IV, and their structural formulas are shown below.

[0031]

[0032] The tomato early blight pathogen (Alternaria solani), wheat scab (Gibberella zeae), rice blast pathogen (Pyricularia oryae), pepper phytophthora capsici, rapeseed sclerotinia sclerotiorum, cucumber gray mold (Botrytis cinerea), rice sheath blight pathogen (Riziocotinia solani), cucumber wilt pathogen (Fusarium oxysporum), and apple ring rot pathogen (Botryosphaeria berengriana) all originated from strains long-term preserved in the bactericidal bioassay laboratory of the National Engineering Research Center for Pesticides at Nankai University.

[0033] In the following examples, the sodium hydroxide solution is a mixture of sodium hydroxide and water, and the sodium hydroxide content in the sodium hydroxide solution is 10 wt%.

[0034] In the following examples, the structural formula of o-fluoroaniline is: The structural formula of ethyl 2-methylacetoacetate is:

[0035]

[0036] Examples 1-15

[0037] The synthetic route for 8-substituted aniline chloroquinoline compounds is as follows:

[0038]

[0039] A method for preparing an 8-substituted aniline chloroquinoline compound includes the following steps:

[0040] Step 1: o-Fluoroaniline (11.11 g, 100.00 mmol), ethyl 2-methylacetoacetate (14.42 g, 100.00 mmol), and cyclizing agent (50.69 g, 150.00 mmol) were placed in a 250 mL three-necked flask and stirred until homogeneous. The mixture was heated at 150 °C and the reaction was monitored by thin-layer chromatography (TLC). The reaction was completed after 5 h. After cooling to room temperature, the three-necked flask was placed in an ice bath at 0 °C. The pH was adjusted to 7 with sodium hydroxide solution at 0 °C to precipitate the solid. The solid was filtered to obtain a filter cake. The filter cake was dried under an infrared lamp for 5 hours to constant weight to obtain a white solid, which was compound II, with a yield of 90%. The cyclizing agent was polyphosphoric acid (PPA).

[0041] Step 2: Compound II (0.20 g, 1.05 mmol) was placed in a 250 mL three-necked flask, and phosphorus oxychloride (10 g) was added. The mixture was refluxed at 150 °C, and the reaction was monitored by thin-layer chromatography. The reaction was completed after 8 h. The mixture was cooled to room temperature and placed in an ice-water mixture to allow the solid to precipitate. The solid was filtered to obtain a filter cake, which was then dried under an infrared lamp to constant weight to obtain a pale yellow solid, which was compound III. The yield was 90%.

[0042] Step 3: Compound III (1 mmol), Compound IV (1.16 mmol), base (sodium hydroxide, 1.05 mmol), and ethanol (10 mL) were placed in a 250 mL round-bottom flask and mixed thoroughly to obtain a reaction solution. The mixture was refluxed at 78 °C for 8 h. The reaction solution was placed in a separatory funnel and diluted with water (30 mL) to form an aqueous phase. The aqueous phase was extracted three times with ethyl acetate (10 mL each time). The organic phases were combined and extracted three times with saturated brine (10 mL each time). The organic phase was collected, dried with anhydrous sodium sulfate, filtered, and the filtrate was collected. The filtrate was rotary evaporated and purified by column chromatography (the eluent for column chromatography was a mixture of ethyl acetate and petroleum ether, with a volume ratio of ethyl acetate to petroleum ether of 1:2). A white solid was obtained, which was an 8-substituted aniline chloroquinoline compound (compound I).

[0043] The general structural formula of compound IV used in Examples 1-15 is RNH2. The compounds IV used and the R in the general structural formula are shown in Table 1. The numbering and yield of the 8-substituted aniline-chloroquinoline compounds prepared in Examples 1-15 are shown in Table 1, and their 1H NMR spectra are shown in Table 2. The 1H NMR spectrum of the 8-substituted aniline-chloroquinoline compound prepared in Example 15 is shown in Table 2. Figure 1 As shown.

[0044] Table 1

[0045]

[0046] Table 2

[0047]

[0048]

[0049] Example 16

[0050] The inhibition zone method was used to evaluate the indoor bactericidal activity of the 8-substituted aniline chloroquinoline compounds obtained in Examples 1-15 against the test targets (bacteria) at a dose of 10 mg / L.

[0051] Indoor sterilization activity test:

[0052] Treatment group: 1) Weigh 3 mg of the test compound and dissolve it in 0.1 mL of DMSO to prepare a stock solution of 30000 mg / L. Use a pipette to take a certain amount of the stock solution and disperse it evenly in sterile Tween water (sterile Tween water is a mixture of Tween-80 and water, and the content of Tween-80 in sterile Tween water is 1‰) to prepare a drug solution with a concentration of 100 mg / L of the test compound.

[0053] 2) Using a pipette, draw 1 mL of the drug solution into a sterilized petri dish, then add 9 mL of PDA medium, shake well, and cool to room temperature. Use a punch to create circular mycelial cakes, then use an inoculation needle to transfer them to the center of the petri dish (the concentration of the test compound in the petri dish is 10 mg / L). Place the petri dish in an incubator and incubate at 25°C for 72 hours. After 72 hours, measure the colony diameter. The pathogens on the circular fungal cakes are one of the following: Alternaria solani (early blight of tomato), Gibberella zeae (wheat scab), Pyricularia oryae (rice blast fungus), Phytophthora capsici (pepper spore blight), Sclerotinia sclerotiorum (rapeseed sclerotinia), Botrytis cinerea (cucumber gray mold), Riziocotinia solani (rice sheath blight), Fusarium oxysporum (cucumber wilt), and Botryosphaeria berengriana (apple ring rot). Among them, the test compound is one of the 8-substituted aniline chloroquinoline compounds obtained in Examples 1-15 and the fungicide Tebufloquin.

[0054] Control group: The control group was basically the same as the treatment group, except for the medication. The medication in the control group was sterile Tween water, while the medication in the treatment group was replaced with sterile Tween water.

[0055] The inhibition rate (%) was calculated according to the inhibition rate formula. The inhibition rates of the 8-substituted aniline chloroquinoline compounds and the bactericide Tebufloquin obtained in Examples 1 to 15 against various pathogens are shown in Table 3. The inhibition rate formula is as follows.

[0056]

[0057] Among them, the pure colony growth is the difference between the average diameter of the colony and the diameter of the circular mycelial cake.

[0058] Table 3 Antibacterial rate (unit: %)

[0059]

[0060] Table 3 shows that at a concentration of 10 mg / L, compounds I-4, I-11, I-12, I-13, I-14, and I-15 exhibited inhibition rates exceeding 50.0% against *Early Blight* causal agent of tomato, and were superior to Tebufloquin; compounds I-3, I-11, and I-14 showed inhibition rates exceeding 50% against *Fusarium graminearum* causal agent of wheat, and were superior to Tebufloquin; compounds I-1, I-4, I-9, I-11, I-12, I-13, I-14, and I-15 showed inhibition rates exceeding 50% against *Bacillus oryzae* causal agent of rice blast, with compound I-4 showing an inhibition rate (75.5%) exceeding that of the fungicide Tebufloquin (63.6%); compounds I-13 and I-15... The inhibition rate against *Phytophthora capsici* exceeded 60%, which is also superior to the inhibition rate of fungicide Tebufloquin (58.1%). Compounds I-4, I-6, I-11, I-13, I-14, and I-15 all showed inhibition rates exceeding 75% against *Sclerotinia sclerotiorum*, with compound I-15 reaching an inhibition rate as high as 92.0%. The fungicidal efficacy of these compounds also exceeded that of fungicide Tebufloquin (55.0%). Compounds I-4, I-13, I-14, and I-15 all showed inhibition rates exceeding 65.0% against *Rhizoctonia solani*, the causal agent of rice sheath blight, and exceeding 50% against *Fusarium wilt*, all superior to the inhibition rate of fungicide Tebufloquin. Compound I-3 showed a fungicidal activity of 82.3% against *Rhizoctonia solani*, the causal agent of apple ring rot.

[0061] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. The application of an 8-substituted aniline-chloroquinoline compound as a pesticide for antibacterial purposes, characterized in that, The general structural formula of 8-substituted aniline-chloroquinoline compounds is: ， Wherein, R is 2,4-diFPh, 3-ClPh, 3,4-diClPh, 4-BrPh, 2-Br-4-FPh, 2-Br-5-FPh, 4-FPh, or 3-MePh, wherein: When R is 2,4-diFPh, the fungus is *Pseudomonas aeruginosa*, the causal agent of apple ring rot. When R is 3-ClPh, the bacterium is one of the following: early blight pathogen of tomato, sclerotinia sclerotinia of rapeseed, rice sheath blight pathogen, cucumber wilt pathogen, and apple ring rot pathogen; When R is 3,4-diClPh, the bacterium is *Sclerotinia sclerotiorum*, the causal agent of rapeseed disease. When R is 4-BrPh, the bacterium is one of the following: early blight pathogen of tomato, sclerotinia sclerotinia of rapeseed, rice sheath blight pathogen, and cucumber wilt pathogen; When R is 2-Br-4-FPh, the bacterium is *Tomato Early Blight*. When R is 2-Br-5-FPh, the fungus is one of the following: early blight pathogen of tomato, Phytophthora in pepper, Sclerotinia sclerotiorum of rapeseed, Rhizoctonia solani of rice, and Fusarium wilt pathogen of cucumber; When R is 4-FPh, the bacterium is one of the following: early blight pathogen of tomato, sclerotinia sclerotinia of rapeseed, rice sheath blight pathogen, and cucumber wilt pathogen; When R is 3-MePh, the fungus is one of the following: early blight pathogen of tomato, Phytophthora in pepper, Sclerotinia sclerotiorum of rapeseed, rice sheath blight pathogen, cucumber wilt pathogen, and apple ring rot pathogen.

2. The application according to claim 1, characterized in that, The preparation method of 8-substituted aniline-chloroquinoline compounds includes the following steps: Compound III, Compound IV, base, and ethanol are mixed to obtain a reaction solution, which is refluxed at 70-80℃ for 5-10 h. After the reaction is completed, the organic phase is extracted, dried, rotary evaporated, and purified by column chromatography to obtain 8-substituted aniline-chloroquinoline compounds. The ratio of Compound III, Compound IV, and base, by molar amount, is 1:(1-1.2):(1-1.1). The general structural formula of Compound IV is RNH2, where R is 2,4-diFPh, 3-ClPh, 3,4-diClPh, 4-BrPh, 2-Br-4-FPh, 2-Br-5-FPh, 4-FPh, or 3-MePh. The structural formula of Compound III is... The base is potassium carbonate, triethylamine, pyridine, or sodium hydroxide.

3. The application according to claim 2, characterized in that, The ratio of the molar fraction of compound III to the volume fraction of ethanol is 1.16:(8~15), where the molar fraction is in mmol and the volume fraction is in mL.

4. The application according to claim 2, characterized in that, Extraction includes: Extracted sequentially with water, ethyl acetate, and saturated saline solution.

5. The application according to claim 2, characterized in that, The method for obtaining compound III includes: adding phosphorus oxychloride to compound II, refluxing at 140-160°C for 8-12 h, monitoring the reaction until completion by thin-layer chromatography, cooling to room temperature, placing in an environment of 0°C to allow solid precipitation, filtering, and drying to obtain compound III. The mass ratio of compound II to phosphorus oxychloride is 1.05:(10-100), where mass parts are in g and molar parts are in mmol. The structural formula of compound II is [insert structural formula here]. .

6. The application according to claim 5, characterized in that, A method for obtaining compound II includes: mixing o-fluoroaniline, ethyl 2-methylacetoacetate, and a cyclizing agent; reacting the mixture at 140–160 °C; monitoring the reaction until completion by thin-layer chromatography; cooling to -10–0 °C; adjusting the pH to 7–8 at -10–0 °C to precipitate the solid; filtering; and drying to obtain compound II. The structural formula of o-fluoroaniline is [insert structural formula here]. The structural formula of the ethyl 2-methylacetoacetate is as follows: The cyclizing agent is polyphosphoric acid, and the ratio of o-fluoroaniline, ethyl 2-methylacetoacetate and cyclizing agent by molar amount is 1:(1~1.5):1.

5.

7. The application according to claim 6, characterized in that, In the method for obtaining compound II, the reaction time is 4.5 to 5.5 h.

8. The application according to claim 7, characterized in that, The pH is adjusted to 7-8 with sodium hydroxide solution to cause solid precipitation. The sodium hydroxide content in the sodium hydroxide solution is 9-11 wt%.

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