An amino acid isoxazolide compound and its use as an agricultural fungicide

Abstract

This invention discloses an amino acid isoxazole ester compound and its application as an agricultural fungicide, belonging to the fields of organic chemistry and pesticide technology. The general structural formula of the amino acid isoxazole ester compound of this invention is shown below. The amino acid isoxazole ester compound of this invention has inhibitory effects on various crop pathogenic fungi such as rice sheath blight and rice blast fungus, and can be used to prepare agricultural fungicides.

Description

Technical Field

[0001] This invention relates to the fields of organic chemistry and pesticide science, and in particular to an amino acid isoxazole ester compound and its application as an agricultural fungicide. Background Technology

[0002] Food security is a crucial guarantee for world peace and development. Fungal diseases in crops, due to their high susceptibility and transmissibility, can easily lead to large-scale crop yield losses, thus posing a significant threat to food security. Chemical fungicides, due to their high efficiency and broad spectrum, remain the primary strategy for controlling fungal diseases in crops. However, traditional fungicides face increasing risks and pressures in field application due to issues such as toxicity, residues, and resistance.

[0003] Isoxazole compounds possess antibacterial, herbicidal, and insecticidal biological activities, and are highly effective, low in toxicity, and environmentally friendly, making them a research hotspot in the development of new pesticides. Existing commercial pesticides, such as hymexazol, isoxaflutole, isoxcycloseram, and Zorvec™ (oxathiapiprolin), all contain isoxazole structural units. Amino acid pesticides are green, environmentally friendly, and highly effective, exhibiting significant advantages in fungicide, insecticidal, stress-resistance, and plant immunity enhancement. Currently, no active amino acid isoxazole pesticide molecules have been reported. Therefore, the development of highly effective, low-dosage, and environmentally friendly green amino acid isoxazole pesticides is particularly important and urgent. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides an amino acid isoxazole ester compound that exhibits excellent inhibitory activity against plant pathogenic fungi. This invention also provides an agricultural fungicide, comprising an amino acid isoxazole ester compound, which can control various fungal diseases of crops. Specifically, this is achieved through the following techniques.

[0005] An amino acid isoxazole ester compound has the following general structural formula:

[0006]

[0007] In general formula I or general formula II, A1 and A2 are each independently carbon or nitrogen atoms, Ar are both aryl or heteroaryl, and R 1 It is a substituent at the α-position of an α-amino acid molecule;

[0008] In general formula II, R 2 It is one of hydrogen atoms, halogens, or C1-C2 alkyl groups.

[0009] Preferably, Ar in formula I or formula II is one of phenyl, pyridyl, thiophenyl, naphthyl, furanyl, pyrazolyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, p-nitrophenyl, o-nitrophenyl, m-nitrophenyl, p-methylphenyl, o-methylphenyl, m-methylphenyl, p-bromophenyl, o-bromophenyl, or m-bromophenyl.

[0010] Preferably, R in general formula I or general formula II 1均 It is one of hydrogen atom, methyl, isopropyl, cyclopropyl, isobutyl, sec-butyl, methylthio, or benzyl.

[0011] Preferably, R in general formula II 2 It is one of fluorine atom, chlorine atom or trifluoromethyl.

[0012] The preparation method of the above-mentioned amino acid isoxazole ester compounds includes the following steps:

[0013] First, p-hydroxybenzaldehyde oxime, N-chlorosuccinimide (NCS), and N,N-dimethylformamide solution were mixed evenly and stirred. Then, a substance containing unsaturated bonds, 1,8-diazabicyclo(5,4,0)undecyl-7-ene (DBU), was added, and the reaction was carried out again. The reaction was monitored by TLC. After the reaction was completed, the reaction solution was extracted, concentrated, and dried to obtain the intermediate compound.

[0014] The above intermediate compound, α-amino acid, EDC hydrochloride, and dichloromethane were mixed and reacted for the third time. The reaction was monitored by TLC. After the reaction was completed, the reaction solution was extracted, concentrated and dried, the amino protecting group - tert-butoxycarbonyl (boc-) was removed, and the solution was recrystallized to obtain the amino acid isoxazole ester compound.

[0015] Preferably, the substance containing unsaturated bonds is ethylene or acetylene.

[0016] Preferably, the α-amino acid is one of valine, isoleucine, phenylalanine, and glycine.

[0017] Preferably, the stirring time is 0.5-1.0 h.

[0018] Preferably, the reaction time is 5-6 hours.

[0019] Preferably, the third reaction time is 7-8 hours.

[0020] The synthesis reaction process of the above-mentioned amino acid isoxazole ester compounds is as follows:

[0021]

[0022] The objective is to obtain a compound of structural formula I or II after the reactions in steps i and ii. All reactions can be carried out at room temperature and post-processing can be performed according to conventional methods.

[0023] The above-mentioned amino acid isoxazole ester compounds are used as agricultural fungicides.

[0024] An agricultural fungicide comprising the above-mentioned amino acid isoxazole ester compounds, wherein the mass fraction of the amino acid isoxazole ester compounds in the fungicide is 1-99.9%.

[0025] Preferably, the formulation of the above-mentioned agricultural fungicide includes at least one of emulsifiable concentrate, water emulsion, microemulsion, wettable powder, water-dispersible granules, or suspension concentrate.

[0026] The above-mentioned agricultural fungicides are used in the prevention and control of fungal diseases in crops. The fungi in crops include at least one of the following: rice sheath blight fungus, rice blast fungus, *Pseudomonas aeruginosa*, apple ring rot fungus, mango stem rot fungus, wheat stem rot fungus, *Botrytis cinerea*, or banana anthracnose fungus.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] The synthesis process of this invention is simple, and the obtained amino acid isoxazole ester compounds have inhibitory effects on various crop pathogenic fungi, including *Rhizoctonia solani*, *Bacillus oryzae*, *Pseudomonas aeruginosa*, *Hymenops gracilis*, *Hymenops spp.*, *Anthracis chinensis*, *Hymenops spp.*, and *Hymenops rubrum*. For example, the amino acid isoxazole ester compound (compound I-39) can achieve an inhibition rate of approximately 97% against *Rhizoctonia solani*. 50 The concentration can be as low as 6.94 mg / L; the amino acid isoxazole ester compounds of the present invention have the advantages of high safety, good antibacterial activity, broad antibacterial spectrum, and low tendency to induce drug resistance; the amino acid isoxazole ester compounds of the present invention have excellent activity, and these compounds can be used to prepare agricultural fungicides. Moreover, because these compounds have high inhibition rates against a variety of crop pathogenic fungi and low indoor toxicity, these compounds have a broad application prospect as fungicides. Detailed Implementation

[0029] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0030] This invention provides an amino acid isoxazole ester compound having the following general structural formula:

[0031]

[0032] In general formula I or general formula II, A1 and A2 are each independently carbon or nitrogen atoms, Ar are both aryl or heteroaryl, and R 1 All of them are substituents at the α-position of α-amino acid molecules;

[0033] In general formula II, R 2 It is one of hydrogen atoms, halogens, or C1-C2 alkyl groups.

[0034] Optionally, Ar in formula I or formula II is one of phenyl, pyridinyl, thiophene, naphthyl, furanyl, pyrazolyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, p-nitrophenyl, o-nitrophenyl, m-nitrophenyl, p-methylphenyl, o-methylphenyl, m-methylphenyl, p-bromophenyl, o-bromophenyl, or m-bromophenyl.

[0035] Optionally, R in formula I or formula II 1 It is one of hydrogen atom, methyl, isopropyl, cyclopropyl, isobutyl, sec-butyl, methylthio, or benzyl.

[0036] Optionally, R in Formula II 2 It is one of fluorine atom, chlorine atom or trifluoromethyl.

[0037] The preparation method of the above-mentioned amino acid isoxazole ester compounds includes the following steps:

[0038] First, p-hydroxybenzaldehyde oxime, N-chlorosuccinimide (NCS), and N,N-dimethylformamide solution were mixed evenly and stirred. Then, a substance containing unsaturated bonds, 1,8-diazabicyclo(5,4,0)undecyl-7-ene (DBU), was added, and the reaction was carried out again. The reaction was monitored by TLC. After the reaction was completed, the reaction solution was extracted, concentrated, and dried to obtain the intermediate compound.

[0039] The above intermediate compound, α-amino acid, EDC hydrochloride, and dichloromethane were mixed and reacted for the third time. The reaction was monitored by TLC. After the reaction was completed, the reaction solution was extracted, concentrated and dried, the amino protecting group - tert-butoxycarbonyl (boc-) was removed, and the solution was recrystallized to obtain the amino acid isoxazole ester compound.

[0040] Optionally, the substance containing unsaturated bonds is an ethylene or acetylene compound.

[0041] Optionally, the α-amino acid is one of valine, isoleucine, phenylalanine, or glycine.

[0042] Optionally, the stirring time is 0.5-1.0 h.

[0043] Optionally, the reaction time is 5-6 hours.

[0044] Optionally, the third reaction time is 7-8 hours.

[0045] The technical solution 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.

[0046] Example 1

[0047] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-1 below:

[0048]

[0049] Its synthesis method is as follows:

[0050] S1. First, add p-hydroxybenzaldehyde oxime (5 mmol, 0.685 g), N-chlorosuccinimide (NCS) (6 mmol, 0.810 g), and N,N-dimethylformamide solution (20 mL) to a 100 mL round-bottom flask. After mixing and stirring at room temperature for 1 hour, add phenylacetylene (6 mmol, 0.612 g) and 1,8-diazabicyclo(5,4,0)undec-7-ene (DBU) (5 mmol, 0.761 g). Continue the reaction for 5 hours and monitor the reaction by TLC. After the reaction is complete, extract the reaction solution in an ethyl acetate-water system, concentrate and dry the organic phase to obtain the intermediate phenylisoxazole compound with a yield of 93%.

[0051] S2. To a 100 mL round-bottom flask, add the phenylisoxazole compound (2.5 mmol, 0.62 g), Boc-L-valine (3.8 mmol, 0.861 g), EDC hydrochloride (3.8 mmol, 0.811 g), and dichloromethane (22 mL) sequentially. React at room temperature for 8 hours, monitored by TLC. After the reaction is complete, extract the reaction solution with a dichloromethane-water system. After concentrating and drying the organic phase, remove the amino protecting group - tert-butoxycarbonyl (boc-) in a dichloromethane-trifluoroacetic acid system. Finally, recrystallize with ethyl acetate to obtain the amino acid isoxazol(line) ester compound, with a yield of 87%. Among them, Ar and R... 1 The substitutions of A1 and A2 correspond to number 1 in Table 1 below.

[0052] Example 2

[0053] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-4 below:

[0054]

[0055] Its synthesis method is as follows:

[0056] S1. First, add p-hydroxybenzaldehyde oxime (5 mmol, 0.687 g), N-chlorosuccinimide (NCS) (6 mmol, 0.814 g), and N,N-dimethylformamide solution (20 mL) to a 100 mL round-bottom flask. After mixing and stirring at room temperature for 0.5 hours, add phenylacetylene (6 mmol, 0.610 g) and 1,8-diazabicyclo(5,4,0)undec-7-ene (DBU) (5 mmol, 0.760 g). Continue the reaction for 6 hours. After TLC monitoring, the reaction solution was extracted in an ethyl acetate-water system after the reaction was completed. The organic phase was concentrated and dried to obtain the intermediate phenylisoxazole compound with a yield of 91%.

[0057] S2. To a 100 mL round-bottom flask, add the phenylisoxazole compound (2.5 mmol, 0.62 g), Boc-L-isoleucine (3.8 mmol, 0.878 g), EDC hydrochloride (3.8 mmol, 0.815 g), and dichloromethane (20 mL) from step S1 sequentially. React at room temperature for 7 hours under TLC monitoring. After the reaction is complete, extract the reaction solution with a dichloromethane-water system. After concentrating and drying the organic phase, remove the protecting group - tert-butoxycarbonyl (boc-) in a dichloromethane-trifluoroacetic acid system. Finally, recrystallize with ethyl acetate to obtain the amino acid isoxazole ester compound I-4, with a yield of 89%. Ar and R... 1 The substitution cases for A1 and A2 correspond to number 4 in Table 1 below.

[0058] Example 3

[0059] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-14 below:

[0060]

[0061] Its synthesis method is as follows:

[0062] S1. First, add p-hydroxybenzaldehyde oxime (5 mmol, 0.687 g), N-chlorosuccinimide (NCS) (6 mmol, 0.812 g), and N,N-dimethylformamide solution (21 mL) to a 100 mL round-bottom flask. After mixing and stirring at room temperature for 1 hour, add 4-fluorophenylacetylene (6 mmol, 0.712 g) and 1,8-diazabicyclo(5,4,0)undec-7-ene (DBU) (5 mmol, 0.760 g). Continue the reaction for 5 hours and monitor the reaction by TLC. After the reaction is complete, extract the reaction solution in an ethyl acetate-water system, concentrate and dry the organic phase to obtain the intermediate 4-fluorophenylisoxazole compound with a yield of 94%.

[0063] S2. Add 4-fluorophenyl isoxazole compound (2.5 mmol, 0.638 g), Boc-L-phenylalanine (3.8 mmol, 1.11 g), EDC hydrochloride (3.8 mmol, 0.801 g), and dichloromethane (21 mL) sequentially to a 100 mL round-bottom flask. React at room temperature for 7 hours under TLC monitoring. After the reaction is complete, extract the reaction solution with a dichloromethane-water system. After concentrating and drying the organic phase, remove the protecting group - tert-butoxycarbonyl (boc-) in a dichloromethane-trifluoroacetic acid system. Finally, recrystallize with ethyl acetate to obtain amino acid isoxazole ester compound I-14, with a yield of 91%. Ar and R... 1 The substitutions of A1 and A2 correspond to number 14 in Table 1 below.

[0064] Example 4

[0065] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-31 below:

[0066]

[0067] The synthesis method of the amino acid isoxazole ester compound in this embodiment is basically the same as that in Example 3, except that:

[0068] The 4-fluorophenylacetylene in step S1 was replaced with 4-methylphenylacetylene (6 mmol, 0.696 g); step S1 yielded the intermediate 4-methylphenylisoxazole compound in 91% yield.

[0069] The 4-fluorophenylisoxazole compound in step S2 was replaced with the 4-methylphenylisoxazole compound (2.5 mmol, 0.628 g); the Boc-L-phenylalanine in step S2 was replaced with the Boc-L-valine compound (3.8 mmol, 0.864 g); step S2 yielded amino acid isoxazole ester compound I-31, with a yield of 87%.

[0070] Among them, Ar and R 1 The substitutions of A1 and A2 correspond to number 31 in Table 1 below.

[0071] Example 5

[0072] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-34 below:

[0073]

[0074] The synthesis method of the amino acid isoxazole ester compound in this embodiment is basically the same as that in Example 3, except that:

[0075] The 4-fluorophenylacetylene in step S1 was replaced with 4-methylphenylacetylene (6 mmol, 0.711 g); step S1 yielded the intermediate 4-methylphenylisoxazole compound in 87% yield.

[0076] The 4-fluorophenylisoxazole compound in step S2 was replaced with the 4-methylphenylisoxazole compound (2.5 mmol, 0.628 g); the Boc-L-phenylalanine in step S2 was replaced with the Boc-L-isoleucine (3.8 mmol, 0.880 g); step S2 yielded amino acid isoxazole ester compound I-34, with a yield of 89%;

[0077] Among them, Ar and R 1 The substitution cases for A1 and A2 correspond to number 34 in Table 1 below.

[0078] Example 6

[0079] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-39 below:

[0080]

[0081] The synthesis method of the amino acid isoxazole ester compound in this embodiment is basically the same as that in Example 3, except that:

[0082] The 4-fluorophenylacetylene in step S1 was replaced with thienylacetylene (6 mmol, 0.648 g); step S1 yielded the intermediate thienylisoxazole compound in 88% yield.

[0083] The 4-fluorophenyl isoxazole compound in step S2 was replaced with a thienyl isoxazole compound (2.5 mmol, 0.608 g); the Boc-L-phenylalanine in step S2 was replaced with Boc-L-valine (3.8 mmol, 0.865 g); step S2 yielded amino acid isoxazole ester compound I-39, with a yield of 91%.

[0084] Among them, Ar and R 1 The substitution cases for A1 and A2 correspond to number 39 in Table 1 below.

[0085] Example 7

[0086] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-42 below:

[0087]

[0088] The synthesis method of the amino acid isoxazole ester compound in this embodiment is basically the same as that in Example 3, except that:

[0089] The 4-fluorophenylacetylene in step S1 was replaced with thienylacetylene (6 mmol, 0.648 g); step S1 yielded the intermediate thienylisoxazole compound in 89% yield.

[0090] The 4-fluorophenyl isoxazole compound in step S2 was replaced with a thienyl isoxazole compound (2.5 mmol, 0.608 g); the Boc-L-phenylalanine in step S2 was replaced with Boc-L-isoleucine (3.8 mmol, 0.881 g); step S2 yielded amino acid isoxazole ester compound I-42, with a yield of 95%.

[0091] Among them, Ar and R 1 The substitution cases for A1 and A2 correspond to number 42 in Table 1 below.

[0092] Example 8

[0093] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in I-44 below:

[0094]

[0095] The synthesis method of the amino acid isoxazole ester compound in this embodiment is basically the same as that in Example 3, except that:

[0096] The 4-fluorophenylacetylene in step S1 was replaced with thienylacetylene (6 mmol, 0.648 g); step S1 yielded the intermediate thienylisoxazole compound in 89% yield.

[0097] The 4-fluorophenyl isoxazole compound in step S2 was replaced with a thienyl isoxazole compound (2.5 mmol, 0.608 g); step S2 yielded amino acid isoxazole ester compound I-44, with a yield of 94%.

[0098] Among them, Ar and R 1 The substitution cases for A1 and A2 correspond to number 44 in Table 1 below.

[0099] Example 9

[0100] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in II-45 below:

[0101]

[0102] S1. First, add p-hydroxybenzaldehyde oxime (5 mmol, 0.687 g), N-chlorosuccinimide (NCS) (6 mmol, 0.812 g), and N,N-dimethylformamide solution (21 mL) to a 100 mL round-bottom flask. After mixing and stirring at room temperature for 1 hour, add styrene (6 mmol, 0.622 g) and 1,8-diazabicyclo(5,4,0)undec-7-ene (DBU) (5 mmol, 0.760 g). Continue the reaction for 5 hours and monitor the reaction by TLC. After the reaction is complete, extract the reaction solution in an ethyl acetate-water system, concentrate and dry the organic phase to obtain the intermediate phenylisoxazoline compound with a yield of 82%.

[0103] S2. Add phenyl isoxazoline compound (2.5 mmol, 0.602 g), Boc-L-glycine (3.8 mmol, 0.676 g), EDC hydrochloride (3.8 mmol, 0.801 g), and dichloromethane (21 mL) sequentially to a 100 mL round-bottom flask. React at room temperature for 7 hours under TLC monitoring. After the reaction is complete, extract the reaction solution with a dichloromethane-water system. After concentrating and drying the organic phase, remove the amino protecting group - tert-butoxycarbonyl (boc-) in a dichloromethane-trifluoroacetic acid system. Finally, further purify by column chromatography (PE / EA = 10 / 1) to obtain amino acid isoxazoline compound II-45, with a yield of 83%.

[0104] Among them, Ar and R 1 R 2 The substitution cases for A1 and A2 correspond to number 45 in Table 1 below.

[0105] Example 10

[0106] The structural formula of the amino acid isoxazole ester compound in this embodiment is shown in II-47 below:

[0107]

[0108] The synthesis method of the amino acid isoxazole ester compound in this embodiment is basically the same as that in Example 9, except that:

[0109] Step S1 yielded the intermediate phenylisoxazoline compound in 81% yield;

[0110] In step S2, Boc-L-glycine was replaced with Boc-L-valine (3.8 mmol, 0.861 g); step S2 yielded amino acid isoxazole ester compound II-47 in 85% yield.

[0111] Among them, Ar and R 1 R 2The substitution cases for A1 and A2 correspond to number 47 in Table 1 below.

[0112] Table 1 provides structural descriptions of some compounds.

[0113]

[0114]

[0115]

[0116] Table 2 lists some of the compounds. 1 H NMR, 13 C NMR data

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] Application examples

[0125] 1. Antibacterial activity assay

[0126] Experimental method (using a toxic medium):

[0127] Some of the amino acid isoxazole ester compounds of this invention were prepared into a drug solution with a concentration of 100 mg / L. Agar plates containing bacterial culture were taken using a 5 mm punch and inoculated onto PDA medium containing the test drug. Each test sample was repeated three times, with a medium containing the same concentration of DMSO but without the drug serving as a blank control. The samples were incubated at 28°C for 2-3 days in a biochemical incubator, and the diameter of the colonies on the medium was measured. The effect of the test samples on mycelial growth was observed by comparing them with the blank control group, and the inhibition rate of the test samples on colony growth at 100 mg / L was calculated. Inhibition rate (%) = [(blank control colony diameter - test sample colony diameter) / (blank colony diameter - punch diameter)] × 100%. The determination results of some amino acid isoxazole ester compounds are shown in Table 3 below.

[0128] Table 3 Results of antibacterial activity test

[0129]

[0130] As shown in Table 3, the amino acid isoxazole ester compounds of the present invention exhibited certain inhibitory activity against crop pathogenic fungi such as rice sheath blight, rice blast fungus, grape stem rot fungus, grape cotyledon, mango stem rot fungus, banana anthracnose fungus, wheat stem rot fungus, and apple ring rot fungus at 100 mg / L. Most of the compounds showed high inhibition rates against rice sheath blight and rice stem rot fungus, and all showed a certain degree of broad-spectrum activity. Among them, compound I-39 achieved an inhibition rate of about 97% against rice sheath blight.

[0131] 2. Indoor toxicity testing

[0132] Experimental method (using a toxic medium):

[0133] Some of the amino acid isoxazole ester compounds of this invention were prepared into drug solutions with concentration gradients of 100, 50, 25, 12.5, and 6.25 mg / L. Agar plates containing bacterial cultures were taken using a 5 mm punch and inoculated onto PDA medium containing the test drugs. Each test sample was repeated three times. A medium containing the same concentration of DMSO but without the drug served as a blank control group. The samples were incubated at 28°C for 2-3 days in a biochemical incubator, and the diameter of the colonies on the medium was measured. The effect of the test samples on mycelial growth was observed by comparing them with the blank control group, and the inhibition rate of the test samples on colony growth at different concentrations was calculated. Inhibition rate (%) = [(Coronal diameter of blank control - Colony diameter of test sample) / (Coronal colony diameter of blank control - Punch diameter)] × 100%. The toxicity regression equations for each test drug and the median inhibitory concentration (EC50 value) and correlation coefficient (r) of different drugs were then calculated. The EC50 values ​​of some amino acid isoxazole ester compounds were also calculated. 50 The measurement results are shown in Table 4.

[0134] Table 4 Results of Indoor Toxicity Testing

[0135]

[0136] As shown in Table 4, compound I-39 exhibited the best inhibitory activity against rice sheath blight pathogens, EC 10. 50 The value was only 6.94 mg / L.

[0137] Note: In Tables 1-4, the numbers of the amino acid isoxazole ester compounds correspond.

[0138] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. An amino acid isoxazole ester compound, characterized in that, The following are general structural formulas: or ; In general formula I or general formula II, A1 and A2 are each independently carbon or nitrogen atoms, and R 1 It is one of hydrogen atom, methyl, isopropyl, cyclopropyl, isobutyl, sec-butyl, methylthio, or benzyl; In general formula II, R 2 It is one of hydrogen atoms, halogens, or C1-C2 alkyl groups; Ar in general formula I or general formula II is one of phenyl, pyridyl, thiophenyl, naphthyl, furanyl, pyrazolyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, p-nitrophenyl, o-nitrophenyl, m-nitrophenyl, p-methylphenyl, o-methylphenyl, m-methylphenyl, p-bromophenyl, o-bromophenyl, or m-bromophenyl.

2. The amino acid isoxazole ester compound according to claim 1, characterized in that, R in general formula II 2 It is one of fluorine atom, chlorine atom or trifluoromethyl.

3. The method for preparing the amino acid isoxazole ester compound according to claim 1 or 2, characterized in that, Includes the following steps: p-hydroxybenzaldehyde oxime, N-chlorosuccinimide (NCS), and N,N-dimethylformamide solution were mixed evenly and stirred to react. Then, a substance containing unsaturated bonds, 1,8-diazabicyclo(5,4,0)undec-7-ene, was added, and the reaction was carried out again. The reaction was monitored by TLC. After the reaction was completed, the reaction solution was extracted, concentrated, and dried to obtain the intermediate compound. The above intermediate compound, α-amino acid, EDC hydrochloride, and dichloromethane were mixed and reacted for the third time. The reaction was monitored by TLC. After the reaction was completed, the reaction solution was extracted, concentrated and dried, the amino protecting group - tert-butyloxycarbonyl (boc-) was removed, and the solution was recrystallized to obtain the amino acid isoxazole ester compound.

4. The method for preparing amino acid isoxazole ester compounds according to claim 3, characterized in that, The substance containing unsaturated bonds is an ethylene or acetylene compound.

5. The application of the amino acid isoxazole ester compounds according to claim 1 or 2 as agricultural fungicides.

6. An agricultural fungicide, characterized in that, The fungicide includes the amino acid isoxazole ester compound as described in claim 1 or 2, wherein the mass fraction of the amino acid isoxazole ester compound in the fungicide is 1-99.9%.

7. The agricultural fungicide according to claim 6, characterized in that, The formulation of the agricultural fungicide includes at least one of emulsifiable concentrate, water emulsion, microemulsion, wettable powder, water-dispersible granules, or suspension concentrate.

8. The application of the agricultural fungicide according to claim 6 or 7 in the control of fungal diseases of crops, characterized in that, The crop fungi include at least one of the following: rice sheath blight fungus, rice blast fungus, *Pseudomonas aeruginosa*, apple ring rot fungus, mango stem rot fungus, wheat stem rot fungus, *Botrytis cinerea*, or banana anthracnose fungus.

Images