An indoleacetate compound, a preparation method thereof and application thereof in herbicides

Abstract

This application provides an indole ketone ester compound, its preparation method, and its application in herbicides. The preparation method uses a substituted α,β-unsaturated ketone ester as a single raw material, and obtains it through a one-step tandem cyclization reaction in anhydrous ethanol under Lewis acid catalysis. These compounds exhibit excellent growth-inhibiting activity against barnyard grass and other gramineous weeds; most compounds show inhibition rates exceeding 70% at a concentration of 50 mg / L. They are also safe for wheat, corn, rapeseed, and bok choy, and can be used to prepare herbicides. The compounds of this invention have novel structures, good stability, and a simple, mild, and environmentally friendly preparation process. Furthermore, the constructed framework contains multiple functional groups, which facilitates the subsequent synthesis and application of this framework.

Description

Technical Field

[0001] This application relates to an indole ketone ester compound, its preparation method, and its application in herbicides, belonging to the field of pharmaceutical intermediates and organic pesticide synthesis technology. Background Technology

[0002] Weeds are one of the core biological stressors threatening agricultural production and restricting crop yield and quality. According to statistics from the Food and Agriculture Organization of the United Nations, global crop yields are reduced by more than 30% annually due to weed infestations, resulting in direct economic losses exceeding hundreds of billions of US dollars. In my country's agricultural production, weed control has always been a core aspect of field management, with herbicides accounting for more than 60% of total pesticide use, making them a key production material for ensuring food security and agricultural production efficiency.

[0003] With the long-term and large-scale use of herbicides, the problem of weed resistance has become increasingly serious. The area affected by herbicide-resistant weeds in field crops such as wheat and corn in my country is expanding year by year, and the control efficacy of existing herbicides continues to decline. At the same time, the public's requirements for agricultural product quality and safety and agricultural ecological environment protection are constantly increasing. Developing new herbicides with novel structures, high efficiency and low toxicity, low risk of resistance, environmental friendliness, and crop safety has become a core issue and urgent need in the current pesticide research and development field.

[0004] In pesticide research and development, indole compounds have been proven to possess a variety of biological activities, including herbicides, insecticides, and fungicides, and are an important framework for developing new pesticide lead compounds. Among them, indole ketone esters combine the biological activity of indole heterocycles with the modifiability of ketone ester groups, making them important organic synthesis intermediates and precursors of bioactive molecules. However, existing synthetic techniques for indole ketone esters still have many problems: the synthesis of indole ketone esters mainly relies on routes such as Friedel-Crafts acylation reactions, which involve cumbersome reaction steps, low overall yield, harsh reaction conditions (requiring anhydrous and oxygen-free environments, high temperature and pressure, noble metal catalysis, etc.), poor functional group compatibility, and serious pollution from waste, making it difficult to achieve large-scale production and limiting the application and development of these compounds in the pesticide field.

[0005] Chinese invention patent application CN121014643A discloses a compound containing alkylamine unsaturated ketoesters and its herbicidal application. This compound is prepared by condensation reaction of o-aminobenzaldehyde and ethyl pyruvate under alkaline conditions and has a certain inhibitory effect on the growth of weeds such as barnyard grass. However, in this technical solution, the active ingredient is an open-chain α,β-unsaturated ketoester compound, and its chemical stability and persistence need to be improved; at the same time, it is mainly safe for broadleaf crops such as tomatoes, radishes, and lettuce, and its herbicidal spectrum is limited.

[0006] Therefore, developing a new class of indole ketone ester compounds with excellent herbicidal activity and good crop safety, along with an efficient and green synthesis process, is of great theoretical significance and industrial value for the research and development of new herbicides. Summary of the Invention

[0007] To address the aforementioned issues, this application provides an indole ketone ester compound, its preparation method, and its application in herbicides. The indole ketone ester structure provided in this application will offer a novel model molecule for drug development. It exhibits novel structure, excellent herbicidal activity, and good chemical stability. The synthetic method for the indole ketone ester skeleton provided in this application is the first to efficiently synthesize the skeleton in one step via N-dealkylation / substitution reaction of α,β-unsaturated ketoesters. The method is simple, efficient, and practical, and the constructed skeleton contains multiple functional groups, which is beneficial for the subsequent synthetic applications of the skeleton.

[0008] According to one aspect of this application, an indole acetoketide compound is provided, the structural formula of which is shown in Formula 1: Formula 1 In Equation 1, R 1 It is any one of benzyl, ethyl, and methyl; R 3 It is any one of hydrogen atom, methyl, fluorine, chlorine, bromine, cyano, or methoxy; R 4 It is an ethyl group; wherein, R 1 R 3 Whether they are the same or different, each represents a substituent independently.

[0009] Furthermore, the indole ketone ester compounds of the present invention also include their pesticide-acceptable salts and stereoisomers. The stereoisomers include mixtures of any one or more of the following: tautomers, geometric isomers, enantiomers, and diastereomers.

[0010] According to another aspect of this application, a method for preparing the indole ketone ester compound as described above is also provided, comprising the following steps: The substituted α,β-unsaturated keto esters shown in Formula 2 are mixed evenly in a solvent and reacted at 70℃~120℃ under the action of an acidic catalyst to obtain the indole ketone ester compounds. The substituted α,β-unsaturated keto esters have the structural formula shown in Formula 2: Formula 2; In Equation 2, R 1 It is any one of benzyl, ethyl, and methyl; R 2 It is any one of benzyl, ethyl, and methyl; R 3 It is any one of hydrogen atom, methyl, fluorine, chlorine, bromine, cyano, or methoxy; R4 It is an ethyl group.

[0011] Specifically, this application provides a one-step preparation method for the above-mentioned indole ketone ester compounds. The core reaction route is as follows: using the substituted α,β-unsaturated keto ester shown in Formula 2 as a single reactant, an indole fused ring skeleton is constructed in one step through a tandem cyclization reaction under Lewis acid catalysis to obtain the target indole ketone ester compound.

[0012] Optionally, the acidic catalyst is a Lewis acid, selected from any one or more of ferric chloride, scandium trifluoromethanesulfonate, copper trifluoromethanesulfonate, and trifluoromethanesulfonic acid; Preferably, the acidic catalyst is ferric chloride.

[0013] Optionally, the amount of the acidic catalyst is 20-100 mol% of the molar amount of the α,β-unsaturated keto ester substituted. Preferably, the amount of acidic catalyst used is 30 mol, which replaces the molar amount of α,β-unsaturated keto ester.

[0014] Optionally, the solvent is selected from either anhydrous ethanol or dichloromethane; Preferably, the solvent is anhydrous ethanol.

[0015] Specifically, anhydrous ethanol, as a protic solvent, can not only fully dissolve the reactants and catalysts, but also promote the hydrolysis step in the series reaction, significantly improving the reaction efficiency and product yield.

[0016] Optionally, the amount of solvent used is 10-25 L per mole of α,β-unsaturated keto ester replaced; Preferably, the amount of solvent used is 10 L.

[0017] Optionally, the reaction temperature is 80℃ and the reaction time is 4~12h, preferably 8h, depending on the completion of the reaction of the raw materials in actual preparation.

[0018] According to another aspect of this application, the use of the above-mentioned indole ketone ester compounds in the preparation of herbicides is also provided.

[0019] Optionally, the herbicide is used for weed control in the cultivation of wheat, corn, rapeseed, and bok choy.

[0020] Optionally, the indole ketone ester compound may be the sole active ingredient of the herbicide, or may be combined with other ingredients as an active ingredient.

[0021] The beneficial effects of this application include, but are not limited to: 1. This application is the first to use α,β-unsaturated ketoesters as a single raw material to efficiently construct the indole ketone ester skeleton through a one-step tandem cyclization synthesis method under mild acidic conditions. This method overcomes the drawbacks of the traditional multi-step Friedel-Crafts acylation route and has the advantages of fewer steps, simple operation, high atom economy, inexpensive catalyst without precious metals, low heavy metal residue, and high yield.

[0022] 2. The indole ketone ester compounds prepared in this application contain multiple functional groups that can be further modified, which facilitates the construction of a rich compound library and provides a novel active scaffold model for subsequent pesticide and drug molecule design.

[0023] 3. The indole ketone ester compounds prepared in this application exhibit excellent biological activity in weed control applications, with high inhibition rates on the root and stem growth of noxious weeds such as barnyard grass. They can be used for weed control in fields of major economic crops such as wheat, corn, rapeseed, and Chinese cabbage, providing important candidate compounds for the development of novel, highly efficient, and low-toxicity herbicides.

[0024] 4. The synthesis method provided in this application is green and environmentally friendly, with mild conditions and easy to scale up, laying a solid foundation for the industrial production of indole ketone esters and the creation of pesticides. Attached Figure Description

[0025] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of the synthesis process for Example 1 of this application. Detailed Implementation

[0026] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described in this patent are for illustrative purposes only. The reaction vessel used in the following examples is a 25 mL thick-walled pressure-resistant tube.

[0028] Example 1 This embodiment provides a method for preparing indole ketone ester compounds, which includes the following steps: 0.1 mmol of substituted α,β-unsaturated keto ester was added to a reaction flask, along with 0.03 mmol of catalyst (FeCl3), and finally 1 mL of anhydrous ethanol (EtOH) as solvent. The reaction temperature was controlled at 80 °C, and the mixture was continuously stirred. The reaction was monitored by spotting the sample onto a conventional thin-layer chromatography plate until the reactants had completely reacted. After the reaction, the crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate, volume ratio 20:1), followed by concentrated under reduced pressure by rotary evaporation (rotary evaporation temperature set at 40 °C, vacuum degree -0.08 MPa) to obtain the target product. The separation yield was calculated.

[0029] The reaction formula is as follows:

[0030] The above reaction process is as follows: α,β-Unsaturated keto esters undergo intramolecular 1,5-hydrogen migration under ferric chloride catalysis to generate imine ion intermediate I. This intermediate I then undergoes hydrolysis / dealkylation / oxidation to yield intermediate II, followed by radical cyclization under FeCl3 oxidation to form a compound with an indole ketone ester skeleton. The synthetic route is shown below:

[0031] 1.1 Screening of Catalyst Types and Solvents Following the above method, five parallel experimental groups were established, each using different acidic catalysts and solvents. The catalysts were ferric chloride (FeCl3), scandium trifluoromethanesulfonate (Sc(OTf)3), copper trifluoromethanesulfonate (Cu(OTf)2), and trifluoromethanesulfonic acid (TfOH), respectively; the solvents were anhydrous ethanol (EtOH) and dichloromethane (DCM), respectively. The specific acidic catalysts, solvents, and corresponding yields used in each experimental group are shown in Table 1. Table 1. Yields under different acidic catalysts and solvents

[0032] Note: α,β-unsaturated keto ester substitution (0.1 mmol), solvent (1 mL), acidic catalyst dosage (0.03 mmol); the above yields are separation yields. Analysis of the above parallel experimental results shows that, under the same reaction temperature and catalyst dosage conditions, using ferric chloride (FeCl3) as the catalyst and anhydrous ethanol (EtOH) as the solvent results in the highest separation yield of the target product, reaching 75%, which is the preferred catalytic and solvent system of this invention.

[0033] 1.2 Screening of reaction temperature Following the general operating procedures described above, with FeCl3 as the catalyst, a catalyst dosage of 0.03 mmol (30 mol%), anhydrous ethanol as the solvent, and a solvent volume of 1 mL, three parallel experiments were set up to investigate the effect of different reaction temperatures on the product yield. The experimental results are shown in Table 2.

[0034] Table 2. Reaction Yields under Different Temperature Conditions

[0035] Note: Catalyst FeCl3 (0.03 mmol), solvent (1 mL); the above yields are separation yields.

[0036] Based on the analysis of the parallel experimental results above, it can be seen that the synthesis reaction of the present invention, using anhydrous ethanol (EtOH) as solvent, replacing α,β-unsaturated keto ester (0.1 mmol), and catalyst FeCl3 (0.03 mmol), under the preferred catalytic and solvent system, results in the highest separation yield of the target product at a reaction temperature of 80°C. Too low a temperature will lead to incomplete reaction and decreased yield, while too high a temperature will cause an increase in side reactions, which will also lead to a decrease in yield. Therefore, the preferred reaction temperature of the present invention is 80°C.

[0037] In summary, the optimal preparation process for the indole ketone ester compounds of this invention is as follows: using FeCl3 as a Lewis acid catalyst, with a catalyst dosage of 30 mol% of the raw material molar amount, using anhydrous ethanol as a solvent, with a solvent dosage of 10 L per 1 mole of raw material, and a reaction temperature of 80 °C. Examples 2-21 below all employ this optimal process for the preparation of the target compounds.

[0038] Example 2 raw material:

[0039] Product 2: Chemical formula: C 13 H 13 NO3 Structural formula:

[0040] Yield: 75% 1H NMR (500 MHz, CDCl3) δ 7.71 (dt, J = 8.2, 1.0 Hz, 1H), 7.58 (d, J =0.9 Hz, 1H), 7.43 (ddd, J = 8.0, 6.7, 1.2 Hz, 1H), 7.38 (dq, J = 8.7, 1.0 Hz,1H), 7.16 (ddd, J = 7.9, 6.7, 1.1 Hz, 1H), 4.45 (q, J = 7.1 Hz, 2H), 4.09 (s,3H), 1.44 (t, J = 7.2 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 178.0, 163.2, 141.4,131.2, 127.7, 126.1, 123.9, 121.3, 117.6, 110.5, 62.4, 32.2, 14.1. Example 3 raw material:

[0041] Product 3: Chemical formula: C 13 H 12 ClNO3 Structural formula:

[0042] Yield: 74% 1 H NMR (500 MHz, CDCl3) δ 7.65 – 7.60 (m, 1H), 7.61 – 7.53 (m, 1H), 7.42 – 7.35 (m, 1H), 7.17 – 7.10 (m, 1H), 4.45 (qd, J = 7.2, 1.2 Hz, 2H),4.08 – 4.02 (m, 3H), 1.44 (td, J = 7.2, 1.1 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ177.7, 162.8, 141.5, 133.8, 131.8, 124.8, 124.5, 122.5, 117.5, 110.4, 62.5,32.4, 14.1. Example 4 raw material:

[0043] Product 4: Chemical formula: C 13 H 12BrNO3 Structural formula:

[0044] Yield: 80% 1 H NMR(500 MHz, CDCl3) δ 7.58 – 7.54 (m, 3H), 7.26 (dd, J = 8.6, 1.5Hz, 1H), 4.45 (q, J = 7.2 Hz, 2H), 4.04 (s, 3H), 1.44 (t, J = 7.1 Hz, 3H); 13 CNMR(126 MHz, CDCl3) δ 177.8, 162.8, 141.8, 131.7, 125.0, 124.7, 121.8, 117.5,113.5, 62.5, 32.4, 14.1. Example 5 raw material:

[0045] Product 5: Chemical formula: C 13 H 12 ClNO3 Structural formula:

[0046] Yield: 77% 1 H NMR (500 MHz, CDCl3) δ 7.65 (dt, J = 4.3, 1.0 Hz, 1H), 7.35 – 7.30(m, 1H), 7.28 (d, J = 3.4 Hz, 1H), 7.18 – 7.13 (m, 1H), 4.47 (qd, J = 7.1, 1.0Hz, 2H), 4.10 – 4.07 (m, 3H), 1.46 (td, J = 7.1, 0.9 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 178.0, 162.8, 141.7, 131.4, 129.1, 127.9, 125.2, 120.9, 115.6,109.2, 62.6, 32.7, 14.1. Example 6 raw material:

[0047] Product 6: Chemical formula: C14 H 12 N2O3 Structural formula:

[0048] Yield: 83% 1 H NMR (500 MHz, CDCl3) δ 7.84 – 7.80 (m, 1H), 7.78 (d, J = 1.3 Hz, 1H), 7.65 (d, J = 0.9 Hz, 1H), 7.38 (dd, J = 8.4, 1.3 Hz, 1H), 4.47 (q, J = 7.1 Hz,2H), 4.13 (s, 3H), 1.46 (t, J = 7.2 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 178.1,162.3, 139.5, 133.7, 128.5, 124.9, 123.2, 119.5, 116.7, 115.9, 109.9, 62.8,32.6, 14.1. Example 7 raw material:

[0049] Product 7: Chemical formula: C 14 H 12 F3NO3 Structural formula:

[0050] Yield: 80% 1 H NMR (500 MHz, CDCl3) δ 8.03 (dd, J = 1.9, 1.0 Hz, 1H), 7.69 (d, J =0.9 Hz, 1H), 7.63 (dd, J = 9.0, 1.7 Hz, 1H), 7.49 (d, J = 8.9 Hz, 1H), 4.47 (q, J = 7.2 Hz, 2H), 4.13 (s, 3H), 1.46 (t, J = 7.2 Hz, 3H); 13C NMR(126 MHz, CDCl3)δ 178.0, 162.6, 141.9, 132.6, 125.1, 123.9, 123.8, 123.7, 123.6, 121.8,121.8, 121.7, 118.0, 111.1, 62.7, 32.6, 14.1. Example 8 raw material:

[0051] Product 8: Chemical formula: C 13 H 12 FNO3 Structural formula:

[0052] Yield: 86% 1 H NMR (500 MHz, CDCl3) δ 7.55 (qd, J = 2.0, 1.3 Hz, 1H), 7.44 (ddt, J =7.7, 3.0, 1.4 Hz, 1H), 7.04 (dddd, J = 10.7, 7.9, 5.2, 3.7 Hz, 2H), 4.45 (q, J = 7.1 Hz, 2H), 4.29 (dt, J = 4.3, 1.3 Hz, 3H), 1.44 (t, J = 7.2 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 178.0, 162.9, 151.3, 149.4, 131.9, 129.9, 129.8, 129.5,129.4, 121.2, 121.1, 119.6, 119.6, 117.9, 117.9, 112.6, 112.4, 62.5, 35.0,34.9, 14.1. Example 9 raw material:

[0053] Product 9: Chemical formula: C 13 H 12 BrNO3 Structural formula:

[0054] Yield: 87% 1H NMR (500 MHz, CDCl3) δ 7.82 (t, J = 1.7 Hz, 1H), 7.52 – 7.44 (m, 2H), 7.27 – 7.24 (m, 1H), 4.45 (q, J = 7.1 Hz, 2H), 4.08 – 4.04 (m, 3H), 1.44 (t, J = 7.2 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 177.9, 162.7, 139.7, 131.8, 130.5,127.4, 126.0, 116.3, 114.4, 112.0, 62.6, 32.4, 14.1. Example 10 raw material:

[0055] Product 10: Chemical formula: C 13 H 12 ClNO3 Structural formula:

[0056] Yield: 70% 1 H NMR (500 MHz, CDCl3) δ 7.67 – 7.64 (m, 1H), 7.50 (s, 1H), 7.36 (ddd, J = 9.0, 2.1, 1.0 Hz, 1H), 7.31 (dd, J = 8.9, 1.0 Hz, 1H), 4.45 (q, J = 7.1 Hz, 2H), 4.06 (d, J = 1.0 Hz, 3H), 1.44 (t, J = 7.1 Hz, 3H); 13 C NMR(126 MHz, CDCl3)δ 177.9, 162.8, 139.5, 132.0, 128.1, 126.9, 126.7, 122.7, 116.5, 111.7, 62.6,32.4, 14.1. Example 11 raw material:

[0057] Product 11: Chemical formula: C 13 H12 ClNO3 Structural formula:

[0058] Yield: 79% 1 H NMR (500 MHz, CDCl3) δ 7.59 (dd, J = 8.1, 2.3 Hz, 1H), 7.54 (d, J =2.6 Hz, 1H), 7.36 (dd, J = 7.7, 2.4 Hz, 1H), 7.04 (td, J = 7.6, 1.8 Hz, 1H),4.48 – 4.45 (m, 4H), 4.44 (d, J = 7.0 Hz, 1H), 1.44 (t, J = 7.1 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 178.1, 163.0, 136.8, 132.4, 129.3, 129.0, 122.7, 121.7,118.2, 117.9, 62.6, 34.9, 14.1. Example 12 raw material:

[0059] Product 12: Chemical formula: C 14 H 15 NO3 Structural formula:

[0060] Yield: 79% 1 H NMR (500 MHz, CDCl3) δ 7.58 (d, J = 8.3 Hz, 1H), 7.54 (s, 1H), 7.16(s, 1H), 7.00 (d, J = 8.3 Hz, 1H), 4.44 (q, J = 7.2 Hz, 2H), 4.06 (d, J = 2.5Hz, 3H), 2.51 (s, 3H), 1.44 (t, J = 7.2 Hz, 3H); 13C NMR(126 MHz, CDCl3) δ177.6, 163.3, 142.0, 138.5, 130.9, 124.1, 123.7, 123.5, 117.9, 110.0, 62.3,32.1, 22.5, 14.1. Example 13 raw material:

[0061] Product 13: Chemical formula: C 14 H 14 ClNO3 Structural formula:

[0062] Yield: 82% 1 H NMR (500 MHz, CDCl3) δ 7.69 (d, J = 1.8 Hz, 1H), 7.53 (s, 1H), 7.40 –7.32 (m, 2H), 4.59 (qd, J = 7.1, 1.4 Hz, 2H), 4.46 (q, J = 7.2 Hz, 2H), 1.45(t, J = 7.1 Hz, 3H), 1.39 (dd, J = 7.8, 6.6 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ177.6, 162.9, 138.6, 131.3, 128.1, 126.9, 122.8, 116.8, 111.7, 62.6, 40.5,15.5, 14.1. Example 14 raw material:

[0063] Product 14: Chemical formula: C 14 H 14 BrNO3 Structural formula:

[0064] Yield: 84% 1 H NMR (500 MHz, CDCl3) δ 7.61 – 7.55 (m, 3H), 7.26 (dd, J = 8.5, 1.6Hz, 1H), 4.56 (q, J= 7.1 Hz, 2H), 4.45 (q, J = 7.1 Hz, 2H), 1.45 (t, J = 7.2Hz, 3H), 1.39 (t, J = 7.1 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 177.4, 162.9,140.9, 130.9, 125.1, 125.0, 121.9, 117.9, 113.5, 62.5, 40.4, 15.5, 14.1. Example 15 raw material:

[0065] Product 15: Chemical formula: C 15 H 14 N2O3 Structural formula:

[0066] Yield: 82% 1 H NMR (500 MHz, CDCl3) δ 7.84 – 7.79 (m, 2H), 7.66 (d, J = 0.9 Hz, 1H), 7.38 (dd, J = 8.4, 1.3 Hz, 1H), 4.63 (q, J = 7.2 Hz, 2H), 4.48 (q, J = 7.2 Hz, 2H), 1.46 (t, J = 7.1 Hz, 3H), 1.43 (t, J = 7.1 Hz, 3H); 13 C NMR(126 MHz, CDCl3)δ 177.8, 162.4, 138.6, 132.9, 128.7, 125.0, 123.2, 119.5, 117.1, 115.9,109.9, 62.8, 40.7, 15.6, 14.1. Example 16 raw material:

[0067] Product 16: Chemical formula: C 14 H 14 BrNO3 Structural formula:

[0068] Yield: 83% 1 H NMR (500 MHz, CDCl3) δ 7.85 (d, J = 1.9 Hz, 1H), 7.53 (d, J = 1.0 Hz, 1H), 7.49 (dd, J = 9.0, 1.9 Hz, 1H), 7.30 (dt, J = 9.0, 0.8 Hz, 1H), 4.58 (q, J = 7.1 Hz, 2H), 4.46 (q, J = 7.2 Hz, 2H), 1.45 (t, J = 7.2 Hz, 3H), 1.39 (t, J =7.2 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 177.6, 162.9, 138.8, 131.1, 130.5,127.6, 126.1, 116.7, 114.4, 112.0, 62.6, 40.4, 15.5, 14.1. Example 17 raw material:

[0069] Product 17: Chemical formula: C 14 H 15 NO3 Structural formula:

[0070] Yield: 84% 1 H NMR (500 MHz, CDCl3) δ 7.72 (dt, J = 8.2, 1.1 Hz, 1H), 7.59 (d, J =0.7 Hz, 1H), 7.46 – 7.37 (m, 2H), 7.16 (ddd, J = 7.9, 5.9, 1.9 Hz, 1H), 4.61(q, J = 7.1 Hz, 2H), 4.45 (q, J = 7.2 Hz, 2H), 1.44 (t, J = 7.1 Hz, 3H), 1.40(t,J = 7.1 Hz, 3H); 13 C NMR (126 MHz, CDCl3) δ 177.6, 163.3, 140.4, 130.4, 127.7, 126.2, 124.0, 121.3, 118.0, 110.5, 62.4, 40.2, 15.5, 14.2. Example 18 raw material:

[0071] Product 18: Chemical formula: C 14 H 14 ClNO3 Structural formula:

[0072] Yield: 82% 1 H NMR (500 MHz, CDCl3) δ 7.63 (dd, J = 8.7, 1.6 Hz, 1H), 7.58 (d, J =1.0 Hz, 1H), 7.43 – 7.37 (m, 1H), 7.12 (dt, J = 8.6, 1.5 Hz, 1H), 4.58 – 4.53(m, 2H), 4.45 (q, J = 7.1 Hz, 2H), 1.44 (t, J = 7.2 Hz, 3H), 1.39 (td, J = 7.1, 1.1 Hz, 3H); 13 C NMR(126 MHz, CDCl3) δ 177.4, 163.0, 140.6, 133.8, 131.1,124.9, 124.7, 122.5, 117.9, 110.3, 62.5, 40.4, 15.4, 14.1. Example 19 raw material:

[0073] Product 19: Chemical formula: C 15 H 17 NO4 Structural formula:

[0074] Yield: 81% 1H NMR (500 MHz, CDCl3) δ 7.47 (d, J = 0.8 Hz, 1H), 7.27 (d, J = 9.1 Hz, 1H), 7.11 (dd, J = 9.1, 2.5 Hz, 1H), 7.04 (d, J = 2.5 Hz, 1H), 4.44 (q, J = 7.1Hz, 2H), 4.06 (s, 3H), 3.84 (s, 3H), 1.44 (t, J = 7.1 Hz, 3H); 13 C NMR (126 MHz, CDCl3) δ 177.7, 163.3, 155.0, 137.2, 131.3, 126.3, 120.2, 116.6, 111.5, 102.6, 62.4, 55.6, 32.4, 14.1. Example 20 raw material:

[0075] Product 20: Chemical formula: C 15 H 17 NO3 Structural formula:

[0076] Yield: 82% 1 H NMR (500 MHz, CDCl3) δ 7.58 (d, J = 8.3 Hz, 1H), 7.54 (d, J = 0.9 Hz,1H), 7.19 – 7.15 (m, 1H), 6.99 (dd, J = 8.2, 1.4 Hz, 1H), 4.58 (q, J = 7.1 Hz, 2H), 4.44 (q, J = 7.2 Hz, 2H), 2.50 (s, 3H), 1.44 (t, J = 7.2 Hz, 3H), 1.39 (t, J = 7.1 Hz, 3H); 13C NMR(126 MHz, CDCl3) δ 177.3, 163.4, 141.1, 138.4, 130.1,124.3, 123.6, 123.6, 118.2, 109.9, 62.3, 40.1, 22.5, 15.5, 14.2. Example 21 raw material:

[0077] Product 21: Chemical formula: C 19 H 17 NO3 Structural formula:

[0078] Yield: 73% 1 H NMR (500 MHz, CDCl3) δ 7.75 (d, J = 8.1 Hz, 1H), 7.71 (d, J = 1.3 Hz, 1H), 7.38 (d, J = 5.3 Hz, 2H), 7.22 (d, J = 1.4 Hz, 2H), 7.22 – 7.17 (m, 2H), 7.08 (d, J = 7.4 Hz, 2H), 5.83 (s, 2H), 4.42 (qd, J = 7.1, 1.5 Hz, 2H), 1.42(td, J = 7.1, 1.5 Hz, 3H); 13 C NMR(126 MHz, CDCl3)δ 177.5, 163.0, 141.3, 137.7,130.8, 128.7, 128.1, 127.4, 126.6, 126.3, 124.0, 121.6, 118.7, 111.1, 62.5,48.4, 14.1. Experimental example: Herbicidal activity test of indole ketone ester compounds The herbicidal activity of the indole ketone ester compounds described in this invention against barnyardgrass was determined using the plate method to verify their application effect in the preparation of herbicides. The specific test methods and results are as follows: 1. Test targets and reagents The tested weed was barnyard grass (Echinochloa crus-galli). The seeds were fresh, plump seeds harvested that year. They were disinfected with sodium hypochlorite, soaked in water to germinate until they showed white sprouts, and then used for testing. Test compounds: Target indole ketone ester compounds prepared in Examples 2-21; Positive control agent: 95% acetochlor technical grade (commercially available); Other reagents: N,N-dimethylformamide (DMF) and Tween-80, both of analytical grade.

[0079] 2. Testing Methods Preparation of test solution: Accurately weigh 5 mg of the test compound, dissolve it completely in 100 μL of DMF, and then add distilled water containing 0.1% Tween-80 to a final volume of 100 mL to prepare a test solution with a concentration of 50 mg / L; prepare a 50 mg / L acetochlor positive control solution in the same way; use distilled water containing equal amounts of DMF and Tween-80 as a blank control.

[0080] Treatment procedure: Two layers of qualitative filter paper were laid flat in a sterile petri dish with a diameter of 9 cm. 5 mL of the above-mentioned test solution, positive control solution, and blank control solution were added respectively. Barnyard grass seeds with the same degree of whitening were selected, and 10 seeds were evenly placed in each dish. Each treatment was set up with 3 biological replicates.

[0081] Culture conditions: Place the petri dishes in an artificial climate incubator with a light cycle of 12 h light / 12 h darkness, a culture temperature of 25 ℃, a relative humidity of 70%, and incubate at a constant temperature for 7 days.

[0082] 3. Indicator Measurement and Result Grading After cultivation, the stem length and root length of each barnyard grass plant were measured, and the average inhibition rate of stem growth and the average inhibition rate of root growth for each treatment group were calculated using the following formula: Growth inhibition rate (%) = (Mean length of blank control group - Mean length of treatment group) / Mean length of blank control group × 100% Inhibition rate grading criteria: "++++": Inhibition rate 90%~100% "++++": Inhibition rate 70%~90% "+++": Inhibition rate 50%~70% "++": Inhibition rate 30%~50% "+": Inhibition rate 10%~30% 4. Test Results The results of the inhibitory activity of the indole ketone ester compounds of the present invention on the stems and roots of barnyard grass are shown in Table 3.

[0083] Table 3. Results of the inhibitory activity of the target compounds on barnyard grass growth.

[0084] 5. Results Analysis As shown in Table 3, the indole ketone ester compounds prepared in this application exhibit significant inhibitory effects on the stem and root growth of barnyard grass at a concentration of 50 mg / L. Most compounds showed inhibition rates exceeding 70% on the roots and stems of barnyard grass, with some highly active compounds achieving inhibition rates of 90%-100%. Their herbicidal activity is superior to that of the commercially available control herbicide acetochlor. The test results confirm that the indole ketone ester compounds prepared in this application possess excellent herbicidal activity and can be used as active ingredients in the preparation of herbicides, demonstrating promising prospects for industrial development and application.

[0085] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An indole acetoketone ester compound, characterized in that, Its structural formula is shown in Equation 1: Formula 1 In formula 1, R 1 is any one of benzyl, ethyl, and methyl; R 3 is any one of a hydrogen atom, methyl, fluorine, chlorine, bromine, cyano, and methoxy; R 4 is ethyl; wherein R 1 and R 3 are the same as or different from each other and each independently represent a substituent.

2. A method for preparing the indoleacetone ester compound as described in claim 1, characterized in that, Includes the following steps: The substituted α,β-unsaturated keto esters shown in Formula 2 are mixed evenly in a solvent and reacted at 70℃~120℃ under the action of an acidic catalyst to obtain the indole ketone ester compounds. The substituted α,β-unsaturated keto esters have the structural formula shown in Formula 2: Formula 2; In Equation 2, R 1 It is any one of benzyl, ethyl, and methyl; R 2 It is any one of benzyl, ethyl, and methyl; R 3 It is any one of hydrogen atom, methyl, fluorine, chlorine, bromine, cyano, or methoxy; R 4 It is an ethyl group.

3. The preparation method according to claim 2, characterized in that, The acidic catalyst is a Lewis acid, selected from any one or more of ferric chloride, scandium trifluoromethanesulfonate, copper trifluoromethanesulfonate, and trifluoromethanesulfonic acid.

4. The preparation method according to claim 2, characterized in that, The amount of the acidic catalyst used is 20-100 mol of the molar amount of the α,β-unsaturated keto ester substituted.

5. The preparation method according to claim 2, characterized in that, The solvent is selected from either anhydrous ethanol or dichloromethane.

6. The preparation method according to claim 2, characterized in that, The amount of solvent used is 10-25 L per mole of α,β-unsaturated keto ester.

7. The preparation method according to claim 2, characterized in that, The reaction temperature is 80℃.

8. The use of the indole ketone ester compound of claim 1 in the preparation of herbicides.

9. The application according to claim 8, characterized in that, The herbicide is used for weed control in the cultivation of wheat, corn, rapeseed, and bok choy.

10. The application according to claim 8, characterized in that, The indole ketone ester compound may be the sole active ingredient of the herbicide, or may be used in combination with other ingredients as an active ingredient.

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