An oxadiazole derivative having antitumor activity and a preparation method thereof

Abstract

The application discloses a polysubstituted oxadiazole derivative with antitumor activity and a preparation method and application thereof, and has the structure as shown in the specification. 1 is selected from H, 4-Br, 4-CH3, 3-CH3, 2-Cl; R 2 is selected from H, CH3, Ph; R 3 is selected from H, C4H 10 ; R 4 is selected from C6H4, 4-ClC6H4, 4-BrC6H4, 3-ClC6H4, 2-BrC6H4, 2-ClC6H4, 4-CH3C6H4, 4-CH3OC6H4, 4-NO2C6H4, Et, 2-Thiophene. The polysubstituted oxadiazole derivative disclosed by the application has strong antitumor activity on liver cancer cells.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical technology, specifically relating to an oxadiazole derivative with antitumor activity, its preparation method, and its application. Background Technology

[0002] Compounds containing oxadiazole skeletons have important applications in organic synthesis and medicinal chemistry, and possess a wide range of biological activities, such as antibiotic, antiproliferative, anticancer, antibacterial, and anti-inflammatory activities. Due to the excellent biological and pharmacological properties of this type of heterocyclic skeleton, it has attracted widespread attention from researchers. Therefore, in recent years, researchers have been committed to synthesizing various polysubstituted oxadiazole compounds, and so far, a number of strategies for constructing oxadiazole skeletons have been established. Among them, representative methods include: (1) using chloroform as a carbon monoxide (CO) source and cesium hydroxide as a base, aryl halides react with tetrazolium under palladium catalysis to generate 2,5-disubstituted oxadiazoles (Adv. Synth. Catal. 2015, 357, 3469-3473). (2) copper-catalyzed direct cyclization reaction of hydrazine with N,N-dimethylformamide (DMF) to efficiently synthesize a class of polysubstituted oxadiazoles (Adv. Synth. Catal. 2019, 361, 3986-3990). While these methods each have their own advantages, they also have some drawbacks, such as low yields, numerous operational steps, poor functional group tolerance, and harsh reaction conditions. Therefore, developing a simple and mild method for the synthesis / preparation of oxadiazole remains of great significance.

[0003] Cancer is a major global public health problem. Data from the World Health Organization's International Agency for Research on Cancer shows that in 2020, there were approximately 20 million new cancer cases and 10 million cancer deaths worldwide. Due to its large population, China has a high incidence and mortality rate, far exceeding that of other countries, making the situation particularly severe. Liver cancer, in particular, has a high incidence and mortality rate, with a 5-year survival rate of approximately 18%, making it the second leading cause of cancer death after pancreatic cancer. Data shows that China accounts for 50% of new liver cancer cases and 50% of cancer deaths globally each year. Traditional chemotherapy drugs for liver cancer have significant side effects, and the development of molecularly targeted drugs is more beneficial in improving patients' quality of life. Therefore, the synthesis of small molecule compounds with anti-tumor (especially anti-liver cancer) activity is a great boon for patients. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an oxadiazole derivative with antitumor activity, its preparation method, and its application.

[0005] This invention provides a multi-substituted oxadiazole derivative with antitumor activity, the structure of which is shown in Formula I:

[0006]

[0007] in,

[0008] R 1 Selected from one of H, 4-Br, 4-CH3, 3-CH3, and 2-Cl;

[0009] R 2 Selected from one of H, CH3, and Ph;

[0010] R 3 Selected from H, C4H 10 One of them;

[0011] R 4 It is selected from one of C6H4, 4-ClC6H4, 4-BrC6H4, 3-ClC6H4, 2-BrC6H4, 2-ClC6H4, 4-CH3C6H4, 4-CH3OC6H4, 4-NO2C6H4, Et, and 2-Thiophene.

[0012] This invention also provides a method for preparing the polysubstituted oxadiazole derivative as described above, and the synthetic route (II) is as follows:

[0013]

[0014] Furthermore, this includes the following steps:

[0015] S1. Add cuprous chloride and tert-butyl hydroperoxide to a dry three-necked flask, wherein the molar ratio of cuprous chloride to tert-butyl hydroperoxide is 1:(13.5-16.5), and then evacuate the three-necked flask and purge it with nitrogen for protection.

[0016] S2. At room temperature, add (N-isocyano)triphenylphosphine imine (structural formula shown in reactant 1 of synthetic route (II), polysubstituted tertiary amine (structural formula shown in reactant 2 of synthetic route (II),) and acid (structural formula shown in reactant 3 of synthetic route (II)) in sequence, and add anhydrous acetonitrile. The molar ratio of cuprous chloride to (N-isocyano)triphenylphosphine imine is 1:(9-11), the molar ratio of (N-isocyano)triphenylphosphine imine, the polysubstituted tertiary amine to acid is 2:(3.6-4.4):(2.7-3.3), and the molar volume ratio of acid to anhydrous acetonitrile is 0.27-0.33 mmol / mL.

[0017] S3. Heat to 55-66℃ and stir for 8-12 hours to react. After the reaction is complete, remove the solvent to obtain the crude product.

[0018] S4. The crude product is separated by column chromatography to obtain a polysubstituted oxadiazole derivative (the structural formula of which is shown in product 4 in synthetic route (II)).

[0019] Furthermore, in step S3, the reaction temperature is 60°C, the reaction is monitored by TLC to ensure complete reaction, and the reaction time is 8-12 hours.

[0020] Furthermore, the solvent used for column chromatography separation in step S4 is a mixed solution of ethyl acetate and petroleum ether, wherein the volume ratio of ethyl acetate to petroleum ether is 1:4.

[0021] Furthermore, in step S1, the molar ratio of cuprous chloride to tert-butyl hydroperoxide is 1:15.

[0022] Furthermore, in step S2, the molar ratio of (N-isocyano)triphenylphosphine imine, the polysubstituted tertiary amine, and the acid is 2:4:3.

[0023] Furthermore, the specific steps of the preparation method are as follows:

[0024] 10 mg (0.1 mmol) of cuprous chloride and 1.5 mmol of tert-butyl hydroperoxide were added to a dry 25 mL three-necked flask. The flask was then evacuated and protected with nitrogen. At room temperature, 302 mg (1.0 mmol) of (N-isocyano)triphenylphosphine imine, 270 mg (2.0 mmol) of a polysubstituted tertiary amine, and 234 mg (1.5 mmol) of acid were added sequentially, followed by 5 mL of anhydrous acetonitrile. The reaction mixture was heated to 60 °C and stirred for 8–12 hours (monitored by TLC). After the reaction was complete, the solvent was removed to obtain the crude product. The crude product was separated by column chromatography to obtain the oxadiazole derivative.

[0025] Furthermore, the polysubstituted oxadiazole derivatives obtained in step S4 are as follows:

[0026]

[0027] Furthermore, the polysubstituted oxadiazol derivative obtained in step S4 is compound 4f(4-bromo-N-methyl-N-((5-(p-tolyl)-1,3,4-oxadiazol-2-yl)methyl)aniline), whose structural formula is as follows:

[0028]

[0029] The present invention also provides the use of the above-described polysubstituted oxadiazole derivative in the preparation of a tumor-treating drug.

[0030] The present invention also provides the use of the above-described polysubstituted oxadiazole derivative in the preparation of a drug for treating liver cancer.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. This invention provides an oxadiazole derivative with antitumor activity, its preparation method, and its application. The preparation method utilizes simple and readily available raw materials ((N-isocyano)triphenylphosphineimide, polysubstituted tertiary amine, and acid) to carry out a continuous copper-catalyzed oxidation Ugi / aza-Wittig reaction to synthesize a novel oxadiazole compound in one step. In vitro tumor cell inhibitory activity tests were conducted on the compound, and the results showed that it has strong antitumor activity against liver cancer cells.

[0033] 2. The preparation method of the present invention has a simple synthesis route, mild conditions, and high yield, which is a significant improvement over existing preparation methods. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 For compound 4f 1 1H NMR (400MHz, CDCl3) plot;

[0036] Figure 2 For compound 4f 13 C{1H}NMR (100MHz, CDCl3) plot;

[0037] Figure 3 This is a statistical chart showing the average OD values ​​of cells in each group for the activity detection of rat liver cancer cells in Example 2.

[0038] Figure 4 These are images of the cell monolayer healing of each group of scratches under a microscope at 0, 24, and 48 hours, as shown in Example 3.

[0039] Figure 5 This is a statistical chart showing the total number of migrating cells in each group in Example 3;

[0040] Figure 6 The images show the staining patterns of cell crystalloids in each group of Example 4.

[0041] Figure 7 This is a statistical chart showing the number of plate clones in each group in Example 4;

[0042] Figure 8 The image shows the fluorescence staining of EdU and DAPI in Example 5.

[0043] Figure 9 This is a statistical graph showing the percentage of Edu-positive cells in Example 5. Detailed Implementation

[0044] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The present invention will be specifically described below with reference to specific embodiments.

[0045] This invention provides a multi-substituted oxadiazole derivative with antitumor activity, the structure of which is shown in Formula I:

[0046]

[0047] in,

[0048] R 1 Selected from one of H, 4-Br, 4-CH3, 3-CH3, and 2-Cl;

[0049] R 2 Selected from one of H, CH3, and Ph;

[0050] R 3 Selected from H, C4H 10 One of them;

[0051] R 4 It is selected from one of C6H4, 4-ClC6H4, 4-BrC6H4, 3-ClC6H4, 2-BrC6H4, 2-ClC6H4, 4-CH3C6H4, 4-CH3OC6H4, 4-NO2C6H4, Et, and 2-Thiophene.

[0052] Preferably, the structure of the polysubstituted oxadiazole derivative is as follows:

[0053] This invention also provides a method for preparing the polysubstituted oxadiazole derivative as described above, and the synthetic route (II) is as follows:

[0054]

[0055] Specifically, it includes the following steps:

[0056] S1. Add cuprous chloride and tert-butyl hydroperoxide to a dry three-necked flask, wherein the molar ratio of cuprous chloride to tert-butyl hydroperoxide is 1:(13.5-16.5), and then evacuate the three-necked flask and purge it with nitrogen for protection.

[0057] S2. At room temperature, add (N-isocyano)triphenylphosphine imine (structural formula shown in reactant 1 of synthetic route (II), polysubstituted tertiary amine (structural formula shown in reactant 2 of synthetic route (II),) and acid (structural formula shown in reactant 3 of synthetic route (II)) in sequence, and add anhydrous acetonitrile. The molar ratio of cuprous chloride to (N-isocyano)triphenylphosphine imine is 1:(9-11), the molar ratio of (N-isocyano)triphenylphosphine imine, the polysubstituted tertiary amine to acid is 2:(3.6-4.4):(2.7-3.3), and the molar volume ratio of acid to anhydrous acetonitrile is 0.27-0.33 mmol / mL.

[0058] S3. Heat to 55-66℃ and stir for 8-12 hours to react. After the reaction is complete, remove the solvent to obtain the crude product.

[0059] S4. The crude product is separated by column chromatography to obtain a polysubstituted oxadiazole derivative (the structural formula of which is shown in product 4 in synthetic route (II)).

[0060] Specifically, in step S3, the reaction temperature is 60°C, the reaction is monitored by TLC to ensure complete reaction, and the reaction time is 8-12 hours.

[0061] Specifically, the solvent used in the column chromatography separation of step S4 is a mixed solution of ethyl acetate and petroleum ether, wherein the volume ratio of ethyl acetate to petroleum ether is 1:4.

[0062] Preferably, the molar ratio of cuprous chloride to tert-butyl hydroperoxide in step S1 is 1:15.

[0063] Preferably, in step S2, the molar ratio of (N-isocyano)triphenylphosphine imine, the polysubstituted tertiary amine, and the acid is 2:4:3.

[0064] Specifically, the preparation method comprises the following steps:

[0065] 10 mg (0.1 mmol) of cuprous chloride and 1.5 mmol of tert-butyl hydroperoxide were added to a dry 25 mL three-necked flask. The flask was then evacuated and protected with nitrogen. At room temperature, 302 mg (1.0 mmol) of (N-isocyano)triphenylphosphine imine, 270 mg (2.0 mmol) of a polysubstituted tertiary amine, and 234 mg (1.5 mmol) of acid were added sequentially, followed by 5 mL of anhydrous acetonitrile. The reaction mixture was heated to 60 °C and stirred for 8–12 hours (monitored by TLC). After the reaction was complete, the solvent was removed to obtain the crude product. The crude product was separated by column chromatography to obtain the oxadiazole derivative.

[0066] Specifically, the polysubstituted oxadiazole derivatives obtained in step S4 are as follows:

[0067]

[0068] Preferably, the polysubstituted oxadiazol derivative obtained in step S4 is compound 4f(4-bromo-N-methyl-N-((5-(p-tolyl)-1,3,4-oxadiazol-2-yl)methyl)aniline), whose structural formula is as follows:

[0069]

[0070] This invention also provides the use of the above-described polysubstituted oxadiazole derivative in the preparation of a tumor treatment drug.

[0071] Preferably, the polysubstituted oxadiazole derivative is the aforementioned compound 4f.

[0072] This invention also provides the use of the above-described polysubstituted oxadiazole derivative in the preparation of a drug for treating liver cancer.

[0073] Preferably, the polysubstituted oxadiazole derivative is the aforementioned compound 4f.

[0074] This invention also provides the use of the polysubstituted oxadiazole derivative as described above in the treatment of tumor diseases.

[0075] Preferably, the tumor disease is liver cancer.

[0076] Preferably, the polysubstituted oxadiazole derivative is the aforementioned compound 4f.

[0077] The present invention will be further described below with reference to specific embodiments, but the content of the present invention is not limited thereto.

[0078] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available, and techniques not described in detail were performed according to standard methods well known to those skilled in the art. Data in the following examples were statistically processed using SPSS 26.0 software. Data are expressed as mean ± standard deviation (mean ± SD). One-way ANOVA was used for comparisons between groups, and p < 0.05 was considered statistically significant.

[0079] Example 1: Preparation of polysubstituted oxadiazole derivatives

[0080] Prepare polysubstituted oxadiazole derivatives according to the following steps:

[0081] (1) 10 mg (0.1 mmol) of cuprous chloride and 1.5 mmol of tert-butyl hydroperoxide were added to a dry 25 mL three-necked flask. The flask was then evacuated and protected with nitrogen. At room temperature, 302 mg (1.0 mmol) of (N-isocyano)triphenylphosphine imine, 270 mg (2.0 mmol) of polysubstituted tertiary amine, and 234 mg (1.5 mmol) of acid were added sequentially, followed by 5 mL of anhydrous acetonitrile. The reaction solution was heated to 60 °C and stirred for 8-12 hours (monitored by TLC). After the reaction was complete, the solvent was removed to obtain the crude product.

[0082] (2) The crude product was separated by column chromatography (ethyl acetate: petroleum ether = 1:4 v / v) to obtain the target product oxadiazole derivative.

[0083] (3) Characterization of the target product: 4-bromo-N-methyl-N-((5-(p-tolyl)-1,3,4-oxadiazol-2-yl)methyl)aniline(4f). White solid (yield 0.233g, 65%), mp 97-98 (C; 1 H NMR (CDCl3, 400MHz): δ (ppm) 7.86 (d, J=8.0Hz, 2H), 7.35-7.27 (m, 4H), 6.77-6.75 (m, 2H), 4.71 (s, 2H), 3.11 (s, 3H), 2.41 (s, 2H); 13 C{ 1 H}NMR (CDCl3, 100MHz): δ (ppm) 165.4, 163.1, 147.4, 142.4, 131.9, 129.7, 126.8, 120.8, 114.8, 110.3, 47.5, 39.0, 21.6. LCMS (ESI) m / z [M+H] + :358.Anal.Calcd for C 17 H 16 BrN3O:C, 57.00;H,4.50;Br,22.30;N,11.73;O,4.47;Found:C,56.82;H,4.62;Br,22.08;N,11.60;O,4.21.

[0084] See Figure 1 and Figure 2 The structure of the target product is known to be that of compound 4f:4-bromo-N-methyl-N-((5-(p-tolyl)-1,3,4-oxadiazol-2-yl)methyl)aniline.

[0085] Example 2: Anti-hepatocellular carcinoma activity test of polysubstituted oxadiazole derivatives

[0086] Follow these steps to perform the test:

[0087] 2.1 Cell Culture: Rat liver cancer cells were cultured in 5% CO2... Cells were cultured in a constant temperature incubator. The culture medium used was DMEM containing 10% FBS and 1% penicillin-streptomycin. Cells were passaged when they reached approximately 75% confluence. All cell experiments were performed using cells in the logarithmic growth phase and were repeated three times.

[0088] 2.2 CCK8 assay for cell viability: 5 × 10⁻⁶ cells / year. 3 Rat hepatocellular carcinoma cells were seeded into 96-well plates and cultured for 24 h. The cells were then treated with different concentrations of compound 4f (0, 3, 10, 30 μM) prepared in Example 1 for 48 h. 10 μL of CCK-8 reagent was added to each well, and the cells were incubated for 3 h. The absorbance at 450 nm was measured using a microplate reader, and cell survival curves were plotted using Graphpad Prism 8 software. Figure 3 As shown, the cell viability values ​​of compound 4f at concentrations of 0, 3, 10, and 30 μM were 100±1, 84±1.6, 75±3.2, and 40±2.2, respectively (data are expressed as mean ± standard deviation (n=3), the same below). This result indicates that compound 4f has no cytotoxicity at concentrations below 10 μM (p>0.05). This provides a basis for drug concentration in subsequent cell experiments.

[0089] Example 3 Cell Scratch Assay

[0090] The cell scratch assay was used to analyze the effect of compound 4f on the migration ability of hepatocellular carcinoma cells. Five lines were drawn at 0.5 cm intervals on the back of a 6-well plate using a marker pen. Cells in the logarithmic growth phase were collected and celled at a density of 5 × 10⁶ cells per well. 5 Cells were seeded into 6-well plates and incubated for 24 hours until confluence reached approximately 90%. Vertical horizontal scratches were made in each well using a 20 μL sterile pipette tip. After washing away detached cells with PBS, serum-free medium containing different concentrations (0, 1, 3 μM) of compound 4f was added for further culture. The wells were observed and photographed under a microscope at 0, 24, and 48 hours. Each experiment was repeated at least three times. The scratch area was measured using ImageJ software, and the scratch healing rate was measured using Graphpad Prism8 software. Figure 4 and Figure 5As shown, at 24 h, the total number of migrating cells in the control group, the 1 μM and 3 μM compound 4f treatment groups were 215±2.2, 174±0.9, and 52±1.8, respectively; at 48 h, the total number of migrating cells in the control group, the 1 μM and 3 μM compound 4f treatment groups were 462±0.9, 296±2.1, and 183±2.3, respectively. Compared with the control group, the total number of migrating cells in the experimental groups was reduced, and the cell closure time at the scratch site was prolonged (p>0.05), indicating that compound 4f can significantly inhibit the migration of liver cancer cells.

[0091] Example 4: Transwell Migration Test

[0092] Transwell chambers can be used to detect the migration ability of liver cancer cells. Transwell polyester transparent membrane-nested cell chambers (3407) were purchased from Corning Incorporated, USA. Liver cancer cells were starved for 12 hours and then digested with trypsin. Cell suspensions were prepared using serum-free culture medium. 200 μL of cell suspension containing compound 4f molecules was added to each chamber at concentrations of 0, 1, and 3 μmol / L. The seeding density was 1 × 10⁻⁶ cells per well. 4 Each chamber was placed in a 24-well plate containing complete culture medium with 10% serum. After incubation for 48 hours, the chambers were removed and fixed in 4% paraformaldehyde for 15 minutes, then stained with 0.5% crystal violet for 10 minutes. After drying, the chambers were photographed and counted using a fluorescence microscope (Olympus IX73, Olympus, Tokyo, Japan). Cell migration rate = number of cells in the experimental group / number of cells in the control group. Each experiment was repeated three times. Figure 6 and Figure 7 As shown, the number of cloned cells in the control group was 409.88±14.5; the number of cloned cells in the 1 μM and 3 μM compound 4f treatment groups were 222.33±21.3 and 74.45±8.75, respectively. Compared with the control group, the cell colony-forming ability of the 1 μM and 3 μM groups was significantly reduced (p<0.05), indicating that compound 4f treatment can significantly inhibit the migration of liver cancer cells in a dose-dependent manner.

[0093] Example 5: EDU Cell Proliferation Experiment

[0094] The EdU method was used to detect the proliferation of hepatocellular carcinoma cells treated with compound 4f. Different concentrations of compound 4f (0, 1, and 3 μM) were used to treat the hepatocellular carcinoma cells. The specific procedure was as follows: 14 mm cell spread sheets were seeded in 24-well plates, and C6 hepatocellular carcinoma cells in the logarithmic growth phase were seeded at 1 × 10⁻⁶ cells per well. 4 Cells were seeded at a density of 1000 μL on cell crawling slides. After adjusting the cell density to a suitable level, the cells were counted. Once the cells adhered, compound 4f molecules were added at concentrations of 0, 1, and 3 μmol / L. After culturing for 24 hours, 100 μL of 50 μmol / L EdU medium was added to each well. After incubation for 2 hours, cells were fixed in 4% paraformaldehyde at room temperature for 30 minutes, washed three times with PBS, incubated with permeabilization buffer at room temperature for 20 minutes, washed twice with PBS, and then incubated with the prepared Click reaction solution at room temperature in the dark for 30 minutes. After washing once with PBS, nuclear staining was performed with DAPI. Cell luminescence was observed under a fluorescence microscope (Olympus IX73, Olympus, Tokyo, Japan). Red fluorescence indicated proliferating cells, and blue fluorescence indicated nuclear staining. The EdU-488 cell proliferation assay kit (C0071S) was purchased from Shanghai Beyotime Biotechnology Co., Ltd. Figure 8 and Figure 9 As shown, the EdU-positive cell rate in the control group was 0.46±0.03; the EdU-positive cell rate in the 1μM compound 4f treatment group was 0.37±0.04 (p<0.05); and the EdU-positive cell rate in the 3μM compound 4f treatment group was 0.22±0.05 (p<0.05). These results indicate that the number of EdU-positive cells in liver cancer gradually decreased with increasing compound 4f concentration, suggesting that compound 4f can significantly inhibit the proliferation of liver cancer cells.

[0095] All the above results indicate that compound 4f has no cytotoxicity at concentrations below 10 μM and has certain inhibitory activity against liver cancer.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polysubstituted oxadiazole derivative, characterized in that, The synthetic route for the oxadiazole derivative is as follows: ； R 1 Selected from one of H, 4-Br, 4-CH3, 3-CH3, and 2-Cl; R 2 Selected from one of H, CH3, and Ph; R 3 For H; R 4 It is selected from one of 4-ClC6H4, 4-BrC6H4, 3-ClC6H4, 2-BrC6H4, 2-ClC6H4, 4-CH3C6H4, 4-CH3OC6H4, 4-NO2C6H4, Et, and 2-thiophene.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: S1. Add cuprous chloride and tert-butyl hydroperoxide to a dry three-necked flask, wherein the molar ratio of cuprous chloride to tert-butyl hydroperoxide is 1:(13.5-16.5), and then evacuate the three-necked flask and purge it with nitrogen for protection. S2. At room temperature, (N-isocyano)triphenylphosphine imide, a polysubstituted tertiary amine, and an acid are added sequentially, followed by anhydrous acetonitrile. The molar ratio of cuprous chloride to (N-isocyano)triphenylphosphine imide is 1:(9-11), the molar ratio of (N-isocyano)triphenylphosphine imide, the polysubstituted tertiary amine, and the acid is 2:(3.6-4.4):(2.7-3.3), and the molar volume ratio of the acid to the anhydrous acetonitrile is 0.27-0.33 mmol / mL. S3. Heat to 60℃ and stir for 8-12 hours to react. After the reaction is complete, remove the solvent to obtain the crude product. S4. The crude product is separated by column chromatography to obtain polysubstituted oxadiazole derivatives.

3. The preparation method according to claim 2, characterized in that, In step S3, the reaction temperature is 60°C, the reaction is monitored by TLC to ensure complete reaction, and the reaction time is 8-12 hours.

4. The preparation method according to claim 2, characterized in that, The solvent used in the column chromatography separation of step S4 is a mixed solution of ethyl acetate and petroleum ether, wherein the volume ratio of ethyl acetate to petroleum ether is 1:

4.

5. The preparation method according to claim 2, characterized in that, In step S1, the molar ratio of cuprous chloride to tert-butyl hydroperoxide is 1:

15.

6. The preparation method according to claim 2, characterized in that, In step S2, the molar ratio of (N-isocyano)triphenylphosphine imine, the polysubstituted tertiary amine, and the acid is 2:4:

3.

7. The preparation method according to claim 2, characterized in that, The structural formula of the polysubstituted oxadiazole derivative obtained in step S4 is: .

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