Arylation derivatives of indole at position 3 and their synthesis and use

Abstract

The application discloses a 3-arylation derivative of indole and a synthesis method and application thereof. 2-methylindole is used as raw material, and after iodization, the raw material is reacted with aryl boronic acid to obtain the target compound. The method has simple synthesis steps and mild reaction conditions, and the 3-arylation derivative of indole has obvious inhibitory effect on Zika virus, and can be expected to be used in potential antiviral drugs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic chemistry, and particularly relates to a 3-arylated derivative of indole and a synthetic method and application thereof. BACKGROUND

[0002] Indole is a basic heterocyclic compound, which is present in many compounds and plays a vital role in biology, such as the essential amino acid tryptophan, its metabolite serotonin, and the neurotransmitter melatonin, this nitrogen-containing aromatic heterocycle is also part of many natural products. In the field of medicinal chemistry, indole is considered as a special scaffold because it can bind to many biological targets with high affinity. Therefore, indole is a common component of many biologically active compounds. In fact, the number of such compounds reported in the literature is so large that Smythe wrote in a review published in 2003: "Indoles probably represent the most important class of all structural classes in drug discovery.

[0003] In 2014, Njardarson analyzed all drugs marketed in the United States as of 2012, and the results showed that 59% of the drugs contained at least one nitrogen heterocycle. Among all saturated and unsaturated nitrogen-containing heterocycles, indole ranked ninth with a frequency of 6.8%. Another analysis published the same year by Taylor showed that, as of 2012, among all FDA-approved drugs, indole was the 13th most common ring system. Njardarson and Taylor both found that indole was the fourth most common aromatic heterocycle in drugs, second only to pyridine, imidazole, and thiazole ring. Methods that allow the late functionalization of indole are important for medicinal chemistry applications.

[0004] Notably, among the various functionalized indole groups, the 3-arylindole scaffold is an attractive heterocyclic framework that is ubiquitous in organic synthesis, materials science, pharmaceuticals, and natural molecules. Without doubt, direct C-H bond functionalization of pre-existing indole rings is a more powerful and efficient tool for the construction of these structurally diverse heterocyclic scaffolds. Correspondingly, aryl halides, aryl hydrazines, diaryl azoniurn salts, benzoic acids, and diaryl azoniurn salts have been used as arylating reagents. Despite these achievements, direct C-3 arylation of indole with ready-made arylating reagents remains rare.

[0005] In view of the above-mentioned shortcomings of the prior art, it is necessary to develop an economically effective 3-arylated derivative of indole at the carbon 3 position. SUMMARY

[0006] In order to overcome the above technical defects, the present application provides a 3-arylated derivative of indole and a synthesis method and application thereof, and studies the synthesis method and the activity application of the compound. A 3-arylated derivative compound of indole containing biological activity is obtained by using 2-methylindole as a raw material, iodinating, and coupling with boric acid through two-step reactions. The synthesis steps of the indole derivative prodrug are simple, the yield is high, and the activity against Zika virus is tested, and the inhibition effect is obvious.

[0007] The present application provides a 3-arylated derivative of indole, which is at least one of the following structures:

[0008]

[0009] The present application also provides a synthesis method of the above-mentioned 3-arylated derivative of indole, which comprises the following steps:

[0010] (1) using compound 1 and iodine as raw materials, and obtaining compound 2 through alkalization of potassium hydroxide and iodination;

[0011] (2) compound 2 reacts with arylboronic acid 3 or 4 under the action of palladium acetate, S-PhOS ligand and anhydrous sodium carbonate to obtain the target compound.

[0012] The reaction equation is shown as follows:

[0013]

[0014] Further, in step (1), the reaction solvent is DMF, the molar ratio of compound 1, iodine and potassium hydroxide is 1:1:(2-3), the reaction temperature is room temperature, and the DMF solution of iodine is added after compound 1 reacts with potassium hydroxide for 10-30 minutes.

[0015] Further, in step (2), the reaction solvent is a mixed solvent of toluene: water: ethanol = (2-4): 1: 1 in volume ratio, the molar ratio of compound 2, arylboronic acid 3 or 4, palladium acetate, S-PhOS and anhydrous sodium carbonate is 1:(1-1.5):(0.01-0.05):(0.1-0.2):(4-6), and the reaction temperature is 90-110 DEG C.

[0016] The present application also provides the application of the above-mentioned 3-arylated derivative of indole in preparing an antiviral drug.

[0017] Further, in the above technical solution, the virus is Zika virus.

[0018] The present application has the following beneficial effects:

[0019] 1. The present application synthesizes arylated derivatives of indole at carbon 3 position by two-step reaction with 2-methylindole as raw material, avoids the problems of long synthetic route, harsh reaction conditions and low yield, and reduces safety hazards.

[0020] 2. The arylated derivatives of indole at carbon 3 position of the present application 5, 6 show significant inhibitory effect on ZIKV-NLuc recombinant virus. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The experiment procedure is for preliminary screening of compounds to inhibit ZIKV-NLuc luciferase activity;

[0022] Figure 2 The luciferase expression amount of 5 μM of two compounds;

[0023] Figure 3 The EC of compound 5 is 50 (Compound 5 EC 50 = 8.18 μM);

[0024] Figure 4 The CC of compound 5 is 50 (Compound 5 CC 50 = 118.4 μM);

[0025] Figure 5 The EC of compound 6 is 50 (Compound 6 EC 50 = 1.367 μM);

[0026] Figure 6 The CC of compound 6 is 50 (Compound 6 CC 50 = 108.7 μM). DETAILED DESCRIPTION

[0027] The present application will be further described below by specific examples. These examples should be understood as merely illustrative of the present application and not used to limit the protection scope of the present application. After reading the content described in the present application, those skilled in the art can make various changes or modifications to the present application, and these equivalent changes and modifications also fall within the scope defined by the claims of the present application.

[0028] Example 1

[0029] Synthesis of compound 5:

[0030]

[0031] To a round-bottom flask was added compound 1 (1.00 mmol) and KOH (2.5 mmol, 2.5 eq) at room temperature, DMF (10 mL) was added to dissolve compound 1 completely, stirred for 20 minutes, then iodine (1.00 mmol, 1 eq) in DMF (6 mL) was added, stirred at room temperature for 45 minutes, the reaction was completed, 10 mL of water was added, extracted with ethyl acetate (10 mL x 3), the organic phase was collected, concentrated and then entered the next step.

[0032] To a two-necked flask was added compound 2 (1.00 mmol), compound 3 (1.10 mmol, 1.1 eq), palladium acetate (0.05 mmol, 0.05 eq), S-PhOS (0.1 mmol, 0.1 eq) and anhydrous sodium carbonate (5 mmol, 5 eq) under nitrogen atmosphere, a mixed solvent of toluene: water: ethanol = 3: 1: 1 (6 mL: 2 mL: 2 mL) was added, stirred at 100 °C for 12 hours, the reaction was completed, quenched with 10 mL of cold water, extracted with dichloromethane (10 mL) for three times, the organic phase was collected, dried over anhydrous sodium sulfate, concentrated and then passed through a column (volume ratio, petroleum ether: ethyl acetate = 20: 1) to obtain compound 5 (244 mg).

[0033] 1 H NMR (400 MHz, CDCl3) δ 8.11-8.08 (d, 1H), 8.06 (s, 1H), 7.80 (d, J = 1.3 Hz, 1H), 7.54 (ddd, J = 8.3, 6.7, 1.4 Hz, 1H), 7.44-7.33 (m, 4H), 7.25-7.15 (m, 2H), 7.08-6.98 (m, 1H), 2.79 (s, 3H), 2.33 (s, 3H). 13 C{ 1 H}NMR (100 MHz, CDCl3) δ 135.22, 133.34, 133.06, 133.01, 132.65, 131.11, 129.55, 128.35, 127.42, 126.48, 125.50, 125.28, 124.38, 121.35, 119.73, 119.42, 113.16, 110.21, 19.59, 12.51.HRMS (ESI) calcd. for C 20 H 17 NNa + ([M+Na] + ):294.1253, found:294.1248. Example 2

[0034] Synthesis of compound 6:

[0035]

[0036] To a round-bottom flask was added compound 1 (1.00 mmol) and KOH (2.5 mmol, 2.5 eq) at room temperature, DMF (10 mL) was added to fully dissolve compound 1, after stirring for 20 minutes, iodine (1.00 mmol, 1 eq) in DMF (6 mL) was added, the reaction was carried out for 45 minutes, after the reaction was completed, 10 mL of water was added, extracted with ethyl acetate (10 mL x 3), the organic phase was collected, concentrated and subjected to the next step.

[0037] To a two-necked flask was added compound 2 (1.00 mmol), 4 (1.10 mmol, 1.1 eq), palladium acetate (0.05 mmol, 0.05 eq), S-PhOS (0.1 mmol, 0.1 eq) and anhydrous sodium carbonate (5 mmol, 5 eq) under nitrogen atmosphere, a mixed solvent of toluene: water: ethanol = 3: 1: 1 (6 mL: 2 mL: 2 mL) was added, heated at 100 °C for 12 hours, after the reaction was completed, the reaction was quenched with 10 mL of cold water, extracted with dichloromethane (10 mL) three times, the organic phase was collected, dried over anhydrous sodium sulfate, concentrated and subjected to column chromatography (volume ratio, petroleum ether: ethyl acetate = 20: 1) to obtain compound 6 (240 mg).

[0038] 1 H NMR (400 MHz, CDCl3) δ 8.00 (s, 1H), 7.75-7.65 (m, 5H), 7.63-7.58 (m, 2H), 7.47 (t, J = 7.7 Hz, 2H), 7.36 (t, J = 7.3 Hz, 2H), 7.21-7.10 (m, 2H), 2.57 (s, 3H). 13 C{ 1 H}NMR (100 MHz, CDCl3) δ 141.12, 138.54, 135.29, 134.56, 131.58, 129.72, 128.82, 127.86, 127.24, 127.11, 127.05, 121.63, 120.07, 118.87, 114.13, 110.35, 12.70. HRMS (ESI) calcd. for C 21 H 18 N + ([M+H] + ): 284.1433, found: 284.1428.

[0039] Example 3

[0040] This example is a preliminary detection process and results of the compounds 5, 6 described in examples 1, 2 inhibiting Zika virus at the cellular level. The materials and consumables listed in this example can be obtained from commercial channels unless otherwise specified. Cells and viruses come from the cell and microbial resource library of CTCC or other relevant institutions. The experimental methods of this example are standard molecular biology, cell biology or virology operation procedures, which can be easily understood and operated by researchers in the field. The specific steps are as follows:

[0041] 1. Cells:

[0042] Vero (African green monkey kidney cells), culture conditions: DMEM medium 90% + 10% bovine serum + 1% Penicillin-Streptomycin.

[0043] 2. Virus

[0044] The Zika virus gene sequence and Nano luciferase (NLuc) gene sequence were connected on plasmid pACYC177 using existing conventional genetic means to obtain plasmid pZIKV-NLuc (preserved in the laboratory). The cells were inoculated one day in advance so that they reached 70-90% confluence at the time of transfection, and Lipofectamine 3000 TM Plasmid DNA-liposome complexes were prepared, and then the DNA-liposome complexes were added to the cells. After 48 h, the supernatant was harvested to infect Vero cells, and the recombinant virus ZIKV-NLuc was obtained (for specific process, please refer to Gao, J.; Chen, J.; Lu, W.; Cai, J.; Shi, L.; Zhao, W.; Zhang, B., Construction of an infectious clone of Zika virus stably expressing an EGFP marker in a eukaryotic expression system. Virology Journal 2021, 18 (1)).

[0045] 3. Main reagents:

[0046] DMEM (Gibco, cat: C11995500BT);

[0047] Fetal bovine serum FBS (Gibco, cat: 10270-106);

[0048] Plasmid pACYC177 (Mingling Biological, cat: P0995);

[0049] Pen-Strep (10,000 U / mL) (M&C gene biotechnology, cat: G2723M3);

[0050] Anti-Zika virus positive drug: Ribavirin (Solarbio, cat:IR0090);

[0051] Gaussia-Lumi TM Gaussian luciferase reporter gene assay kit (Beyotime, cat:RG072S);

[0052] pZIKV-NLuc transfection reagent Lipofectamine 3000 TM (invitrogen, cat:2319757).

[0053] 4. Experimental steps:

[0054] Step 1: As Figure 1 As shown, the compound inhibits ZIKV replication as detected: Vero cells were injected at a concentration of 1.5 × 10⁻⁶. 4 Cells were seeded per well in 96-well plates and incubated at 37°C for 12 h until cell confluence reached 90–95%. The original culture medium was discarded, and 100 μL of the assay compound (final concentration 5 μM) or positive control drug (Ribavirin, final concentration 100 μM) was added to each well (3 replicates). The cells were incubated at 37°C for 4 h, the supernatant was discarded, and ZIKV-NLuc virus dilution buffer (MOI = 0.01) and the assay compound (final concentration 5 μM) or positive control drug (final concentration 100 μM) were added. The cells were incubated at 37°C for 2 h, the free virus was washed away, and 100 μL of the assay compound or positive control drug was added to bring the final concentration of the assay compound to 5 μM and the final concentration of the positive control drug to 100 μM. The cells were incubated at 37°C for 48 h, and then 100 μL of Gausssia-LumiNova was added to each well. TM The detection reagents were used to detect Nanoluciferase (NLuc) using a multi-functional microplate reader, and the fluorescence values ​​were read. This yielded a preliminary screening result for Zika anti-Zika activity at a single concentration (5 μM), such as... Figure 2 As shown, the compound concentration was 5 μM, and the control drug concentration was 100 μM.

[0055] Step 2: Replace the 5μM test compound from Step 1 with test compounds at final concentrations of 0.04μM, 0.2μM, 1μM, 5μM, and 25μM. Following Step 1, calculate the relative ZIKV infection luciferase activity as: compound fluorescence value / virus control fluorescence value. Then, based on the relative ZIKV infection luciferase activity, use GraphPad Prism software to determine the EC50 inhibitory effect on viral replication.50 For details, please see the results. Figure 3 and Figure 5 ,Depend on Figure 3 It can be seen that the EC of compound 5 50 =8.18μM, from Figure 5 It can be seen that the EC of compound 6 50 =1.367μM.

[0056] The experiment included three control groups:

[0057] Positive drug group: Added virus and added Ribavirin at a final concentration of 100 μM;

[0058] Virus infection group: only add viruses, no compounds;

[0059] Normal cell group: No virus or drug added.

[0060] Step 3: MTT assay for cytotoxicity: 1.5 × 10⁻⁶ 4 Cells were seeded in 96-well cell culture plates with 100 μL of cell culture medium. 100 μL of a gradient concentration of compound solution was added, resulting in final concentrations of 1 μM, 5 μM, 25 μM, 50 μM, and 250 μM, respectively; each concentration was repeated in triplicate. A control without the compound was also included. After 48 h of cell culture, 100 μL of supernatant was discarded, and 20 μL of MTT (5 mg / mL) was added. The cells were incubated at 37°C for 4 h. After centrifugation, 100 μL of supernatant was discarded, and 100 μL of DMSO was added. The cells were incubated at room temperature in the dark, and shaken for 15 minutes until the blue formaldehyde dissolved. Cell viability was measured using a microplate reader at OD595 (OD630 as a reference wavelength). The cell viability was calculated, and the CC (cell cytotoxicity) was determined using GraphPad Prism software. 50 For details, please see the results. Figure 4 and Figure 6 ,Depend on Figure 4 It can be seen that the CC of compound 5 50 =118.4μM, from Figure 6 It can be seen that the CC50 of compound 6 is 108.7 μM.

[0061] Step 4: Calculation of the Selective Index of Drug Antiviral Activity: Selective Index (SI) = CC 50 / EC 50 4. Test Results:

[0062] Conclusion: At a concentration of 5 μM, compounds 5 and 6 significantly inhibited ZIKV-NLuc recombinant virus. The selective index (SI) for antiviral activity was 14.47 and 79.52, respectively (the selective index for the control drug Ribavirin was 75).

[0063] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent substitutions or changes according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. An arylated derivative of indole at the 3-position, characterized in that, The structure is as follows:

2. The process for the synthesis of arylated derivatives of indole at position 3 according to claim 1, characterized in that, The method comprises the following steps: (1) using compound 1 and iodine as raw materials, after alkalization by potassium hydroxide, compound 2 is obtained by iodination; (2) compound 2 reacts with aryl boronic acid 3 under the action of palladium acetate and S-PhOS ligand and anhydrous sodium carbonate to obtain the target compound.

3. The process for the synthesis of arylated derivatives of indole at the 3 position according to claim 2, characterized in that: In step (1), the molar ratio of compound 1, iodine and potassium hydroxide is 1:1: (2-3).

4. The process for the synthesis of arylated derivatives of indole at the 3 position according to claim 2, characterized in that: In step (2), the molar ratio of compound 2, aryl boronic acid 3, palladium acetate, S-PhOS and anhydrous sodium carbonate is 1: (1-1.5): (0.01-0.05): (0.1-0.2): (4-6).

5. The process for the synthesis of arylated derivatives of indole at the 3 position according to claim 2, characterized by the fact that: In step (1), the reaction solvent is DMF, and the reaction temperature is room temperature; in step (2), the reaction solvent is a mixed solvent of toluene: water: ethanol = (2-4): 1: 1 in volume ratio, and the reaction temperature is 90-110 DEG C.

6. The process for the synthesis of arylated derivatives of indole at the 3 position according to claim 5, characterized by the fact that: In step (1), compound 1 and potassium hydroxide are first reacted for 10-30 minutes, and then iodine solution in DMF is added; in step (2), the reaction is carried out under nitrogen protection.

7. Use of an arylated derivative of indole at position 3 for the preparation of an antiviral medicament, characterized in that, The arylated derivative of the indole at the 3-position is at least one of the following structures: 、 。 8. Use of the arylated derivatives of indole at position 3 according to claim 7 for the preparation of antiviral medicaments, characterized in that: The virus is Zika virus.

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