Preparation method of 3-selenoindole compound

Abstract

The invention discloses a preparation method of a 3-selenoindole compound, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: putting 2-amino diaryl acetylene, diaryl diselenide, an electrolyte and an organic solvent into a non-separated electrolytic tank for constant-current electrolysis, and after the reaction is finished, separating and purifying to obtain the 3-selenoindole compound. According to the method, C-C bonds and C-Se bonds are constructed at the same time under the electrolysis condition, the preparation steps are simple and easy to operate, the reaction conditions are mild, and the method is green and efficient; the reaction takes electrons as a cleaning reagent, conversion of organic compounds is realized under voltage driving, a large amount of oxidizing agent (hydrogen peroxide) is not needed, potential safety hazards caused by use of a large amount of oxidizing agent are avoided, and the method is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and particularly relates to a method for preparing 3-selenylindole compounds. Background Art

[0002] Indole derivatives are a series of compounds formed by chemically modifying different functional groups or substituents based on the important organic compound skeleton of indole (chemical formula: C8H7N). They are the core structural units of many natural biological products and drug molecules, possessing unique chemical properties and a wide range of biological activities (such as anti-cancer activity, anti-inflammatory activity, neuroprotective effects, plant growth regulators, etc.), and occupy a crucial position in the fields of organic synthesis and drug development. Organoselenium compounds are a class of compounds formed by the combination of selenium elements with organic molecules. Due to their excellent biological activities, such as antioxidant, anti-aging, anti-cancer and anti-cancer properties, they have attracted much attention in the field of organic chemistry in recent years. Introducing selenium groups into the indole skeleton to form selenylindole compounds not only enriches the diversity of indole compounds but also is expected to exhibit more excellent biological activities, providing new strategies and approaches for drug research and development.

[0003] In recent years, the preparation of 3-selenylindole compounds has become a research hotspot in the field of organic synthesis. A large number of synthetic methods for 3-selenylindole compounds have been successively reported. These methods mainly use indole derivatives as starting materials and achieve the aryl(alkyl)selenylation of indole in the presence of metal catalysts or oxidants to prepare a series of selenylindole compounds. These methods have cumbersome preparation steps and cannot achieve the simultaneous construction of the indole skeleton and the C-Se bond in one step. In 2012, the Wang Lei research group reported a method for constructing 3-selenylindole compounds in one step by the reaction of 2-(2,2-dibromoethenyl)aniline with diaryl diselenide catalyzed by iodine in the presence of tert-butyllithium [Chem. Commun., 2012, 48, 10052.]. This method uses 2 equivalents of tert-butyllithium as a strong base, the reaction temperature is as high as 110 °C, and the raw materials are difficult to prepare, which does not meet the requirements of green development. In 2014, the Fan Renhua research group first reported the efficient synthesis of 3-thioindole compounds using 2-aminodiarylacetylene as the starting material promoted by iodobenzene diacetate [Org. Lett., 2014, 16, 6508.]. However, this method uses a mercaptan compound with a foul smell as the sulfurization reagent, and the operation is complex, which is not conducive to industrial production.

[0004] Based on the above research foundation, in 2017, the research group of Wang Lei further improved the synthesis method of 3-selenaindole compounds. This method uses readily available 2-aminodiarylacetylene and stable diaryldiselenide as starting materials. Under photocatalytic conditions, with 1 equivalent of H2O2 as the oxidant, the high-yield preparation of 3-selenaindole compounds was achieved at room temperature [Org. Chem. Front., 2017, 4, 1322 - 1330]. However, the safety hazards such as explosion and corrosion caused by the use of a large amount of hydrogen peroxide make this method still not suitable for industrial production. Summary of the Invention

[0005] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a preparation method of 3-selenaindole compounds, so as to solve the problems that the existing preparation methods need to use a large amount of hydrogen peroxide, have safety hazards and are not suitable for industrial production.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A preparation method of 3-selenaindole compounds, the preparation process is as follows:

[0008]

[0009] Among them, R is H, alkyl or halogen; R' is aryl, halogen-substituted aryl or alkyl-substituted aryl.

[0010] Further, Ar is phenyl, and R' is phenyl, halogen-substituted phenyl or alkyl-substituted phenyl.

[0011] Further, 2-aminodiarylacetylene shown in Formula 1, diaryldiselenide shown in Formula 2, electrolyte and organic solvent are placed in a non-separable electrolytic cell for constant current electrolysis. After the reaction is completed, the 3-selenaindole compound shown in Formula 3 is obtained by separation and purification.

[0012] Further, the electrode pair used for electrolysis is C(+)|Pt(-) electrode pair, Pt(+)|Pt(-) electrode pair, Pt(-)|Ni(+) electrode pair, RVC(+)|Pt(-) electrode pair, Pt(+)|Cu(-) electrode pair, Pt(+)|SS(-) electrode pair, C(+)|C(-) electrode pair or RVC(+)|RVC(-) electrode pair.

[0013] Further, the electrolyte is one or more of potassium iodide, lithium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, ammonium iodide, tetraethylammonium perchlorate, lithium perchlorate or tetrabutylammonium iodide.

[0014] Further, the organic solvent is one or more of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, methanol or N,N-dimethylacetamide.

[0015] Further, the current intensity is 6 - 20 mA.

[0016] Further, the electrolysis temperature is 25 - 80 °C.

[0017] Further, the electrolysis time is 10 - 24 h.

[0018] Further, the separation and purification are as follows: water is added to the reaction system to quench the reaction, then the reaction solution is extracted several times with ethyl acetate, the organic phases after each extraction are combined, the combined organic phase is dried over anhydrous sodium sulfate and then concentrated, and the residue after concentration is separated by column chromatography to obtain the 3-selena-indole compound.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. In the preparation method of the 3-selena-indole compound of the present invention, 2-aminodiarylacetylene and diaryl diselenide are used as raw materials. Under electrolysis conditions, the construction of C-N bond and C-Se bond is achieved simultaneously. The preparation steps are simple and easy to operate. Moreover, this reaction uses electrons as a clean reagent, and under the drive of voltage, the transformation of organic compounds is realized. There is no need to use a large amount of oxidant (hydrogen peroxide), avoiding the safety hazards caused by the use of a large amount of oxidant. The reaction conditions are mild, green and efficient, and are suitable for industrial production. Specific Embodiments

[0021] The following combines specific embodiments to further describe the specific embodiments of the present invention in detail.

[0022] The numerical ranges in the present invention should be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0023] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail. Regarding the use of "comprising", "including", "having", "containing", etc. in this text, they are all open-ended terms, meaning including but not limited to.

[0024] Unless otherwise specified, the experimental methods used in this invention are all conventional methods.

[0025] The materials, reagents, etc. used in this invention, unless otherwise specified, can be purchased or synthesized by known methods.

[0026] In the quantitative tests of this invention, three repeated experiments are set, and the results are averaged.

[0027] Example 1

[0028] This example provides a preparation method of a 3-selenoindole compound, and the preparation process is as follows:

[0029]

[0030] 2-Aminodiarylacetylene (1a, 0.5 mmol), diphenyldiselenide (2a, 0.25 mmol), KI (0.5 mmol) and 6 mL of dimethyl sulfoxide (DMSO) were placed in a non-separating electrolytic cell, using a C(+)|Pt(-) electrode pair as the electrodes, and electrolytic reaction was carried out at a constant current of 15 mA for 8 h. After the reaction was completed, the reaction solution was diluted with water, and then the reaction solution was extracted multiple times with ethyl acetate. The organic phases obtained after each extraction were combined. The combined organic phase was dried over Na2SO4 and then concentrated by removing the solvent using a rotary evaporator. The concentrated residue was separated by column chromatography (the elution solvent was: ethyl acetate / petroleum ether, volume ratio 3:1) to obtain the target product 3a (yield: 70%). Its characterization data are as follows: 1 HNMR(500MHz,CDCl3)δ8.30(d,J=7.5Hz,1H),7.40-7.36(m,2H),7.35-7.32(m,3H),7.26-7.24(m,4H),7.20-7.19(m,1H),7.03-7.00(m,3H),6.99-6.96(m,2H),6.87(d,J=7.5Hz,1H); 1313C NMR (126 MHz, CDCl3) δ 144.93, 144.88, 137.54, 134.94, 132.12, 131.82, 131.64, 130.92, 129.43, 129.23, 129.03, 127.17, 126.93, 126.06, 125.75, 124.69, 121.23, 116.31, 110.55, 101.88, 21.66.

[0031] In product 3a, Ts is p-toluenesulfonyl and Ph is phenyl.

[0032] Example 2

[0033] This example provides a method for preparing a 3-selena-indole compound. The preparation process is as follows:

[0034] Using a Pt(+)|Pt(-) electrode pair instead of a C(+)|Pt(-) electrode pair, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 52%.

[0035] Example 3

[0036] This example provides a method for preparing a 3-selena-indole compound. The preparation process is as follows:

[0037] Using a Pt(-)|Ni(+) electrode pair instead of a C(+)|Pt(-) electrode pair, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 8%.

[0038] Example 4

[0039] This example provides a method for preparing a 3-selena-indole compound. The preparation process is as follows:

[0040] Using an RVC(+)|Pt(-) electrode pair instead of a C(+)|Pt(-) electrode pair, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 31%. RVC is glassy carbon.

[0041] Example 5

[0042] This example provides a method for preparing a 3-selena-indole compound. The preparation process is as follows:

[0043] Using a Pt(+)|Cu(-) electrode pair instead of a C(+)|Pt(-) electrode pair, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 16%.

[0044] Example 6

[0045] This example provides a method for preparing a 3-selena-indole compound. The preparation process is as follows:

[0046] Replace the C(+)|Pt(-) electrode pair with a Pt(+)|SS(-) electrode pair, and keep the other conditions the same as in Example 1. The yield of the target product 3a is 7%. SS is stainless steel.

[0047] Example 7

[0048] This example provides a method for preparing a 3-selenylindole compound, and the preparation process is as follows:

[0049] Replace the C(+)|Pt(-) electrode pair with a C(+)|C(-) electrode pair, and keep the other conditions the same as in Example 1. The yield of the target product 3a is 42%.

[0050] Example 8

[0051] This example provides a method for preparing a 3-selenylindole compound, and the preparation process is as follows:

[0052] Replace the C(+)|Pt(-) electrode pair with a Pt(+)|Fe(-) electrode pair, and keep the other conditions the same as in Example 1. The yield of the target product 3a is trace.

[0053] Example 9

[0054] This example provides a method for preparing a 3-selenylindole compound, and the preparation process is as follows:

[0055] Replace the C(+)|Pt(-) electrode pair with an RVC(+)|RVC(-) electrode pair, and keep the other conditions the same as in Example 1. The yield of the target product 3a is 31%.

[0056] Example 10

[0057] This example provides a method for preparing a 3-selenylindole compound, and the preparation process is as follows:

[0058] Replace DMSO with acetonitrile (CH3CN), and keep the other conditions the same as in Example 1. The yield of the target product 3a is 15%.

[0059] Example 11

[0060] This example provides a method for preparing a 3-selenylindole compound, and the preparation process is as follows:

[0061] Replace DMSO with N,N-dimethylformamide (DMF), and keep the other conditions the same as in Example 1. The yield of the target product 3a is 32%.

[0062] Example 12

[0063] This example provides a method for preparing a 3-selenylindole compound, and the preparation process is as follows:

[0064] Using methanol (MeOH) to replace DMSO, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 9%.

[0065] Example 13

[0066] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0067] Using N,N-dimethylacetamide (DMA) to replace DMSO, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 28%.

[0068] Example 14

[0069] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0070] Using lithium tetrafluoroborate (LiBF4) to replace KI, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 8%.

[0071] Example 15

[0072] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0073] Using tetrabutylammonium tetrafluoroborate ( n Bu4NBF4) to replace KI, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 7%.

[0074] Example 16

[0075] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0076] Using NH4I to replace KI, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 15%.

[0077] Example 17

[0078] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0079] Using tetraethylammonium perchlorate (Et4NClO 4) to replace KI, with the remaining conditions the same as in Example 1, the yield of the target product 3a was 18%.

[0080] Example 18

[0081] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0082] Using lithium perchlorate (LiClO4) to replace KI, with the other conditions the same as in Example 1, the yield of the target product 3a was 14%.

[0083] Example 19

[0084] This example provides a method for preparing a 3-selena-indole compound, and the preparation process is as follows:

[0085] Using tetrabutylammonium iodide ( n Bu4NI) to replace KI, with the other conditions the same as in Example 1, the yield of the target product 3a was 53%.

[0086] Example 20

[0087] This example provides a method for preparing a 3-selena-indole compound, and the preparation process is as follows:

[0088] Using 8 mA instead of 15 mA for the current intensity, with the other conditions the same as in Example 1, the yield of the target product 3a was 34%.

[0089] Example 21

[0090] This example provides a method for preparing a 3-selena-indole compound, and the preparation process is as follows:

[0091] Using 20 mA instead of 15 mA for the current intensity, with the other conditions the same as in Example 1, the yield of the target product 3a was 41%.

[0092] Example 22

[0093] This example provides a method for preparing a 3-selena-indole compound, and the preparation process is as follows:

[0094] Using 50 °C instead of room temperature for the reaction temperature, with the other conditions the same as in Example 1, the yield of the target product 3a was 37%.

[0095] Example 23

[0096] This example provides a method for preparing a 3-selena-indole compound, and the preparation process is as follows:

[0097] Extending the reaction time to 24 h, with the other conditions the same as in Example 1, the yield of the target product 3a was 54%.

[0098] As can be seen from the above Examples 1-18, the optimal reaction conditions are those of Example 1, namely, the C(+)|Pt(-) electrode pair, a current intensity of 15 mA, KI as the electrolyte, DMSO as the solvent, a reaction temperature of room temperature, and a reaction time of 8 h. Under the optimized reaction conditions, the inventors further selected 2-aminodiarylacetylenes and diaryl(alkyl) diselenides with different substituents as raw materials to develop a method for the efficient preparation of 3-selaindole compounds.

[0099] Example 24

[0100] This example provides a method for the preparation of 3-selaindole compounds, and the preparation process is as follows:

[0101]

[0102] 2-Aminodiphenylacetylene (1a, 0.5 mmol), bis(4-methylphenyl) diselenide (2b, 0.25 mmol), KI (0.5 mmol) and 6 mL of DMSO were placed in a non-separating electrolytic cell. Using the C(+)|Pt(-) electrode pair, electrolytic reaction was carried out at a constant current of 15 mA for 8 h. After the reaction was completed, the reaction solution was diluted with water, and then the reaction solution was extracted with ethyl acetate multiple times. The organic phases obtained each time were combined. The combined organic phase was dried over Na2SO4 and then concentrated by removing the solvent with a rotary evaporator. The concentrated residue was separated by column chromatography (the elution solvent was: ethyl acetate / petroleum ether, volume ratio 3:1) to obtain the target product 3b (yield: 61%). Its characterization data are as follows: 1 HNMR(500MHz,CDCl3)δ8.36(d,J=8.5Hz,1H),7.48-7.32(m,9H),7.27-7.24(m,1H),7.07(d,J=8.0Hz,2H),6.85-6.80(m,4H),2.31(s,3H),2.22(s,3H); 13 C NMR(125MHz,CDCl3)δ144.70,144.44,137.43,135.91,135.04,132.10,131.65,130.93,129.72,129.65,129.28,129.00,127.67,127.01,126.80,125.52,124.48,121.17,116.16,110.90,21.45,20.84.

[0103] Example 25

[0104] This example provides a method for the preparation of 3-selaindole compounds, and the preparation process is as follows:

[0105]

[0106] 2-Aminodiphenylacetylene (1a, 0.5 mmol), bis(4-chlorophenyl) diselenide (2c, 0.25 mmol), KI (0.5 mmol) and 6 mL of DMSO were placed in a non-separating electrolytic cell. Using the C(+)|Pt(-) electrode pair, electrolysis was carried out at a constant current of 15 mA for 8 h. After the reaction, the reaction solution was diluted with water, and then the reaction solution was extracted several times with ethyl acetate. The organic phases obtained each time were combined. The combined organic phase was dried over Na2SO4 and then concentrated by removing the solvent using a rotary evaporator. The concentrated residue was separated by column chromatography (elution solvent: ethyl acetate / petroleum ether, volume ratio 3:1) to obtain the target product 3c (yield: 52%). Its characterization data are as follows: 1 HNMR (500 MHz, CDCl3) δ 8.35 (d, J = 8.5 Hz, 1H), 7.42 - 7.34 (m, 5H), 7.30 - 7.22 (m, 5H), 7.06 (d, J = 8.0 Hz, 2H), 6.95 (d, J = 8.5 Hz, 2H), 6.83 (d, J = 8.5 Hz, 2H), 2.30 (s, 3H); 13 C NMR (125 MHz, CDCl3) δ 144.90, 144.88, 137.40, 135.02, 132.08, 131.70, 131.52, 130.70, 130.56, 129.94, 129.35, 129.20, 129.02, 127.10, 126.82, 125.76, 124.62, 120.92, 116.22, 110.07, 21.52.

[0107] Example 26

[0108] This example provides a method for preparing a 3-selenoindole compound. The preparation process is as follows:

[0109]

[0110] 2-Amino-5-methyldiphenylacetylene (1b, 0.5 mmol), diphenyldiselenide (2a, 0.25 mmol), KI (0.5 mmol) and 6 mL of DMSO were placed in a non-separating electrolytic cell, and C(+)|Pt(-) electrodes were used as the electrode pair. The electrolytic reaction was carried out at a constant current of 15 mA for 8 h. After the reaction was completed, the reaction solution was diluted with water, and then the reaction solution was extracted several times with ethyl acetate. The organic phases obtained after each extraction were combined. The combined organic phase was dried over Na2SO4 and concentrated by removing the solvent using a rotary evaporator. The concentrated residue was separated by column chromatography (elution solvent: ethyl acetate / petroleum ether, volume ratio 3:1) to obtain the target product 3d (yield: 61%). Its characterization data are as follows: 1 1H NMR (500 MHz, CDCl3) δ 8.22 (d, J = 8.5 Hz, 1H), 7.40 - 7.26 (m, 7H), 7.23 (s, 1H), 7.20 (d, J = 9.5 Hz, 1H), 7.05 - 6.97 (m, 5H), 6.90 (d, J = 6.0 Hz, 2H), 2.32 (s, 3H), 2.25 (s, 3H); 13 13C NMR (125 MHz, CDCl3) δ 145.05, 144.65, 135.70, 135.05, 134.38, 132.37, 132.00, 131.52, 130.92, 129.25, 129.00, 128.88, 127.07, 127.00, 126.80, 125.88, 120.92, 15.95, 110.22, 21.45, 21.20.

[0111] Example 27

[0112] This example provides a method for preparing a 3-selenoindole compound, and the preparation process is as follows:

[0113]

[0114] 2-Amino-5-chlorodiphenylacetylene (1c, 0.5 mmol), diphenyldiselenide (2a, 0.25 mmol), KI (0.5 mmol) and 6 mL of DMSO were placed in a non-separating electrolytic cell, and C(+)|Pt(-) electrodes were used as the electrode pair. The electrolytic reaction was carried out at a constant current of 15 mA for 8 h. After the reaction was completed, the reaction solution was diluted with water, and then the reaction solution was extracted several times with ethyl acetate. The organic phases obtained after each extraction were combined. The combined organic phase was dried over Na2SO4 and concentrated by removing the solvent using a rotary evaporator. The concentrated residue was separated by column chromatography (elution solvent: ethyl acetate / petroleum ether, volume ratio 3:1) to obtain the target product 3e (yield: 52%). Its characterization data are as follows:1 1H NMR (500 MHz, CDCl3) δ 8.25 (d, J = 9.0 Hz, 1H), 7.44 - 7.40 (m, 2H), 7.35 - 7.33 (m, 3H), 7.28 - 7.26 (m, 4H), 7.06 - 7.00 (m, 5H), 6.90 (d, J = 7.5 Hz, 2H), 2.30 (s, 3H); 13 13C NMR (125 MHz, CDCl3) δ 146.24, 145.10, 135.80, 134.72, 133.57, 131.52, 131.32, 130.44, 130.32, 129.42, 129.32, 129.22, 129.03, 127.10, 126.80, 126.21, 125.82, 120.68, 117.35, 109.60, 21.52.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions shall be covered by the scope of the claims of the present invention.

Claims

1. A method for preparing a 3-selenoindole compound, characterized in that: The preparation process is as follows: Wherein, R is H, alkyl or halogen; R' is aryl, halogen-substituted aryl or alkyl-substituted aryl.

2. The method for preparing the 3-selenoindole compound according to claim 1, characterized in that: Ar is a phenyl group, and R' is a phenyl group, a phenyl group substituted with a halogen, or a phenyl group substituted with an alkyl group.

3. The method for preparing the 3-selenoindole compound according to claim 1, characterized in that: The 2-aminodiaryl acetylene shown in Formula 1, the diaryl diselenide shown in Formula 2, an electrolyte and an organic solvent are placed in a non-separation electrolytic cell for constant current electrolysis. After the reaction is completed, the 3-selenoindole compound shown in Formula 3 is separated and purified.

4. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The electrode pair used for electrolysis is a C(+)|Pt(-) electrode pair, a Pt(+)|Pt(-) electrode pair, a Pt(-)|Ni(+) electrode pair, a RVC(+)|Pt(-) electrode pair, a Pt(+)|Cu(-) electrode pair, a Pt(+)|SS(-) electrode pair, a C(+)|C(-) electrode pair or a RVC(+)|RVC(-) electrode pair.

5. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The electrolyte is one or more of potassium iodide, lithium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, ammonium iodide, tetraethylammonium perchlorate, lithium perchlorate or tetrabutylammonium iodide.

6. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The organic solvent is one or more of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, methanol or N,N-dimethylacetamide.

7. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The current intensity is 6~20mA.

8. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The electrolysis temperature is 25-80°C.

9. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The electrolysis time is 10 to 24 hours.

10. The method for preparing the 3-selenoindole compound according to claim 3, characterized in that: The separation and purification comprises: adding water to the reaction system to quench the reaction, then extracting the reaction solution several times with ethyl acetate, combining the organic phases after each extraction, drying the combined organic phases over anhydrous sodium sulfate and then concentrating them, and separating the residue after concentration by column chromatography to obtain the 3-selenoindole compound.

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