Nitrogen-doped carbon-loaded bimetallic catalyst as well as preparation method and application thereof

Abstract

The invention provides preparation of a nitrogen-doped carbon-loaded bimetallic catalyst and a method for constructing a 3-thioindole compound with a C-S bond by catalyzing S-C aerobic oxidation through the nitrogen-doped carbon-loaded bimetallic catalyst, and belongs to the technical field of chemical engineering. The nitrogen-doped carbon-loaded bimetallic catalyst is prepared through pyrolysis, the catalyst is of a mesoporous structure, the nitrogen-doped carbon-loaded bimetallic catalyst serves as the catalyst, a sulfhydryl compound and an indole compound are heated and stirred in a solvent in an oxygen-containing environment, the 3-thioindole compound with an S-C bond is generated, the preparation method of the catalyst is simple, the catalytic activity is excellent, and the catalyst can be used for preparing the 3-thioindole compound with the S-C bond. The reaction efficiency is high, the product selectivity is high, the catalyst can be repeatedly used, and the industrial application prospect is relatively strong.

Description

Technical Field

[0001] The invention belongs to the technical field of compound synthesis and preparation, and specifically relates to a method for preparing a nitrogen-doped carbon-supported bimetallic catalyst and catalyzing SC aerobic oxidation to construct a 3-thioindole compound with a CS bond. Background Art

[0002] Sulfur-containing compounds play a very important role in chemical industry, medicine and biology. Therefore, the development of CS construction methods is of great significance for promoting organic synthesis, drug synthesis and new material preparation. Traditional CS can be constructed by metal-catalyzed cross-coupling reaction or nucleophilic substitution reaction. Such reactions can be prepared by relatively expensive halogenated hydrocarbons. In recent years, the preparation of alkyl aryl sulfide by decarboxylation of aliphatic carboxylic acids and free radical reaction of thiophenol has also been developed. While CH activation reaction has made great progress, the construction of CS by CH activation has also attracted people's attention.

[0003] Indole and its derivatives are a very important class of aromatic heterocyclic compounds, which are widely present in nature. Due to their strong pharmacological and biological activities, indole compounds are widely used in the fields of medicine, pesticides, fragrances, dyes and fine chemicals. 3-Sulfur-substituted indole compounds are important synthetic intermediates, which are widely present in many natural products and are also common structural units in many biologically active compounds. Compounds containing 3-sulfur-substituted indole skeletons are used in the treatment of diseases such as tumors, AIDS, and heart disease. At present, a large number of biologically active 3-sulfide-substituted indoles and their derivatives have been isolated from natural products. Such compounds are an important class of drug intermediates with multiple biological and pharmaceutical activities. They can be used to treat bacterial infectious diseases, obesity, HIV, heart disease, allergies and cancer, etc. They can also be used as cyclooxygenase inhibitors and can well inhibit the polymerization of microtubules. They have an irreplaceable position in medicinal chemistry.

[0004] In the preparation of 3-thioindole compounds, in the prior art, Giuseppe La R. et al. replaced thiol derivatives with diphenyl disulfide derivatives, reacted with indole derivatives, and generated diaryl sulfide compounds under the conditions of sodium hydride as catalyst and DMF as solvent. The disadvantages of this synthesis method are that the substrate diphenyl disulfide derivative used needs to be further synthesized, the process is cumbersome, the cost is high, and sodium hydride as a catalyst has certain dangers. Hailei Z. et al. used indole and its derivatives and benzenethiol derivatives to react to generate CS-bonded diaryl sulfide compounds. This experiment used iodine as a catalyst, tert-butyl hydroperoxide (TBHP) as an oxidant, and acetonitrile as a solvent to produce an oxidative coupling reaction. The disadvantages of this synthesis method are that the separation yield of the target product in the method is not high, all around 80%, and it is difficult to avoid the generation of by-products. In addition, tert-butyl hydroperoxide is neither safe nor economical. Jhillu S.Y. et al. first used ferric chloride as a catalyst and acetonitrile as a solvent to react indole and its derivatives with benzenethiol derivatives under reflux conditions to generate 3-sulfur substituted indole compounds, and the separation yield of the obtained target products was above 80%. The disadvantage of this method is that the catalyst used cannot be recycled, it is easy to cause metal pollution, and does not meet the requirements of environmental protection. Summary of the invention

[0005] In view of the above problems, the first object of the present invention is to provide a method for preparing a nitrogen-doped carbon-supported bimetallic catalyst, which method can simply, efficiently, and stably prepare a nitrogen-doped carbon-supported bimetallic catalyst. The second object is to provide a nitrogen-doped carbon-supported bimetallic catalyst, which has a mesoporous structure, and the metal active components on the surface are evenly dispersed, the catalyst activity is high, and the stability is good. The third object is to provide the use of the catalyst in the aerobic oxidation of thiol compounds and indole compounds to prepare 3-thioindole. The fourth object is to provide a method for synthesizing a 3-thioindole compound with a CS bond, which method does not require the addition of additional reaction aids, has high catalytic efficiency, mild conditions, easy separation, simple post-treatment and product purification, a wide range of substrate applications, and has significant industrial application prospects.

[0006] In order to achieve the above technical objectives, the specific scheme adopted by the present invention is:

[0007] In the first aspect, a method for preparing a nitrogen-doped carbon-supported bimetallic catalyst is provided, wherein cobalt dicyanamide, transition metal dicyanamide salt and 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid are taken as reaction raw materials, mixed and reacted to obtain a dicyanamide-containing bimetallic ionic liquid precursor, and the obtained precursor is pyrolyzed and carbonized under inert gas protection conditions to obtain a nitrogen-doped carbon-supported bimetallic catalyst.

[0008] Furthermore, the transition metal in the transition metal dicyanamide salt is any one of Zn, Cu, Fe, Mn and Ni; the alkyl in the 1-alkyl-3-methylimidazolium dicyanamide salt ionic liquid is any one of methyl, ethyl, butyl and pentyl.

[0009] Furthermore, the molar ratio of dicyanamide cobalt, transition metal dicyanamide salt and 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid in the reaction raw materials is 1:(0.25-1.5):(1-4).

[0010] Furthermore, the pyrolysis carbonization is carried out in a tubular muffle furnace, the pyrolysis temperature is 600-1000°C, the time is 2-6h, and the heating rate during pyrolysis is 4-6°C / min.

[0011] Furthermore, after mixing and reacting, the reaction raw materials need to be vacuum dried to obtain a dicyanamide-containing bimetallic ion liquid precursor.

[0012] Furthermore, after pyrolysis and carbonization, the obtained reaction product needs to be acid-washed, water-washed, centrifuged and dried to obtain a pure nitrogen-doped carbon-supported bimetallic catalyst; The pickling agent is dilute hydrochloric acid or sulfuric acid, the water washing needs to be performed 2-4 times, and the drying is performed in a vacuum environment at a temperature of 60-80°C for 5-14 hours.

[0013] In a second aspect, a nitrogen-doped carbon-supported bimetallic catalyst.

[0014] Thirdly, the application of nitrogen-doped carbon-supported bimetallic catalysts in the synthesis of 3-thioindole compounds with CS bonds.

[0015] In a fourth aspect, a method for synthesizing a 3-thioindole compound having a CS bond is provided, wherein a thiol compound and an indole compound are used as reaction raw materials, at least one of air and oxygen is used as an oxidant, and under the catalytic action of a nitrogen-doped carbon-supported bimetallic catalyst, the uniformly mixed reaction system is placed in an environment with an oxidant pressure of 0.1-1.0 MPa and a temperature of 20-100°C for reaction for 0.5-18 hours, thereby obtaining a 3-thioindole compound having a CS bond.

[0016] Furthermore, the thiol compound is any one of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole and thiophenol; the indole compound is any one of 1-methylindole, 5-bromoindole and 2-phenylindole; the molar ratio between the indole compound and the thiol compound in the reaction raw materials is 1:(0.5-4); the added amount of the nitrogen-doped carbon-supported bimetallic catalyst is 0.5-10 mol% of the thiol compound.

[0017] Furthermore, the molar ratio between the indole compound and the thiol compound in the reaction raw material is 1:(1-2); the addition amount of the nitrogen-doped carbon-supported bimetallic catalyst is 1-8 mol% of the thiol compound; the oxidant pressure is 0.1-0.3 MPa, and the temperature is 40-90°C.

[0018] Furthermore, after the reaction is completed, the heating needs to be stopped, and after the reaction system is cooled to room temperature, the gas in the reaction container is evacuated, and the materials in the reaction container are separated into solid and liquid. The obtained solid is the recovered nitrogen-doped carbon-supported bimetallic catalyst, which is washed and dried for repeated use. The obtained liquid is decompressed to remove low-boiling impurities, recrystallized or purified by column chromatography to obtain a finished product 3-thioindole compound with a CS bond.

[0019] Compared with the prior art, the present invention has the following advantages: (1) In the preparation process of the nitrogen-doped carbon-supported bimetallic catalyst, the present invention uses 1-alkyl-3-methylimidazole dicyandiamide salt ionic liquid to prepare the precursor, compared with the conventional impregnation method and hydrothermal synthesis method in the prior art. The method is simple to operate, has a short preparation cycle, and saves costs; and the prepared precursor has stable chemical properties.

[0020] (2) The nitrogen-doped carbon-supported bimetallic catalyst prepared by the present invention has a small particle size, a distinct mesoporous structure, and a uniform dispersion of metal active components on the surface, high catalyst activity, and good stability. After being used in the synthesis method, the reaction efficiency of the CS bond oxidative coupling can be effectively improved, the reaction time can be shortened, and the production efficiency can be improved.

[0021] (3) In the present invention, air or oxygen is used as an oxidant in the synthesis of 3-thioindole compounds having a C-S bond using a nitrogen-doped carbon-supported bimetallic catalyst, which can overcome the current disadvantage of requiring the use of an organic peroxide oxidant, save costs, and reduce the difficulty of post-processing of the product.

[0022] (4) In the synthesis process of the 3-thioindole compound having a C-S bond, the catalyst recovery is simple, and the catalyst can be repeatedly used after simple filtration, washing and drying, and has excellent catalytic activity. No additional reaction aid is required in the reaction system of the synthesis method, the catalytic efficiency is high, the conditions are mild, the separation is easy, the post-treatment and product purification are simple, the substrate has a wide range of application, the product purity is high, and it has significant industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 TEM image of the nitrogen-doped carbon-supported bimetallic catalyst prepared in Example 1 of the present invention; Figure 2This is a nitrogen isothermal adsorption-desorption curve of the nitrogen-doped carbon-supported bimetallic catalyst prepared in Example 1 of the present invention; Figure 3 This is a pore size distribution diagram of the nitrogen-doped carbon-supported bimetallic catalyst prepared in Example 1 of the present invention; Figure 4 The NMR spectrum of 5-bromo-3-((4-methoxyphenyl)thio)indole synthesized in Example 1 of the present invention; Figure 5 This is the NMR spectrum of 3-((3-methylphenyl)thio)indole synthesized in Example 15 of the present invention. DETAILED DESCRIPTION

[0024] In order to more clearly understand the above-mentioned purposes, features and advantages of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical scheme of the present invention, and detailed implementation methods and specific operating procedures are given. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the following embodiments.

[0025] In view of the shortcomings of the current preparation methods of 3-thioindole compounds, the inventors of the present application have proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, implementation process, etc. are now further explained.

[0026] The technical solution includes two parts: 1. Preparation of nitrogen-doped carbon-supported bimetallic catalyst using dicyanamide-containing bimetallic ion liquid precursor; 2. Application of nitrogen-doped carbon-supported bimetallic catalyst in organic CS bond synthesis.

[0027] 1. Preparation of nitrogen-doped carbon-supported bimetallic catalyst using dicyanamide-containing bimetallic ion liquid precursor: Cobalt dicyanamide and other metal dicyanamide salts are prepared using sodium dicyanamide as a raw material by an ion exchange method. In the ion exchange method, the metal salt that performs ion exchange with sodium dicyanamide is usually nitrate; the molar ratio of the metal salt to sodium dicyanamide is 1:2, and the solvent used includes one of water, methanol, ethanol, acetone, and N,N-dimethylformamide; then, cobalt dicyanamide and another metal dicyanamide salt are mixed with 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid in a certain amount to obtain a dicyanamide-containing bimetallic ionic liquid precursor, and the precursor is pyrolyzed and carbonized to obtain a nitrogen-doped carbon-supported bimetallic catalyst; the metal center form of the finally prepared nitrogen-doped carbon-supported bimetallic catalyst includes nitrogen-doped graphitic carbon-coated metal single atoms, metal nanoparticles, metal oxides, bimetallic alloy nanoparticles, etc.

[0028] The metal types in the metal dicyanamide salt are mainly transition metals, including Zn, Cu, Fe, Mn and Ni.

[0029] The molar ratio of the dicyanamide cobalt, another metal dicyanamide salt, and the 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid is 1:(0.25-1.5):(1-4).

[0030] The alkyl group in the 1-alkyl-3-methylimidazole dicyandiamide salt ionic liquid is methyl, ethyl, butyl, pentyl and the like.

[0031] The pyrolysis carbonization is to put the catalyst precursor into a tubular muffle furnace for calcination, the pyrolysis temperature range is 600°C-1000°C, the pyrolysis time is 2-6h; inert gas is used for protection to obtain a nitrogen-doped carbon-loaded bimetallic catalyst.

[0032] As a further optimization of the above scheme, the obtained catalyst is used as a reaction catalyst after being acid-washed, water-washed, centrifuged and dried; the washing process is not necessary; the acid-washing is dilute hydrochloric acid or sulfuric acid; the water-washing, centrifugation and drying are to wash the acid-washed catalyst with water 2-4 times, place it in a centrifuge tube for centrifugation, and then dry it in a vacuum drying oven at a temperature range of 60°C-80°C for 5-14 hours.

[0033] 2. Application of nitrogen-doped carbon-supported bimetallic catalysts in organic CS bond synthesis:

[0034] Taking a thiol compound and an indole compound as reaction raw materials, taking at least one of air and oxygen as an oxidant, placing a uniformly mixed reaction system in an environment with an oxidant pressure of 0.1-1.0 MPa and a temperature of 20-100° C. for reaction for 0.5-18 hours under the catalytic action of a nitrogen-doped carbon-supported bimetallic catalyst, a 3-thioindole compound with a CS bond can be prepared.

[0035] The mercapto compound is any one of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole and thiophenol.

[0036] The indole compound is any one of 1-methylindole, 5-bromoindole and 2-phenylindole.

[0037] The molar ratio of the indole compound to the thiol compound in the reaction raw materials is 1:(0.5-4); the more preferred ratio is 1:(1-2).

[0038] The addition amount of the nitrogen-doped carbon-supported bimetallic catalyst is 0.5-10 mol %, preferably 1-8 mol % of the mercapto compound.

[0039] The reaction conditions are preferably: oxygen / air pressure of 0.1-0.3 MPa, temperature of 40-90° C., and reaction time of 1-4 h.

[0040] The above-mentioned 3-thioindole compound having a CS bond also includes the following post-treatment process: after the reaction is completed, the heating is stopped, and after the temperature of the reaction system drops to room temperature, the power is turned off and the drain valve is opened to discharge excess gas, and then the reactor is opened; the catalyst and the reaction liquid are separated by filtration, the catalyst is washed, and low-boiling point substances are removed under reduced pressure to obtain a crude product, which is then purified by recrystallization or column chromatography to obtain a further purified product; after the catalyst is washed and dried, it can be directly added to the reaction system again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped transition metal carbon catalyst.

[0041] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention.

[0042] Example 1: Preparation of 5-bromo-3-((4-methoxyphenyl)thio)indole

[0043] (1) 1.9094 g of cobalt dicyanamide, 1.9748 g of zinc dicyanamide and 7.0884 g of 1-ethyl-3-methylimidazole dicyanamide salt were placed in a flask and heated and mixed thoroughly. The resulting mixture was placed in a vacuum drying oven at 65° C. and dried for 10 hours to obtain a catalyst precursor.

[0044] (2) The catalyst precursor was placed in a tubular muffle furnace, filled with nitrogen for protection, and the pyrolysis temperature was set to 920°C. The temperature was raised to 920°C at a rate of 5°C / min, maintained for 3 hours, and then cooled to room temperature. The obtained reaction product was acid-washed with dilute hydrochloric acid, then washed with water 3 times, centrifuged, and dried in a vacuum environment at 70°C for 10 hours to obtain a pure nitrogen-doped carbon-supported bimetallic catalyst.

[0045] (3) Add 1.0 mmol of 5-bromoindole and 2.0 mmol of p-methoxythiophenol into the reaction kettle. The nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step with 1 mol% of thiol compound added was evacuated and filled with 0.30 MPa of oxygen, and magnetically stirred at 80° C. for 17 h.

[0046] (4) After the reaction is completed, the heating is stopped. After the temperature of the reaction system drops to room temperature, the power is turned off and the drain valve is opened to discharge excess gas, and then the reactor is opened; the catalyst and the reaction liquid are separated by filtration, the catalyst is washed, the organic phase is collected, and the low-boiling substances are removed under reduced pressure to obtain a crude product, which is purified by column chromatography to obtain the target product. The yield is 94%, and the purity of the product according to gas chromatography analysis is 99%. After the catalyst is washed and dried, it can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0047] Characterization analysis:

[0048] Figure 1 This is a TEM image of the nitrogen-doped carbon-supported bimetallic catalyst prepared in this example. From this TEM image, it can be seen that cobalt nanoparticles coated with nitrogen-doped graphitic carbon are attached to the inside of the nitrogen-doped carbon nanotubes, and the average particle size of the cobalt nanoparticles is 29 nm.

[0049] Figure 2 is the nitrogen isothermal adsorption-desorption curve of the nitrogen-doped carbon-supported bimetallic catalyst prepared in this example, Figure 2 It can be seen that the adsorption curve and the desorption curve form a closed hysteresis loop, which conforms to the type IV curve, indicating that the prepared catalyst Co-Zn / (1:1) -920 carbon material is a mesoporous material.

[0050] Figure 3 is the pore size distribution diagram of the nitrogen-doped carbon-supported bimetallic catalyst prepared in this embodiment of the present invention, Figure 3 It can be seen that the prepared catalyst Co-Zn / (1:1) -920 carbon material has a specific surface area of ​​144.9m 2 / g, and the pore size is 6.7nm, which proves that the Co-Zn-920 carbon material is a mesoporous carbon material.

[0051] Figure 4 The NMR spectrum of 5-bromo-3-((4-methoxyphenyl)thio)indole synthesized in this example. After testing, the NMR data obtained in this example are: 1 H NMR(400MHz,Chloroform-d)δ8.42(s,1H),7.78(d,J=2.0Hz,1H),7.45(d,J=2.6Hz,1H),7.33(d d,J=8.6,1.9Hz,1H),7.28(d,J=5.1Hz,1H),7.17-7.09(m,2H),6.80-6.73(m,2H),3.75(s,3H). 13C NMR (101MHz, Chloroform-d) δ158.1,135.2,133.0,132.8,131.3,131.0,129.1,128.9,126.1,122.3,116.2,114.8,114.7,114.4,113.1,104.7,55.5.

[0052] Example 2: Preparation of 6-methyl-3-((4-methoxyphenyl)thio)indole

[0053] (1) 1.9094 g of cobalt dicyanamide, 1.9094 g of nickel dicyanamide and 7.0884 g of 1-ethyl-3-methylimidazole dicyanamide salt were placed in a flask and heated and mixed thoroughly. The resulting mixture was placed in a vacuum drying oven at 85° C. and dried for 12 hours to obtain a catalyst precursor.

[0054] (2) The precursor was placed in a tubular muffle furnace, filled with nitrogen for protection, and the pyrolysis temperature was set to 900°C. The temperature was raised to 900°C at a rate of 5°C / min, maintained for 4 hours, and then cooled to room temperature. The obtained reaction product was acid-washed with dilute hydrochloric acid, then washed with water 4 times, centrifuged, and dried in a vacuum environment at 60°C for 14 hours to obtain a pure nitrogen-doped carbon-supported bimetallic catalyst.

[0055] (3) Add 1.0 mmol of 6-methylindole and 2.0 mmol of p-methoxythiophenol into a reaction kettle, and add 3 mol% of the thiol compound to the nitrogen-doped carbon-supported cobalt-nickel bimetallic catalyst prepared in the above step. Vacuum the reaction kettle, fill it with 0.20 MPa of oxygen, and stir it magnetically at 70° C. for 10 h.

[0056] (4) After the reaction is completed, the heating is stopped. After the temperature of the reaction system drops to room temperature, the power is turned off and the drain valve is opened to discharge excess gas, and then the reactor is opened; the catalyst and the reaction liquid are separated by filtration, the catalyst is washed, the organic phase is collected, and the low-boiling substances are removed under reduced pressure to obtain a crude product, which is purified by column chromatography to obtain the target product. The yield is 68%, and the purity of the product according to gas chromatography analysis is 99%. After the catalyst is washed and dried, it can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0057] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1H NMR(400MHz,Chloroform-d)δ8.23(s,1H),7.51(d,J=8.0Hz,1H),7.37(d,J=2.6Hz,1H),7. 22-7.10(m,3H),7.00(dd,J=8.1,1.4Hz,1H),6.81-6.71(m,2H),3.73(s,3H),2.47(s,3H). 13 C NMR (101MHz, Chloroform-d) δ157.8,137.0,133.0,129.8,129.6,128.5,126.9,122.7,119.4,114.6,111.6,104.3,55.4,21.8.

[0058] Example 3: Preparation of 2-methyl-3-((4-methoxyphenyl)thio)indole

[0059] (1) 1.9094 g of cobalt dicyanamide, 1.9565 g of copper dicyanamide and 7.0884 g of 1-ethyl-3-methylimidazole dicyanamide salt were placed in a flask and heated and mixed thoroughly. The resulting mixture was placed in a vacuum drying oven at 75° C. and dried for 14 hours to obtain a catalyst precursor.

[0060] (2) The precursor was placed in a tubular muffle furnace, filled with nitrogen for protection, and the pyrolysis temperature was set to 700°C. The temperature was raised to 700°C at a rate of 5°C / min, maintained for 3 h, and then cooled to room temperature. The obtained reaction product was acid-washed with sulfuric acid, then washed with water twice, centrifuged, and dried in a vacuum environment at 80°C for 5 h to obtain a pure nitrogen-doped carbon-supported bimetallic catalyst.

[0061] (3) Add 1.0 mmol of 2-methylindole and 1.00 mmol of p-methoxythiophenol into the reaction kettle. The nitrogen-doped carbon-supported cobalt-copper bimetallic catalyst prepared in the above step with 4 mol% of the thiol compound added was evacuated and filled with 0.50 MPa of oxygen, and magnetically stirred at 70° C. for 15 h.

[0062] (4) After the reaction is completed, the heating is stopped. After the temperature of the reaction system drops to room temperature, the power is turned off and the drain valve is opened to discharge excess gas, and then the reactor is opened; the catalyst and the reaction liquid are separated by filtration, the catalyst is washed, the organic phase is collected, and the low-boiling substances are removed under reduced pressure to obtain a crude product, which is purified by column chromatography to obtain the target product. The yield is 90%, and the purity of the product according to gas chromatography analysis is 99%. After the catalyst is washed and dried, it can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0063] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.26(s,1H),7.58(dd,J=7.7,1.3Hz,1H),7.32(dt,J=8.1,1.0Hz,1H),7. 15(dddd,J=21.6,8.1,7.1,1.2Hz,2H),7.08-7.01(m,2H),6.76-6.69(m,2H),3.73(s,3H),2.52(s,3H). 13 C NMR (101MHz, Chloroform-d) δ157.6,140.8,135.5,130.4,130.0,128.0,122.2,120.7,119.1,114.6,110.7,100.9,55.5,12.3.

[0064] Example 4: Preparation of 5-chloro-3-((4-methoxyphenyl)thio)indole

[0065] The preparation method of the catalyst used in this example is the same as that in Example 1.

[0066] Add 1.0mmol of 5-chloroindole and 1.2mmol of p-methoxythiophenol, 1mol% of the thiol compound added to the nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step into the reactor, evacuate and fill with 0.30MPa of oxygen, and stir magnetically at 80°C for 12h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reactor; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 74%, and the purity of the product by gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0067] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.47(s,1H),7.60(d,J=2.0Hz,1H),7.47(t,J=2.6Hz,1H),7.31(dd, J=8.6,2.1Hz,1H),7.19(dd,J=8.6,2.0Hz,1H),7.16-7.08(m,2H),6.79-6.72(m,2H),3.74(s,3H). 13C NMR (101MHz, Chloroform-d) δ158.1,134.9,131.5,130.4,129.1,128.9,126.9,123.5,119.2,119.2,114.7,112.7,112.7,104.8,55.5.

[0068] Example 5: Preparation of 5-methoxy-3-((4-methoxyphenyl)thio)indole

[0069] The preparation method of the catalyst used in this example is the same as that in Example 1.

[0070] Add 1.0 mmol of 5-methoxyindole and 2.00 mmol of p-methoxybenzenethiol to the reaction kettle. The nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step with an addition amount of 8 mol% of the thiol compound is evacuated and filled with 0.60 MPa of oxygen, and magnetically stirred at 90°C for 18 hours. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reaction kettle; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 84%, and the purity of the product according to gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0071] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.47(d,J=3.9Hz,1H),7.38(d,J=2.7Hz,1H),7.26(d,J=8.8Hz,1H ),7.17-7.09(m,3H),6.92(dd,J=8.8,2.5Hz,1H),6.79-6.73(m,2H),3.81(s,3H),3.74(s,3H). 13 C NMR (101MHz, Chloroform-d) δ157.7,154.9,131.5,131.1,129.8,128.2,114.6,114.0,113.3,112.6,103.4,55.8,55.4.

[0072] Example 6: Preparation of 5-fluoro-3-((4-methoxyphenyl)thio)indole

[0073] The preparation method of the catalyst used in this example is the same as that in Example 2.

[0074] Add 1.0 mmol of 5-fluoroindole and 3.0 mmol of p-methoxybenzenethiol to the reaction kettle. The nitrogen-doped carbon-supported cobalt-nickel bimetallic catalyst prepared in the above step with 4 mol% of the thiol compound added is evacuated and filled with 0.30 MPa of oxygen, and magnetically stirred at 60°C for 18 hours. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reaction kettle; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 75%, and the purity of the product according to gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0075] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR (400MHz, Chloroform-d) δ8.46 (s, 1H), 7.49 (d, J = 2.7Hz, 1H), 7.35-7.27 (m, 2H ),7.16-7.09(m,2H),6.98(td,J=9.0,2.5Hz,1H),6.79-6.72(m,2H),3.74(s,3H). 13 C NMR (101MHz, Chloroform-d) δ159.6,157.8,157.3,132.8,131.6,129.8,129.7,128.9,114.5,112.3,111.5,111.3,104.8,55.3.

[0076] Example 7: Preparation of 2-phenyl-3-((4-methoxyphenyl)thio)indole

[0077] The preparation method of the catalyst used in this example is the same as that in Example 2.

[0078] Add 1.0mmol of 2-phenylindole and 1.2mmol of p-methoxybenzenethiol to the reaction kettle. The nitrogen-doped carbon-supported cobalt-nickel bimetallic catalyst prepared in the above step with 6mol% of the thiol compound added is evacuated and filled with 0.30MPa of oxygen, and magnetically stirred at 80°C for 17h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reaction kettle; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 92%, and the purity of the product according to gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0079] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.54(s,1H),7.83-7.75(m,2H),7.66(dt,J=7.9,1.0Hz,1H) ,7.51-7.35(m,5H),7.21-7.13(m,1H),7.11-7.04(m,2H),6.76-6.69(m,2H),3.72(s,3H). 13 C NMR (101MHz, Chloroform-d) δ157.7,141.7,135.9,132.8,131.7,131.3,129.9,128.9,128.8,128.3,127.9,123.4,121.2,120.1,114.7,111.2,55.4.

[0080] Example 8: Preparation of 5-methyl-3-((4-methoxyphenyl)thio)indole

[0081] The preparation method of the catalyst used in this example is the same as that in Example 2.

[0082] Add 1.0mmol of 5-methylindole and 2.0mmol of p-methoxybenzenethiol to the reaction kettle. The nitrogen-doped carbon-supported cobalt-nickel bimetallic catalyst prepared in the above step with 7mol% of the thiol compound added is evacuated and filled with 0.50MPa of oxygen, and magnetically stirred at 50°C for 16h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reaction kettle; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 75%, and the purity of the product according to gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0083] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR (400MHz, Chloroform-d) δ8.30(s,1H),7.43(d,J=2.7Hz,2H),7.31(d,J=8.4Hz,1H),7.15-7.04(m,3H),6.80-6.68(m,2H),3.73(s,3H),2.42(s,3H). 13 C NMR (101MHz, Chloroform-d) δ157.8,134.9,130.4,130.4,130.0,129.5,128.3,124.8,119.3,114.6,111.3,103.9,55.5,21.6.

[0084] Example 9: Preparation of 1-methyl-2-phenyl-3-((4-methoxyphenyl)thio)indole

[0085] The preparation method of the catalyst used in this example is the same as that in Example 3.

[0086] Add 1.0mmol of 1-methyl-2-phenylindole and 1.6mmol of p-methoxybenzenethiol into the reaction kettle. The nitrogen-doped carbon-supported cobalt-copper bimetallic catalyst prepared in the above step with 3mol% of the thiol compound added is evacuated and filled with 0.10MPa of oxygen, and magnetically stirred at 80°C for 15h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reaction kettle; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 90%, and the purity of the product according to gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0087] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.57(s,1H),7.83-7.75(m,2H),7.65(dq,J=7.9,1.0Hz,1H),7.54-7 .32(m,6H),7.17(ddd,J=8.0,7.1,1.0Hz,1H),7.12-7.02(m,2H),6.76-6.68(m,2H),3.72(s,4H). 13 C NMR(101MHz,Chloroform-d)δ157.7,141.7,138.5,135.9,131.3,130.1,129.9,128.9,128. 8,128.3,127.9,123.4,121.2,120.1,115.1,114.7,114.0,111.2,101.0,55.8,55.6,55.5.

[0088] Example 10: Preparation of 4-methoxy-3-((4-methoxyphenyl)thio)indole

[0089] The preparation method of the catalyst used in this example is the same as that in Example 2.

[0090] 1.0 mmol of 4-methoxyindole and 2.0 mmol of p-methoxybenzenethiol were added to the reaction kettle. The nitrogen-doped carbon-supported cobalt-nickel bimetallic catalyst prepared in the above step with 1 mol% of the thiol compound added was evacuated and filled with 0.10 MPa of oxygen, and magnetically stirred at 60°C for 17 hours. After the reaction was completed, the heating was stopped, and after the temperature of the reaction system dropped to room temperature, the power was turned off and the drain valve was opened to discharge excess gas, and then the reaction kettle was opened; the catalyst and the reaction liquid were separated by filtration, the catalyst was washed, the organic phase was collected, and the low-boiling substances were removed under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain the target product. The yield was 85%, and the purity of the product according to gas chromatography analysis was 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0091] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.32(s,1H),7.26-7.21(m,2H),7.17-7.09(m,2H),6. 98(d,J=8.1Hz,1H),6.81-6.72(m,2H),6.53(d,J=8.0Hz,1H),3.76(d,J=9.8Hz,6H). 13 C NMR (101MHz, Chloroform-d) δ158.0,154.7,138.5,130.6,129.9,128.2,123.9,118.4,115.1,114.4,114.0,104.9,101.3,55.6,55.4.

[0092] Example 11: Preparation of 5-cyano-3-((4-methoxyphenyl)thio)indole

[0093] The preparation method of the catalyst used in this example is the same as that in Example 1.

[0094] Add 1.0 mmol of 5-cyanoinole and 2.0 mmol of p-methoxybenzenethiol to the reaction kettle. The nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step with 6 mol% of the thiol compound added is evacuated and filled with 0.10 MPa of oxygen, and magnetically stirred at 55°C for 18 hours. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reaction kettle; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 90%, and the purity of the product according to gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0095] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.64(s,1H),7.98(dd,J=1.6,0.8Hz,1H),7.51-7.46(m,1H),7.45-7.37 (m,2H),7.32(dd,J=3.3,2.4Hz,1H),7.24(d,J=1.9Hz,1H),6.88-6.79(m,2H),3.83(d,J=15.7Hz,3H). 13 CNMR(101MHz,Chloroform-d)δ163.7,162.4,138.5,135.0,130.0,127.8,126.5,125.0,120.9,119.0,115.1,114.0,112.1,103.6,55.8,55.6.

[0096] Example 12: Preparation of 3-((2-bromophenyl)thio)indole

[0097] The preparation method of the catalyst used in this example is the same as that in Example 1.

[0098] Add 1.0mmol of indole and 2.0mmol of 2-bromobenzenethiol, 8mol% of the thiol compound added to the nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step into the reactor, evacuate and fill with 0.80MPa of oxygen, and stir magnetically at 100°C for 2.5h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reactor; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 82%, and the purity of the product is 99% according to gas chromatography analysis. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0099] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.51(s,1H),7.60(d,J=7.9Hz,1H),7.55-7.43(m,3H),7.30(t,J=7 .6Hz,1H),7.19(t,J=7.5Hz,1H),6.94(dtd,J=26.6,7.5,1.6Hz,2H),6.64(dd,J=7.9,1.7Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ140.6,136.7,132.7,131.4,129.0,127.6,126.5,125.8,123.4,121.3,119.8,119.7,111.9,102.1.

[0100] Example 13: Preparation of 3-((2-chlorophenyl)thio)indole

[0101] The preparation method of the catalyst used in this example is the same as that in Example 1.

[0102] Add 1.0mmol of indole and 1.0mmol of 2-chlorothiophenol, 4mol% of the thiol compound added to the nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step into the reactor, evacuate and fill with 0.40MPa of oxygen, and stir magnetically at 100°C for 3h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reactor; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 82%, and the purity of the product is 99% according to gas chromatography analysis. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0103] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR(400MHz,Chloroform-d)δ8.50(s,1H),7.61(dd,J=8.0,1.1Hz,1H),7.54-7.43(m,2H),7.31(ddd,J=16.2,8. 0,1.4Hz,2H),7.19(ddd,J=8.1,7.1,1.0Hz,1H),6.96(dtd,J=24.8,7.5,1.6Hz,2H),6.66(dd,J=7.9,1.7Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ138.6,136.7,131.4,130.2,129.4,129.1,127.0,126.5,125.5,123.4,121.3,119.7,111.9,101.3.

[0104] Example 14: Preparation of 3-((2-aminophenyl)thio)indole

[0105] The preparation method of the catalyst used in this example is the same as that in Example 3.

[0106] Add 1.0mmol of indole and 1.8mmol of 2-aminothiophenol, 2mol% of the thiol compound added to the nitrogen-doped carbon-supported cobalt-copper bimetallic catalyst prepared in the above step into the reactor, evacuate and fill with 0.10MPa of oxygen, and stir magnetically at 100°C for 5h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reactor; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 82%, and the purity of the product by gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0107] After testing, the nuclear magnetic resonance data obtained in this embodiment are: 1 H NMR (400MHz, DMSO-d6) δ11.49(s,1H),7.74(d,J=2.6Hz,1H),7.59-7.38(m,2H),7.14(ddd,J=8.2,7.0,1.3Hz,1H),7.09 -6.97(m,2H),6.90(ddd,J=8.6,7.2,1.6Hz,1H),6.66(dd,J=7.9,1.3Hz,1H),6.41(td,J=7.5,1.3Hz,1H),5.29(s,2H). 13 C NMR (101MHz, DMSO-d6) δ147.1,136.5,131.3,131.2,128.7,127.6,121.9,119.7,119.1,118.5,116.5,114.5,112.1,101.4.

[0108] Example 15: Preparation of 3-((3-methylphenyl)thio)indole

[0109] The preparation method of the catalyst used in this example is the same as that in Example 1.

[0110] Add 1.0mmol of indole and 2.0mmol of 3-methylthiophenol, 6mol% of the thiol compound added to the nitrogen-doped carbon-supported cobalt-zinc bimetallic catalyst prepared in the above step into the reactor, evacuate and fill with 0.10MPa of oxygen, and stir magnetically at 90°C for 5h. After the reaction is completed, stop heating, wait for the temperature of the reaction system to drop to room temperature, turn off the power and open the drain valve to exhaust excess gas, then open the reactor; filter to separate the catalyst and the reaction liquid, wash the catalyst, collect the organic phase, remove low-boiling substances under reduced pressure to obtain a crude product, and purify it by column chromatography to obtain the target product. The yield is 82%, and the purity of the product by gas chromatography analysis is 99%. After washing and drying, the catalyst can be directly added to step (3) again to catalyze the reactants for oxidative coupling reaction, thereby achieving the reuse of the nitrogen-doped carbon-supported bimetallic catalyst.

[0111] Figure 5 The NMR spectrum of 3-((3-methylphenyl)thio)indole synthesized in this example. After testing, the NMR data obtained in this example are: 1 H NMR(400MHz,Chloroform-d)δ8.31(s,1H),7.73-7.62(m,1H),7.47-7.39(m,2H),7.30(ddd,J=8.2,7 .0,1.2Hz,1H),7.21(ddd,J=8.0,7.0,1.0Hz,1H),7.12-7.01(m,2H),6.96-6.88(m,2H),2.26(s,3H). 13 C NMR (101MHz, Chloroform-d) δ139.4,138.9,136.9,131.1,129.6,129.0,126.9,126.2,123.4,123.4,121.3,120.1,112.0,103.2,21.8.

[0112] It should be noted that the above-described embodiments should be understood as illustrative rather than limiting the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims. For those skilled in the art, some non-essential improvements and adjustments made to the present invention still fall within the scope of protection of the present invention without departing from the essence and scope of the present invention.

Claims

1. A method for preparing a nitrogen-doped carbon-supported bimetallic catalyst, characterized in that: Cobalt dicyanamide, transition metal dicyanamide salt and 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid are taken as reaction raw materials for mixing and reacting to obtain a dicyanamide-containing bimetallic ionic liquid precursor. Under inert gas protection conditions, the obtained precursor is pyrolyzed and carbonized to obtain a nitrogen-doped carbon-loaded bimetallic catalyst.

2. The method for preparing a nitrogen-doped carbon-supported bimetallic catalyst according to claim 1, characterized in that: The transition metal in the transition metal dicyanamide salt is any one of Zn, Cu, Fe, Mn and Ni; the alkyl group in the 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid is any one of methyl, ethyl, butyl and pentyl.

3. The method for preparing a nitrogen-doped carbon-supported bimetallic catalyst according to claim 1, characterized in that: The molar ratio of dicyanamide cobalt, transition metal dicyanamide salt and 1-alkyl-3-methylimidazole dicyanamide salt ionic liquid in the reaction raw materials is 1: (0.25-1.5): (1-4); The pyrolysis carbonization is carried out in a tubular muffle furnace, the pyrolysis temperature is 600-1000°C, the time is 2-6 h, and the heating rate during pyrolysis is 4-6°C / min.

4. The method for preparing a nitrogen-doped carbon-supported bimetallic catalyst according to claim 1, characterized in that: After mixing, the reaction raw materials need to be vacuum dried to obtain a dicyanamide-containing bimetallic ionic liquid precursor; after pyrolysis and carbonization, the obtained reaction product needs to be acid washed, washed with water, centrifuged and dried to obtain a pure nitrogen-doped carbon-supported bimetallic catalyst; The pickling agent is dilute hydrochloric acid or sulfuric acid, the water washing needs to be performed 2-4 times, and the drying is performed in a vacuum environment at a temperature of 60-80°C for 5-14 hours.

5. A nitrogen-doped carbon-supported bimetallic catalyst prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the nitrogen-doped carbon-supported bimetallic catalyst according to claim 5 in the synthesis of 3-thioindole compounds having a C-S bond.

7. The method for using the nitrogen-doped carbon-supported bimetallic catalyst in the synthesis of 3-thioindole compounds having a C-S bond according to claim 6, characterized in that: Taking a thiol compound and an indole compound as reaction raw materials, taking at least one of air and oxygen as an oxidant, and placing a uniformly mixed reaction system in an environment with an oxidant pressure of 0.1-1.0 MPa and a temperature of 20-100° C. for reaction for 0.5-18 h under the catalytic action of a nitrogen-doped carbon-supported bimetallic catalyst, a 3-thioindole compound with a CS bond can be prepared.

8. The method for using the nitrogen-doped carbon-supported bimetallic catalyst in the synthesis of 3-thioindole compounds having a C-S bond according to claim 7, characterized in that: The thiol compound is any one of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole and thiophenol; the indole compound is any one of 1-methylindole, 5-bromoindole and 2-phenylindole; the molar ratio between the indole compound and the thiol compound in the reaction raw materials is 1:(0.5-4); the addition amount of the nitrogen-doped carbon-supported bimetallic catalyst is 0.5-10 mol% of the thiol compound.

9. The method for using the nitrogen-doped carbon-supported bimetallic catalyst in the synthesis of 3-thioindole compounds having a C-S bond according to claim 8, characterized in that: The molar ratio between the indole compound and the thiol compound in the reaction raw materials is 1:(1-2); the addition amount of the nitrogen-doped carbon-supported bimetallic catalyst is 1-8 mol% of the thiol compound; the oxidant pressure is 0.1-0.3 MPa, and the temperature is 40-90°C.

10. The method for using the nitrogen-doped carbon-supported bimetallic catalyst in the synthesis of 3-thioindole compounds having a C-S bond according to claim 7, characterized in that: After the reaction is completed, the heating needs to be stopped. After the reaction system is cooled to room temperature, the gas in the reaction container is evacuated, and the materials in the reaction container are separated into solid and liquid. The obtained solid is a nitrogen-doped carbon-supported bimetallic catalyst, which is used for repeated use after washing and drying. The obtained liquid is decompressed to remove low-boiling impurities, recrystallized or purified by column chromatography to obtain a finished product 3-thioindole compound with a CS bond.

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