A method for synthesizing a benzothienoquinoxaline compound

Abstract

The application provides a method for synthesizing a benzothienoquinoxaline compound, and belongs to the technical field of fine chemical synthesis. H The quinoxaline-2(1 The benzothienoquinoxaline compound is synthesized by mixing quinoxaline-2(1 The method has the advantages of no transition metal catalysis, wide substrate range, cheap and easily available fluorine source and additive, simple operation, no environmental pollution in the synthesis process and the like. The yield of the benzothienoquinoxaline compound synthesized by the method can reach 99%, and the synthesis can be scaled up to a kilogram level, so that the method has extremely high industrial popularization value.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis technology, specifically relating to a method for synthesizing benzothiophene-quinoxaline compounds. Background Technology

[0002] Quinoxaline is a class of nitrogen-containing heterocyclic structural units and a core structure in many bioactive molecules. It possesses a unique electronic structure and aromaticity, and molecules with this structure exhibit a variety of biological activities, including antibacterial, anti-inflammatory, anticancer, and antiviral activity, making quinoxaline a popular target in drug development. Furthermore, the quinoxaline skeleton also holds significant value in functional optoelectronic materials such as semiconductors, OLEDs, and organic photovoltaics. Benzothiophene-quinoxaline is a class of highly fused polycyclic aromatic hydrocarbons with great application potential in functional materials and biological fields.

[0003] In existing technologies, benzothiophenequinoxaline is used as the parent nucleus as the electron-deficient fragment for molecular electron transport, combined with molecules such as carbazole, fluorene, and triarylamines as electron-donating side chains to prepare the main body of the emitting layer of red phosphorescent OLEDs. Existing technologies also disclose the preparation of an organic electroluminescent material, the main compound of which is an HL-Ar three-segment donor-acceptor (DA) structure, where the Ar segment can be a benzothiophenequinoxaline-like compound, serving as the core unit for electron transport. However, current research mainly focuses on indolequinoxaline, while reports on the synthesis of thiophenequinoxaline and furanoquinoxaline are relatively few. Therefore, developing synthetic methods for these compounds is of significant research importance.

[0004] Existing techniques utilize aryl isothiocyanates and diazonium salts of 2-cyanoaryltetrafluoroborate as reaction substrates to synthesize benzo[4,5]thieno[2,3-b]quinoxaline via a one-pot radical tandem [3+2] cyclization method. This is a rare radical [3+2] cyclization synthesis method, but it suffers from problems such as poor stability of diazonium tetrafluoroborates, demanding operation, and poor atom economy. In contrast, benzo[4,5]thieno[2,3-b]quinoxaline was synthesized using 2,2'-dicyanodiphenyl disulfide as a sulfur radical precursor and aryl isonitriles as cyclization substrates. This method exhibits excellent regioselectivity, but the reaction is dependent on a high-pressure ultraviolet mercury lamp, making it suitable only for small-scale laboratory experiments; scale-up experiments suffer from low conversion rates. In summary, current synthetic methods for benzothiophenequinoxaline compounds suffer from problems such as poor raw material stability, harsh reaction conditions, cumbersome synthetic routes, and low yields. Developing a synthetic method for benzothiophenequinoxaline compounds that is high-yield, environmentally friendly, uses readily available raw materials, and is easy to operate remains of great significance. Summary of the Invention

[0005] To address some shortcomings in existing technologies, this invention provides a method for synthesizing benzothiophene-quinoxaline compounds. This invention involves mixing quinoxaline-2(1H)-thionone compounds, fluorides, additives, and tetrahydrofuran, then adding a benzoyne precursor to synthesize benzothiophene-quinoxaline compounds at room temperature. This method offers advantages such as no need for transition metal catalysis, a broad substrate range, readily available and inexpensive fluorine sources and additives, simple operation, and no environmental pollution during synthesis. The yield of benzothiophene-quinoxaline compounds synthesized by this method can reach up to 99%, and it can be scaled up to gram-scale, possessing extremely high industrial application value.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] This invention first provides a method for synthesizing benzothiophene-quinoxaline compounds, the method comprising:

[0008] Quinoxaline-2(1H)-thione compounds, fluorine sources, and additives were mixed and dissolved in a solvent. Then, Kobayashi benzoyne precursor was added to the solvent to carry out a [3+2] cycloaddition reaction. After the reaction was completed, the solvent was evaporated and the benzothiophene-quinoxaline compounds were obtained.

[0009] Preferably, the quinoxaline-2(1H)-thione compound comprises the following structural formula: Quinoxaline-2(1H)-thiones;

[0010] In the formula, R 1 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group;

[0011] In the formula, R 2 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group.

[0012] Preferably, the fluorine source includes one or more of potassium fluoride, cesium fluoride, tetra-n-butylammonium difluorotriphenylsilicate, and tetrabutylammonium fluoride;

[0013] The additive includes 18-crown-6;

[0014] The solvent includes one or more of tetrahydrofuran, ethylene glycol dimethyl ether, dichloromethane, acetonitrile, and toluene.

[0015] Preferably, the Kobayashi benzylene precursor comprises the structural formula: Benzyne precursor;

[0016] In the formula, R 3Including any one of hydrogen-based, 4,5-phenyl, 4,5-difluoro, 4,5-methoxy, 3-methoxy, 4-methoxy, 3-fluoro, 3-methyl, 4-methyl, 4-chloro, and [1,3]dioxacyclopenten-5-yl.

[0017] Preferably, the ratio of the quinoxaline-2(1H)-thione compound, fluoride, additive, and solvent is 0.2 mmol: 0.6 mmol: 0.6 mmol: 2.0 mL.

[0018] Preferably, the molar ratio of the quinoxaline-2(1H)-thione compound to the benzylene precursor is 1:1.1~2.0.

[0019] Preferably, the [3+2] cycloaddition reaction is carried out under air conditions at room temperature for 12-13 hours.

[0020] Preferably, the general structural formula of the benzothiophene-quinoxaline compound is:

[0021] ;

[0022] In the formula, R 1 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group;

[0023] In the formula, R 2 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group;

[0024] In the formula, R 3 Including any one of hydrogen-based, 4,5-phenyl, 4,5-difluoro, 4,5-methoxy, 3-methoxy, 4-methoxy, 3-fluoro, 3-methyl, 4-methyl, 4-chloro, and [1,3]dioxacyclopenten-5-yl.

[0025] The present invention also provides benzothiophene-quinoxaline compounds synthesized by the above method.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention involves mixing a quinoxaline-2(1H)-thione compound, cesium fluoride, 18-crown-6, and tetrahydrofuran, adding a Kobayashi benzoyne precursor, and synthesizing the benzothiophene-quinoxaline compound in a single step at 25°C. During the [3+2] cycloaddition reaction described in this invention, the cavity of the additive 18-crown-6 complexes the Cs of cesium fluoride. + weaken Electrostatic binding of ions generates desolvated free fluoride ions. These fluoride ions act as nucleophiles attacking silicon and simultaneously drive a basic elimination to form benzyne: the fluoride ion attacks the silicon atom of the ortho-trimethylsilyl group in the benzyne precursor, forming a strong fluorine-silicon bond. The carbon-silicon bond breaks to form an ortho-aromatic carbanion with an OTf leaving group, followed by intramolecular 1,2-elimination, where the strong OTf leaving group departs to form the reactive benzyne intermediate. Excess free fluoride ions act as a base, removing the NH proton from quinoxaline-2(1H)-thione to generate a nucleophilic thiolate anion. This thiolate anion nucleophilically attacks the accumulated double bonds of the highly reactive benzyne intermediate, forming a carbon-sulfur bond and simultaneously generating an anionic species. This anion attacks the electron-deficient C=N imine bond on the quinoxaline ring, undergoing intramolecular addition to ultimately form the benzothiophene-quinoxaline compound.

[0028] This invention is the first to propose the preparation of benzothiophene-quinoxaline compounds using benzoyne and quinoxaline-2(1H)-thiones. The synthetic method described in this invention has advantages such as being simple and rapid, requiring no transition metal catalysis, having a broad substrate range, using inexpensive and readily available fluorine sources, having some of the raw materials commercially available, and being able to be prepared using simple methods with o-phenylenediamine and ethyl glyoxylate reagents, and causing no environmental pollution.

[0029] The synthesis method described in this invention is simple and widely applicable. The yield of benzothiophenequinoxaline compounds obtained by this method can reach up to 99%, which has extremely high industrial application value. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions in the art, or according to the product instructions. Reagents and raw materials in the following embodiments that do not specify specific components can be prepared by conventional methods or are commercially available.

[0031] Example 1:

[0032] In this embodiment, benzo[4,5]thieno[2,3-b]quinoxaline was prepared using quinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0033] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir at room temperature for 5 minutes until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir and react at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure and separate by column chromatography to obtain benzo[4,5]thieno[2,3-b]quinoxaline.

[0034] The benzo[4,5]thieno[2,3-b]quinoxaline was a white solid with a yield of 46.7 mg and a yield of 99%. The prepared benzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the characterization results were as follows:

[0035] 1 H NMR (400 MHz, CDCl3) δ 8.61 – 8.54 (m, 1H), 8.31 – 8.24 (m, 1H), 8.19 – 8.12 (m, 1H), 7.89 – 7.85 (m, 1H), 7.84 – 7.78 (m, 2H), 7.66 (td, J =7.6, 1.4 Hz, 1H), 7.58 (td, J = 7.5, 1.1 Hz, 1H).

[0036] 13 C NMR (100 MHz, CDCl3) δ 157.3, 147.8, 141.4, 140.5, 140.0, 131.4, 131.0, 129.8, 129.6, 129.1, 128.3, 125.8, 124.4, 123.6.

[0037] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The benzo[4,5]thieno[2,3-b]quinoxaline shown.

[0038] Example 2:

[0039] In this embodiment, 8,9-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline was prepared using 6,7-dimethylquinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0040] Accurately weigh 0.2 mmol of 6,7-dimethylquinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate, a precursor of benzoyne, dropwise. Stir and react at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure and separate by column chromatography to obtain 8,9-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline.

[0041] The 8,9-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 47.5 mg, representing a yield of 90%. The prepared 8,9-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0042] 1 H NMR (400 MHz, CDCl3) δ 8.60 – 8.51 (m, 1H), 8.03 (s, 1H), 7.92 –7.83 (m, 2H), 7.64 (td, J = 7.6, 1.5 Hz, 1H), 7.57 (td, J = 7.5, 1.1 Hz, 1H),2.55 (s, 6H).

[0043] 13 C NMR (100 MHz, CDCl3) δ 156.4, 146.9, 140.6, 140.5, 139.7, 139.5,131.8, 130.5, 128.5, 127.4, 125.6, 124.0, 123.5, 20.5, 20.4.

[0044] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 8,9-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0045] Example 3:

[0046] In this embodiment, 8,9-difluorobenzo[4,5]thieno[2,3-b]quinoxaline was prepared using 6,7-difluoroquinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0047] Accurately weigh 0.2 mmol of 6,7-difluoroquinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe and stir at room temperature for 5 minutes. After the added substances are completely dissolved, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate, a precursor of benzoyne, dropwise. Stir and react at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure and separate by column chromatography to obtain 8,9-difluorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0048] The 8,9-difluorobenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 41.0 mg, representing a yield of 74%. The prepared 8,9-difluorobenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0049] 1 H NMR (400 MHz, CDCl3) δ 8.58 – 8.52 (m, 1H), 8.02 (dd, J = 10.6, 8.2Hz, 1H), 7.94 – 7.86 (m, 2H), 7.70 (td, J = 7.7, 1.4 Hz, 1H), 7.61 (td, J =7.5, 1.1 Hz, 1H).

[0050] 13 C NMR (100 MHz, CDCl3) δ 156.6, 138.8, 130.3, 130.0, 124.9, 123.4,122.6, 113.9 (d, J = 18.0 Hz), 112.9 (d, J = 19.0 Hz)

[0051] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 8,9-difluorobenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0052] Example 4:

[0053] In this embodiment, 8,9-dichlorobenzo[4,5]thieno[2,3-b]quinoxaline was prepared using 6,7-dichloroquinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0054] Accurately weigh 0.2 mmol of 6,7-dichloroquinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate, a precursor of benzoyne, dropwise. Stir and react at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure and separate by column chromatography to obtain 8,9-dichlorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0055] The 8,9-dichlorobenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 55.3 mg, representing a yield of 91%. The prepared 8,9-dichlorobenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0056] 1 H NMR (400 MHz, CDCl3) δ 8.57 – 8.54 (m, 1H), 8.40 (s, 1H), 8.28 (s,1H), 7.90 – 7.87 (m, 1H), 7.71 (td, J = 7.6, 1.3 Hz, 1H), 7.61 (td, J = 7.5,1.1 Hz, 1H).

[0057] 13 C NMR (100 MHz, CDCl3) δ 148.7, 140.2, 139.9, 139.2, 134.2, 133.5,131.6, 130.9, 130.0, 128.9, 126.1, 124.7, 123.7.

[0058] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The figure shown is 8,9-dichlorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0059] Example 5:

[0060] In this embodiment, 8,9-bis(3-fluorophenyl)quinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate were used to prepare 8,9-bis(3-fluorophenyl)benzo[4,5]thieno[2,3-b]quinoxaline. The specific steps are as follows:

[0061] Accurately weigh 0.2 mmol of 6,7-bis(3-fluorophenyl)quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe, and stir at room temperature for 5 minutes until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate, a precursor of benzyne, dropwise. Stir at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure, and separate by column chromatography to obtain 8,9-bis(3-fluorophenyl)benzo[4,5]thieno[2,3-b]quinoxaline.

[0062] The 8,9-bis(3-fluorophenyl)benzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 45.0 mg and a yield of 53%. The prepared 8,9-bis(3-fluorophenyl)benzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0063] 1 H NMR (400 MHz, CDCl3) δ 8.56 – 8.46 (m, 1H), 8.24 (s, 1H), 8.11 (s,1H), 7.82 (d, J = 7.9 Hz, 1H), 7.62 (td, J = 7.6, 1.4 Hz, 1H), 7.53 (td, J =7.6, 1.1 Hz, 1H), 7.24 – 7.20 (m, 1H), 7.19 –7.16 (m, 1H), 7.19 –7.16 (m, ,6H).

[0064] 13 C NMR (100 MHz, CDCl3) δ 163.7, 161.3, 158.2, 148.5, 142.2 (dd, J =7.7, 3.6 Hz), 141.5 (d, J = 2.1 Hz), 140.9 (d, J = 2.2 Hz), 140.6, 140.1,139.7, 131.3, 131.2, 130.8, 129.8 (dd, J = 8.3, 4.9 Hz), 129.6, 125.9, 125.7(t, J = 2.8 Hz), 124.5, 123.6, 116.9, 116.7, 114.4 (dd, J = 21.0, 8.0 Hz).

[0065] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 8,9-bis(3-fluorophenyl)benzo[4,5]thieno[2,3-b]quinoxaline shown.

[0066] Example 6:

[0067] In this embodiment, 8-fluorobenzo[4,5]thieno[2,3-b]quinoxaline was prepared using 7-fluoroquinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0068] Accurately weigh 0.2 mmol of 7-fluoroquinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate, a precursor of benzyne, dropwise. Stir and react at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure and separate by column chromatography to obtain 8-fluorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0069] The 8-fluorobenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 48.3 mg and a yield of 95%. The prepared 8-fluorobenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0070] 1 H NMR (400 MHz, CDCl3) δ 8.54 (dd, J = 7.8, 1.4 Hz, 1H), 8.27 (dd, J= 9.3, 5.8 Hz, 1H), 7.87 (d, J = 7.9 Hz, 1H), 7.77 (dd, J = 9.3, 2.8 Hz, 1H),7.67 (td, J = 7.6, 1.4 Hz, 1H), 7.62 – 7.55 (m, 2H).

[0071] 13C NMR (100 MHz, CDCl3) δ 164.0, 161.5, 158.4 (d, J = 3.6 Hz), 147.4 (d, J = 3.1 Hz), 142.0 (d, J = 3.6 Hz), 139.61, 137.64, 131.5 (d, J = 10.1Hz), 131.1 (d, J = 23.3 Hz), 125.6, 124.3, 123.6, 119.5 (d, J = 25.9 Hz), 111.9 (d, J = 23.3 Hz).

[0072] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 8-fluorobenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0073] Example 7:

[0074] In this embodiment, 9-chlorobenzo[4,5]thieno[2,3-b]quinoxaline was prepared using 6-chloroquinoxaline-2(1H)-thione and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0075] Accurately weigh 0.2 mmol of 6-chloroquinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe and stir at room temperature for 5 minutes. After the added substances are completely dissolved, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate, a precursor of benzyne, dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 9-chlorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0076] The 9-chlorobenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 51.3 mg and a yield of 95%. The prepared 9-chlorobenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0077] 1H NMR (400 MHz, CDCl3) δ 8.58 – 8.53 (m, 1H), 8.27 (d, J = 2.3 Hz,1H), 8.09 (d, J = 9.0 Hz, 1H), 7.90 – 7.85 (m, 1H), 7.75 (dd, J = 9.0, 2.3Hz, 1H), 7.69 (td, J = 7.7, 1.4 Hz, 1H), 7.60 (td, J = 7.6, 1.1 Hz, 1H).

[0078] 13 C NMR (100 MHz, CDCl3) δ 157.5, 148.5, 140.7, 140.2, 139.8, 134.7,131.4, 131.1, 130.7, 129.5, 128.4, 125.9, 124.6, 123.6.

[0079] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The figure shown is 9-chlorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0080] Example 8:

[0081] In this embodiment, 8-bromobenzo[4,5]thieno[2,3-b]quinoxaline and 9-bromobenzo[4,5]thieno[2,3-b]quinoxaline were prepared using 7-bromoquinoxaline-2(1H)-thieno and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0082] Accurately weigh 0.2 mmol of a mixture of 7-bromoquinoxaline-2(1H)-thione and 6-bromoquinoxaline-2(1H)-thione (molar ratio of the two in the mixture is 1:1), 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them into a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe, and stir at room temperature for 5 minutes. After the above substances are completely dissolved, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate, a precursor of benzyne, dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure, and separate the mixture by column chromatography. The mixture includes 8-bromobenzo[4,5]thieno[2,3-b]quinoxaline and 9-bromobenzo[4,5]thieno[2,3-b]quinoxaline.

[0083] The mixture was a yellow solid with a total yield of 47.1 mg and a total yield of 75%. The prepared mixture was characterized, and the characteristics were as follows:

[0084] 1 H NMR (400 MHz, CDCl3) δ 8.55 (s, 1H), 8.53 (s, 1H), 8.44 (d, J = 2.2Hz, 1H), 8.32 (d, J = 2.1 Hz, 1H), 8.12 (d, J = 8.9 Hz, 1H), 8.01 (d, J = 9.0Hz, 1H), 7.89 – 7.86 (m, 2H), 7.86 – 7.81 (m, 2H), 7.71 – 7.64 (m, 2H), 7.61– 7.55 (m, 2H).

[0085] 13 C NMR (100 MHz, CDCl3) δ 158.2, 157.6, 148.4, 148.0, 141.7, 141.0,140.2, 140.0, 139.2, 133.1, 132.6, 131.7, 131.4, 131.2, 131.1, 130.8, 130.6,129.6, 125.9, 124.6, 124.5, 123.7, 123.6, 122.8.

[0086] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 8-bromobenzo[4,5]thieno[2,3-b]quinoxaline shown and such The 9-bromobenzo[4,5]thieno[2,3-b]quinoxaline shown has a molar ratio of 1:1.

[0087] Example 9:

[0088] In this embodiment, 8-methoxyquinoxaline-2(1H)-thione, 6-methoxyquinoxaline-2(1H)-thione, and the benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate were used to prepare 8-methoxybenzo[4,5]thieno[2,3-b]quinoxaline and 9-methoxybenzo[4,5]thieno[2,3-b]quinoxaline. The specific steps are as follows:

[0089] Accurately weigh 0.2 mmol of a mixture of 7-methoxyquinoxaline-2(1H)-thione and 6-methoxyquinoxaline-2(1H)-thione (molar ratio of the two in the mixture is 1:1.2), 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them into a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe, and stir at room temperature for 5 minutes until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of benzoyne precursor 2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir the reaction at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure, and separate the mixture by column chromatography.

[0090] The mixture was a yellow solid with a total yield of 38.3 mg and a total yield of 72%. The prepared mixture was characterized, and the characteristics were as follows:

[0091] 1 H NMR (400 MHz, CDCl3) δ 8.51 – 8.41 (m, 2H), 8.06 (d, J = 9.0 Hz, 1H), 7.95 (d, J = 9.3 Hz, 1H), 7.78 (t, J = 7.5 Hz, 2H), 7.60 – 7.45 (m, 5H),7.41 – 7.33 (m, 3H), 3.95 (s, 3H), 3.93 (s, 3H).

[0092] 13 C NMR (100 MHz, CDCl3) δ 160.9, 160.2, 157.5, 154.6, 147.5, 145.6,143.1, 142.1, 140.1, 139.0, 137.8, 136.7, 131.8, 131.5, 130.6, 130.5, 130.2,129.2, 126.8, 125.6, 125.6, 124.1, 123.7, 123.5, 123.4, 123.3, 122.6, 106.6,105.8, 55.9, 55.8.

[0093] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 8-methoxybenzo[4,5]thieno[2,3-b]quinoxaline shown and such The 9-methoxybenzo[4,5]thieno[2,3-b]quinoxaline shown has a molar ratio of 1:1.2.

[0094] Example 10:

[0095] In this embodiment, quinoxaline-2(1H)-thione and 2-(trimethylsilyl)phenyltrifluoromethane sulfonate were used to prepare naphtho[2',3':4,5]thieno[2,3-b]quinoxaline. The specific steps are as follows:

[0096] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain naphtho[2',3':4,5]thieno[2,3-b]quinoxaline.

[0097] The prepared naphtho[2',3':4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 36.6 mg and a yield of 64%. The prepared naphtho[2',3':4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0098] 1 H NMR (400 MHz, CDCl3) δ 9.06 (s, 1H), 8.30 – 8.25 (m, 1H), 8.23 ​​(s,1H), 8.16 – 8.09 (m, 2H), 7.92 (d, J = 8.1 Hz, 1H), 7.83 – 7.78 (m, 2H), 7.64– 7.53(m, 2H).

[0099] 13 C NMR (100 MHz, CDCl3) δ 158.5, 148.2, 141.7, 140.4, 135.4, 134.8,131.2, 130.1, 129.9, 129.5, 129.4, 129.0, 128.2, 128.0, 127.2, 126.1, 124.4,121.7.

[0100] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The example shown is naphtho[2',3':4,5]thieno[2,3-b]quinoxaline.

[0101] Example 11:

[0102] In this embodiment, 2,3-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline was prepared using quinoxaline-2(1H)-thione and 4,5-dimethyl-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0103] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 4,5-dimethyl-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir and react at 25 °C for 13 hours. After the reaction is complete, remove the solvent under reduced pressure and separate by column chromatography to obtain 2,3-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline.

[0104] The 2,3-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 39.1 mg and a yield of 74%. The prepared 2,3-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the characterization results were as follows:

[0105] 1 H NMR (400 MHz, CDCl3) δ 8.34 (s, 1H), 8.28 – 8.23 ​​(m, 1H), 8.17 –8.12 (m, 1H), 7.81 – 7.76 (m, 2H), 7.62 (s, 1H), 2.46 (s, 3H), 2.45 (s, 3H).

[0106] 13 C NMR (100 MHz, CDCl3) δ 157.8, 148.0, 141.2, 141.1, 140.3, 137.5,135.0, 129.3, 129.2, 128.9, 128.3, 124.8, 124.0, 20.7, 19.9.

[0107] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 2,3-dimethylbenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0108] Example 12:

[0109] In this embodiment, 2,3-difluorobenzo[4,5]thieno[2,3-b]quinoxaline was prepared using quinoxaline-2(1H)-thione and 4,5-difluoro-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0110] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 4,5-difluoro-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 2,3-difluorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0111] The 2,3-difluorobenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 22.8 mg, representing a yield of 42%. The prepared 2,3-difluorobenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0112] 1 H NMR (400 MHz, CDCl3) δ 8.38 (dd, J = 9.6, 7.6 Hz, 1H), 8.30 – 8.25 (m, 1H), 8.20 – 8.14 (m, 1H), 7.88 – 7.82 (m, 2H), 7.68 (dd, J = 9.4, 6.7 Hz,1H).

[0113] 13 C NMR (100 MHz, CDCl3) δ 156.9, 153.9, 151.3 (d, J = 15.0 Hz), 148.6 (d, J = 13.0 Hz), 146.5, 141.24, 140.5, 135.6 (d, J = 8.0 Hz), 130.2, 129.5(d, J = 15.0 Hz), 128.4, 127.8, 112.6 (d, J = 19.0 Hz), 112.2 (d, J = 21.0Hz).

[0114] Based on the characterization results above, it can be seen that the structure prepared in this embodiment is as follows: The 2,3-difluorobenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0115] Example 13:

[0116] In this embodiment, 2,3-dimethoxybenzo[4,5]thieno[2,3-b]quinoxaline was prepared using quinoxaline-2(1H)-thione and 4,5-dimethoxy-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0117] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe and stir at room temperature for 5 minutes. After the added substances are completely dissolved, stir at 450 r / min and add 0.3 mmol of 4,5-dimethoxy-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir the reaction at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 2,3-dimethoxybenzo[4,5]thieno[2,3-b]quinoxaline.

[0118] The 2,3-dimethoxybenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 45.6 mg, representing a yield of 77%. The prepared 2,3-dimethoxybenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0119] 1 H NMR (400 MHz, CDCl3) δ 8.27 – 8.21 (m, 1H), 8.17 – 8.12 (m, 1H), 8.00 (s, 1H), 7.83 – 7.75 (m, 2H), 7.31 (s, 1H), 4.10 (s, 3H), 4.05 (s, 3H).

[0120] 13 C NMR (100 MHz, CDCl3) δ 152.8, 148.8, 148.0, 140.6, 140.4, 133.4,132.0, 129.1, 129.1, 129.0, 128.4, 123.9, 105.6, 105.2, 56.4.

[0121] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 2,3-dimethoxybenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0122] Example 14:

[0123] In this embodiment, quinoxaline-2(1H)-thione and 6-(trimethylsilyl)benzo[d][1,3]dioxacyclopenten-5-yl ester were used to prepare [1,3]dioxacyclopenten[4'',5'':4',5']benzo[1',2':4,5]thieno[2,3-b]quinoxaline. The specific steps are as follows:

[0124] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 6-(trimethylsilyl)trifluoromethanesulfonic acid benzo[d][1,3]dioxacyclopenten-5-yl ester dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain [1,3]dioxacyclopenten[4'',5'':4',5']benzo[1',2':4,5]thieno[2,3-b]quinoxaline.

[0125] The [1,3]dioxacyclopenteno[4'',5'':4',5']benzo[1',2':4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 32.5 mg and a yield of 58%. The prepared [1,3]dioxacyclopenteno[4'',5'':4',5']benzo[1',2':4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0126] 1 H NMR (400 MHz, CDCl3) δ 8.26 – 8.20 (m, 1H), 8.17 – 8.10 (m, 1H), 7.95 (s, 1H), 7.83 – 7.74 (m, 2H), 6.15 (s, 2H).

[0127] 13 C NMR (100 MHz, CDCl3) δ 157.3, 151.2, 147.6, 147.5, 140.6, 140.4,134.6, 129.2, 129.2, 129.0, 128.3, 125.2, 103.6, 103.4, 102.2.

[0128] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The [1,3]dioxacyclopenteno[4'',5'':4',5']benzo[1',2':4,5]thieno[2,3-b]quinoxaline is shown.

[0129] Example 15:

[0130] In this embodiment, 1-methoxybenzo[4,5]thieno[2,3-b]quinoxaline was prepared using quinoxaline-2(1H)-thione and 3-methoxy-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0131] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe and stir at room temperature for 5 minutes. After the added substances are completely dissolved, stir at 450 r / min and add 0.3 mmol of 3-methoxy-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir the reaction at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 1-methoxybenzo[4,5]thieno[2,3-b]quinoxaline.

[0132] The 1-methoxybenzo[4,5]thieno[2,3-b]quinoxaline was a yellow solid with a yield of 35.1 mg and a yield of 66%. The prepared 1-methoxybenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0133] 1 H NMR (400 MHz, CDCl3) δ 8.39 – 8.33 (m, 1H), 8.16 – 8.11 (m, 1H), 7.83 – 7.77 (m, 2H), 7.62 (t, J = 8.1 Hz, 1H), 7.48 (dd, J = 7.9, 0.8 Hz,1H), 7.07 (dd, J = 8.3, 0.8 Hz, 1H), 4.21 (s, 3H).

[0134] 13 C NMR (100 MHz, CDCl3) δ 159.0, 156.6, 148.2, 141.6, 140.5, 140.1,131.9, 130.1, 129.6, 128.7, 128.0, 119.6, 115.9, 107.7, 56.4.

[0135] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 1-methoxybenzo[4,5]thieno[2,3-b]quinoxaline shown is an example.

[0136] Example 16:

[0137] In this embodiment, 2-methoxybenzo[4,5]thieno[2,3-b]quinoxaline was prepared using quinoxaline-2(1H)-thione and 4-methoxy-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0138] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe and stir at room temperature for 5 minutes. After the added substances are completely dissolved, stir at 450 r / min and add 0.3 mmol of 4-methoxy-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir the reaction at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 2-methoxybenzo[4,5]thieno[2,3-b]quinoxaline.

[0139] The 2-methoxybenzo[4,5]thieno[2,3-b]quinoxaline was a white solid with a yield of 39.4 mg, representing a yield of 74%. The prepared 2-methoxybenzo[4,5]thieno[2,3-b]quinoxaline was characterized, and the results were as follows:

[0140] 1 H NMR (400 MHz, CDCl3) δ 8.44 (d, J = 8.7 Hz, 1H), 8.25 – 8.20 (m,1H), 8.15 – 8.09 (m, 1H), 7.81 – 7.74 (m, 2H), 7.32 (d, J = 2.2 Hz, 1H), 7.13(dd, J = 8.7, 2.3 Hz, 1H), 3.95 (s, 3H).

[0141] 13 C NMR (100 MHz, CDCl3) δ 162.3, 157.3, 147.8, 142.1, 140.6, 140.5,129.2, 129.1, 129.0, 128.3, 125.5, 124.4, 114.2, 107.3, 55.8.

[0142] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 2-methoxybenzo[4,5]thieno[2,3-b]quinoxaline shown.

[0143] Example 17:

[0144] In this embodiment, 4-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 1-methylbenzo[4,5]thieno[2,3-b]quinoxaline were prepared using quinoxaline-2(1H)-thione and 2-methyl-6-(trimethylsilyl)phenyl trifluoromethanesulfonate. The specific steps are as follows:

[0145] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of trifluoromethanesulfonate-2-methyl-6-(trimethylsilyl)phenyl ester dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 4-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 1-methylbenzo[4,5]thieno[2,3-b]quinoxaline.

[0146] The 4-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 1-methylbenzo[4,5]thieno[2,3-b]quinoxaline are yellow solids with a total yield of 43.5 mg and a total yield of 87%.

[0147] The prepared 4-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 1-methylbenzo[4,5]thieno[2,3-b]quinoxaline were characterized, and the characterization results are as follows:

[0148] 1 H NMR (400 MHz, CDCl3) δ 8.30 – 8.22 (m, 1H), 8.16 – 8.08 (m, 1H), 7.81 – 7.73 (m, 2H), 7.68 (d, J = 7.9 Hz, 1H), 7.50 (t, J = 7.7 Hz, 1H), 7.36– 7.29 (m, 1H), 3.15 (s, 3H).

[0149] 13C NMR (100 MHz, CDCl3) δ 157.29, 149.66, 140.26, 140.12, 140.09,139.53, 130.00, 129.98, 129.55, 128.80, 128.59, 128.05, 127.98, 120.90,20.68.

[0150] 1 H NMR (400 MHz, CDCl3) δ 8.47 – 8.41 (m, 1H), 8.32 – 8.26 (m, 1H), 8.20 – 8.15 (m, 1H), 7.85 – 7.79 (m, 2H), 7.55 – 7.47 (m, 2H), 2.62 (s, 3H).

[0151] 13 C NMR (100 MHz, CDCl3) δ 157.4, 148.5, 141.4, 140.5, 140.0, 132.9,131.4, 131.3, 129.7, 129.5, 129.0, 128.4, 125.9, 121.8, 20.1.

[0152] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 4-methylbenzo[4,5]thieno[2,3-b]quinoxaline shown and such The 1-methylbenzo[4,5]thieno[2,3-b]quinoxaline shown has a mass ratio of 1:1.

[0153] Example 19:

[0154] In this embodiment, 3-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 2-methylbenzo[4,5]thieno[2,3-b]quinoxaline were prepared using quinoxaline-2(1H)-thione and 4-methyl-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0155] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 4-methyl-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 3-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 2-methylbenzo[4,5]thieno[2,3-b]quinoxaline.

[0156] The 3-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 2-methylbenzo[4,5]thieno[2,3-b]quinoxaline were yellow solids, with a total yield of 42.5 mg and a total yield of 85%. The prepared 3-methylbenzo[4,5]thieno[2,3-b]quinoxaline and 2-methylbenzo[4,5]thieno[2,3-b]quinoxaline were characterized, and the characterization results were as follows:

[0157] 1 H NMR (400 MHz, CDCl3) δ 8.41 (s, 1H), 8.32 – 8.24 (m, 1H), 8.19 –8.13 (m, 1H), 7.85 – 7.78 (m, 2H), 7.76 (d, J = 8.1 Hz, 1H), 7.53 – 7.46 (m,1H), 2.58 (s, 3H).

[0158] 13 C NMR (100 MHz, CDCl3) δ 147.9, 141.4, 140.4, 136.9, 135.9, 132.4,131.4, 129.6, 129.5, 129.0, 128.3, 124.5, 123.2, 21.3.

[0159] 1 H NMR (400 MHz, CDCl3) δ 8.46 (d, J = 8.0 Hz, 1H), 8.30 – 8.24 (m,1H), 8.19 – 8.12 (m, 1H), 7.83 – 7.77 (m, 2H), 7.68 (s, 1H), 7.40 (dd, J =8.1, 1.5 Hz, 1H), 2.57 (s, 3H).

[0160] 13 C NMR (100 MHz, CDCl3) δ 157.4, 156.3, 147.9, 142.0, 141.2, 140.5,140.2, 129.4, 129.4, 129.0, 128.3, 127.2, 124.1, 123.7, 22.2.

[0161] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 3-methylbenzo[4,5]thieno[2,3-b]quinoxaline shown and such The 2-methylbenzo[4,5]thieno[2,3-b]quinoxaline shown has a mass ratio of 1:1.3.

[0162] Example 20:

[0163] In this embodiment, 3-chlorobenzo[4,5]thieno[2,3-b]quinoxaline and 2-chlorobenzo[4,5]thieno[2,3-b]quinoxaline were prepared using quinoxaline-2(1H)-thione and 4-chloro-2-(trimethylsilyl)phenyltrifluoromethanesulfonate. The specific steps are as follows:

[0164] Accurately weigh 0.2 mmol of quinoxaline-2(1H)-thione, 0.6 mmol of cesium fluoride, and 0.6 mmol of 18-crown-6, and place them in a dry 10 mL Shrek tube. Then, add 2.0 mL of tetrahydrofuran using a syringe. Stir for 5 minutes at room temperature until the added substances are completely dissolved. Then, stir at 450 r / min and add 0.3 mmol of 4-chloro-2-(trimethylsilyl)phenyltrifluoromethanesulfonate dropwise. Stir and react at 25 °C for 13 hours. After the reaction is completed, remove the solvent under reduced pressure and separate by column chromatography to obtain 3-chlorobenzo[4,5]thieno[2,3-b]quinoxaline and 2-chlorobenzo[4,5]thieno[2,3-b]quinoxaline.

[0165] The 3-chlorobenzo[4,5]thieno[2,3-b]quinoxaline and 2-chlorobenzo[4,5]thieno[2,3-b]quinoxaline were yellow solids with a total yield of 27.0 mg and a total yield of 50%. The prepared 3-chlorobenzo[4,5]thieno[2,3-b]quinoxaline and 2-chlorobenzo[4,5]thieno[2,3-b]quinoxaline were characterized, and the characterization results were as follows:

[0166] 1H NMR (400 MHz, CDCl3) δ 8.56 (d, J = 2.2 Hz, 1H), 8.49 (d, J = 8.4Hz, 1H), 8.32 – 8.23 ​​(m, 2H), 8.21 – 8.12 (m, 2H), 7.88 – 7.78 (m, 5H), 7.63 (dd, J = 8.5, 2.2 Hz, 1H), 7.56 (dd, J = 8.4, 1.9 Hz, 1H).

[0167] 13 C NMR (100 MHz, CDCl3) δ 157.4, 146.7, 141.6, 141.4, 140.5, 138.0,137.1, 132.8, 132.2, 131.1, 130.2, 130.0, 129.9, 129.7, 129.5, 129.4, 129.4,128.4, 126.6, 125.2, 124.6, 124.2, 123.4.

[0168] Based on the characterization results above, it can be seen that this embodiment successfully prepared a structure with the following structural formula: The 3-chlorobenzo[4,5]thieno[2,3-b]quinoxaline shown and such The 2-chlorobenzo[4,5]thieno[2,3-b]quinoxaline shown has a molar ratio of 1:1.8.

[0169] In summary, this invention is the first to propose the simultaneous preparation of benzothiophene-quinoxaline compounds using benzylene. The method is simple and rapid, requires no transition metal catalysis, has a wide substrate range, uses inexpensive and readily available fluorine sources, and does not cause environmental pollution. The method has the advantages of simple process and good universality, and the synthesized benzothiophene-quinoxaline compounds have moderate to good yields, with the highest yield reaching 99%, making it of great industrial application value.

[0170] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for synthesizing benzothiophene-quinoxaline compounds, characterized in that, The method includes: Quinoxaline-2(1H)-thione compounds, fluorine sources, and additives were mixed and dissolved in a solvent. Then, Kobayashi benzoyne precursor was added to the solvent to carry out a [3+2] cycloaddition reaction. After the reaction was completed, the solvent was evaporated and the benzothiophene-quinoxaline compounds were obtained.

2. The method according to claim 1, characterized in that, The quinoxaline-2(1H)-thione compounds include those with the structural formula […]. Quinoxaline-2(1H)-thiones; In the formula, R 1 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group; In the formula, R 2 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group.

3. The method according to claim 1, characterized in that, The fluorine source includes one or more of potassium fluoride, cesium fluoride, tetra-n-butylammonium difluorotriphenylsilicate, and tetrabutylammonium fluoride. The additive includes 18-crown-6; The solvent includes one or more of tetrahydrofuran, ethylene glycol dimethyl ether, dichloromethane, acetonitrile, and toluene.

4. The method according to claim 1, characterized in that, The Kobayashi benzoyne precursor includes the structural formula: Benzyne precursor; In the formula, R 3 Including any one of hydrogen-based, 4,5-phenyl, 4,5-difluoro, 4,5-methoxy, 3-methoxy, 4-methoxy, 3-fluoro, 3-methyl, 4-methyl, 4-chloro, and [1,3]dioxacyclopenten-5-yl.

5. The method according to claim 1, characterized in that, The ratio of the quinoxaline-2(1H)-thione compound, fluoride, additive, and solvent is 0.2 mmol: 0.6 mmol: 0.6 mmol: 2.0 mL.

6. The method according to claim 1, characterized in that, The molar ratio of the quinoxaline-2(1H)-thione compound to the benzyne precursor is 1:1.1~2.

0.

7. The method according to claim 1, characterized in that, The conditions for the [3+2] cycloaddition reaction are: reaction at room temperature for 12-13 hours under air conditions.

8. The method according to claim 1, characterized in that, The general structural formula of the benzothiophenequinoxaline compounds is: ； In the formula, R 1 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group; In the formula, R 2 Including any one of hydrogen group, methyl group, fluorine atom substituent, chlorine atom substituent, bromine atom substituent, 3-fluorophenyl, and methoxy group; In the formula, R 3 Including any one of hydrogen-based, 4,5-phenyl, 4,5-difluoro, 4,5-methoxy, 3-methoxy, 4-methoxy, 3-fluoro, 3-methyl, 4-methyl, 4-chloro, and [1,3]dioxacyclopenten-5-yl.

9. The benzothiophene-quinoxaline compound synthesized by the method according to any one of claims 1 to 8.

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