A method for synthesizing naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds

Abstract

This invention relates to the field of fluorescent compound preparation technology, and discloses a method for synthesizing naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds, including a cyclized compound, wherein the cyclized compound includes styrene compounds and imidazolium heterocyclic compounds, and the cyclized compound is a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound; it also includes a method for synthesizing naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds. This invention utilizes a synergistic combination of a photo-redox catalyst and a cobalt oxime catalyst to achieve a [4+2] cyclization reaction of olefins with imidazopyridines. Under photochemical conditions, imidazopyridine compounds and styrene compounds undergo a [4+2] cyclization reaction with the addition of the photo-redox catalyst and the cobalt oxime catalyst. This facilitates the rapid synthesis of naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds. It avoids the use of precious metal catalysts or chemical oxidants, and the reaction conditions are mild, making it suitable for the mass production and processing of naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds, reducing synthesis and production conditions, saving costs, and improving efficiency.

Description

Technical Field

[0001] This invention relates to the field of fluorescent compound preparation technology, and in particular to a method for synthesizing naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds. Background Technology

[0002] Due to their unique electronic properties, diverse biological activities, and catalytic activities, naphtho[1',2':4,5]imidazo[1,2-a]pyridine fluorescent compounds are of great significance in organic synthesis, materials science, and pharmaceutical science. Therefore, in the past few decades, a great deal of research has been dedicated to developing efficient and practical methods for synthesizing these compounds. These compounds are generally obtained through [3+2] / [4+2] cyclization reactions of alkynes with imidazo heterocycles. However, the reaction of imidazo heterocycles with alkynes mainly yields [3+2] cyclization products, while only electron-deficient alkynes can be converted to [4+2] cyclization products. Although alkenes are sometimes involved in cyclization or alkylation reactions, the main problem is that alkenes may be converted to cyclization products under reaction conditions containing free radical intermediates. These reactions require electron / H transfer processes to complete aromatization or cyclization under the promotion of suitable external oxidants. To address these problems, transition metal-catalyzed cyclization reactions of imidazopyridine heterocycles have been developed. Despite these advances, most reported reactions still suffer from several drawbacks, including: 1) only activated olefins are suitable substrates; 2) the need for Nobel metal catalysts (Rh, Ru, etc.); 3) the requirement for stoichiometric oxidants; and 4) harsh reaction conditions. Furthermore, the unique monolithic structure of activated olefins leads to a lack of structural diversity in the products. Therefore, developing a mild and green cyclization scheme to obtain naphtho[1',2':4,5]imidazo[1,2-a]pyridine fluorescent compounds via the selective oxidative dehydrogenation [4+2] cyclization of imidazole heterocycles with olefins is both highly attractive and challenging. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides a method for synthesizing naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds.

[0004] This invention is achieved using the following technical solution: a cyclized compound, wherein the cyclized compound includes styrene compounds and imidazole heterocyclic compounds, and the cyclized compound is a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound, and the structure of the cyclized compound is as follows:

[0005] .

[0006] As a further improvement to the above scheme, the structure of the imidazole heterocyclic compound is as follows:

[0007] ;

[0008] Wherein, R1 is a substituent at C7-C8 of the pyridine ring; R2 is any one of an electron-donating group or an electron-withdrawing substituent at the para position of the benzene ring.

[0009] As a further improvement to the above scheme, the structure of the styrene compound is as follows:

[0010] ;

[0011] R3 can be any one of an electron-donating group, an electron-withdrawing group, or a halogen substituent.

[0012] A method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound, comprising the following steps:

[0013] S1 photocatalytic reaction:

[0014] Styrene compounds, imidazole heterocyclic compounds, solvents, photo-redox catalysts, and cobalt oxime catalysts were added to reaction tubes, nitrogen gas was introduced, and the mixtures were reacted under light source irradiation to obtain a mixed initial solution.

[0015] S2 separation and purification:

[0016] The mixed initial liquid was separated and purified to obtain olefins and imidazole heterocyclic cyclization products.

[0017] As a further improvement to the above scheme, the molar ratio of the imidazole heterocyclic compound to the styrene compound is 1:2.

[0018] As a further improvement to the above scheme, the cobalt oxime catalyst is Co(dmgH)2Cl2.

[0019] As a further improvement to the above scheme, the photo-oxidation-reduction catalyst is Acr. + -MesClO4 - .

[0020] As a further improvement to the above scheme, the solvent is a mixed solvent system of 1,2-dichloroethane and hexafluoroisopropanol, with a volume ratio of 3.4-4.6:0.1 mL.

[0021] As a further improvement to the above scheme, the separation and purification are performed using at least one of column chromatography and recrystallization, and the temperature of the mixing reaction is room temperature.

[0022] As a further improvement to the above scheme, the molar ratio of the imidazole heterocyclic compound to the styrene compound, the cobalt oxime catalyst and the photo-redox catalyst is 95-150:187-226:5.6-9.2:5.4-8.7.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This invention utilizes the synergistic combination of photo-redox catalysts and cobalt oxime catalysts to achieve a synthetic method for the oxidative dehydrogenation [4+2] cyclization reaction of olefins and imidazopyridines. By adding photo-redox catalysts and cobalt oxime catalysts to imidazopyridine compounds and styrene compounds under photochemical conditions, a [4+2] cyclization reaction is achieved, which facilitates the rapid synthesis of naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds.

[0025] 2. This invention does not use precious metal catalysts or chemical oxidants, and the reaction conditions are mild, which facilitates the mass production and processing of naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds, reduces the synthesis and production conditions, saves costs and improves efficiency. Attached Figure Description

[0026] in, Figure 1 A in the diagram represents the product obtained in Example 4 of this invention. 1 H NMR, Figure 1 B is the product obtained in Example 4 of this invention. 13 C NMR;

[0027] in, Figure 2 A in this invention is the product obtained in Example 5. 1 H NMR, Figure 2 B is the product obtained in Example 5 of this invention. 13 C NMR;

[0028] in, Figure 3 A in this invention is the product obtained in Example 6. 1 H NMR, Figure 3 B is the product obtained in Example 6 of this invention. 13 C NMR, Figure 3 C represents the product obtained in Example 6 of this invention. 19 F NMR;

[0029] in, Figure 4 A in this invention is the product obtained in Example 7. 1 H NMR, Figure 4 B is the product obtained in Example 7 of this invention. 13 C NMR;

[0030] in, Figure 5 In the middle, A is the product obtained in Example 8 of this invention. 1 H NMR, Figure 5 B is the product obtained in Example 8 of this invention. 13 C NMR;

[0031] in, Figure 6 In the middle, A is the product obtained in Example 9 of this invention. 1 H NMR, Figure 6 B is the product obtained in Example 9 of this invention. 13 C NMR;

[0032] in, Figure 7 In the middle, A is the product obtained in Example 10 of this invention. 1 H NMR, Figure 7 B is the product obtained in Example 10 of this invention. 13 C NMR, Figure 7 C represents the product obtained in Example 10 of this invention. 19 F NMR;

[0033] in, Figure 8 A in the diagram represents the product obtained in Example 11 of this invention. 1 H NMR, Figure 8 B is the product obtained in Example 11 of this invention. 13 C NMR;

[0034] in, Figure 9 In the middle, A is the product obtained in Example 12 of this invention. 1 H NMR, Figure 9 B is the product obtained in Example 12 of this invention. 13 C NMR;

[0035] in, Figure 10 A in the diagram represents the product obtained in Example 13 of this invention. 1 H NMR, Figure 10 B is the product obtained in Example 13 of this invention. 13 C NMR, Figure 10 C in the middle refers to the product obtained in Example 13 of this invention. 19 F NMR;

[0036] in, Figure 11 A in this invention is the product obtained in Example 14. 1 H NMR, Figure 11 B is the product obtained in Example 14 of this invention. 13 C NMR;

[0037] in, Figure 12 A in this invention is the product obtained in Example 15.1 H NMR, Figure 12 B is the product obtained in Example 15 of this invention. 13 C NMR;

[0038] in, Figure 13 In the middle, A is the product obtained in Example 16 of this invention. 1 H NMR, Figure 13 B is the product obtained in Example 16 of this invention. 13 C NMR. Detailed Implementation

[0039] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Example

[0040] A cyclized compound, including styrene compounds and imidazole heterocyclic compounds, wherein the cyclized compound is a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound, and the structure of the cyclized compound is as follows:

[0041] .

[0042] The structure of imidazole heterocyclic compounds is as follows:

[0043]

[0044] Wherein, R1 is a substituent at C7-C8 of the pyridine ring; R2 is any one of an electron-donating group or an electron-withdrawing substituent at the para position of the benzene ring.

[0045] The structures of styrene compounds are as follows:

[0046]

[0047] R3 can be any one of an electron-donating group, an electron-withdrawing group, or a halogen substituent. Example

[0048] A method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound, comprising the following steps:

[0049] S1 photocatalytic reaction:

[0050] Styrene compounds, imidazole heterocyclic compounds, solvents, photo-redox catalysts, and cobalt oxime catalysts were added to a Schlenk reaction tube, nitrogen gas was introduced, and the mixture was reacted under light source to obtain a mixed initial solution.

[0051] S2 separation and purification:

[0052] The mixed initial liquid was separated and purified to obtain olefins and imidazole heterocyclic cyclization products.

[0053] The molar ratio of imidazole heterocyclic compounds to styrene compounds is 1:2.

[0054] The cobalt oxime catalyst is Co(dmgH)2Cl2.

[0055] The photo-oxidation-reduction catalyst is Acr + -MesClO4 - .

[0056] The solvent is a mixed solvent system of 1,2-dichloroethane and hexafluoroisopropanol, with a volume ratio of 3.4-4.6 : 0.1 mL.

[0057] The separation and purification are performed using at least one of column chromatography and recrystallization, and the temperature of the mixed reaction is room temperature.

[0058] The molar ratio of imidazole heterocyclic compounds to styrene compounds, cobalt oxime catalysts, and photoredox catalysts was 95-150:187-226:5.6-9.2:5.4-8.7. Example

[0059] A synthetic method for the oxidative dehydrogenation [4+2] cyclization of olefins with imidazolium pyridine using a synergistic combination of a photoredox catalyst and a cobalt oxime catalyst, comprising the following steps:

[0060] Photocatalytic reaction, involving styrene compounds, imidazole heterocyclic compounds, solvent, and photo-oxidation-reduction catalyst (Acr). + -MesClO4 - Cobalt oxime catalyst (Co(dmgH)2Cl2) was added to a Schlenk reaction tube, nitrogen gas was introduced, and a 3 W blue light source was installed. The reaction was carried out for 24 hours.

[0061] Separation and purification were performed on the solution after the photocatalytic reaction to obtain the alkylene-imidazolium heterocyclic cyclization product; the cyclization product has the structure shown below:

[0062] ;

[0063] Wherein, R1 is a substituent of the pyridine ring at C7-C8 (such as methyl, methoxy, and fluorine).

[0064] R2 is a benzene ring with an electron-donating group (-Me, -) at the para position. n Pr, -OCH3, -Ph) or electron-withdrawing substituents (-CN, -CF3, -F, -Cl, -Br, etc.);

[0065] R3 is an electron donor (-CH3, - t Bu, - n Bu and Ph) or electron-withdrawing (-CF3) groups, as well as halogen substituents (-F, -Cl, -Br);

[0066] Specifically, in a 10 mL well-sealed Schlenk reaction tube, imidazole heterocyclic compounds, styrene compounds, and a photo-oxidation-reduction catalyst (Acr) were added. + -MesClO4 - The cobalt oxime catalyst (Co(dmgH)₂Cl₂) was added to a Schlenk reaction tube, nitrogen gas was introduced, and a 3 W blue light source was installed. The reaction was carried out for 24 hours with stirring. The amount of imidazole heterocyclic compound was 0.2 mmol. The amount of styrene compound was 0.4 mmol. The molar ratio of imidazole heterocyclic compound to styrene compound was 1:2. The amount of cobalt oxime catalyst (Co(dmgH)₂Cl₂) was 0.016 mmol. The photoredox catalyst (Acr) + -MesClO4 - The amount of substance was 0.014 mmol. The reaction was carried out at room temperature.

[0067] The solution after the reaction was completed was evaporated to dryness under reduced pressure, and the residue was separated by silica gel column chromatography using a petroleum ether / ethyl acetate system as the eluent. This does not mean that other eluent systems are not required by this application; any reagent that meets the elution purpose can be used.

[0068] The reaction formula is:

[0069]

[0070] This led to the realization of a method for synthesizing olefins and imidazole heterocycles through the synergistic combination of a photo-redox catalyst and a cobalt oxime catalyst via oxidative dehydrogenation [4+2] cyclization.

[0071] The imidazole heterocyclic compounds and styrene compounds used in the examples were all purchased analytical grade reagents directly from Anaiji Chemical, Jiuding Chemical, Aladdin and Adamas. They were not treated before use, and the solvents or eluents used were purchased from Sinopharm. Example

[0072] 7-Methyl-2-phenylimidazo[1,2-a]pyridine (0.2 mmol, 41.6 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product, 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 75% yield.

[0073] The 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine product was analyzed by nuclear magnetic resonance spectroscopy. The results are shown below. Figure 1 , Figure 1 In this context, A is a product of 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 1 B is a product of 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0074] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.89 (d, J = 8.1Hz, 1H), 8.33 (d, J = 6.9 Hz, 1H), 8.01 (d, J = 8.4 Hz, 1H), 7.79 (s, 1H), 7.69 (t, J = 8.0 Hz, 1H), 7.60 (s, 1H), 7.52 (t, J = 7.7 Hz, 1H), 7.48 (d, J = 8.6 Hz, 2H), 7.06 (d, J= 8.6 Hz, 2H), 6.74 (d, J = 7.0 Hz, 1H), 3.91 (s, 3H), 2.49 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 159.08, 148.00, 140.75, 139.01,134.26, 133.63, 131.56, 130.92, 127.17, 127.01, 126.42, 125.83, 123.91,123.60, 123.30, 116.29, 114.15, 113.89, 110.92, 55.53, 21.99.

[0075] The structural formula of the prepared 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0076]

[0077] Example 5:

[0078] 4-(7-methylimidazo[1,2-a]pyridin-2-yl)benzyl nitrile (0.2 mmol, 46.6 mg), Acr + -MesClO4 - (0.014 mmol, 5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 5 / 1, v / v) as eluents to give a yellow solid product 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxynitrile, in 65% yield.

[0079] The 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxynitrile product was analyzed by nuclear magnetic resonance spectroscopy. The results are shown below. Figure 2 , Figure 2In this context, A is the product of 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxynitrile. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 2 B is a product of 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxynitrile. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0080] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.95 (d, J = 8.4Hz, 1H), 8.45 – 8.34 (m, 2H), 7.93 (s, 1H), 7.83 (d, J = 8.5 Hz, 1H), 7.64(s, 1H), 7.45 (d, J = 8.2 Hz, 2H), 7.10 (d, J = 8.2 Hz, 2H), 6.85 (d, J = 7.0Hz, 1H), 3.95 (s, 3H), 2.54 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 159.58,148.65, 140.28, 140.16, 134.31, 133.29, 132.06, 131.53, 130.15, 128.80,127.28, 125.63, 124.50, 123.79, 119.91, 116.54, 114.92, 114.33, 112.63, 109.06, 55.63, 22.12.

[0081] The structural formula of the prepared 5-(4-methoxyphenyl)-10-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxynitrile compound is as follows:

[0082]

[0083] Example 6:

[0084] 7-Methyl-2-(4-(trifluoromethyl)phenyl)imidazo[1,2-a]pyridine (0.2 mmol, 55.3 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product, 5-(4-methoxyphenyl)-10-methyl-3-(trifluoromethyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 78% yield.

[0085] The 5-(4-methoxyphenyl)-10-methyl-3-(trifluoromethyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine product was analyzed by nuclear magnetic resonance spectroscopy. The results are shown in [link to relevant documentation]. Figure 3 , Figure 3 In this context, A is a product of 5-(4-methoxyphenyl)-10-methyl-3-(trifluoromethyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 3 B is a product of 5-(4-methoxyphenyl)-10-methyl-3-(trifluoromethyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum; Figure 3 C is a product of 5-(4-methoxyphenyl)-10-methyl-3-(trifluoromethyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 19 F nuclear magnetic resonance (F) 19 F-NMR spectrum.

[0086] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.96 (d, J = 8.5Hz, 1H), 8.33 (d, J = 6.9 Hz, 1H), 8.30 (s, 1H), 7.85 (d, J= 7.5 Hz, 2H),7.60 (s, 1H), 7.45 (d, J = 8.5 Hz, 2H), 7.08 (d, J = 8.5 Hz, 2H), 6.77 (d, J = 6.7 Hz, 1H), 3.93 (s, 3H), 2.49 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 159.39,148.35, 140.20, 139.90, 134.70, 132.58, 131.49, 129.93, 128.54, 127.54 (q, J C-F = 31.8 Hz), 125.05, 124.75 (q, J C-F = 273.7 Hz), 124.75 (q, J C-F = 4.4 Hz),124.30, 123.73, 122.14 (q, J C-F = 3.1 Hz), 116.41, 114.65, 114.20, 112.23,55.56, 22.06. 19 F NMR (376 MHz, CDCl3) δ -61.68.

[0087] The structural formula of the prepared 5-(4-methoxyphenyl)-10-methyl-3-(trifluoromethyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0088]

[0089] Example 7:

[0090] 7-Methyl-2-(4-(methanesulfonyl)phenyl)imidazo[1,2-a]pyridine (0.2 mmol, 57.2 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 1 / 1, v / v) as eluents to give a yellow solid product, 5-(4-methoxyphenyl)-10-methyl-3-(methanesulfonyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 85% yield.

[0091] The 5-(4-methoxyphenyl)-10-methyl-3-(methanesulfonyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine product was analyzed by nuclear magnetic resonance spectroscopy. The results are shown in [link to relevant documentation]. Figure 4 , Figure 4 In this context, A is a product of 5-(4-methoxyphenyl)-10-methyl-3-(methanesulfonyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 4 B is a product of 5-(4-methoxyphenyl)-10-methyl-3-(methanesulfonyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0092] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 9.01 (d, J = 8.5Hz, 1H), 8.67 (s, 1H), 8.36 (d, J = 6.8 Hz, 1H), 8.10 (d, J = 8.4 Hz, 1H),7.91 (s, 1H), 7.59 (s, 1H), 7.44 (d, J = 8.3 Hz, 2H), 7.06 (d, J = 8.3 Hz, 2H), 6.80 (d, J= 6.7 Hz, 1H), 3.91 (s, 3H), 3.09 (s, 3H), 2.51 (s, 3H). 13 CNMR (101 MHz, CDCl3) δ 159.45, 148.53, 140.24, 140.00, 137.10, 134.92,132.00, 131.41, 129.80, 129.37, 127.82, 125.69, 124.89, 123.78, 122.83,116.34, 114.80, 114.31, 112.79, 55.49, 44.69, 22.04.

[0093] The structural formula of the prepared 5-(4-methoxyphenyl)-10-methyl-3-(methanesulfonyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0094]

[0095] Example 8:

[0096] 7-Methyl-2-(naphth-2-yl)imidazo[1,2-a]pyridine (0.2 mmol, 51.6 mg), Acr + -MesClO4 - 0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product 7-(4-methoxyphenyl)-12-methylphenanthro[1',2':4,5]imidazo[1,2-a]pyridine in 70% yield.

[0097] The 7-(4-methoxyphenyl)-12-methylphenanthro[1',2':4,5]imidazo[1,2-a]pyridine product was analyzed by nuclear magnetic resonance spectroscopy. The results are shown in [link to relevant documentation]. Figure 5 , Figure 5In this context, A is a product of 7-(4-methoxyphenyl)-12-methylphenanthro[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 5 B is a product of 7-(4-methoxyphenyl)-12-methylphenanthro[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0098] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.90 (d, J = 8.8Hz, 1H), 8.34 (d, J = 6.9 Hz, 1H), 8.01 (d, J = 8.8 Hz, 1H), 7.92 (d, J = 7.9Hz, 1H), 7.86 (d, J = 8.7 Hz, 1H), 7.83 (s, 1H), 7.63 (s, 1H), 7.44 (t, J =7.4 Hz, 1H), 7.39 (d, J = 8.5 Hz, 2H), 7.16 (t, J = 7.7 Hz, 1H), 7.03 (d, J =8.5 Hz, 2H), 6.75 (d, J = 6.9 Hz, 1H), 3.93 (s, 3H), 2.49 (s, 3H). 13 C NMR(101 MHz, CDCl3) δ 158.90, 148.56, 141.30, 140.09, 138.39, 134.13, 133.66,131.19, 130.47, 128.84, 128.35, 128.32, 126.80, 125.96, 125.53, 124.82,123.99, 121.97, 116.19, 114.53, 114.06, 113.60, 55.53, 22.09.

[0099] The structural formula of the prepared 7-(4-methoxyphenyl)-12-methylphenanthro[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0100]

[0101] Example 9:

[0102] 7-Methyl-2-(thiophen-2-yl)imidazo[1,2-a]pyridine (0.2 mmol, 42.8 mg), Acr + -MesClO4 - 0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (with thin-layer chromatography for monitoring), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product, 4-(4-methoxyphenyl)-9-methylthieno[3'',2'':5',6']benzo[1',2':4,5]imidazo[1,2-a]pyridine, in 55% yield.

[0103] The 4-(4-methoxyphenyl)-9-methylthiopheno[3'',2'':5',6']benzo[1',2':4,5]imidazo[1,2-a]pyridine product was analyzed by nuclear magnetic resonance spectroscopy. The results are shown in [link to relevant documentation]. Figure 6 , Figure 6 In part A, 4-(4-methoxyphenyl)-9-methylthiopheno[3'',2'':5',6']benzo[1',2':4,5]imidazo[1,2-a]pyridine is a product of 4-(4-methoxyphenyl)-9-methylthiopheno[3'',2'':5',6']benzo[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 6 B is a product of 4-(4-methoxyphenyl)-9-methylthiopheno[3'',2'':5',6']benzo[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0104] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.36 (d, J= 7.0Hz, 1H), 7.72 (s, 1H), 7.58 (d, J = 5.1 Hz, 2H), 7.55 (d, J = 5.9 Hz, 2H), 7.51 (d, J = 5.4 Hz, 1H), 7.06 (d, J = 8.6 Hz, 2H), 6.74 (d, J = 7.6 Hz, 1H), 3.91 (s, 3H), 2.49 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 159.14, 148.61, 140.28,137.23, 133.91, 131.58, 130.63, 130.10, 125.23, 125.10, 124.72, 124.28,116.14, 114.12, 107.80, 55.55, 22.06.

[0105] The structural formula of the prepared 4-(4-methoxyphenyl)-9-methylthiopheno[3'',2'':5',6']benzo[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0106]

[0107] Example 10:

[0108] 7-Fluoro-2-phenylimidazo[1,2-a]pyridine (0.2 mmol, 42.4 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 5 / 1, v / v) as eluents to give a yellow solid product, 10-fluoro-5-(4-methoxyphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 81% yield.

[0109] The results of nuclear magnetic resonance spectroscopy analysis of 10-fluoro-5-(4-methoxyphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine are shown in [reference]. Figure 7 , Figure 7 In this context, A is a product of 10-fluoro-5-(4-methoxyphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 7 B is a product of 10-fluoro-5-(4-methoxyphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum; Figure 7 C is a product of 10-fluoro-5-(4-methoxyphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 19 F nuclear magnetic resonance (F) 19 F-NMR spectrum.

[0110] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.85 (d, J = 8.1Hz, 1H), 8.40 – 8.32 (m, 1H), 8.00 (d, J = 8.4 Hz, 1H), 7.73 (s, 1H), 7.70(t, J = 7.5 Hz, 1H), 7.53 (t, J= 7.2 Hz, 1H), 7.48 – 7.40 (m, 3H), 7.05 (d, J = 8.6 Hz, 2H), 6.76 (t, J = 7.2 Hz, 1H), 3.91 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 161.93 (d, J C-F = 255.1 Hz), 159.17, 147.79 (d, J C-F = 14.2 Hz),141.39, 135.05, 133.29, 131.49, 130.90, 127.21, 126.78, 126.67, 126.11,125.91 (d, J C-F = 11.4 Hz), 123.78, 123.23, 113.91, 110.58, 104.05 (d, J C-F =29.8 Hz), 101.43 (d, J C-F = 23.6 Hz), 55.52. 19 F NMR (376 MHz, CDCl3) δ -108.10.

[0111] The structural formula of the prepared 10-fluoro-5-(4-methoxyphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0112]

[0113] Example 11:

[0114] 2-Phenylenzi[d]imidazo[2,1-b]thiazole (0.2 mmol, 50 mg), Acr + -MesClO4 -(0.014 mmol, 5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a white solid product, 5-(4-methoxyphenyl)benzo[d]naphtho[1',2':4,5]imidazo[2,1-b]thiazole, in 85% yield.

[0115] The results of nuclear magnetic resonance spectroscopy for 5-(4-methoxyphenyl)benzo[d]naphtho[1',2':4,5]imidazo[2,1-b]thiazole are shown in [reference]. Figure 8 , Figure 8 In this context, A represents a product of 5-(4-methoxyphenyl)benzo[d]naphtho[1',2':4,5]imidazo[2,1-b]thiazole. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 8 B is a product of 5-(4-methoxyphenyl)benzo[d]naphtho[1',2':4,5]imidazo[2,1-b]thiazole. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0116] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.72 (d, J = 8.1Hz, 1H), 8.00 – 7.92 (m, 3H), 7.70 (d, J = 7.9 Hz, 1H), 7.65 (t, J = 7.4 Hz,1H), 7.52 – 7.43 (m, 4H), 7.31 (t, J = 7.6 Hz, 1H), 7.07 (d, J = 8.4 Hz, 2H), 3.92 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 159.19, 152.65, 143.35, 135.21,133.44, 133.12, 131.60, 129.55, 129.41, 126.99, 126.70, 126.65, 126.62,126.30, 125.22, 124.57, 124.44, 122.50, 113.93, 112.70, 111.70, 55.55.

[0117] The structural formula of the prepared 15-(4-methoxyphenyl)benzo[d]naphtho[1',2':4,5]imidazo[2,1-b]thiazole compound is as follows:

[0118]

[0119] Example 12:

[0120] 2-(4-(tert-butyl)phenyl-2H-indazole (0.2 mmol, 50 mg), Acr + -MesClO4 - 0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 4-methoxystyrene (0.4 mmol, 53.6 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 30 / 1, v / v) as eluents to give a yellow solid product 3-(tert-butyl)-5-(4-methoxyphenyl)inzazo[2,3-a]quinoline in 70% yield.

[0121] The results of nuclear magnetic resonance spectroscopy analysis of 3-(tert-butyl)-5-(4-methoxyphenyl)inzazo[2,3-a]quinoline are shown below. Figure 9 , Figure 9 In this context, A is a product of 3-(tert-butyl)-5-(4-methoxyphenyl)inzazo[2,3-a]quinoline. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 9 B is a product of 3-(tert-butyl)-5-(4-methoxyphenyl)inzazo[2,3-a]quinoline.13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0122] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.95 (d, J = 8.9Hz, 1H), 8.06 (d, J = 8.2 Hz, 1H), 7.99 (d, J = 2.2 Hz, 1H), 7.97 (d, J = 8.5Hz, 1H), 7.88 (d, J = 8.1 Hz, 2H), 7.55 (dd, J = 8.7, 6.6 Hz, 3H), 7.26 –7.21 (m, 1H), 7.11 (d, J = 8.4 Hz, 2H), 3.94 (s, 3H), 1.38 (s, 9H). 13 C NMR(101 MHz, CDCl3) δ 159.65, 149.44, 149.09, 135.85, 132.38, 131.93, 131.16,131.12, 128.05, 127.66, 124.36, 123.29, 120.52, 119.90, 117.27, 117.01,116.59, 115.52, 114.19, 55.56, 35.19, 31.51.

[0123] The structural formula of the prepared 3-(tert-butyl)-5-(4-methoxyphenyl)inzazo[2,3-a]quinoline compound is as follows:

[0124]

[0125] Example 13:

[0126] 7-Methyl-2-phenylimidazo[1,2-a]pyridine (0.2 mmol, 41.6 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 1-(trifluoromethyl)-4-vinylbenzene (0.4 mmol, 68.9 mg) were injected into the reaction tube using a syringe. The reaction mixture was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was complete (tracked by TLC), the residue obtained by rotary evaporation was purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product, 10-methyl-5-(4-(trifluoromethyl)phenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 62% yield.

[0127] The results of nuclear magnetic resonance spectroscopy analysis of 10-methyl-5-(4-(trifluoromethyl)phenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine are shown in [reference]. Figure 10 , Figure 10 In this context, A is a product of 10-methyl-5-(4-(trifluoromethyl)phenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 10 B is a product of 10-methyl-5-(4-(trifluoromethyl)phenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum; Figure 10 C is a product of 10-methyl-5-(4-(trifluoromethyl)phenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 19 F nuclear magnetic resonance (F) 19 F-NMR spectrum.

[0128] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.92 (d, J = 8.1Hz, 1H), 8.39 (d, J = 6.9 Hz, 1H), 7.92 (d, J = 8.4 Hz, 1H), 7.83 (s, 1H), 7.79 (d, J = 7.9 Hz, 2H), 7.70 (t, J= 7.9 Hz, 3H), 7.64 (s, 1H), 7.55 (t, J = 7.6 Hz, 1H), 6.81 (d, J = 6.9 Hz, 1H), 2.52 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 148.33, 145.05, 141.38, 139.56, 132.86, 130.89, 130.23, 129.58 (q, J C-F = 32.5 Hz), 127.02, 126.75, 126.61, 126.26, 125.44 (q, J C-F = 3.7 Hz), 124.46 (q, J C-F = 272.7 Hz), 123.78, 123.66, 123.50, 116.43, 114.46, 111.30,22.07. 19 F NMR (376 MHz, CDCl3) δ -62.31.

[0129] The structural formula of the prepared 10-methyl-5-(4-(trifluoromethyl)phenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0130]

[0131] Example 14:

[0132] 7-Methyl-2-phenylimidazo[1,2-a]pyridine (0.2 mmol, 41.6 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 2-vinylnaphthalene (0.4 mmol, 61.7 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product, 10-methyl-5-(naphth-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 66% yield.

[0133] The results of nuclear magnetic resonance spectroscopy analysis of 10-methyl-5-(naphth-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine are shown in [reference]. Figure 11 , Figure 11 In this context, A represents the product of 10-methyl-5-(naphth-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 11 B is a product of 10-methyl-5-(naphth-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0134] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.93 (d, J = 8.1Hz, 1H), 8.37 (d, J = 6.9 Hz, 1H), 8.03 (d, J = 6.6 Hz, 2H), 8.00 – 7.94 (m,2H), 7.92 (s, 2H), 7.74 – 7.68 (m, 2H), 7.64 (s, 1H), 7.58 – 7.54 (m, 2H),7.52 (d, J = 7.5 Hz, 1H), 6.78 (d, J = 6.9 Hz, 1H), 2.51 (s, 3H). 13C NMR (101MHz, CDCl3) δ 148.10, 140.98, 139.27, 138.86, 134.47, 133.59, 132.68, 130.79,129.09, 128.96, 128.16, 127.91, 127.81, 127.20, 126.99, 126.57, 126.53,126.23, 126.02, 123.93, 123.67, 123.38, 116.34, 114.29, 111.37, 22.06.

[0135] The structural formula of the prepared 10-methyl-5-(naphth-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0136]

[0137] Example 15:

[0138] 7-Methyl-2-phenylimidazo[1,2-a]pyridine (0.2 mmol, 41.6 mg), Acr + -MesClO4 - 0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 2-vinylthiophene (0.4 mmol, 44.1 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 10 / 1, v / v) as eluents to give a yellow solid product, 10-methyl-5-(thiophene-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 63% yield.

[0139] The results of nuclear magnetic resonance spectroscopy analysis of 10-methyl-5-(thien-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine are shown in [reference]. Figure 12 , Figure 12 In this context, A represents a product of 10-methyl-5-(thiophen-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1H-NMR spectrum; Figure 12 B is a product of 10-methyl-5-(thiophen-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0140] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.89 (d, J = 8.1Hz, 1H), 8.38 (d, J = 6.9 Hz, 1H), 8.30 (d, J = 8.4 Hz, 1H), 7.99 (s, 1H), 7.72 (t, J = 7.4 Hz, 1H), 7.65 – 7.56 (m, 2H), 7.46 (d, J = 5.1 Hz, 1H), 7.29(d, J = 2.9 Hz, 1H), 7.24 – 7.20 (m, 1H), 6.79 (d, J = 6.9 Hz, 1H), 2.51 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 148.33, 142.38, 141.46, 139.56, 130.98,127.88, 127.48, 126.96, 126.87, 126.71, 126.35, 126.31, 125.70, 123.74,123.70, 123.37, 116.38, 114.42, 112.42, 22.05.

[0141] The structural formula of the prepared 10-methyl-5-(thiophen-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0142]

[0143] Example 16:

[0144] 7-Methyl-2-phenylimidazo[1,2-a]pyridine (0.2 mmol, 41.6 mg), Acr + -MesClO4 -0.014 mmol (5.8 mg) and Co(dmgH)₂Cl₂ (0.016 mmol, 5.8 mg) were added to a clean, dry, and sealed 25 mL Schlenk tube, and a stir bar was added. After purging the Schlenk tube with nitrogen, degassed DCE (4 mL) / HFIP (0.1 mL) and 2-vinylpyridine (0.4 mmol, 42.1 mg) were injected into the reaction tube using a syringe. The reaction system was then irradiated with a 3 W blue LED lamp and stirred at room temperature for 24 hours. After the reaction was completed (monitored by thin-layer chromatography), the reaction solution was evaporated to dryness using a rotary evaporator and purified by column chromatography using petroleum ether and ethyl acetate (PE / EA = 1 / 1, v / v) as eluents to give a yellow solid product, 10-methyl-5-(pyridin-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, in 45% yield.

[0145] The results of nuclear magnetic resonance spectroscopy analysis of 10-methyl-5-(pyridin-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine are shown in [reference]. Figure 13 , Figure 13 In this context, A represents a product of 10-methyl-5-(pyridin-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 H-NMR spectrum; Figure 13 B is a product of 10-methyl-5-(pyridin-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine. 13 C nuclear magnetic resonance (C10) 13 C-NMR spectrum.

[0146] The product was analyzed, and its characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.91 (d, J = 8.0Hz, 1H), 8.84 (d, J = 4.3 Hz, 1H), 8.42 (d, J = 6.9 Hz, 1H), 8.19 (d, J = 8.5Hz, 1H), 8.10 (s, 1H), 7.86 (t, J = 8.5 Hz, 1H), 7.74 – 7.67 (m, 2H), 7.63(s, 1H), 7.58 (t, J = 8.1 Hz, 1H), 7.39 – 7.35 (m, 1H), 6.78 (d,J = 6.8 Hz, 1H), 2.51 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 159.36, 150.00, 148.51, 141.80,139.55, 136.38, 132.73, 130.03, 127.17, 126.55, 126.41, 126.30, 125.67,123.96, 123.80, 123.50, 122.12, 116.39, 114.35, 112.05, 22.03.

[0147] The structural formula of the prepared 10-methyl-5-(pyridin-2-yl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is as follows:

[0148] .

[0149] This invention provides a method for synthesizing olefins and imidazopyridines via an oxidative dehydrogenation [4+2] cyclization reaction using a synergistic combination of a photo-redox catalyst and a cobalt oxime catalyst. The [4+2] cyclization reaction is achieved by adding a photo-redox catalyst and a cobalt oxime catalyst to imidazopyridine compounds and styrene compounds under photochemical conditions. This method does not use precious metal catalysts or chemical oxidants and the reaction conditions are mild.

[0150] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound, characterized in that, Includes the following steps: S1 photocatalytic reaction: Styrene compounds, imidazole heterocyclic compounds, solvents, photo-redox catalysts, and cobalt oxime catalysts were added to reaction tubes, nitrogen gas was introduced, and the mixtures were reacted under light source irradiation to obtain a mixed initial solution. The cobalt oxime catalyst is Co(dmgH)2Cl2; The photo-oxidation-reduction catalyst is Acr + -MesClO4 - ; The structure of imidazole heterocyclic compounds is as follows: ； R1 is methyl, methoxy, or fluorine, and R2 is -Me, -... at the para position of the benzene ring. n Any one of Pr, -OCH3, -Ph or -CN, -CF3, -F, -Cl, -Br; The structures of styrene compounds are as follows: ； R3 is -CH3, - t Bu, - n Bu, Ph, or any one of -CF3, -F, -Cl, -Br; S2 separation and purification: The mixed initial solution was separated and purified to obtain naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compounds; The structure of the naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound is as follows: 。 2. The method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound as described in claim 1, characterized in that, The molar ratio of the imidazole heterocyclic compound to the styrene compound is 1:

2.

3. The method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound as described in claim 1, characterized in that, The solvent is a mixed solvent system of 1,2-dichloroethane and hexafluoroisopropanol, with a volume ratio of 3.4-4.6 : 0.1 mL.

4. The method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound as described in claim 1, characterized in that, The separation and purification process employs at least one of column chromatography and recrystallization, with the mixing reaction occurring at room temperature.

5. The method for synthesizing a naphtho[1',2'4,5]imidazo[1,2-a]pyridine fluorescent compound as described in claim 1, characterized in that, The molar ratio of the imidazole heterocyclic compound to the styrene compound, the cobalt oxime catalyst, and the photoredox catalyst is 95-150:187-226:5.6-9.2:5.4-8.7.

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