Synthesis process of pyridine carbazole compound

Abstract

The invention discloses a synthesis process of a pyridine carbazole compound. Under the protection of nitrogen, a cyano carbazole compound is subjected to a redox reaction under the combined action of blue light, alkali, 4-cyanopyridine, TPP and a sacrificial agent DIPEA to form a pyridine carbazole compound; wherein the cyano carbazole compound is a derivative with a substituent R1 on a carbazole aromatic ring of 4CzIPN, and the substituent R1 is H, a methoxy group, a tertiary butyl group or a phenyl group; the alkali is inorganic alkali; according to the process, heteroarylation modification of the cyano carbazole photocatalyst is realized for the first time, the reaction yield is high, and the process has the characteristics of low cost, environment friendliness and safety in operation.

Description

Technical Field

[0001] The invention relates to the technical field of organic photocatalyst synthesis, and in particular to a synthesis process of pyridinecarbazole compounds. Background Art

[0002] Photocatalysis is considered to be one of the clean and green organic synthesis methods and is widely used in free radical chemistry. Traditional cyanocarbazole compounds contain carbazole groups as electron donors and cyanobenzene skeletons as electron acceptors, thus forming a typical "donor-acceptor (DA)" structure, which has the function of a photocatalyst. It is of great significance to modify this type of skeleton and expand the redox window range of this type of compound to synthesize non-metallic photocatalysts with different redox potentials. At the same time, the product can also be added to organic light-emitting devices as a thermally activated delayed fluorescent material, which is conducive to the development of organic OLEDs. The specific methods are:

[0003] Method 1: Using cyanocarbazole catalysts as substrates and N,N-dimethylacetamide (DMA) as solvent, alkyl-modified cyanocarbazole compounds are generated.

[0004]

[0005] This method uses cheap and readily available alkyl carboxylic acid raw materials to achieve modification of the photocatalyst skeleton through photocatalysis, which is in line with the concept of green chemistry, but is limited to alkylation modification reactions.

[0006] Method 2: Using cyanocarbazole catalyst as substrate, acetonitrile as solvent, N,N-diisopropylmethylamine (DIPMA) as sacrificial agent and methyl source, methyl-modified cyanocarbazole compounds are generated.

[0007]

[0008] This method has fewer side reactions and a fast reaction time, but can only perform methyl or ethyl modifications.

[0009] Combining the above two methods, there is no literature in the prior art that provides a better synthesis method or process for arylation modification synthesis. Summary of the invention

[0010] In view of the above problems, the present invention aims to provide a synthesis process for arylation modification of cyanocarbazole compounds which has low cost, simple operation, no heavy metal involvement and mild reaction conditions.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows: a synthesis process of pyridine carbazole compounds, and the synthesis method thereof is as follows:

[0012]

[0013] The reaction is carried out under the conditions of a base, TPP, a sacrificial agent and a solvent; the base is an inorganic base; TPP is triphenylphosphine; the sacrificial agent is N,N-diisopropylethylamine DIPEA; the cyanocarbazole compound is a carbazole aromatic ring of 4CzIPN with a substituent R 1 The derivative, R 1 The substituents are H, methoxy, tert-butyl or phenyl.

[0014] In the synthesis method of the present invention, the molar ratio of the cyanocarbazole compound to 4-cyanopyridine is 1:10.

[0015] In the synthesis method of the present invention, the molar ratio of 4-cyanopyridine to the sacrificial agent is 1:2-10; the preferred molar ratio is 1:6; when the molar ratio of 4-cyanopyridine to the sacrificial agent is 1:6, the yield of the final product reaches the highest.

[0016] In the synthesis method of the present invention, the molar ratio of 4-cyanopyridine to the base is 2 to 5:1, and the preferred molar ratio is 5:1. When the molar ratio of 4-cyanopyridine to the base is 5:1, the yield of the final product reaches the highest.

[0017] In the synthesis method of the present invention, the molar ratio of the cyanocarbazole compound to TPP is 1 to 10:1, and the preferred molar ratio is 10:1; when the molar ratio of the cyanocarbazole compound to triphenylphosphine is 10:1, the yield of the final product reaches the highest.

[0018] In the synthesis method of the present invention, the inorganic base is one of potassium carbonate, sodium carbonate, cesium carbonate, potassium phosphate, sodium hydroxide and sodium sulfite; the preferred base is sodium sulfite, and the yield of the final product reaches the highest.

[0019] In the synthesis method of the present invention, the wavelength of the blue light is 450nm, and a 15W blue light LED lamp is used.

[0020] The solvent in the synthesis method of the present invention is acetonitrile; the molar concentration of the cyanocarbazole compound in the reaction solvent is 0.01 mmol / mL.

[0021] In the synthesis method of the present invention, the reaction temperature is 10°C to 50°C, preferably 35°C; when the cyanocarbazole compound is 0.1 mmol, the reaction time is 36h to 72h, preferably 72h; the reaction time can be adjusted according to the amount of the reactants.

[0022] The method for refining pyridinecarbazole compounds of the present invention is as follows: after the reaction is completed, the pyridinecarbazole compounds are separated by column chromatography to obtain the refined pyridinecarbazole compounds.

[0023] The advantages of the present invention are: the present invention uses cyanocarbazole compounds and 4-cyanopyridine as reaction substrates, adopts cheap and readily available sodium sulfite as a base, and DIPEA as a sacrificial agent, and simply and efficiently synthesizes pyridinecarbazole compounds under green conditions without heating under illumination. Compared with other methods for modifying cyanocarbazole photocatalysts, the present invention realizes heteroarylation modification of cyanocarbazole photocatalysts for the first time, has a high reaction yield, and has the characteristics of low cost, environmental friendliness, and safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The H NMR spectrum of 3,4,6-tris(carbazol-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile described in Example 1;

[0025] Figure 2 The H NMR spectrum of 3,4,6-tris[3,6-bis(2-methylpropan-2-yl)carbazole-9-yl]-2-(pyridin-4-yl)benzene-1-carbonitrile described in Example 2;

[0026] Figure 3 The carbon NMR spectrum of 3,4,6-tris[3,6-bis(2-methylpropan-2-yl)carbazole-9-yl]-2-(pyridin-4-yl)benzene-1-carbonitrile described in Example 2;

[0027] Figure 4 The H NMR spectrum of 3,4,6-tris(3,6-diphenylcarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile described in Example 3;

[0028] Figure 5 This is the H NMR spectrum of 3,4,6-tris(2-methoxycarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile described in Example 4. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0030] The raw materials used in the following specific examples can all be purchased commercially, and each reagent is purified by means known in the art before use when necessary.

[0031] In the present invention, "cyanocarbazole compounds" have the meaning commonly understood by those skilled in the art, ie, compounds containing carbazole and cyanobenzene skeletons, such as 4CzIPN, 4CzPN and various derivatives thereof.

[0032] 1 H NMR and 13C NMR was measured using a Bruker Avance 400 spectrometer. The test temperature was room temperature, the solvent was deuterated chloroform, and the reference was selected: 1 H NMR:CHCl 3 7.260ppm; 13 C NMR:CHCl 3 It is 77.000ppm.

[0033] Example 1: Synthesis of 3,4,6-tris(carbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile

[0034] Add 4CzIPN (78.9 mg, 0.1 mmol), 4-cyanopyridine (104.0 mg, 1 mmol), triphenylphosphine (2.6 mg, 0.01 mmol), sodium sulfite (25.2 mg, 0.02 mmol) to a 15 mL sample bottle equipped with a magnetic stirrer, cover the sample bottle cap, evacuate with an oil pump, flush with nitrogen, add acetonitrile MeCN (10.0 mL) to dissolve to form a solution of 4CzIPN, 4-cyanopyridine, triphenylphosphine and sodium sulfite, and add DIPEA (1.0 mL) under nitrogen protection. Irradiate with a blue light with a wavelength of 450 nm for 72 hours at room temperature with stirring. After the reaction is completed, remove the solvent in vacuo, concentrate by rotary evaporation, and then perform column chromatography to obtain 62.9 mg of 3,4,6-tris(carbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile with a yield of 93%.

[0035] Product 3,4,6-tris(carbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile: 1 H NMR (400MHz, CDCl3) δ8.31(s,2H),8.19(d,J=7.6Hz,2H),8.13(s,1H),7.74(d,J=6.4Hz,2H),7.65(d,J=5.6 Hz,2H),7.62–7.54(m,4H),7.45–7.39(m,2H),7.23–7.19(m,2H),7.14(d,J=4.4Hz,2H),7.09–6.98(m,10H).

[0036] Example 2: Synthesis of 3,4,6-tris[3,6-bis(2-methylpropane-2-yl)carbazole-9-yl]-2-(pyridin-4-yl)benzene-1-carbonitrile

[0037] 2,4,5,6-tetrakis[3,6-bis(2-methylpropane-2-yl)carbazole-9-yl]benzene-1,3-dicarbonitrile (123.6 mg, 0.1 mmol), 4-cyanopyridine (104.0 mg, 1 mmol), triphenylphosphine (2.6 mg, 0.01 mmol), sodium sulfite (25.2 mg, 0.02 mmol) were added to a 15 mL sample bottle equipped with a magnetic stirrer, the sample bottle cap was covered, vacuumed with an oil pump, flushed with nitrogen, acetonitrile MeCN (10.0 mL) was added to dissolve to form a solution of 2,4,5,6-tetrakis[3,6-bis(2-methylpropane-2-yl)carbazole-9-yl]benzene-1,3-dicarbonitrile, 4-cyanopyridine, triphenylphosphine and sodium sulfite, and DIPEA (1.0 mL) was added under nitrogen protection. The sample bottle was irradiated with a blue light with a wavelength of 450 nm for 72 hours under stirring at room temperature. After the reaction was completed, the solvent was removed in vacuo, concentrated by rotary evaporation, and then subjected to column chromatography to obtain 88.2 mg of 3,4,6-tris[3,6-bis(2-methylpropane-2-yl)carbazole-9-yl]-2-(pyridin-4-yl)benzene-1-carbonitrile with a yield of 87%.

[0038] Product 3,4,6-tris[3,6-bis(2-methylpropane-2-yl)carbazole-9-yl]-2-(pyridin-4-yl)benzene-1-carbonitrile: 1 H NMR(400MHz, CDCl3)δ8.43(d,J=5.4Hz,2H),8.20(s,2H),8.09(s,1H),7.66–7.61(m,2H),7.59–7.53(m,4H),7.4 6(s,2H),7.37(d,J=5.4Hz,2H),6.89–6.78(m,7H),6.67–6.63(m,2H),1.51(s,18H),1.32(s,18H),1.31(s,18H). 13 C NMR (101MHz, CDCl3) δ149.8,146.3,144.5,143.7,143.2,142.5,142.1,138.8,137.3,136.9,132.4,130.6,124.5, 124.2,124.0,123.8,123.6,122.7,116.9,115.5,115.5,114.9,111.4,109.5,108.8,34.9,34.5,34.4,32.0,31.8.

[0039] Example 3: Synthesis of 3,4,6-tris(3,6-diphenylcarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile

[0040] Add 2,4,5,6-tetrakis(3,6-diphenylcarbazole-9-yl)benzene-1,3-dicarbonitrile (139.7 mg, 0.1 mmol), 4-cyanopyridine (104.0 mg, 1 mmol), triphenylphosphine (2.6 mg, 0.01 mmol), sodium sulfite (25.2 mg, 0.02 mmol) to a 15 mL sample bottle equipped with a magnetic stirrer, cover the sample bottle cap, evacuate with an oil pump, flush with nitrogen, add acetonitrile MeCN (10.0 mL) to dissolve to form a solution of 2,4,5,6-tetrakis(3,6-diphenylcarbazole-9-yl)benzene-1,3-dicarbonitrile, 4-cyanopyridine, triphenylphosphine and sodium sulfite, and add DIPEA (1.0 mL) under nitrogen protection. Irradiate with a blue light lamp with a wavelength of 450 nm for 72 hours at room temperature with stirring. After the reaction was completed, the solvent was removed in vacuo, and the mixture was concentrated by rotary evaporation and then subjected to column chromatography to obtain 63.8 mg of 3,4,6-tris(3,6-diphenylcarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile with a yield of 56%.

[0041] Product 3,4,6-tris(3,6-diphenylcarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile: 1 H NMR (400MHz, CDCl3) δ8.48–8.43(m,4H),8.31(s,1H),7.94(s,2H),7.88–7.84(m,4H),7.79–7. 73(m,6H),7.55–7.48(m,12H),7.43–7.36(m,10H),7.34–7.27(m,12H),7.10(d,J=8.4Hz,2H).

[0042] Example 4: Synthesis of 3,4,6-tris(2-methoxycarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile

[0043] Add 2,4,5,6-tetrakis(2-methoxycarbazole-9-yl)benzene-1,3-dicarbonitrile (90.8 mg, 0.1 mmol), 4-cyanopyridine (104.0 mg, 1 mmol), triphenylphosphine (2.6 mg, 0.01 mmol), sodium sulfite (25.2 mg, 0.02 mmol) to a 15 mL sample bottle equipped with a magnetic stirrer, cover the sample bottle cap, evacuate with an oil pump, flush with nitrogen, add acetonitrile MeCN (10.0 mL) to dissolve to form a solution of 2,4,5,6-tetrakis(2-methoxycarbazole-9-yl)benzene-1,3-dicarbonitrile, 4-cyanopyridine, triphenylphosphine and sodium sulfite, and add DIPEA (1.0 mL) under nitrogen protection. Irradiate with a blue light lamp with a wavelength of 450 nm for 72 hours at room temperature with stirring. After the reaction was completed, the solvent was removed in vacuo, the mixture was concentrated by rotary evaporation and then subjected to column chromatography to obtain 48.1 mg of 3,4,6-tris(2-methoxycarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile with a yield of 63%.

[0044] Product 3,4,6-tris(2-methoxycarbazole-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile: 1 H NMR (400MHz, CDCl3) δ8.33–8.28(s,1H),8.11–8.01(m,3H),7.82–7.34(m,9H),7.25–6. 93(m,9H),6.87–6.67(m,1H),6.65–6.28(m,3H),4.01(m,3H),3.59(m,3H),3.20(m,3H).

[0045]

[0046]

[0047] As can be seen from Examples 1-4, the method of the present invention is based on readily available cyanocarbazole compounds, uses commercially available 4-cyanopyridine as a reaction reagent, uses cheap and readily available sodium sulfite as an inorganic base, and uses DIPEA as a sacrificial agent to simply and efficiently synthesize pyridinecarbazole compounds under green conditions without heating under illumination. Compared with other methods for modifying cyanocarbazole photocatalysts, the present invention can achieve arylation modification of cyanocarbazole photocatalysts, has a high reaction yield, and has the characteristics of low cost, environmental friendliness, and safe operation.

[0048] Example 5: Optimization of Synthesis Conditions of 3,4,6-Tris(carbazol-9-yl)-2-(pyridin-4-yl)benzene-1-carbonitrile

[0049]

[0050] Standard conditions: 1 0.1 mmol (1.0 eq.), base 0.2 mmol (2 eq.), triphenylphosphine 0.01 mmol (0.1 eq.), solvent 10.0 mL, 30 °C, isolated yield.

[0051] DBU = 1,8-diazobispiro[5.4.0]undec-7-ene.

[0052] It should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any combination or equivalent transformation made on the basis of the above embodiments shall fall within the protection scope of the present invention.

Claims

1. A synthesis process for pyridinecarbazole compounds, characterized in that: The synthesis method of the process is as follows: The reaction is carried out under the conditions of a base, TPP, a sacrificial agent and a solvent; the base is an inorganic base; TPP is triphenylphosphine; the sacrificial agent is N,N-diisopropylethylamine DIPEA; The cyanocarbazole compound is a derivative of the carbazole aromatic ring of 4CzIPN with a substituent R1, and the substituent R1 is H, methoxy, tert-butyl or phenyl.

2. The synthesis process according to claim 1, characterized in that In the synthesis method, the molar ratio of the cyanocarbazole compound to 4-cyanopyridine is 1:

10.

3. The synthesis process according to claim 1, characterized in that In the synthesis method, the molar ratio of 4-cyanopyridine to the sacrificial agent is 1:2-10, and the preferred molar ratio is 1:

6.

4. The synthesis process according to claim 1, characterized in that In the synthesis method, the molar ratio of 4-cyanopyridine to the base is 2 to 5:1, and the preferred molar ratio is 5:

1.

5. The synthesis process according to claim 1, characterized in that In the synthesis method, the molar ratio of the cyanocarbazole compound to TPP is 1 to 10:1, and the preferred molar ratio is 10:

1.

6. The synthesis process according to claim 1, characterized in that In the synthesis method, the inorganic base is one of potassium carbonate, sodium carbonate, cesium carbonate, potassium phosphate, sodium hydroxide and sodium sulfite; the preferred base is sodium sulfite.

7. The synthesis process according to claim 1, characterized in that The wavelength of the blue light in the synthesis method is 450nm.

8. The synthesis process according to claim 1, characterized in that The solvent in the synthesis method is acetonitrile; the molar concentration of the cyanocarbazole compound in the reaction solvent is 0.01 mmol / mL.

9. The synthesis process according to claim 1, characterized in that: In the synthesis method, the reaction temperature is 10°C to 50°C, preferably 35°C; when the cyanocarbazole compound is 0.1 mmol, the reaction time is 36h to 72h, preferably 72h.

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