Preparation method of 1, 4-bis (9-carbazolyl) benzene

Abstract

The invention relates to a preparation method of 1, 4-bis (9-carbazolyl) benzene, and belongs to the technical field of organic synthesis.The preparation method comprises the steps that 1, 4-dichlorobenzene and carbazole serve as raw materials, [2-(2, 4, 6-triisopropyl-3-(4-methoxyphenyl) phenyl)-6-(2, 4, 6-trimethoxyphenyl) phenyl]-1, 4-bis (9-carbazolyl) phenyl]-1, 4-dichlorobenzene and carbazole serve as raw materials, and the raw materials are reacted in a solvent to obtain the 1, 4-bis (9- The method comprises the following steps: by taking 2-(2, 4, 6-triisopropylphenyl) phenyl)-dicyclohexylphosphine and {[2-(2, 4, 6-triisopropyl-3-(4-methoxyphenyl) phenyl)-6-(2, 4, 6-triisopropylphenyl) phenyl]-dicyclohexylphosphine} (allyl-eta 3) trifluoromethanesulfonic palladium (II) as catalysts, catalyzing carbon-nitrogen coupling to prepare 1, 4-bis (9-carbazolyl) benzene under the condition of an organic magnesium reagent and in the atmosphere of inert gas. The method disclosed by the invention has the advantages of low cost, simplicity and convenience in operation, high yield, good environmental friendliness and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for preparing 1,4-di(9-carbazolyl)benzene. Background Art

[0002] Polycarbazolyl organic compounds are often used in the research and use of organic optoelectronic materials, among which 1,4-di(9-carbazolyl)benzene is a common chemical component of OLED devices. The traditional preparation method is to use the copper-catalyzed Ullmann reaction, but the reaction temperature is high, the amount of Cu catalyst is large, and the presence of heavy metal residues leads to insufficient product purity and cannot meet the requirements of many optoelectronic materials.

[0003] In the 1990s, palladium-catalyzed CN coupling reactions gradually entered the field of vision of chemists, especially Professor Hartwig and Professor Buchwald of MIT who conducted the most in-depth research on this type of reaction. Currently, this type of palladium-catalyzed CN coupling reaction is also called Buchwald-Hartwig coupling amination reaction, which has been widely used in the amination reaction of aryl halides. Currently, there are few literature reports on palladium-catalyzed coupling reactions of carbazole and aryl halides. For details, see [1) G. Mann, et al., j. Am. Chem. Soc., 1998, 120, 827; 2) JF Hartwig, et al., j. Org. Chem., 1999, 64, 5575; 3) DW Old, et al., Org. Lett., 2002, 2, 1403; 4) M. Watanabe, et al., Tetrahedron Lett., 2000, 41, 481; 5) GA. Grasa, et al., J. Org. Chem., 2001, 66, 7729; 6) K. Suzuki, et al., Adv. Synth. Catal., 2008, 350, 652]. The main reason is the P-π conjugation between the N atom and the benzene ring in carbazole, which makes the nucleophilic ability of the N atom low. In these reported literatures, the amount of catalyst used is often as high as 5%.

[0004] With the gradual improvement of synthesis technology, in 2013, Japan's Takasago Company described in patent WO2013032035A1 that the phosphine ligand (2,2-diphenyl-1-methyl-cyclopropyl-1)-di-tert-butylphosphine (cBRIDP) developed by the company performed better than the biphenyl phosphine ligand developed by Buchwald et al. of MIT in the palladium-catalyzed coupling reaction of carbazole and chloroaryl hydrocarbons. This technology is currently the world's most advanced technology for preparing N-aryl carbazole derivatives. Takasago's patents and literature (Y. Nakayama, et al., Adv. Synth. Catal. 2015, 357, 322) describe: Under heating reflux at 110°C, a catalytic system of 0.3 mol% allylpalladium chloride and 0.6 mol% cBRIDP phosphine ligand is used to catalyze the reaction of 1,4-dichlorobenzene with carbazole, and 3.06 equivalents of methylmagnesium chloride is used as a base to obtain 1,4-di(9-carbazolyl)benzene with a yield of 95%.

[0005] In 2018, the domestic Dongguan Juncheng High-tech Materials Co., Ltd. disclosed in patent CN 111039923A that 2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine (TXPhos) has excellent performance in the palladium-catalyzed CN coupling reaction of primary aromatic amines (a) F. Zhou, L. Zhang, J.-c. Shi, J. Catal. 402 (2021) 238-243) (b) F. Zhou, L. Zhang, W. Hu, B. Yuan, J.-c. S hi, J. Catal. 422 (2023) 36-42), significantly broadened the substrate range and reduced the catalyst dosage, and broke through the range of bases. In many reactions, KHCO3 and KOAc are the best base choices. Its performance in the CN coupling reaction of secondary aromatic amines is also extremely excellent. It is the best supporting ligand for many substrates including carbazole (CN111056986A, CN111039848A and CN111039923A). However, the catalyst dosage of Pd in ​​this patent is still relatively high.

[0006] Since palladium metal is scarce and expensive, developing coupling reaction processes with low catalyst usage is an important topic in green chemistry research. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes a novel method for preparing 1,4-di(9-carbazolyl)benzene.

[0008] The invention uses a new phosphine ligand and a palladium complex thereof as a new catalyst to catalyze the CN coupling between 1,4-dichlorobenzene and carbazole to prepare a method for 1,4-di(9-carbazolyl)benzene, wherein the synthesis method of the phosphine ligand is as follows: sodium phenolate, tetrahydrofuran and 4-methoxychlorobenzene are added to [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium chloride (II), heating for reaction, passing through diatomaceous earth after the reaction is complete, and then column chromatography to obtain the phosphine ligand. In the above reaction, [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium(II) chloride is activated under alkaline conditions of sodium phenolate to generate a zero-valent palladium species, which undergoes an oxidative addition reaction with 4-methoxychlorobenzene to generate [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](4-methoxyphenyl)palladium(II) chloride. Subsequently, under the reaction conditions, the hydrogen at the 3-position on one of the benzene rings containing a 2,4,6-triisopropyl group is activated by the action of the Pd complex formed by the oxidative addition, allowing it to react with 4-methoxychlorobenzene to finally generate TAlPhos.

[0009] The chemical name is [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (TAlPhos), and its structural formula is as follows:

[0010]

[0011] In the preparation method of the phosphine ligand, the temperature of the heating reaction is 80° C. and the time is 2 hours.

[0012] The preparation method of the phosphine ligand is as follows: add 860 mg of [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium(II) chloride into a pressure tube, add 116 mg of sodium phenolate, 2 mL of tetrahydrofuran and 142 mg of 4-methoxychlorobenzene, heat at 80° C. for 2 hours, pass through diatomaceous earth after the reaction is complete, and obtain the phosphine ligand by column chromatography.

[0013] The chemical name is {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium(II) (TAlPhos palladium complex), and its structural formula is as follows:

[0014]

[0015] The preparation method of TAlPhos palladium complex is as follows: allyl dimer palladium and silver trifluoromethanesulfonate are added into a dry pressure-resistant tube, tetrahydrofuran is added, and allyl trifluoromethanesulfonate palladium is generated after stirring at room temperature for 2 hours, and then [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine is added, and stirring is performed at room temperature for 2 hours to allow the phosphine ligand to fully complex with allyl trifluoromethanesulfonate palladium, and after the reaction is complete, the mixture is passed through diatomaceous earth and dried in a spin-drying manner to obtain the palladium complex of the phosphine ligand.

[0016] In the preparation method of the palladium complex of the phosphine ligand, the molar ratio of the allyl dimer palladium, silver trifluoromethanesulfonate and [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine is 1:2:2.

[0017] The preparation method of the palladium complex of the phosphine ligand is as follows: allyl dimer palladium (0.18 g, 0.5 mmol) and silver trifluoromethanesulfonate (0.26 g, 1.0 mmol) are added into a dry 15 mL pressure tube, 2 mL of tetrahydrofuran is added, and the mixture is stirred at room temperature for 30 min, and then [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.76 g, 1.0 mmol) is added, and the mixture is stirred for 2 h. After the reaction is complete, the mixture is passed through diatomaceous earth and dried to obtain the palladium complex of the phosphine ligand.

[0018] One of the technical solutions of the present invention:

[0019] The present invention also provides a 1,4-di(9-carbazolyl)benzene Preparation method: 1,4-dichlorobenzene and carbazole As a raw material, an organic magnesium reagent, the phosphine ligand and a palladium complex of the phosphine ligand are added to prepare the 1,4-di(9-carbazolyl)benzene through a carbon-nitrogen coupling (CN coupling) reaction.

[0020] Preferably, the method for preparing 1,4-di(9-carbazolyl)benzene comprises the following steps:

[0021] Under an inert atmosphere, a stirring bar is added to a dry Schlenk bottle, carbazole and xylene are added, the bottle is cooled to 5°C, an organomagnesium reagent is added dropwise, the reaction is stirred after the addition is completed, and the reaction is transferred to a glove box after the reaction is completed; in the glove box, 1,4-dichlorobenzene, the palladium complex of the phosphine ligand, the phosphine ligand and an organic solvent are added to another pressure tube, the reaction solution in the Schlenk bottle is transferred to the pressure tube at room temperature, the reaction is carried out under an oil bath, and the reaction is separated and purified after the reaction is completed to obtain the 1,4-di(9-carbazolyl)benzene.

[0022] The present invention uses a new phosphine ligand, namely, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (TAlPhos) and a palladium complex supported by the same, namely, {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (TAlPhos palladium complex), and increases the steric hindrance of the phosphorus atom on the phosphine ligand by adding a 4-methoxyphenyl group to the 3-position on the 2,4,6-triisopropylbenzene ring. As the steric hindrance of the phosphorus atom increases, the performance of the palladium catalyst is greatly improved compared with the prior art due to the principle that the dicyclohexyl group itself is electron-rich. Whether compared with the cBRIDP series ligand catalysts of Takasago Co., Ltd. or the terphenylphosphine TXPhos series catalysts in CN 111039923A, the method for preparing 1,4-di(9-carbazolyl)benzene by carbon-nitrogen coupling using 1,4-dichlorobenzene and carbazole as raw materials using the palladium catalyst of the present invention can not only greatly reduce the amount of palladium used, but also obtain 1,4-di(9-carbazolyl)benzene in high yield, thereby greatly reducing the cost.

[0023] Preferably, in the method for preparing 1,4-di(9-carbazolyl)benzene, the molar ratio of 1,4-dichlorobenzene to the palladium complex of the phosphine ligand is 1:0.0003.

[0024] Preferably, in the method for preparing 1,4-di(9-carbazolyl)benzene, the molar ratio of the phosphine ligand to the palladium complex of the phosphine ligand is (1-3):1.

[0025] Preferably, in the method for preparing 1,4-di(9-carbazolyl)benzene, the molar ratio of 1,4-dichlorobenzene to carbazole is 1:(2.0-2.2).

[0026] Preferably, in the method for preparing 1,4-di(9-carbazolyl)benzene, the molar ratio of carbazole to the organomagnesium reagent is 1:(1-1.1).

[0027] Preferably, in the preparation method of 1,4-di(9-carbazolyl)benzene, the organomagnesium reagent is RMgX; wherein R is selected from methyl or isopropyl; X is selected from chlorine or bromine; more preferably isopropylmagnesium bromide or methylmagnesium chloride.

[0028] Preferably, in the preparation method of 1,4-di(9-carbazolyl)benzene, the organic solvent is selected from at least one of tetrahydrofuran (THF), dioxane, toluene and xylene, and the organic solvent contains THF. That is, the present invention introduces the solvent tetrahydrofuran when adding the organomagnesium reagent, so the organic solvent here is preferably tetrahydrofuran and toluene or xylene; dioxane, tetrahydrofuran and toluene or xylene.

[0029] In the present invention, both isopropylmagnesium bromide and methylmagnesium chloride react with carbazole to generate the same N-Mg species and isopropane and methane respectively; the N-Mg species involved in the catalytic cycle are the same, so the difference in the types of these two Grignard reagents has no practical effect on the reaction process and results, and there is no significant difference in the yield of 1,4-di(9-carbazolyl)benzene.

[0030] Preferably, in the method for preparing 1,4-di(9-carbazolyl)benzene, when heating under reflux in an oil bath, the reaction temperature is 100-150°C, the reaction temperature is 6h, and more preferably the reaction temperature is 110°C.

[0031] The 1,4-di(9-carbazolyl)benzene prepared by the method of the present invention can be used in the fields of medicine or agricultural chemical products, organic photoconductor materials, organic electroluminescent element materials, etc. at low cost and high efficiency.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] The invention uses 1,4-dichlorobenzene and carbazole as raw materials, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine and {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) as catalysts, and catalyzes carbon-nitrogen coupling under the conditions of an organic magnesium reagent and an inert gas atmosphere to prepare 1,4-di(9-carbazolyl)benzene. The method of the invention has the advantages of low cost, simple operation, high yield, good environmental protection, etc., and has broad application prospects. DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0036] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0037] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0038] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0039] Unless otherwise specified, the room temperature in the present invention is 25±2°C.

[0040] In an embodiment of the present invention, the preparation method of [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (TAlPhos) is as follows: 860 mg of [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium(II) chloride is added to a pressure tube, 116 mg of sodium phenolate, 2 mL of tetrahydrofuran and 142 mg of 4-methoxychlorobenzene are added, and the mixture is heated at 80° C. for 2 h. After the reaction is complete, the mixture is passed through diatomaceous earth and TAlPhos is obtained by column chromatography, and its structural formula is as follows:

[0041]

[0042] In an embodiment of the present invention, the preparation method of {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium(II) (TAlPhos palladium complex) is as follows: allyl dimer palladium (0.18 g, 0.5 mmol), trifluoromethanesulfonate silver (0.26 g, 1.0 mmol) l) was added to a dry 15 mL pressure tube, 2 mL of tetrahydrofuran was added, and the mixture was stirred at room temperature for 30 min. Then, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.76 g, 1.0 mmol) was added and stirred for 2 h. After the reaction was complete, the mixture was passed through diatomaceous earth and dried in a spin-drying process to obtain a TAlPhos palladium complex having the following structural formula:

[0043]

[0044] In the examples of the present invention, except TAlPhos and TAlPhos palladium complex, other raw materials and solvents were purchased. As an example, carbazole CAS No. 86-74-8; xylene CAS No. 1330-20-7; tetrahydrofuran CAS No. 109-99-9; dioxane CAS No. 123-91-1; toluene CAS No. 108-88-3; methylmagnesium chloride CAS No. 676-58-4; isopropylmagnesium bromide CAS No. 920-39-8; 1,4-dichlorobenzene CAS No. 108-70-3; dodecane CAS No. 112-40-3; 4-methoxychlorobenzene CAS No. 824-94-2; [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium(II) chloride CAS No. 2376379-97-2; sodium phenolate CAS No. 139-02-6. Carbazole, xylene, tetrahydrofuran, dioxane, toluene, methylmagnesium chloride, isopropylmagnesium bromide, 1,4-dichlorobenzene, dodecane, 4-methoxychlorobenzene, [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium(II) chloride and sodium phenolate were purchased from Shanghai Titan Technology Co., Ltd.

[0045] The technical solution of the present invention is further illustrated by the following embodiments.

[0046] Example 1 Preparation of [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (TAIPhos)

[0047] 860 mg of [2,6-bis(2,4,6-triisopropyl-phenyl)phenyl-dicyclohexylphosphine](allyl-η3)palladium(II) chloride was added to a pressure tube, and 116 mg of sodium phenolate, 2 mL of tetrahydrofuran and 142 mg of 4-methoxychlorobenzene were added. The mixture was heated at 80°C for 2 h. After the reaction was complete, the mixture was filtered through diatomaceous earth and column chromatography was performed to obtain 0.62 g of TAlPhos with a yield of 78.98%. Melting point: 213.9-217.4°C. Its structural formula is as follows:

[0048]

[0049] 1 H NMR (400MHz, CDCl3) δ7.26-7.14 (m, 4H), 7.09 (dd, J=13.6, 7.5Hz, 2H), 7.03 (d, J=5.0Hz, 2H ), 6.91 (d, J=8.0Hz, 2H), 3.87 (s, 3H), 3.01 (p, j=9.7, 8.4Hz, 1H), 2.93 (p, j=7.0Hz, IH), 2.7 5 (dp, J=13.8, 6.9Hz, 2H), 2.63 (p, J=6.6Hz, 1H), 2.52 (p, j=6.7Hz, 1H), 1.79 (d, J=35.0Hz, 3H), 1.53 (s, 5H), 1.33 (dd, J=18.5, 6.8Hz, 19H), 1.22-0.74 (m, 31H), 0.67 (d, J=7.1Hz, 3H).

[0050] 13C NMR (101MHz, CDCl3) δ158.2, 148.5, 148.3, 147.5, 147.4, 147.2, 145.7, 145.4, 142.4, 140.5, 140.4, 139.3, 139.2, 137.7, 13 7.4, 137.3, 133.9, 132.9, 132.0, 132.0, 132.0, 131.9, 131.8, 131.8, 131.7, 126.3, 121.1, 120.9, 120.7, 119.5, 119.1, 112. 5, 112.2, 55.2, 34.5, 34.2, 34.1, 33.4, 33.2, 32.5, 31.9, 31.7, 31.7, 31.6, 31.1, 31.0, 31.0, 30.8, 30.7, 30.4, 30.3, 29.4, 27.6, 27.6, 27.3, 27.3, 27.2, 27.1, 27.0, 26.4, 26.3, 26.2, 25.9, 25.8, 24.4, 24.4, 24.3, 24.2, 24.1, 23.7, 23.4, 22.9, 22.9.

[0051] 31 P NMR (162 MHz, CDCl3) δ 10.1.

[0052] Example 2 Preparation of {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium(II) (TAlPhos palladium complex)

[0053] Allyl dimer palladium (0.18 g, 0.5 mmol) and silver trifluoromethanesulfonate (0.26 g, 1.0 mmol) were added to a dry 15 mL pressure tube, and 2 mL of tetrahydrofuran was added. The mixture was stirred at room temperature for 30 min, and then [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.76 g, 1.0 mmol) was added. The mixture was stirred for 2 h. After the reaction was complete, the mixture was passed through diatomaceous earth and dried in a spin-drying machine to obtain 1.07 g of TAlPhos palladium complex with a yield of 99.98%. The structural formula of the compound is as follows:

[0054]

[0055] 31 p NMR (162MHz, CDCl3) δ: 69.3.

[0056] Example 3 Preparation of 1,4-di(9-carbazolyl)benzene

[0057] Under an inert atmosphere (nitrogen, the same below), a stirring bar was added to a dry 50 mL Schlenk bottle, carbazole (0.552 g, 3.3 mmol) and xylene (3 mL) were added, and the bottle was cooled to 5 ° C. Methyl magnesium chloride (3.0 M in THF, 3.5 mmol, 1.15 mL) was added dropwise via a syringe (about 1.5 min). After the addition, the reaction was stirred for 15 min and transferred to a glove box for use.

[0058] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-1η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.23 mg, 0.0003 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of xylene were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110° C. for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether:ethyl acetate=10:1 (volume ratio, the same below)) to obtain 0.408 g of a white solid, which was 1,4-di(9-carbazolyl)benzene, with a yield of 99.98%.

[0059] 1 H NMR (400MHz, CDCl3)j: 8.19 (d, J=7.6Hz, 4H), 7.85 (s, 4H), 7.58 (d, J=8.2Hz, 4H), 7.50 (ddd,J=8.2, 7.0, 1.2Hz, 4H), 7.36 (ddd,J=7.8, 6.9, 0.9Hz, 4H).

[0060] 13 C NMR (101MHz, CDCl3)j: 140.8, 137.0, 128.4, 126.2, 123.5, 120.7, 120.6, 109.7.

[0061] Example 4 Preparation of 1,4-di(9-carbazolyl)benzene

[0062] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.552g, 3.3mmol) and xylene (3mL), cool to 5°C, add methylmagnesium chloride (3.0M in THF, 3.5mmol, 1.15mL) dropwise via a syringe (about 1.5min), stir and react for 15min, and transfer to a glove box for use.

[0063] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.46 mg, 0.0006 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of toluene were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110° C. for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.408 g of white solid, namely 1,4-di(9-carbazolyl)benzene, with a yield of 99.88%.

[0064] Example 5 Preparation of 1,4-di(9-carbazolyl)benzene

[0065] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.552g, 3.3mmol) and xylene (3mL), cool to 5°C, add methylmagnesium chloride (3.0M in THF, 3.5mmol, 1.15mL) dropwise via a syringe (about 1.5min), stir and react for 15min, and transfer to a glove box for use.

[0066] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.69 mg, 0.0009 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of tetrahydrofuran were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110°C for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.572 g of white solid, namely 1,4-di(9-carbazolyl)benzene, with a yield of 99.70%.

[0067] Example 6 Preparation of 1,4-di(9-carbazolyl)benzene

[0068] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.552g, 3.3mmol) and toluene (3mL), cool to 5°C, add methylmagnesium chloride (3.0M in THF, 3.5mmol, 1.15mL) dropwise via a syringe (about 1.5min), stir and react for 15min, and transfer to a glove box for use.

[0069] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.23 mg, 0.0003 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of xylene were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110° C. for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.408 g of white solid, namely 1,4-di(9-carbazolyl)benzene, with a yield of 99.88%.

[0070] Example 7 Preparation of 1,4-di(9-carbazolyl)benzene

[0071] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.507g, 3.0mmol) and xylene (3mL), cool to 5°C, add methylmagnesium chloride (3.0M in THF, 3.5mmol, 1.15mL) dropwise via a syringe (about 1.5min), stir and react for 15min, and transfer to a glove box for use.

[0072] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.23 mg, 0.0003 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of dioxane were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110°C for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.408 g of white solid, namely 1,4-dichlorobenzene, with a yield of 99.88%.

[0073] Example 8 Preparation of 1,4-di(9-carbazolyl)benzene

[0074] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.552g, 3.3mmol) and xylene (3mL), cool to 5°C, add isopropylmagnesium bromide (2.0M in THF, 3.5mmol, 1.75mL) dropwise via a syringe (about 1.5min), stir and react for 15min, and transfer to a glove box for use.

[0075] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.23 mg, 0.0003 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of xylene were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110° C. for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.408 g of white solid, namely 1,4-di(9-carbazolyl)benzene, with a yield of 99.88%.

[0076] Example 9 Preparation of 1,4-di(9-carbazolyl)benzene

[0077] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.552g, 3.3mmol) and tetrahydrofuran (3mL), cool to 5°C, add methylmagnesium chloride (3.0M in THF, 3.5mmol, 1.15mL) dropwise via a syringe (about 1.5min), stir and react for 15min after addition, and transfer to a glove box for use.

[0078] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.23 mg, 0.0003 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of xylene were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110° C. for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.570 g of a white solid, namely 1,4-di(9-carbazolyl)benzene, with a yield of 99.36%.

[0079] Example 10 Preparation of 1,4-di(9-carbazolyl)benzene

[0080] Under inert atmosphere, add a stirring bar to a dry 50mL Schlenk bottle, add carbazole (0.552g, 3.3mmol) and dioxane (3mL), cool to 5°C, add methylmagnesium chloride (3.0M in THF, 3.5mmol, 1.15mL) dropwise via a syringe (about 1.5min), stir and react for 15min, and transfer to a glove box for use.

[0081] In the glove box, 1,4-dichlorobenzene (0.147 g, 1.0 mmol), {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium (II) (0.33 mg, 0.0003 mmol) prepared in Example 2, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine (0.23 mg, 0.0003 mmol) prepared in Example 1, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of xylene were added to another pressure tube. The reaction solution in the Schlenk bottle was transferred to the pressure tube at room temperature, sealed, and heated under reflux in an oil bath at 110° C. for 6 h. The reaction solution was filtered through silica gel and diatomaceous earth, the filtrate was concentrated under reduced pressure, and the residue was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10: 1) to obtain 0.571 g of white solid, namely 1,4-di(9-carbazolyl)benzene, with a yield of 99.53%.

[0082] Different phosphine ligands [1] Preparation of 1,4-di(9-carbazolyl)benzene via CN coupling reaction [2] The dosage and yield are shown in Table 1, wherein No. 9 represents Example 3.

[0083] Table 1

[0084] serial number Phosphine ligand Palladium complex (mol%) Time (h) Yield (%) 1 TXPhos [(TXPhos)(allyl)PdOTf](0.05) 6 97.02 2 <![CDATA[ i PrTXPhos]]> <]]> 6 94.32 3 3-pentylTXPhos [(3-pentylTXPhos)(allyl)PdOTf](0.05) 6 95.49 4 TKPhos [(TKPhos)(allyl)PdOTf](0.05) 6 94.37 5 tBuXPhos [(tBuXPhos)(allyl)PdOTf](0.05) 6 31.89 6 BippyPhos [(BippyPhos)(ally1)PdOTf](0.05) 6 31.21 7 BRIDP [(cBRIDP)(allyl)PdOTf](0.05) 6 26.36 8 <![CDATA[DmpPMe2]]> <]]> 6 0 9 TAlPhos [(TAlPhos)(allyl)PdOTf](0.03) 6 99.98 [1]

[0086] [2] Under an inert atmosphere (nitrogen), add a stirring bar to a dry 50 mL Schlenk bottle, add carbazole (0.552 g, 3.3 mmol) and xylene (3 mL), cool to 5°C, add methylmagnesium chloride (3.0 M inTHF, 3.5 mmol, 1.15 mL) dropwise via a syringe (about 1.5 min), stir and react for 15 min, and transfer to a glove box for later use.

[0087] In the glove box, add 1,4-dichlorobenzene (0.147 g, 1.0 mmol), the corresponding palladium complex, the phosphine ligand, 0.13 mL of dodecane (as an internal standard for GC analysis) and 1 mL of xylene to another pressure tube. Transfer the reaction solution in the Schlenk bottle to the pressure tube at room temperature, seal it, and heat it in an oil bath under reflux at 110°C for 6 hours. Filter the reaction solution with silica gel and diatomaceous earth, concentrate the filtrate under reduced pressure, and separate and purify the residue by silica gel column chromatography (petroleum ether: ethyl acetate = 10:1) to obtain 1,4-di(9-carbazolyl)benzene.

[0088] 1 H NMR (400MHz, CDCl3)j: 8.19 (d, J=7.6Hz, 4H), 7.85 (s, 4H), 7.58 (d, J=8.2Hz, 4H), 7.50 (ddd,J=8.2, 7.0, 1.2Hz, 4H), 7.36 (ddd,J=7.8, 6.9, 0.9Hz, 4H).

[0089] 13 C NMR (101MHz, CDCl3)j: 140.8, 137.0, 128.4, 126.2, 123.5, 120.7, 120.6, 109.7.

[0090] As can be seen from Table 1, in the catalytic carbon-nitrogen coupling reaction of 1,4-dichlorobenzene and carbazole, TAlPhos and its palladium complex have significantly reduced the amount of palladium used compared with existing similar commercial catalysts and conventional triaryl phosphine ligand catalysts, and the amount used is only less than half of TXPhos. In addition, the catalytic effect is better than that of TXPhos, and the yield can reach 99.98%.

[0091] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing 1,4-di(9-carbazolyl)benzene, characterized in that: 1,4-dichlorobenzene and carbazole are used as raw materials, an organic magnesium reagent, [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine ligand and {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium(II) complex are added, and the 1,4-di(9-carbazolyl)benzene is prepared through a carbon-nitrogen coupling reaction. The chemical name is [2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine, and its structural formula is as follows: The chemical name is {[2-(2,4,6-triisopropyl-3-(4-methoxyphenyl)phenyl)-6-(2,4,6-triisopropylphenyl)phenyl]-dicyclohexylphosphine}(allyl-η3)trifluoromethanesulfonate palladium(II), and its structural formula is as follows:

2. The method for preparing 1,4-di(9-carbazolyl)benzene according to claim 1, characterized in that: The following steps are involved: Under an inert atmosphere, a stirring bar is added to a dry Schlenk bottle, carbazole and xylene are added, the bottle is cooled to 5°C, an organomagnesium reagent is added dropwise, the reaction is stirred after the addition is completed, and the bottle is transferred to a glove box after the reaction is completed; in the glove box, 1,4-dichlorobenzene, the palladium complex of the phosphine ligand according to claim 3, the phosphine ligand according to claim 1 and an organic solvent are added to another pressure tube, the reaction solution in the Schlenk bottle is transferred to the pressure tube at room temperature, the reaction is heated under reflux in an oil bath, and the reaction is separated and purified after the reaction is completed to obtain the 1,4-di(9-carbazolyl)benzene.

3. The method for preparing 1,4-di(9-carbazolyl)benzene according to claim 2, characterized in that: The molar ratio of 1,4-dichlorobenzene to the palladium complex of the phosphine ligand according to claim 3 is 1:0.0003.

4. The method for preparing 1,4-di(9-carbazolyl)benzene according to claim 2, characterized in that: The molar ratio of the phosphine ligand described in claim 1 to the palladium complex of the phosphine ligand described in claim 3 is (1-3):

1.

5. The method for preparing 1,4-di(9-carbazolyl)benzene according to claim 2, characterized in that: The molar ratio of 1,4-dichlorobenzene to carbazole is 1:(2.0-2.2).

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