1, 2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole and synthesis method thereof

Abstract

The invention discloses 1, 2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole and a synthesis method of the 1, 2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl) The method comprises the following steps: taking 3-nitrophthalic acid as an initial raw material, reacting trichloroisocyanuric acid with liquid bromine to obtain 1, 2-dibromo-3-nitrobenzene, reducing by stannous chloride to obtain 2, 3-dibromoaniline, carrying out diazotization reaction to obtain 2, 3-dibromophenylhydrazine, reacting with p-tert-butyl cyclohexanone, and reacting by using 2, 3-dichloro-5, 6-dibromophenylhydrazine to obtain 2, 3-dibromophenylhydrazine. The preparation method comprises the following steps: carrying out dehydrogenation on 2, 6-dicyanobenzoquinone to obtain 1, 2-dibromo-6-tert-butyl-9H-carbazole, and finally reacting the 1, 2-dibromo-6-tert-butyl-9H-carbazole with 4-tert-butyl iodobenzene to obtain the 1, 2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole. Due to the existence of a bromine atom functional group on the 1, 2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole, the further conversion of the compound has expandability, and the compound can be used as a material / drug molecule precursor in the fields of organic light-emitting semiconductors, pharmaceutical chemistry and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthetic chemistry and relates to 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole and a synthesis method thereof. Background Art

[0002] Carbazole and its derivatives are a class of substances with a wide range of applications. The carbazole skeleton is a component of many natural bioactive substances and drug molecules. Organic fluorescent molecules based on carbazole are also important main materials in the field of material chemistry such as polymer light-emitting diodes (PLEDs) and organic light-emitting devices (OLEDs). Since this type of molecule has a wide range of application value in the fields of medicine and materials, the synthesis, preparation and structural modification of carbazole and its derivatives have important research value.

[0003] Since carbazole was first discovered, many methods for synthesizing carbazole molecules have been developed. The Fischer-Borsche synthesis reaction is a very classic method for synthesizing carbazole, which is simple to operate, mild in conditions, low in cost, high in yield, and has high industrial production value. In 1883, Fischer and Jourdan first reported the use of this method for the synthesis of indole ring systems (Fischer E, Jourdan F. Berichte. Der. Deutschen. Chemischen. Gesellschaft., 1883, 16, 2241-2245.). The reaction uses phenylhydrazine and aldehyde / ketone as starting materials and heats and rearranges under acid catalysis to eliminate a molecule of ammonia, which can obtain 2- or 3-substituted indole compounds. Subsequently, in 1908, Borsche pointed out that the Fischer indole synthesis reaction could be applied to carbazole synthesis and reported on this (Borsche W. Justus. Liebigs. Annalen. Der. Chemie., 1908, 359, 49-80.). They synthesized a variety of tetrahydrocarbazoles by replacing one of the reaction substrates, the aldehyde / ketone, with cyclohexanone, verifying the feasibility of the reaction and the universality of the substrate. The tetrahydrocarbazole obtained by the reaction can then be oxidized and dehydrogenated to obtain carbazole compounds.

[0004] The difference between polyhalogenated carbazole and ordinary carbazole is that multiple hydrogen atoms on the carbazole skeleton are replaced by halogen atoms. The presence of halogen atoms enables the compound to be further transformed, thus having scalability in reaction; in addition, halogen atoms are often present in various drugs to enhance their pharmacological activity (Voskressensky L, Golantsov N, Maharramov A. Synthesis., 2016, 48, 615-643.). However, there are relatively few reports on the synthesis of polyhalogenated carbazole.

[0005] In 2015, Humne and Lokhande developed a simple, efficient and direct one-pot tetrahydrocarbazole iodination method (Naykode MS, Humne VT, Lokhande P DJ Org. Chem., 2015, 80, 2392-2396.). The reaction uses molecular iodine with DMSO as solvent to complete the iodination at 110°C. The reaction can be applied to various electron-deficient and electron-rich groups to obtain the desired iodinated carbazole with excellent yield and good regioselectivity. The researchers used tetrahydrocarbazole with chlorine atom substituents to successfully obtain iodine-chlorine mixed substituted carbazole. However, this method is limited by the activity of hydrogen atoms at different positions of carbazole, and can only obtain carbazole with specific high-activity sites.

[0006] In 2016, Zhou and Shi et al. reported an efficient intramolecular CH arylation reaction catalyzed by a bimetallic catalyst system Pd(OAc)2 / CuI for the synthesis of fluorocarbazoles from corresponding N-phenyl-2-haloaniline derivatives (Kong X, Zhang H, Cao C, et al. Bioorg. Med. Chem., 2016, 24: 1376-1383.). In 2019, the same research group synthesized a series of new compounds with two fluorine substituents at the 2nd and 4th positions of carbazole based on this method, and also evaluated the antibacterial activity of these compounds (Zhou SL, Tang HL, Yao M, et al. Chem. Pap., 2019, 73, 2477-2484.). This method requires the use of precious metal palladium, and the synthesis cost is relatively high; the fluorine atom substitution position of the synthesized polyfluorocarbazole depends on the fluorine atom substitution position of the reaction substrate, which limits the ability of this method to synthesize carbazoles with specific substitution positions (such as 1,2-difluorocarbazole). Summary of the invention

[0007] The object of the present invention is to provide 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole and a synthesis method thereof. The method uses cheap and readily available 3-nitrophthalic acid as a starting material, uses trichloroisocyanuric acid and liquid bromine to react to obtain 1,2-dibromo-3-nitrobenzene, then reduces it with stannous chloride to obtain 2,3-dibromoaniline, then obtains 2,3-dibromophenylhydrazine through diazotization, then reacts with p-tert-butylcyclohexanone and uses 2,3-dichloro-5,6-dicyanobenzoquinone for dehydrogenation to obtain 1,2-dibromo-6-tert-butyl-9H-carbazole, and then reacts with 4-tert-butyliodobenzene to obtain 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole.

[0008] The technical solution for achieving the purpose of the present invention is as follows:

[0009] 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole, the structural formula of which is:

[0010] The synthesis method of 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole, the synthesis route is as follows:

[0011]

[0012] The following steps are involved:

[0013] (1) Using bromotrichloromethane as a solvent, 3-nitrophthalic acid (I), trichloroisocyanuric acid and liquid bromine as reaction reagents, a free radical reaction is carried out under white light and blue light irradiation to synthesize 1,2-dibromo-3-nitrobenzene (II);

[0014] (2) using methanol as a solvent and 1,2-dibromo-3-nitrobenzene and stannous chloride hydrochloric acid solution as reaction reagents to reduce and obtain 2,3-dibromoaniline (III);

[0015] (3) 2,3-dibromoaniline reacts with hydrochloric acid to form a salt, then undergoes a diazotization reaction with an aqueous solution of sodium nitrite, and then is reduced with a hydrochloric acid solution of stannous chloride to obtain 2,3-dibromophenylhydrazine (IV);

[0016] (4) using methanol as a solvent, 2,3-dibromophenylhydrazine and p-tert-butylcyclohexanone as reaction reagents, and concentrated hydrochloric acid with a mass concentration of 35 to 38% as a catalyst, and performing a reflux reaction to obtain 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole (V);

[0017] (5) using toluene as solvent, 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole and 2,3-dichloro-5,6-dicyanobenzoquinone as reaction reagents, and dehydrogenating to obtain 1,2-dibromo-6-tert-butyl-9H-carbazole (VI);

[0018] (6) Using p-xylene as solvent, 1,2-dibromo-6-tert-butyl-9H-carbazole, 4-tert-butyl iodobenzene, and potassium carbonate as reaction reagents, and cuprous iodide as catalyst, reflux reaction was performed under an inert atmosphere to obtain 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole (VII).

[0019] Preferably, in step (1), the reaction temperature is 115-130° C., the reaction time is 60-72 hours, and the molar ratio of 3-nitrophthalic acid, trichloroisocyanuric acid, and liquid bromine is 1:2-2.5:4-6.

[0020] Preferably, in step (1), the post-reaction treatment method is: after the reaction liquid is cooled to room temperature, a saturated sodium sulfite solution is used to quench the reaction, the organic phase is separated and collected, the aqueous phase is extracted with dichloromethane, the organic phases are combined, extracted with saturated brine, and then the organic phases are collected and dried over anhydrous sodium sulfate, filtered, and the organic phases are collected, and concentrated by rotary evaporation under reduced pressure to obtain a crude product, and finally separated and purified by column chromatography, the eluent is ethyl acetate / petroleum ether = 1:9, to obtain 1,2-dibromo-3-nitrobenzene.

[0021] Preferably, step (2) is specifically as follows: 1,2-dibromo-3-nitrobenzene is dissolved in methanol, stannous chloride is dissolved in concentrated hydrochloric acid with a mass concentration of 35-38%, and then the hydrochloric acid solution of stannous chloride is slowly added dropwise to the methanol solution of 1,2-dibromo-3-nitrobenzene in a stirring state in an ice water bath, and reacted at room temperature for 2.5-4 hours, the molar ratio of 1,2-dibromo-3-nitrobenzene, stannous chloride and hydrochloric acid is 1:2.5-4:12.4-20, and the mass concentration of concentrated hydrochloric acid is 35-38%.

[0022] Preferably, in step (2), the post-reaction treatment method is: the reaction solution is concentrated by rotary evaporation under reduced pressure to remove methanol, the pH of the remaining reaction solution is adjusted to neutral using a saturated sodium hydroxide solution, then extracted with ethyl acetate, and the organic phase is dried using anhydrous sodium sulfate, the organic phase is collected by filtration, and the crude product is concentrated by rotary evaporation under reduced pressure, and finally separated and purified by column chromatography, with the eluent being ethyl acetate / petroleum ether = 1:9, to obtain 2,3-dibromoaniline.

[0023] Preferably, step (3) is specifically as follows: 2,3-dibromoaniline and hydrochloric acid with a mass concentration of 15-25% are mixed and continuously stirred until a white slurry is formed, and then a sodium nitrite solution is slowly added dropwise in an ice-water bath to react until the reaction liquid is dissolved and clear; stannous chloride is dissolved in concentrated hydrochloric acid with a mass fraction of 35-38%, and the hydrochloric acid solution of stannous chloride is added dropwise to the dissolved and clear reaction liquid in an ice-water bath, and the reaction is carried out at room temperature for 2-4 hours, and the molar ratio of 2,3-dibromoaniline, sodium nitrite and stannous chloride is 1:1-1.1:2-2.5.

[0024] Preferably, in step (3), the post-reaction treatment method is: extracting the reaction solution with ethyl acetate, retaining the aqueous phase, then adjusting the pH to neutral with a saturated sodium hydroxide solution, extracting with ethyl acetate, retaining the organic phase, and drying the organic phase with anhydrous sodium sulfate after extraction, filtering and collecting the organic phase, and concentrating by reduced pressure rotary evaporation to obtain 2,3-dibromophenylhydrazine.

[0025] Preferably, in step (4), the reflux reaction temperature is 80 to 100° C., and the reflux reaction time is 2.5 to 4 hours.

[0026] Preferably, in step (4), the post-reaction treatment method is: after the reaction liquid is cooled to room temperature, it is concentrated by rotary evaporation under reduced pressure, dissolved with ethyl acetate, extracted with saturated sodium carbonate solution and saturated brine respectively, after extraction, the organic phase is dried with anhydrous sodium sulfate, the organic phase is collected by filtration, and concentrated by rotary evaporation under reduced pressure to obtain a crude product 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole.

[0027] Preferably, step (5) is specifically as follows: 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole and 2,3-dichloro-5,6-dicyanobenzoquinone are dissolved in toluene respectively, and the toluene solution of 2,3-dichloro-5,6-dicyanobenzoquinone is added dropwise to the toluene solution of 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole under an ice-water bath, followed by reaction at room temperature for 3 to 5 hours, wherein the molar ratio of 2,3-dibromophenylhydrazine, p-tert-butylcyclohexanone and 2,3-dichloro-5,6-dicyanobenzoquinone is 1:1 to 1.2:2 to 2.5.

[0028] Preferably, in step (5), the post-reaction treatment method is: filtering the insoluble matter in the reaction solution with short silica gel, washing with ethyl acetate, concentrating the filtrate under reduced pressure by rotary evaporation, and then separating and purifying by column chromatography, the eluent is dichloromethane / petroleum ether = 1:9, to obtain 1,2-dibromo-6-tert-butyl-9H-carbazole.

[0029] Preferably, in step (6), the reflux reaction temperature is 140-160° C., the reflux reaction time is 24-48 hours, the inert atmosphere is a nitrogen atmosphere, and the molar ratio of 1,2-dibromo-6-tert-butyl-9H-carbazole, 4-tert-butyl iodobenzene, potassium carbonate, and cuprous iodide is 1:4-6:3-5:0.2-0.5.

[0030] Preferably, in step (6), the post-reaction treatment method is: after the reaction liquid is cooled to room temperature, the insoluble matter is filtered through short silica gel, and after rinsing with ethyl acetate, the filtrate is concentrated by rotary evaporation under reduced pressure, and then separated and purified by column chromatography and pulping, the eluent is dichloromethane / petroleum ether = 1:9, and the mixed solvent used for pulping consists of dichloromethane and methanol, to obtain 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole of the present invention is a new compound. The presence of the bromine atom functional group on the molecule facilitates subsequent transformation and has potential value for application in the synthesis of drug and organic optoelectronic material molecules. For example, the compound can be coupled with 1,3,5,7,8-pentamethyl-2,6-diethyl-4,4-difluoro-4-boron-(3a,4a)-diaza-s-indole (CAS: 1394861-86-9) through the Sonogashira reaction to obtain a fluorescent molecule for use in OLED materials or biomedical imaging fields; the compound can also be further modified to synthesize a metal organic complex luminescent material.

[0033] (2) The synthesis route of the present invention does not use precious metal catalysts, which significantly saves costs. The bromination positions of the synthesized carbazole are positions 1 and 2, which have low reaction activity and are difficult to react.

[0034] (3) The present invention adopts a six-step synthesis reaction, each step of the reaction is stable and reliable, each step of the reaction can be scaled up to the gram scale, and the product is easy to obtain and purify, which shows the practicality of the synthesis route and lays a foundation for further scale-up of the synthesis route. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 For compound II 1 H NMR spectrum.

[0036] Figure 2 For compound II 13 C NMR spectrum.

[0037] Figure 3 For compound III 1 H NMR spectrum.

[0038] Figure 4 For compound IV 1 H NMR spectrum.

[0039] Figure 5 For compound IV 13 C NMR spectrum.

[0040] Figure 6 For compound VI 1 H NMR spectrum.

[0041] Figure 7 For compound VI 13 C NMR spectrum.

[0042] Figure 8 For compound VII 1 H NMR spectrum.

[0043] Fig. 9 For compound VII 13 C NMR spectrum. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below with reference to specific embodiments.

[0045] Example 1

[0046] (1) Synthesis of 1,2-dibromo-3-nitrobenzene:

[0047]

[0048] In a 500 mL round-bottom flask, a magnetic stirrer, 3-nitrophthalic acid (I) (70 mmol, 1 eq.), trichloroisocyanuric acid (2 eq.), bromochloromethane (140 mL) as a solvent were added to dissolve, and finally liquid bromine (4 eq.) was added, and condensed and refluxed using a Graham type condenser, and irradiated with two light sources of blue and white 45W LEDs, and placed in a heating module at 120 ° C for 60 hours. After the reaction was completed, it was cooled to room temperature. The reaction was quenched with a saturated sodium sulfite solution. The organic phase was separated and collected, and the aqueous phase was extracted with dichloromethane. The organic phases were combined and extracted with saturated brine, and then the organic phases were collected and dried with anhydrous sodium sulfate. Filter, collect the organic phase, and concentrate under reduced pressure rotary evaporation to obtain a crude product. After that, it was separated and purified by column chromatography (eluent: ethyl acetate / petroleum ether = 1:9) to obtain a white solid product 1,2-dibromo-3-nitrobenzene (II) with a yield of 33%.

[0049] 1 H NMR (500MHz, CDCl3) δ7.84 (dd, J=8.1, 1.5Hz, 1H), 7.63 (dd, J=8.1, 1.5Hz, 1H), 7.34 (t, J=8.0Hz, 1H). 13 C NMR (126MHz, CDCl3) δ152.22,136.53,128.89,128.05,123.46,117.34.

[0050] (2) Synthesis of 2,3-dibromoaniline:

[0051]

[0052] In a 100 mL round-bottom flask, add a magnetic stirrer, dissolve 1,2-dibromo-3-nitrobenzene (II) (30 mmol, 1 eq.) in methanol (15 mL), dissolve stannous chloride (3 eq.) in concentrated hydrochloric acid (12.4 eq.) with a mass concentration of 38% to prepare a solution, and slowly drop the hydrochloric acid solution of stannous chloride into the stirred methanol solution of 1,2-dibromo-3-nitrobenzene in an ice-water bath. After the dropwise addition, remove the ice-water bath and react at room temperature for 3 hours. After the reaction is completed, the reaction solution is concentrated by vacuum rotary evaporation to remove methanol, and the pH of the remaining reaction solution is adjusted to a neutral solution using a saturated sodium hydroxide solution, and extracted with ethyl acetate. After extraction, the organic phase is dried over anhydrous sodium sulfate. The organic phase is collected by filtration and concentrated by vacuum rotary evaporation to obtain a crude product. After separation and purification by column chromatography (eluent: ethyl acetate / petroleum ether = 1:9), a white solid 2,3-dibromoaniline (III) is obtained with a yield of 87%.

[0053] 1 H NMR (500MHz, CDCl3) δ7.01 (dd, J=7.9, 1.6Hz, 1H), 6.95 (t, J=7.9Hz, 1H), 6.68 (dd, J=7.9, 1.5Hz, 1H), 4.07 (br, 2H).

[0054] (3) Synthesis of 2,3-dibromophenylhydrazine:

[0055]

[0056] First, in a 50mL round-bottom flask, add a magnetic stirrer, 2,3-dibromoaniline (III) (10mmol) and 18% hydrochloric acid (10mL), and continue stirring until the reaction solution is a white uniform slurry. Dissolve sodium nitrite (1eq., 10mmol) in 10mL of water. Slowly drop the sodium nitrite solution into the reaction solution in an ice-water bath. After the addition is complete, wait for the reaction solution to dissolve and then proceed to the second step. Dissolve stannous chloride (2eq., 20mmol) in 38% concentrated hydrochloric acid (6mL) to prepare a solution. Add the stannous chloride solution dropwise to the reaction solution in the first step in an ice-water bath. After the addition is complete, remove the ice-water bath and react at room temperature for 2 hours. After the reaction is completed, extract the reaction solution with ethyl acetate and retain the aqueous phase. Use saturated sodium hydroxide solution to adjust the pH of the solution to a neutral solution. Use ethyl acetate to extract and retain the organic phase. After extraction, dry the organic phase with anhydrous sodium sulfate. The organic phase was collected by filtration and concentrated by rotary evaporation under reduced pressure to obtain white solid 2,3-dibromophenylhydrazine (IV), which gradually oxidized to yellow when exposed to air. The yield was 74%.

[0057] 1H NMR(500MHz, CDCl3)δ7.12(t,J=7.9Hz,1H),7.05(m,2H),5.88(br,1H),3.66(br,2H).13C NMR (126MHz, CDCl3) δ149.52,128.96,125.45,122.98,110.57,109.63.

[0058] (4) Synthesis of 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole:

[0059]

[0060] In a 100mL round-bottom flask, add a magnetic stirrer, 2,3-dibromophenylhydrazine (IV) (15mmol, 1eq.), tert-butylcyclohexanone (1.1eq.), dissolve in methanol (30mL) as a solvent, add concentrated hydrochloric acid (1eq.) with a mass concentration of 38%, condense and reflux using a condenser, and place in a heating module at 100°C for 2.5 hours. After the reaction is completed, cool to room temperature. The reaction solution is concentrated by vacuum rotary evaporation, dissolved in ethyl acetate, and extracted with saturated sodium carbonate solution and saturated brine respectively. After extraction, the organic phase is dried over anhydrous sodium sulfate. The organic phase is collected by filtration and concentrated by vacuum rotary evaporation to obtain the crude product 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole (V), which can be put into the next step without separation.

[0061] (5) Synthesis of 1,2-dibromo-6-tert-butyl-9H-carbazole:

[0062]

[0063] Dissolve the crude product 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro-1H-carbazole (V) in a 100 mL round-bottom flask (with a magnetic stirrer). Take 15 mmol of 2,3-dibromophenylhydrazine added in step (4) as 1 eq. Weigh 2,3-dichloro-5,6-dicyanobenzoquinone (2 eq.), dissolve it in toluene, and drop the toluene solution of 2,3-dichloro-5,6-dicyanobenzoquinone into the round-bottom flask. Add the mixture dropwise under an ice-water bath and react. After the addition is complete, remove the ice-water bath and react at room temperature for 3.5 hours. Ensure that the total amount of toluene is 30 mL. After the reaction is completed, filter the insoluble matter in the reaction solution with short silica gel, rinse with ethyl acetate, and concentrate the filtrate by rotary evaporation under reduced pressure. The product was then separated and purified by column chromatography (eluent: dichloromethane / petroleum ether = 1:9) to obtain a white solid product, 1,2-dibromo-6-tert-butyl-9H-carbazole (VI). The total yield of the two-step reaction of step (4) and step (5) was 97%.

[0064] 1 H NMR (500MHz, CDCl3) δ8.21(br,1H),8.01(s,1H),7.87(d,J=8.2Hz,1H),7.56(dd,J=8.6,1.8Hz,1H),7.44(m,2H),1.44(s,9H). 13 C NMR (126MHz, CDCl3) δ143.71,139.75,137.45,124.99,123.96,123.46,123.25,120.63,119.98,116.82,110.69,106.65,34.81,31.94.

[0065] (6) Synthesis of 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole:

[0066]

[0067] In a 250 mL round-bottom flask, a magnetic stirrer, 1,2-dibromo-6-tert-butyl-9H-carbazole (VI) (15 mmol, 1 eq.), 4-tert-butyl iodobenzene (4 eq.), cuprous iodide (20 mol%) as a catalyst, potassium carbonate (4 eq.) as a base, p-xylene (75 mL) as a solvent, a condenser tube was installed, and after replacing the nitrogen atmosphere, the condensed water circulation was started, and the mixture was placed in a heating module at 150 ° C for 24 hours. After the reaction was completed, it was cooled to room temperature. The insoluble matter in the reaction solution was filtered through short silica gel, rinsed with ethyl acetate, and the filtrate was concentrated by rotary evaporation under reduced pressure. After that, it was separated and purified by column chromatography (eluent: dichloromethane / petroleum ether = 1:9) and beating (dichloromethane / methanol) to obtain a white solid product 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)-9H-carbazole (VII), and the yield was 92%. 1 H NMR(500MHz, CDCl3)δ8.06(d,J=1.5Hz,1H),7.96(d,J=8.2Hz,1H),7.53(m,3H),7.47(dd, J=8.7,1.8Hz,1H),7.29(d,J=8.4Hz,2H),7.01(d,J=8.7Hz,1H),1.43(s,9H),1.42(s,9H). 13CNMR(126MHz, CDCl3)δ151.93,144.02,141.93,139.55,135.31,129.41,125.85,125.19,12 4.90,124.51,123.65,121.54,119.85,115.95,110.67,106.61,34.91,34.81,31.97,31.56.

[0068] Comparative Example 1

[0069] This comparative example is basically the same as Example 1, except that carbon tetrachloride is used as the solvent in step (1). The yield is less than 10%.

[0070] Comparative Example 2

[0071] This comparative example is basically the same as Example 1, except that chloroform is used as the solvent in step (1). The yield is less than 10%.

[0072] Comparative Example 3

[0073] This comparative example is basically the same as Example 1, except that only white light is used for the reaction in step (1). The yield is 23%.

[0074] Comparative Example 4

[0075] This comparative example is basically the same as Example 1, except that ethanol (30 mL) is used as solvent in step (2), reduced iron powder (3 eq.) and concentrated hydrochloric acid (1.24 eq.) with a mass concentration of 38% are used as reaction reagents, and the reaction is refluxed at 85° C. for 2 hours. The yield is 50%.

[0076] Comparative Example 5

[0077] This comparative example is basically the same as Example 1, except that acetic acid is used as solvent in step (4) and hydrochloric acid is not added as catalyst. The two-step comprehensive yield after the dehydrogenation reaction of 2,3-dichloro-5,6-dicyanobenzoquinone is 26%.

[0078] Comparative Example 6

[0079] This comparative example is basically the same as Example 1, except that acetic acid is used as the solvent in step (4). The two-step comprehensive yield after the dehydrogenation reaction of 2,3-dichloro-5,6-dicyanobenzoquinone is 62%.

[0080] Comparative Example 7

[0081] This comparative example is basically the same as Example 1, except that 1,2-dichloroethane is used as the solvent in step (4). The two-step comprehensive yield after the dehydrogenation reaction of 2,3-dichloro-5,6-dicyanobenzoquinone is 45%.

[0082] Comparative Example 8

[0083] This comparative example is basically the same as Example 1, except that cesium carbonate is used as a base in step (6), the reaction is carried out for 12 hours, and the yield of 4-tert-butyl iodobenzene (1.5 eq.) is less than 5%.

[0084] Comparative Example 9

[0085] This comparative example is basically the same as Example 1, except that potassium tert-butoxide is used as a base in step (6), and the reaction is carried out for 12 hours to obtain 4-tert-butyl iodobenzene (1.5 eq.). The yield is 34%.

[0086] Comparative Example 10

[0087] This comparative example is basically the same as Example 1, except that sodium bicarbonate is used as a base in step (6), the reaction is carried out for 12 hours, and the yield of 4-tert-butyl iodobenzene (1.5 eq.) is less than 5%.

[0088] Comparative Example 11

[0089] This comparative example is basically the same as Example 1, except that the reaction in step (6) is carried out for 12 hours, and the yield of 4-tert-butyl iodobenzene (1.5 eq.) is 50%.

[0090] Comparative Example 12

[0091] This comparative example is basically the same as Example 1, except that the reaction in step (6) is carried out under air atmosphere for 12 hours, and the yield of 4-tert-butyl iodobenzene (1.5 eq.) is 45%.

[0092] Comparative Example 13

[0093] This comparative example is basically the same as Example 1, except that the equivalent of 4-tert-butyl iodobenzene in step (6) is changed to 1.5 eq. The yield is 53%.

[0094] Comparative Example 14

[0095] This comparative example is basically the same as Example 1, except that the equivalent of 4-tert-butyl iodobenzene in step (6) is changed to 2 eq. The yield is 66%.

Claims

1. 1,2-Dibromo-6-tert-butyl-9-(4-tert-butylphenyl)- 9H -Carbazole, characterized in that The structural formula is: .

2. The 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)- 9H -A method for synthesizing carbazole, characterized in that The following steps are involved: (1) Using bromotrichloromethane as solvent, 3-nitrophthalic acid, trichloroisocyanuric acid and liquid bromine as reaction reagents, a free radical reaction was carried out under white light and blue light to synthesize 1,2-dibromo-3-nitrobenzene; (2) Using methanol as solvent and 1,2-dibromo-3-nitrobenzene and stannous chloride hydrochloric acid solution as reagents, reduction is performed to obtain 2,3-dibromoaniline; (3) 2,3-dibromoaniline reacts with hydrochloric acid to form a salt, then undergoes a diazotization reaction with an aqueous solution of sodium nitrite, and then is reduced with a hydrochloric acid solution of stannous chloride to obtain 2,3-dibromophenylhydrazine; (4) Using methanol as solvent, 2,3-dibromophenylhydrazine and p-tert-butylcyclohexanone as reaction reagents, and concentrated hydrochloric acid with a mass concentration of 35-38% as catalyst, reflux reaction was performed to obtain 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro- 1H -carbazole; (5) Using toluene as solvent, 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro- 1H -carbazole and 2,3-dichloro-5,6-dicyanobenzoquinone as reaction reagents, dehydrogenation to obtain 1,2-dibromo-6-tert-butyl- 9H -carbazole; (6) Using p-xylene as solvent, 1,2-dibromo-6-tert-butyl 9H -carbazole, 4-tert-butyl iodobenzene, potassium carbonate as reaction reagents, cuprous iodide as catalyst, reflux reaction under inert atmosphere to obtain 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)- 9H -Carbazole.

3. The synthesis method according to claim 2, characterized in that In step (1), the reaction temperature is 115-130°C, the reaction time is 60-72 hours, and the molar ratio of 3-nitrophthalic acid, trichloroisocyanuric acid, and liquid bromine is 1:2-2.5:4-6.

4. The synthesis method according to claim 2, characterized in that In step (1), the post-reaction treatment method is: after the reaction liquid is cooled to room temperature, a saturated sodium sulfite solution is used to quench the reaction, the organic phase is separated and collected, the aqueous phase is extracted with dichloromethane, the organic phases are combined, extracted with saturated brine, and then the organic phases are collected and dried over anhydrous sodium sulfate, filtered, and the organic phases are collected, and concentrated by rotary evaporation under reduced pressure to obtain a crude product, and finally separated and purified by column chromatography, with the eluent being ethyl acetate / petroleum ether = 1:9, to obtain 1,2-dibromo-3-nitrobenzene.

5. The synthesis method according to claim 2, characterized in that Step (2) is specifically as follows: 1,2-dibromo-3-nitrobenzene is dissolved in methanol, stannous chloride is dissolved in concentrated hydrochloric acid with a mass concentration of 35-38%, and then the hydrochloric acid solution of stannous chloride is slowly added dropwise to the methanol solution of 1,2-dibromo-3-nitrobenzene in a stirring state in an ice water bath, and the mixture is reacted at room temperature for 2.5-4 hours. The molar ratio of 1,2-dibromo-3-nitrobenzene, stannous chloride and hydrochloric acid is 1:2.5-4:12.4-20, and the mass concentration of concentrated hydrochloric acid is 35-38%.

6. The synthesis method according to claim 2, characterized in that In step (2), the post-reaction treatment method is: the reaction solution is concentrated by rotary evaporation under reduced pressure to remove methanol, the pH of the remaining reaction solution is adjusted to neutral using a saturated sodium hydroxide solution, then extracted with ethyl acetate, and the organic phase is dried using anhydrous sodium sulfate, the organic phase is collected by filtration, and the crude product is concentrated by rotary evaporation under reduced pressure. Finally, the crude product is separated and purified by column chromatography, and the eluent is ethyl acetate / petroleum ether = 1:9 to obtain 2,3-dibromoaniline.

7. The synthesis method according to claim 2, characterized in that Step (3) is specifically as follows: 2,3-dibromoaniline and hydrochloric acid with a mass concentration of 15-25% are mixed and continuously stirred until a white slurry is formed, and then a sodium nitrite solution is slowly added dropwise thereto in an ice-water bath, and reacted until the reaction liquid is dissolved and clear; stannous chloride is dissolved in concentrated hydrochloric acid with a mass fraction of 35-38%, and the hydrochloric acid solution of stannous chloride is added dropwise to the dissolved and clear reaction liquid in an ice-water bath, and reacted at room temperature for 2-4 hours, wherein the molar ratio of 2,3-dibromoaniline, sodium nitrite and stannous chloride is 1:1-1.1:2-2.5; and the post-reaction treatment method is as follows: extracting the reaction liquid with ethyl acetate, retaining the aqueous phase, and then adjusting the pH to neutral with a saturated sodium hydroxide solution, extracting with ethyl acetate, retaining the organic phase, and drying the organic phase with anhydrous sodium sulfate after extraction, collecting the organic phase by filtration, and concentrating by rotary evaporation under reduced pressure to obtain 2,3-dibromophenylhydrazine.

8. The synthesis method according to claim 2, characterized in that In step (4), the reflux reaction temperature is 80-100°C, and the reflux reaction time is 2.5-4 hours; the post-reaction treatment method is: after the reaction solution is cooled to room temperature, it is concentrated by rotary evaporation under reduced pressure, dissolved with ethyl acetate, and extracted with saturated sodium carbonate solution and saturated brine respectively, after extraction, the organic phase is dried with anhydrous sodium sulfate, the organic phase is collected by filtration, and concentrated by rotary evaporation under reduced pressure to obtain a crude product 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro- 1H -Carbazole.

9. The synthesis method according to claim 2, characterized in that Step (5) is specifically: 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro- 1H -carbazole and 2,3-dichloro-5,6-dicyanobenzoquinone were dissolved in toluene. Under ice water bath, the toluene solution of 2,3-dichloro-5,6-dicyanobenzoquinone was added dropwise to 7,8-dibromo-3-(tert-butyl)-2,3,4,9-tetrahydro- 1H -carbazole toluene solution, then react at room temperature for 3 to 5 hours, the molar ratio of 2,3-dibromophenylhydrazine, p-tert-butylcyclohexanone, and 2,3-dichloro-5,6-dicyanobenzoquinone is 1:1~1.2:2~2.5; the post-reaction treatment method is: filter the insoluble matter in the reaction solution with short silica gel, rinse with ethyl acetate, and concentrate the filtrate by rotary evaporation under reduced pressure, and then separate and purify by column chromatography, the eluent is dichloromethane / petroleum ether = 1:9, to obtain 1,2-dibromo-6-tert-butyl- 9H -Carbazole.

10. The synthesis method according to claim 2, characterized in that In step (6), the reflux reaction temperature is 140-160°C, the reflux reaction time is 24-48 hours, the inert atmosphere is nitrogen atmosphere, 1,2-dibromo-6-tert-butyl- 9H -carbazole, 4-tert-butyl iodobenzene, potassium carbonate, and cuprous iodide have a molar ratio of 1:4~6:3~5:0.2~0.5; the post-reaction treatment method is as follows: after the reaction solution is cooled to room temperature, the insoluble matter is filtered through short silica gel, and after washing with ethyl acetate, the filtrate is concentrated by rotary evaporation under reduced pressure, and then separated and purified by column chromatography and pulping, the eluent is dichloromethane / petroleum ether = 1:9, and the mixed solvent used for pulping is composed of dichloromethane and methanol to obtain 1,2-dibromo-6-tert-butyl-9-(4-tert-butylphenyl)- 9H -Carbazole.

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