Synthesis method of spirofluorene compound for OLED (Organic Light Emitting Diode)
By changing the cyclization site in the synthesis of spirofluorene compounds with OLED, the generation of isomerial impurities is avoided, the purity and yield of the product are improved, and the problems of purification difficulties and high cost in the prior art are solved. .
Patent Information
- Application Number
- CN202411535330.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-01-03
AI Technical Summary
In the synthesis route of spirobenzofluorenone compounds in the prior art, isomeric impurities are easily generated during the ring-closing reaction, resulting in low purity of the product, poor purification effect and high cost.
Suzuki reaction was carried out under the action of alkali and palladium catalyst, followed by Sandmeyer reaction under the action of inorganic acid, sodium nitrite, and copper salt, and then addition reaction with 2-bromototon ketone, and finally closed under acidic conditions. The ring reaction is to change the cyclization site to avoid the formation of isomeric impurities.
The high purity and high yield of spirofluorene compounds for OLED are achieved, and the subsequent processing steps are simplified and the cost is reduced.
Smart Images
Figure CN119241488A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of organic photoelectric materials, and in particular to a method for synthesizing spirofluorene compounds for OLED. Background Art
[0002] Organic electroluminescent devices have the advantages of autonomous luminescence, low voltage drive, full curing, wide viewing angle, simple composition and process, etc. Compared with liquid crystal displays, organic electroluminescent devices do not require backlight and have broad application prospects.
[0003] Organic electroluminescent devices generally include an anode, a metal cathode, and an organic layer sandwiched between the anode and the metal cathode. The organic layer mainly includes a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. In addition, the light-emitting layer mostly adopts a host-guest structure. That is, the luminescent material is doped in a certain concentration in the host material to avoid concentration quenching and triplet-triplet annihilation, thereby improving the luminous efficiency. Therefore, it is generally required that the host material has a higher triplet energy level and has higher stability at the same time.
[0004] Patents CN110835328A and KR1020210071271A disclose a spirobenzofluorenone derivative. The spirobenzofluorenone derivative has high thermal stability, good transmission performance, high triplet state, and simple preparation method. The organic light-emitting device made of the spirobenzofluorenone derivative exhibits the advantages of high luminous efficiency, long life, and low driving voltage, and is an organic electroluminescent material with excellent performance.
[0005] The important intermediate structure of this type of compound (a spirobenzofluorenone derivative) is as follows, and its chemical name is 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene]:
[0006]
[0007] The routes for synthesizing the above intermediates in patents CN110835328A and KR2021 / 71271 are as follows:
[0008]
[0009] However, in this synthetic route, during the last step of the ring-closing reaction, since both the 2nd and 8th positions of the naphthalene ring can react, isomeric impurities will be generated, and the structural formula is as follows:
[0010]
[0011] By NMR (NMR spectrum such as Figure 1As shown in the figure, it is confirmed that the impurity accounts for 16-17%; and because the physicochemical properties of the by-product are similar to those of the product, the purification effect is very poor and it is difficult to completely remove it, which not only affects the product quality, but also has a low yield and high cost due to multiple purifications. Summary of the invention
[0012] In view of this, the present invention provides a method for synthesizing spirofluorene compounds for OLED. The synthesis method provided by the present invention is not easy to produce isomeric impurities, and the product has high purity and high yield.
[0013] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0014] A method for synthesizing a spirofluorene compound for OLED comprises the following steps:
[0015] Under the action of a base and a palladium catalyst, 1-bromo-2-naphthylamine and phenylboronic acid are subjected to a Suzuki reaction in a solvent to obtain a first intermediate; the first intermediate has a structure shown in formula M-1;
[0016]
[0017] Under the action of inorganic acid, sodium nitrite and cuprous salt, the first intermediate and bromine salt are subjected to Sandmeyer reaction in a solvent to obtain a second intermediate; the second intermediate has a structure shown in formula M-2;
[0018]
[0019] Under the action of n-butyl lithium, the second intermediate and 2-bromoxanthone are subjected to an addition reaction in a solvent to obtain a third intermediate; the third intermediate has a structure shown in formula M-3;
[0020]
[0021] Under acidic conditions, the third intermediate is subjected to a ring-closing reaction in a solvent to obtain the spirofluorene compound for OLED; the structural formula of the spirofluorene compound for OLED is shown in Formula M;
[0022]
[0023] Preferably, the molar ratio of 1-bromo-2-naphthylamine to phenylboric acid is 1:(1.1-1.3);
[0024] The palladium catalyst is one or more of di-tert-butyl dichloro-(4-dimethylaminophenyl)phosphine palladium (II), tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium dichloride, Pd(dppf)Cl2 and palladium acetate, and the molar amount of the palladium catalyst is 0.05% to 0.1% of the molar amount of the 1-bromo-2-naphthylamine;
[0025] The base is one or more of alkali metal carbonate, alkali metal bicarbonate, alkali metal hydroxide and alkali metal phosphate; the molar ratio of 1-bromo-2-naphthylamine to the base is 1:(2-4);
[0026] The solvents for the Suzuki reaction are toluene, ethanol and water.
[0027] Preferably, the temperature of the Suzuki reaction is 70-80° C., and the reaction time is 2-5 h.
[0028] Preferably, the inorganic acid is sulfuric acid, and the concentration of the sulfuric acid is 30-50 wt %; the cuprous salt is cuprous bromide; and the bromine salt is sodium bromide;
[0029] The molar ratio of the first intermediate, sodium nitrite and cuprous salt is 1:(1-1.5):(1.1-1.5);
[0030] The molar ratio of the first intermediate to the bromine salt is 1:(1.5-2);
[0031] The solvent of the Sandmeyer reaction is acetic acid.
[0032] Preferably, the temperature of the Sandmeyer reaction is 20-30° C., and the reaction time is 20-30 h.
[0033] Preferably, the molar ratio of the second intermediate to 2-bromoxanthone is 1:(0.8-0.9); the molar ratio of the second intermediate to n-butyl lithium is 1:(1.2-1.5); and the solvent for the addition reaction is tetrahydrofuran.
[0034] Preferably, the temperature of the addition reaction is room temperature, and the reaction time is 2 to 4 hours.
[0035] Preferably, the acidic condition is provided by concentrated hydrochloric acid; the molar ratio of the third intermediate to concentrated hydrochloric acid is 1:(4-6); and the solvent for the ring-closure reaction is acetic acid.
[0036] Preferably, the temperature of the ring-closure reaction is 30-40° C., and the reaction time is 3-5 h.
[0037] Preferably, after the ring-closing reaction is completed, the obtained reaction solution is cooled and then filtered, and the obtained solid product is washed with water, dried and recrystallized to obtain the spirofluorene compound for OLED.
[0038] The present invention provides a method for synthesizing spirofluorene compounds for OLED. The present invention first uses 1-bromo-2-naphthylamine and phenylboronic acid to undergo Suzuki reaction to generate a first intermediate (structural formula as shown in formula M-1), and then converts the amino group in the first intermediate structure into bromine through Sandmeyer reaction to generate a second intermediate (structural formula as shown in formula M-2), and then reacts the second intermediate with 2-bromoxanthone to generate a third intermediate (structural formula as shown in formula M-3), and finally closes the ring to generate the target product. The present invention changes the cyclization site, first connects the naphthalene ring to the substrate, and then attacks the benzene ring through the hydroxyl group to perform a ring-closing reaction, thereby avoiding the generation of isomeric impurities during the ring-closing reaction in the prior art route. The product of the synthesis method provided by the present invention has high purity and high yield, and the post-processing is simple, no multiple purification is required, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Figure 1 The NMR spectrum of the spirofluorene compound for OLED obtained by the prior art synthesis route;
[0040] Figure 2 This is the NMR spectrum of the spirofluorene compound for OLED obtained in Example 1. DETAILED DESCRIPTION
[0041] The present invention provides a method for synthesizing a spirofluorene compound for OLED, comprising the following steps:
[0042] Under the action of a base and a palladium catalyst, 1-bromo-2-naphthylamine and phenylboronic acid are subjected to a Suzuki reaction in a solvent to obtain a first intermediate; the first intermediate has a structure shown in formula M-1;
[0043]
[0044] Under the action of inorganic acid, sodium nitrite and cuprous salt, the first intermediate and bromine salt are subjected to Sandmeyer reaction in a solvent to obtain a second intermediate; the second intermediate has a structure shown in formula M-2;
[0045]
[0046] Under the action of n-butyl lithium, the second intermediate and 2-bromoxanthone are subjected to an addition reaction in a solvent to obtain a third intermediate; the third intermediate has a structure shown in formula M-3;
[0047]
[0048] Under acidic conditions, the third intermediate is subjected to a ring-closing reaction in a solvent to obtain the spirofluorene compound for OLED; the structural formula of the spirofluorene compound for OLED is shown in Formula M;
[0049]
[0050] In the present invention, the synthesis route of the spirofluorene compound for OLED is shown in Formula I:
[0051]
[0052] The following is a detailed description in conjunction with Formula I.
[0053] The present invention conducts a Suzuki reaction of 1-bromo-2-naphthylamine and phenylboric acid in a solvent under the action of a base and a palladium catalyst to obtain a first intermediate (recorded as intermediate M-1). In the present invention, the molar ratio of the 1-bromo-2-naphthylamine and phenylboric acid is preferably 1:(3-4), more preferably 1:(3-3.5); the palladium catalyst is preferably one or more of dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium (II), tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium dichloride, Pd(dppf)Cl2 and palladium acetate, more preferably dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium (II), the molar amount of the palladium catalyst is preferably 0.05% to 0.1% of the molar amount of the 1-bromo-2-naphthylamine, more preferably 0.05% to 0.08%; the base is preferably It is selected from one or more of alkali metal carbonates, alkali metal bicarbonates, alkali metal hydroxides and alkali metal phosphates; the alkali metal carbonate is preferably one or both of potassium carbonate and sodium carbonate; the alkali metal bicarbonate is preferably sodium bicarbonate; the alkali metal hydroxide is preferably one or both of potassium hydroxide and sodium hydroxide; the alkali metal phosphate is preferably potassium phosphate; the molar ratio of the 1-bromo-2-naphthylamine and the base is preferably 1:(2-4), more preferably 1:(2.5-3.5); the solvent of the Suzuki reaction is preferably toluene, ethanol and water; the volume ratio of toluene, ethanol and water is preferably 8:3:3.
[0054] In the present invention, the temperature of the Suzuki reaction is preferably 70-80° C., the reaction time is preferably 2-5 h, and the Suzuki reaction is preferably carried out in a protective atmosphere, and the protective atmosphere is preferably nitrogen.
[0055] In a specific embodiment of the present invention, it is preferred to first stir and mix toluene, ethanol, 1-bromo-2-naphthylamine, phenylboric acid, a base and water, pass nitrogen, and simultaneously heat the system to 30-50° C., stir for 10 minutes, add a palladium catalyst to the system, continue to heat the temperature to 70-80° C., and keep the temperature to react.
[0056] After the Suzuki reaction is completed, the present invention preferably performs post-treatment on the obtained reaction solution, and the post-treatment preferably includes the following steps: cooling the reaction solution obtained by the Suzuki reaction and then separating the liquids, extracting the obtained aqueous phase with toluene, and sequentially washing, drying and concentrating the obtained toluene phase to obtain a crude product; recrystallizing the crude product in n-heptane to obtain the first intermediate; the desiccant used for the drying is preferably anhydrous magnesium sulfate; the recrystallization temperature is preferably 10 to 20°C.
[0057] After obtaining the first intermediate, the present invention performs Sandmeyer reaction on the first intermediate and bromine salt in a solvent under the action of an inorganic acid, sodium nitrite and cuprous salt to obtain a second intermediate (referred to as intermediate M-2). In the present invention, the inorganic acid is preferably sulfuric acid, and the concentration of the sulfuric acid is preferably 30-50wt%, more preferably 40wt%; the cuprous salt is preferably cuprous bromide; the bromine salt is preferably sodium bromide; the molar ratio of the first intermediate, sodium nitrite and cuprous salt is preferably 1:(1-1.5):(1.1-5); the sodium nitrite is used in the form of sodium nitrite aqueous solution, and the concentration of the sodium nitrite aqueous solution is preferably 20-40wt%, more preferably 30wt%; the molar ratio of the first intermediate and sodium bromide is preferably 1:(1.5-2), more preferably 1:(1.5-1.7); the solvent of the Sandmeyer reaction is preferably acetic acid.
[0058] In the present invention, the temperature of the Sandmeyer reaction is preferably 20 to 30° C., and the reaction time is preferably 20 to 30 h.
[0059] In a specific embodiment of the present invention, acetic acid, the first intermediate and the inorganic acid are preferably mixed first, stirred at room temperature and then cooled to -5 to 0°C, and then an aqueous sodium nitrite solution is added dropwise, and the temperature is controlled to be -5 to 0°C during the addition process. After the addition is completed, the reaction is carried out for 0.5 to 2 hours, preferably for 1 hour, and then cuprous salt and bromine salt are added to react at 20 to 30°C.
[0060] After the Sandmeyer reaction is completed, the present invention preferably mixes the obtained reaction solution with water, and then extracts with ethyl acetate to obtain an organic phase; the organic phase is sequentially washed with water, dried and filtered to obtain a crude product; the crude product is recrystallized to obtain the second intermediate; the washing is based on washing the organic phase to neutrality; the desiccant used for the drying is preferably anhydrous magnesium sulfate; the solvent used for the recrystallization is preferably n-heptane.
[0061] After obtaining the second intermediate, the present invention performs an addition reaction on the second intermediate and 2-bromoxanthone in a solvent under the action of n-butyl lithium to obtain a third intermediate (recorded as intermediate M-3). In the present invention, the molar ratio of the second intermediate and 2-bromoxanthone is preferably 1:(0.8-0.9); the molar ratio of the second intermediate and n-butyl lithium is preferably 1:(1.2-1.5); the solvent for the addition reaction is preferably tetrahydrofuran; the temperature of the addition reaction is preferably room temperature, and the reaction time is preferably 2-4h; the addition reaction is preferably carried out in a protective atmosphere, and the protective atmosphere is preferably nitrogen.
[0062] In a specific embodiment of the present invention, the solvent and the second intermediate are preferably mixed first, and then nitrogen is introduced, and the liquid nitrogen is cooled to -78°C under stirring, and then n-butyl lithium is added dropwise. After the addition is completed, the mixture is kept warm at -78°C for 1 hour, and then 2-bromoxanthone is added, and the temperature is naturally raised to room temperature for reaction.
[0063] After the addition reaction is completed, the present invention quenches the obtained reaction solution with hydrochloric acid, then extracts with ethyl acetate, washes the obtained organic phase with water, concentrates it, and then slurries it with n-heptane, and filters the obtained slurry to obtain the third intermediate.
[0064] After obtaining the third intermediate, the present invention performs a ring-closing reaction on the third intermediate in a solvent under acidic conditions to obtain the 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene], the structural formula of which is shown in Formula M. In the present invention, the acidic condition is preferably provided by concentrated hydrochloric acid; the molar ratio of the third intermediate to concentrated hydrochloric acid is preferably 1:(4-6); the solvent for the ring-closing reaction is preferably acetic acid; the temperature of the ring-closing reaction is preferably 30-40° C., and the reaction time is preferably 3-5 hours, more preferably 4 hours.
[0065] In the present invention, after the ring-closure reaction is completed, it is preferred that the obtained reaction solution is cooled and then filtered, and the obtained solid product is washed with water, dried and recrystallized to obtain the 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene]; the solvent used for the recrystallization is preferably a mixed solvent of toluene and ethanol, and the volume ratio of toluene to ethanol in the mixed solvent is preferably 2:(3-4).
[0066] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0067] Example 1
[0068] Synthesis of intermediate M-1: 800mL of toluene, 300mL of ethanol, 100g of 1-bromo-2-naphthylamine, 60.36g of phenylboric acid, 124.5g of potassium carbonate, and 300mL of water were added to a three-necked flask, stirring was started, nitrogen was passed through, and the system was heated to 50°C at the same time. After stirring for 10min, 0.16g of dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium (II) was added to the bottle. When the temperature rose to 70°C, the heat was kept for timing. After reacting for 2h, the reaction was stopped, the temperature was lowered to 20°C, the liquid was separated, the aqueous phase was extracted twice with toluene, the toluene phase was combined and washed three times with water, and then the organic phase was dried with 50g of anhydrous magnesium sulfate, filtered to remove magnesium sulfate, and concentrated to dryness. 400mL of n-heptane was added to the crude product obtained by concentration, and the temperature was lowered to 10°C under stirring to obtain 95.5g of off-white solid with a purity of 98.32% and a yield of 96.78%.
[0069] Synthesis of intermediate M-2: Add 1L of acetic acid, 95.5g of intermediate M-1, and 400mL of 40wt% sulfuric acid to a three-necked flask, stir at room temperature for 2h, then cool to -5°C, start dripping 91g of 30wt% sodium nitrite aqueous solution, control the temperature at -5 to 0°C during the dripping process, and react for 1h after the dripping is completed, then add 68g of cuprous bromide and 54g of sodium bromide to the reaction flask, control the temperature at 20°C and react for 24h. After the reaction is completed, add 1L of water to the reaction solution, extract the aqueous phase with ethyl acetate, wash the organic phase with water until neutral, add 50g of anhydrous magnesium sulfate to the organic phase, dry for 1h, filter out the magnesium sulfate, and concentrate the organic phase. The obtained crude product is recrystallized with n-heptane to obtain 87.95g of product with a purity of 99.2% and a yield of 71.1%.
[0070] Synthesis of intermediate M-3: Add 1L of tetrahydrofuran and 87.95g of intermediate M-2 to a three-necked flask, pass nitrogen, stir, cool the liquid nitrogen to -78°C, add 149mL of n-butyl lithium (2.5mol), add dropwise, keep at -78°C for 1h, add 76.9g of 2-bromoxanthone to the flask, then naturally warm to room temperature, and the reaction is completed. The reaction solution is quenched with dilute hydrochloric acid, extracted with ethyl acetate, the organic phase is washed with water until neutral, concentrated, added with 600mL of n-heptane for pulping, stirred for 1h, and filtered to obtain 122.1g of product with a purity of 98.7% and a yield of 82.0%.
[0071] Synthesis of 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene]: Add 122.1 g of intermediate M-3, 1.3 L of acetic acid, and 122.1 g of concentrated hydrochloric acid into a three-necked flask, heat to 30°C with stirring, react for 4 hours, then cool to room temperature, filter, rinse the solid with water, dry in an oven, and dissolve and crystallize with a mixture of toluene and ethanol to obtain 101.4 g of a white solid with a purity of 99.5% and a yield of 87%.
[0072] The NMR spectrum of 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene] obtained in this example is as follows Figure 2 shown.
[0073] Example 2
[0074] Synthesis of intermediate M-1: Add 800mL of toluene, 300mL of ethanol, 100g of 1-bromo-2-naphthylamine, 60.36g of phenylboric acid, 36.00g of sodium hydroxide, and 300mL of water to a three-necked flask, start stirring, pass nitrogen, and heat the system to 50°C at the same time. After stirring for 10min, add 0.52g of tetrakis(triphenylphosphine)palladium to the flask. When the temperature rises to 70°C, keep warm for a while. After reacting for 3h, stop the reaction, cool to 20°C, separate the liquids, extract the aqueous phase twice with toluene, wash the toluene phases with water three times after merging, and then dry the organic phase with 50g of anhydrous magnesium sulfate, filter to remove magnesium sulfate, and concentrate to dryness. Add 400mL of n-heptane to the crude product obtained by concentration, cool to 10°C while stirring, and obtain 93.59g of off-white solid with a purity of 98.32% and a yield of 94.84%.
[0075] Synthesis of intermediate M-2: Add 1L of acetic acid, 93.59g of intermediate M-1, and 400mL of 40wt% sulfuric acid to a three-necked flask, stir at room temperature for 2h, then cool to -5°C, start dripping 133.5g of 30wt% sodium nitrite aqueous solution, control the temperature -5 to 0°C during the dripping process, and react for 1h after the dripping is completed, then add 83.27g of cuprous bromide and 54g of sodium bromide to the reaction flask, control the temperature at 20°C and react for 24h. After the reaction is completed, add 1L of water to the reaction solution, extract the aqueous phase with ethyl acetate, wash the organic phase with water until neutral, add 50g of anhydrous magnesium sulfate to the organic phase, dry for 1h, filter out the magnesium sulfate, and concentrate the organic phase. The obtained crude product is recrystallized with n-heptane to obtain 87.79g of product with a purity of 99.35% and a yield of 72.1%.
[0076] Synthesis of intermediate M-3: Add 1L of tetrahydrofuran and 87.79g of intermediate M-2 to a three-necked flask, pass nitrogen, stir, cool the liquid nitrogen to -78°C, add 167mL of n-butyl lithium (2.5mol), add the addition, keep it at -78°C for 1h, add 72.49g of 2-bromoxanthone to the flask, then naturally warm it to room temperature, and the reaction is completed. The reaction solution is quenched with dilute hydrochloric acid, extracted with ethyl acetate, and the organic phase is washed with water until neutral. After concentration, 600mL of n-heptane is added for pulping, stirred for 1h, and filtered to obtain 101.05g of product with a purity of 98.9% and a yield of 80.0%.
[0077] Synthesis of 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene]: Add 1.05 g of intermediate M-310, 1.3 L of acetic acid, and 121.67 g of concentrated hydrochloric acid into a three-necked flask, heat to 30°C with stirring, react for 4 hours, then cool to room temperature, filter, rinse the solid with water, dry in an oven, and dissolve and crystallize with a mixture of toluene and ethanol to obtain 85.26 g of a white solid with a purity of 99.7% and a yield of 88%.
[0078] Example 3
[0079] Synthesis of intermediate M-1: Add 800mL of toluene, 300mL of ethanol, 100g of 1-bromo-2-naphthylamine, 68.16g of phenylboric acid, 95.4g of sodium carbonate, and 300mL of water to a three-necked flask, start stirring, pass nitrogen, and heat the system to 50°C at the same time. After stirring for 10min, add 0.24g of bis(triphenylphosphine)palladium dichloride to the flask. When the temperature rises to 70°C, keep warm for a while. After reacting for 3h, stop the reaction, cool to 20°C, separate the liquids, extract the aqueous phase twice with toluene, wash the toluene phases with water three times after merging, and then dry the organic phase with 50g of anhydrous magnesium sulfate, filter to remove magnesium sulfate, and concentrate to dryness. Add 400mL of n-heptane to the crude product obtained by concentration, cool to 10°C under stirring, and obtain 95.52g of off-white solid with a purity of 98.04% and a yield of 96.78%.
[0080] Synthesis of intermediate M-2: Add 1L of acetic acid, 95.52g of intermediate M-1, and 400mL of 40wt% sulfuric acid to a three-necked flask, stir at room temperature for 2h, then cool to -5°C, start dripping 148.35g of 30wt% sodium nitrite aqueous solution, control the temperature -5 to 0°C during the dripping process, and react for 1h after the dripping is completed, then add 91g of cuprous bromide and 56g of sodium bromide to the reaction flask, control the temperature at 20°C and react for 24h. After the reaction is completed, add 1L of water to the reaction solution, extract the aqueous phase with ethyl acetate, wash the organic phase with water until neutral, add 50g of anhydrous magnesium sulfate to the organic phase, dry for 1h, filter out the magnesium sulfate, and concentrate the organic phase. The obtained crude product is recrystallized with n-heptane to obtain 90.58g of product with a purity of 99.0% and a yield of 73.23%.
[0081] Synthesis of intermediate M-3: Add 1L of tetrahydrofuran and 90.58g of intermediate M-2 to a three-necked flask, pass nitrogen, stir, cool the liquid nitrogen to -78°C, add 160mL of n-butyl lithium (2.5mol), add dropwise, keep at -78°C for 1h, add 70.4g of 2-bromoxanthone to the flask, then naturally warm to room temperature, and the reaction is completed. The reaction solution is quenched with dilute hydrochloric acid, extracted with ethyl acetate, the organic phase is washed with water until neutral, concentrated, added with 600mL of n-heptane for pulping, stirred for 1h, and filtered to obtain 122.72g of product with a purity of 98.9% and a yield of 80.0%.
[0082] Synthesis of 2'-bromospiro[7H-benzo[C]fluorene-7,9'-[9H]xanthene]: Add 22.72 g of intermediate M-31, 1.3 L of acetic acid, and 122.1 g of concentrated hydrochloric acid into a three-necked flask, heat to 30°C with stirring, react for 4 hours, then cool to room temperature, filter, rinse the solid with water, dry in an oven, and dissolve and crystallize with a mixture of toluene and ethanol to obtain 103.58 g of a white solid with a purity of 99.58% and a yield of 87.7%.
[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for synthesizing a spirofluorene compound for OLED, characterized in that: The following steps are involved: Under the action of a base and a palladium catalyst, 1-bromo-2-naphthylamine and phenylboronic acid are subjected to a Suzuki reaction in a solvent to obtain a first intermediate; the first intermediate has a structure shown in formula M-1; Under the action of inorganic acid, sodium nitrite and cuprous salt, the first intermediate and bromine salt are subjected to Sandmeyer reaction in a solvent to obtain a second intermediate; the second intermediate has a structure shown in formula M-2; Under the action of n-butyl lithium, the second intermediate and 2-bromoxanthone are subjected to an addition reaction in a solvent to obtain a third intermediate; the third intermediate has a structure shown in formula M-3; Under acidic conditions, subjecting the third intermediate to a ring-closing reaction in a solvent to obtain the spirofluorene compound for OLED; The structural formula of the spirofluorene compound for OLED is shown in Formula M; 2. The preparation method according to claim 1, characterized in that: The molar ratio of 1-bromo-2-naphthylamine to phenylboric acid is 1:(1.1-1.3); The palladium catalyst is one or more of di-tert-butyl dichloro-(4-dimethylaminophenyl)phosphine palladium (II), tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium dichloride, Pd(dppf)Cl2 and palladium acetate, and the molar amount of the palladium catalyst is 0.05% to 0.1% of the molar amount of the 1-bromo-2-naphthylamine; The base is one or more of alkali metal carbonate, alkali metal bicarbonate, alkali metal hydroxide and alkali metal phosphate; the molar ratio of 1-bromo-2-naphthylamine to the base is 1:(2-4); The solvents for the Suzuki reaction are toluene, ethanol and water.
3. The preparation method according to claim 1 or 2, characterized in that: The temperature of the Suzuki reaction is 70-80° C., and the reaction time is 2-5 hours.
4. The preparation method according to claim 1, characterized in that: The inorganic acid is sulfuric acid, and the concentration of the sulfuric acid is 30-50wt%; the cuprous salt is cuprous bromide; and the bromine salt is sodium bromide; The molar ratio of the first intermediate, sodium nitrite and cuprous salt is 1:(1-1.5):(1.1-1.5); The molar ratio of the first intermediate to the bromine salt is 1:(1.5-2); The solvent of the Sandmeyer reaction is acetic acid.
5. The preparation method according to claim 1 or 4, characterized in that: The temperature of the Sandmeyer reaction is 20-30° C., and the reaction time is 20-30 h.
6. The preparation method according to claim 1, characterized in that: The molar ratio of the second intermediate to 2-bromoxanthone is 1:(0.8-0.9); the molar ratio of the second intermediate to n-butyl lithium is 1:(1.2-1.5); and the solvent for the addition reaction is tetrahydrofuran.
7. The preparation method according to claim 1 or 6, characterized in that: The temperature of the addition reaction is room temperature, and the reaction time is 2 to 4 hours.
8. The preparation method according to claim 1, characterized in that: The acidic condition is provided by concentrated hydrochloric acid; the molar ratio of the third intermediate to concentrated hydrochloric acid is 1:(4-6); and the solvent of the ring-closure reaction is acetic acid.
9. The preparation method according to claim 1 or 8, characterized in that: The temperature of the ring-closure reaction is 30-40° C., and the reaction time is 3-5 hours.
10. The preparation method according to claim 1, characterized in that: After the ring-closing reaction is completed, the obtained reaction solution is cooled and then filtered, and the obtained solid product is washed with water, dried and recrystallized to obtain the spirofluorene compound for OLED.