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CN-122010847-A - Synthesis method of 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole

CN122010847ACN 122010847 ACN122010847 ACN 122010847ACN-122010847-A

Abstract

The invention discloses a synthesis method of a photoelectric material intermediate 1- [3, 5-bis (1-methylethyl) [1,1 '-biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole, which takes 2, 6-diisopropylaniline as a starting material, and sequentially obtains the 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole through free radical reaction, coupling reaction, sandmeyer reaction, volmenn reaction and the like. The synthesis method has the advantages of lower synthesis cost, simple post-treatment method, high yield and industrialized production, accords with the development trend of green chemistry, furthest reduces the production cost of the whole process, and has extremely high application value.

Inventors

  • MENG XIANGMING
  • TONG JIANCHENG
  • ZHANG YONGFU

Assignees

  • 安徽大学

Dates

Publication Date
20260512
Application Date
20260202

Claims (10)

  1. 1. The synthesis method of 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole is characterized by comprising the following steps: Step 1, utilizing 2, 6-diisopropylaniline, N-dimethylformamide and a brominating reagent to generate a free radical reaction at low temperature to generate an intermediate 1-4-bromo-2, 6-bis (1-methylethyl) aniline; Step 2, performing a coupling reaction on the intermediate 1, phenylboric acid, triphenylphosphine, palladium acetate and potassium carbonate in a toluene ethanol solution to generate an intermediate 2-3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-amine; Step 3, utilizing intermediate 2 to generate a sandmeyer reaction with a brominating reagent and tert-butyl nitrite in an acetonitrile solvent at high temperature to generate intermediate 3-4-bromo-3, 5-bis (1-methylethyl) -1,1' -biphenyl; Step 4, performing a Walmenn reaction on the intermediate 3 and benzimidazole at a high temperature in the presence of a catalyst and N, N-dimethylacetamide to generate an intermediate 4-1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -1H-benzimidazole; step 5, reacting the intermediate 4 with a brominating reagent to generate a target product, namely, 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole; The reaction scheme is as follows: 。
  2. 2. The synthesis method according to claim 1, wherein: In the step 1, 2, 6-diisopropylaniline is dissolved in N, N-dimethylamide, the temperature is reduced to 0 ℃, a brominating reagent and the N, N-dimethylamide are mixed and then added into a reaction bottle in a dropwise manner, the temperature is controlled to 5 ℃, after the dropwise addition is finished, the reaction is stirred until the 2, 6-diisopropylaniline is reacted completely, ethyl acetate and purified water are added for extraction, then organic phase is sequentially washed by saturated ammonium chloride aqueous solution and saturated saline water, and dried by anhydrous sodium sulfate and then concentrated under reduced pressure to obtain an intermediate 1-4-bromo-2, 6-bis (1-methylethyl) aniline.
  3. 3. The synthesis method according to claim 2, characterized in that: in step 1, the molar ratio of 2, 6-diisopropylaniline to brominating reagent is 1:1.05.
  4. 4. The synthesis method according to claim 2, characterized in that: In the step 2, the intermediate 1 and phenylboronic acid are dissolved in toluene solvent together and are placed in a reaction bottle, palladium acetate and triphenylphosphine are added into the reaction bottle, air in the bottle is pumped to dryness and nitrogen is introduced, then potassium carbonate is dissolved in water and is mixed with ethanol and then is added into the reaction bottle together, stirring reaction is carried out at normal temperature until the intermediate 1 is completely reacted, standing and liquid separation are carried out, then decompression and concentration are carried out, then, the pH value of a system is regulated to 12 by sodium hydroxide solution, dichloromethane solution is used for extraction, and decompression and concentration are carried out, thus obtaining the intermediate 2-3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-amine.
  5. 5. The method of synthesis according to claim 4, wherein: In the step 2, the mol ratio of the intermediate 1 to the phenylboronic acid is 1:1.5, the mol ratio of the intermediate 1 to the potassium carbonate is 1:5, the mass of palladium acetate is 1-2% of the mass of the intermediate 1, and the mass of triphenylphosphine is 2-4% of the mass of the intermediate 1.
  6. 6. The synthesis method according to claim 2, characterized in that: In the step 3, the intermediate 2 is dissolved in acetonitrile and then placed in a reaction bottle, then a brominating reagent and tert-butyl nitrite are added, nitrogen is introduced after the bottle is vacuumized, the temperature is raised to 65 ℃ and the stirring reaction is carried out until the intermediate 2 is completely reacted, purified water and ethyl acetate are added for extraction, the organic phase is collected and washed by saturated saline water, and anhydrous sodium sulfate is added for vacuum concentration, thus obtaining the intermediate 3-4-bromo-3, 5-bis (1-methylethyl) -1,1' -biphenyl.
  7. 7. The method of synthesis according to claim 6, wherein: In the step 3, the mol ratio of the intermediate 2 to the brominating reagent is 1:1.2, and the mol ratio of the intermediate 2 to the tert-butyl nitrite is 1:2.4.
  8. 8. The synthesis method according to claim 2, characterized in that: In the step 4, the intermediate 3 and N, N-dimethyl amine acetate are put into a reaction bottle, a catalyst, benzimidazole, 1, 8-diazabicyclo [5.4.0] undec-7-ene and L-proline are sequentially added, the temperature is raised to 120 ℃ and stirred to react until the intermediate 3 is completely reacted, purified water is added, dilute hydrochloric acid aqueous solution is used for washing, ethyl acetate is added for extraction, finally, the organic phase is added into saturated saline for washing, anhydrous sodium sulfate is added, and then the mixture is decompressed and concentrated to dryness, thus obtaining the intermediate 4-1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -1H-benzimidazole.
  9. 9. The method of synthesis according to claim 8, wherein: In the step 4, the mol ratio of the intermediate 3 to the benzimidazole is 1:1-1.3, the mol ratio of the intermediate 3 to the catalyst is 1:0.2, and the mol ratio of the intermediate 3 to the 1, 8-diazabicyclo [5.4.0] undec-7-ene is 1:2.
  10. 10. The synthesis method according to claim 2, characterized in that: In the step 5, the intermediate 4 is dissolved in tetrahydrofuran and then placed in a reaction bottle, a brominating reagent is added, the temperature is raised to 70 ℃ for reflux reaction until the intermediate 4 is complete, the solution is decompressed, dried and mixed with silica gel, a silica gel column is filled, the mixture is washed by using a developing agent with the volume ratio of petroleum ether to ethyl acetate of 10:1 until the product is completely carried out, and the developing agent is decompressed and concentrated to obtain the target product.

Description

Synthesis method of 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole Technical Field The invention belongs to the field of chemical pharmacy, and particularly relates to a synthesis method of 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole. Background The OLED is a self-luminous device, has the advantages of wide viewing angle, quick response, high brightness and low driving voltage, and structurally comprises an anode, a cathode and an organic layer which is clamped between the anode and the cathode and contains an emitting layer, and when the OLED works, positive holes and negative electrons are combined into excitons through corresponding transmission areas to the emitting layer, and the excitons are transited to a ground state to emit light. 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -1H-benzimidazole is an intermediate for preparing the photoelectric material, and the core application is concentrated in the field of preparation of organic photoelectric functional elements. The benzimidazole nucleus in the molecule has good electron transmission capability, the 3, 5-diisopropyl biphenyl group can improve the solubility, film forming property and thermal stability of the molecule, is often used for preparing electron transmission layer materials of OLED (organic light emitting diode) or used as a main body material doped with fluorescent/phosphorescent light emitting dye, improves the luminous efficiency and service life of the device, and the steric hindrance of isopropyl can inhibit intermolecular agglomeration and reduce fluorescence quenching phenomenon of the device. The current research mainly carries out derivatization modification from three positions of benzimidazole ring, biphenyl skeleton and isopropyl substituent, for example, three-star electronic company, inc. has disclosed a patent for coupling bromine atoms on the benzimidazole ring with 4- (4, 5-tetramethyl-1, 3, 2-dioxa-Shaberland-2-yl) dibenzofuran or phenylboric acid to generate different types of organic light-emitting devices and electronic device materials in 2023, and the product yield can reach 90%. In addition, electron-withdrawing groups such as fluorine, cyano and the like are introduced into the benzene ring part of the benzimidazole, so that the energy level of the molecular LUMO is reduced, the energy level matching degree with the luminescent layer material is optimized, and the electron injection efficiency of the device is improved. However, there is no complete disclosed synthetic route for synthesizing 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -1H-benzimidazole, which is not conducive to large-scale industrial production due to the excessive price required for direct purchase. Disclosure of Invention Aiming at the defects of the existing synthetic route, the invention provides a synthetic method of 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole. The invention takes 2, 6-diisopropylaniline as an initial raw material, and the 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole is obtained through free radical reaction, coupling reaction, sandmeyer reaction, wallman reaction and the like in sequence. The method has the advantages of mild reaction conditions, high yield, low cost, readily available raw materials, innovative synthetic route, capability of improving the utilization rate of the raw materials, reducing resource waste and pollution, furthest reducing the production cost of the whole process and high application value, and meets the requirements of green chemistry. The synthesis method of the 1- [3, 5-bis (1-methylethyl) [1,1' -biphenyl ] -4-yl ] -2-bromo-1H-benzimidazole comprises the following steps: And 1, dissolving 2, 6-diisopropylaniline in N, N-dimethylamide, placing the N, N-dimethylamide in a reaction bottle, mixing a brominating reagent with a small amount of N, N-dimethylamide when the temperature is reduced to 0 ℃, slowly dropwise adding the mixture into the reaction bottle, controlling the temperature to be about 5 ℃ and lower than 10 ℃, stirring and reacting for one hour after the dropwise adding is finished, and sampling LCMS to determine that the 2, 6-diisopropylaniline is reacted. Ethyl acetate and purified water are added for extraction, then the organic phase is repeatedly washed for three times with saturated ammonium chloride aqueous solution, finally the organic phase is washed once with saturated saline water, dried by anhydrous sodium sulfate and then decompressed and concentrated to dryness, and the intermediate 1-4-bromo-2, 6-bis (1-methylethyl) aniline is obtained. Step 2, the intermediate 1 and phenylboronic acid are dissolved in a toluene solvent together and are placed in a reaction bottle, palladium acetate and triphenylphosphine are added into the reaction bottle, air in the bottle is pumped to be dry, nitrogen is introduced, pota