Method for photocatalytic preparation of benzene-epoxidized heterocycle by visible light

Abstract

The application discloses a method for preparing benzene ring epoxidized heterocycle by visible light photocatalysis, and belongs to the field of organic chemical synthesis. The method has the following advantages: (1) the method uses fluorinated oligophenylene compound as raw material, potassium tert-butoxide as external oxygen source, and generates benzene ring epoxidized heterocycle and other products under the catalysis of 300-500 nm light source; (2) the method does not use a catalyst, and generates products through visible light irradiation to form free radical nucleophilic substitution. The application provides a synthesis method for benzene ring epoxidized heterocycle, and reduces fluorinated oligophenylene to synthesize benzene ring epoxidized heterocycle compound crude product in air or in airtight air. The method has the characteristics of simple operation, wide substrate adaptability, no catalyst, mild reaction condition, low cost, high yield, simple post-treatment and the like, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis, specifically relating to a method for preparing benzocyclooxygenated heterocycles by visible light photocatalysis. Background Technology

[0002] In recent years, organic p-conjugated materials have been a focus of attention in academia and industry. Due to their excellent optical and charge properties, they play a key role in the development of organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic photovoltaics (OPVs). Introducing heteroatoms into the carbon skeleton is an excellent tool for regulating and improving the electronic properties of compounds. Currently, the main methods for synthesizing benzo[i]epoxidized or sulfidated heterocycles are as follows: (1) transition metal-catalyzed C-C bond coupling and (2) transition metal-catalyzed CO bond generation. These methods are usually achieved through a two-step deprotection / dehydration procedure, which has the disadvantages of complicated reaction steps, the need for noble metal catalysts, and difficulty in controlling reaction conditions.

[0003] This application uses fluorinated oligophenylene derivatives and potassium tert-butoxide as raw materials, and 1,4-dioxane as solvent, to react at 40-60°C to obtain a series of benzocyclooxygenated heterocyclic derivatives. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the photocatalytic preparation of benzo[a]epoxide heterocycles under visible light. This method does not require a catalyst and uses cyclofluorinated oligophenylene derivatives and potassium tert-butoxide as raw materials to synthesize benzo[a]epoxide heterocycles in 1,4-dioxane as a solvent. This method utilizes a light source for catalysis, avoids the use of traditional precious metal catalysts, simplifies the reaction, reduces pollution, and is more environmentally friendly and economical.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for photocatalytic synthesis of benzo[a]cyclooxygenated heterocycles under visible light comprises the following steps: fluorinated oligophenylene compounds and potassium tert-butoxide or sodium tert-butoxide are used as raw materials under visible light LED irradiation, and 1,4-dioxane is added as a solvent. The reaction is carried out under air conditions at 40–60°C with stirring until complete, thereby generating benzo[a]cyclooxygenated heterocycles.

[0007] Furthermore, the reaction time for the above reaction is 30 minutes.

[0008] Furthermore, the wavelength of the light source is 300–500 nm.

[0009] Furthermore, the amount of potassium tert-butoxide or sodium tert-butoxide added is 1 to 3 times the molar amount of fluorine atoms in the fluorinated oligophenylene compound.

[0010] Furthermore, the R group of the fluorinated oligophenylene derivative can be halogen, methyl, methoxy, phenyl derivative, hydroxyl, trifluoromethyl, etc., all of which can react smoothly to obtain the corresponding benzocyclooxygenated heterocycle.

[0011] Preferably, the fluorinated oligophenylene compound is n = 0, 1, 2, 3...9, 10, R = H, F, Br, Me, OMe, OH or CF3 or R and benzene ring to form naphthalene ring or quinoline ring.

[0012] Furthermore, each 0.1 mmol of fluorinated oligophenylene compound requires 1–3 mL of 1,4-dioxane as a solvent.

[0013] The post-reaction processing is simple, requiring only extraction and a simple column chromatography separation method, using petroleum ether as the eluent to obtain pure benzo[a]cyclooxygenated heterocycles.

[0014] The reaction process and the structural formula of the product obtained in this invention are as follows:

[0015]

[0016]

[0017] The synthesized compound uses 1 H NMR and 13 C NMR characterization showed that the spectral data matched the structure.

[0018] The beneficial effects of this invention are as follows: Benzocycloheterocyclic oxides are an important class of molecules with biological, pharmaceutical, and photoelectric properties, and have wide applications in natural products, pharmaceuticals, and materials chemistry. This application is the first to use fluorinated oligophenylene derivatives and potassium tert-butoxide in 1,4-dioxane under photocatalysis at a wavelength of 300–500 nm to prepare a series of benzocycloheterocyclic oxides 2a–2m, with the highest yield reaching 99%, and the purity of 2a–2m all exceeding 90%, demonstrating good reaction versatility. Detailed Implementation

[0019] Preparation of fluorinated oligomeric phenylene derivatives:

[0020] The corresponding o-fluorobromoaromatic hydrocarbon (1 n mmol halogen) and the corresponding o-fluorophenylboronic acid (1.1 equivalents of halogen) were dissolved in 24 mL of a tetrahydrofuran:H₂O (5:1) mixture containing cesium carbonate (977 n mg, 3 n mmol) and Pd(PPh₃)Cl₂ (35 n mg, 50 μ n mol) as catalysts. The reaction mixture was stirred under reflux (85 °C) and an argon atmosphere for 12 hours. After the reaction was complete, the solvent was evaporated, and the residue was purified by silica gel column chromatography, eluting with petroleum ether to give the corresponding fluorinated oligophenylene derivative.

[0021]

[0022] Example 1

[0023] 1 mL of 1,4-dioxane, 2,2'-difluoro-1,1'-biphenyl (19 mg 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 500 nm wavelength light of the photoreactor and stirred at 40 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent to obtain product 2a. The yield was 99%.

[0024] 1 H NMR (400MHz, CDCl3) δ8.10–8.13(m,2H),7.60(d,J=8.5Hz,2H),7.55–7.49(m,2H),7.39–7.30(m,2H).

[0025] Example 2

[0026] 1 mL of 1,4-dioxane, 5,5'-dibromo-2,2'-difluoro-1,1'-biphenyl (34.6 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1–3 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into a 400 nm wavelength light source in the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2b. The yield was 98%.

[0027] 1 H NMR (400MHz, CDCl3) δ8.15–8.06(m,2H),7.68(dd,J=8.9,2.1Hz,2H),7.58–7.49(m,2H).

[0028] Example 3

[0029] 1 mL of 1,4-dioxane, 3,3'-dibromo-2,2'-difluoro-1,1'-biphenyl (34.6 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 500 nm wavelength light of the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2c. The yield was 99%.

[0030] 1 H NMR (400MHz, CDCl3) δ7.85 (dd, J=7.3, 1.1Hz, 2H), 7.61 (dd, J=7.0, 1.7Hz, 2H), 7.36–7.28 (m, 2H).

[0031] Example 4

[0032] 1 mL of 1,4-dioxane, 2,2'-difluoro-5,5'-dimethyl-1,1'-biphenyl (21.8 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into a 400 nm wavelength light source in the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2d. The yield was 97%.

[0033] 1H NMR (400MHz, CDCl3) δ7.78–7.73(m,2H),7.46(d,J=8.0Hz,2H),7.25(d,J=8.0,2H),2.50(s,6H).

[0034] Example 5

[0035] 1 mL of 1,4-dioxane, 2,2'-difluoro-3,3'-dimethyl-1,1'-biphenyl (21.8 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 500 nm wavelength light of the photoreactor and stirred at 50 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2e. The yield was 94%.

[0036] 1 H NMR (400MHz, CDCl3) δ7.70 (d, J = 7.1, 2H), 7.36–7.27 (m, 4H), 2.66 (s, 6H).

[0037] Example 6

[0038] Two mL of 1,4-dioxane, 2,2'-difluoro-4,4'-dimethyl-1,1'-biphenyl (21.8 mg, 0.1 mmol), and t-BuOK (66 mg, 0.6 mmol, 3 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 500 nm wavelength light of the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2f. The yield was 67%. 1 HNMR (400MHz, CDCl3) δ7.72 (d, J = 7.8 Hz, 2H), 7.33 (s, 2H), 7.16 (d, J = 8.0 Hz, 2H), 2.55 (s, 6H).

[0039] Example 7

[0040] 1 mL of 1,4-dioxane, 2,2'-difluoro-5,5'-dimethoxy-1,1'-biphenyl (25.1 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 400 nm wavelength light of the photoreactor and stirred at 40 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give 2 g of product. The yield was 95%.

[0041] 1 H NMR (400MHz, CDCl3) δ7.43 (d, J = 8.5Hz, 2H), 7.43 (d, J = 2.4Hz, 2H), 7.04 (dd, J = 8.9, 2.7Hz, 2H), 3.80 (s, 3H).

[0042] Example 8

[0043] 1 mL of 1,4-dioxane, 2,2',5,5'-tetrafluoro-1,1'-biphenyl (22.6 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into a 400 nm wavelength light source in the photoreactor and stirred at 40 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give the product over 2 hours. The yield was 95%.

[0044] 1H NMR (400MHz, CDCl3) δ7.60 (d, J = 8.5, 2H), 7.52 (d, J = 9.8, 2H), 7.22 (td, J = 9.1, 2.7Hz, 2H).

[0045] Example 9

[0046] 1 mL of 1,4-dioxane, 6,6'-difluoro-[1,1'-biphenyl]-2,2'-diol (22.2 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 500 nm wavelength light of the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2i. The yield was 98%. 1 HNMR (400MHz, CDCl3) δ7.37(t,J=8.1Hz,2H),7.20(d,J=8.2Hz,2H),6.86(d,J=8.5Hz,2H),5.31(s,2H).

[0047] Example 10

[0048] 1 mL of 1,4-dioxane, 2,2'-difluoro-5,5'-bis(trifluoromethyl)-1,1'-biphenyl (32.6 mg, 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into a 300 nm wavelength light source in the photoreactor and stirred at 40 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2j. The yield was 92%.

[0049] 1 H NMR (400MHz, CDCl3) δ8.34 (d, J = 1.8, 2H), 7.88–7.85 (m, 2H), 7.79 (dd, J = 8.0, 0.9Hz, 2H).

[0050] Example 11

[0051] 1 mL of 1,4-dioxane, 1,1'-difluoro-2,2'-binaphthyl (29 mg 0.1 mmol), and t-BuOK (33 mg, 0.3 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 400 nm wavelength light of the photoreactor and stirred at 40 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2K. The yield was 93%.

[0052] 1 H NMR (400MHz, CDCl3) δ8.62 (dd, J=8.2, 1.1Hz, 2H), 8.08 (d, J=8.8Hz, 2H), 8.07 (d ,J=8.7Hz,2H),7.80(d,J=8.5Hz,2H),7.71(d,J=8.2,Hz,2H),7.66–7.54(m,2H).

[0053] Example 12

[0054] 1 mL of 1,4-dioxane, 2,2',2”,3'-tetrafluoro-1,1':4',1”-terphenyl (30.2 mg, 0.1 mmol), and t-BuOK (66 mg, 0.6 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into the 400 nm wavelength light of the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give 2 L of product. The yield was 93%. 1 H NMR (400MHz, CDCl3) δ8.90 (s, 1H), 8.10–8.03 (m, 2H), 7.74 (d, J = 0.9Hz, 1H), 7.63–7.59 (m, 2H), 7.50–7.40 (m, 2H), 7.40 (t, J = 7.4Hz, 2H).

[0055] Example 13

[0056] 1 mL of 1,4-dioxane, 2,2',2”,2”',3',3”-hexafluoro-1,1':4',1”:4”,1”'-tetraphenyl (40.4 mg, 0.1 mmol), and t-BuOK (99 mg, 0.9 mmol, 1.5 equivalents of F atoms participating in the reaction) were added to a quartz tube used in the photoreactor. The reaction tube was placed open into a 500 nm wavelength light source in the photoreactor and stirred at 60 °C for 30 minutes. After cooling to room temperature, the mixture was filtered through silica using petroleum ether as a solvent. The organic solvent was evaporated under reduced pressure to give product 2 m. The yield was 95%.

[0057] 1 H NMR (400MHz, CDCl3) δ8.08–8.00(m,2H),8.06(d,J=0.8Hz,4H),7.75(dt,J=8.3Hz,2H),7.60–7.50(m,2H),7.44(t,J=7.5Hz,2H).

[0058] The above description is only a partial embodiment of the present invention. For those skilled in the art, several improvements and substitutions can be made without departing from the principle of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for photocatalytic preparation of benzo[a]epoxide heterocycles under visible light, characterized in that, The process is as follows: Under visible light LED irradiation, fluorinated oligophenylene compounds and potassium tert-butoxide or sodium tert-butoxide are used as raw materials, and 1,4-dioxane is added as a solvent. The reaction is carried out under air conditions at 40-60°C with stirring until complete, generating benzo[a]epoxide heterocycles; the visible light wavelength is 300-500 nm; the amount of potassium tert-butoxide or sodium tert-butoxide added is 1-3 times the molar amount of fluorine atoms in the fluorinated oligophenylene compound; the fluorinated oligophenylene compound is... n=0, 1, 2, 3……9, 10, R=H, F, Br, Me, OMe, OH or CF3 or R and benzene ring to form naphthalene ring or quinoline ring.

2. The method for preparing benzo[a]cyclooxygenated heterocycles by visible light photocatalysis according to claim 1, characterized in that, For every 0.1 mmol of fluorinated oligophenylene compound, 1–3 mL of 1,4-dioxane is required as a solvent.

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