Method for preparing carbazole from phenolic compound
A technology for phenolic compounds and carbazoles, which is applied in the field of organic synthesis and achieves the effects of reducing synthesis cost, simple operation and cheap raw materials
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Embodiment 1
[0020] Example 1: Synthesis of 1-methoxy-3-methylcarbazole
[0021] To a dry reaction tube was added 2-methoxy-4-methylphenol (138.0 mg, 1.0 mmol), potassium hydroxide (112.0 mg, 2.0 mmol), 2-bromo-N-phenylpropanamide (228.0 mg) , 1.0 mmol) and toluene (3 ml), reacted at 50 °C for 4 hours, and then heated to 100 °C for 16 hours. The reaction was quenched by adding 10 ml of water, extracted with dichloromethane (3 × 25 ml), the organic phase was washed with saturated brine (2 × 20 ml), dried over anhydrous sodium sulfate, filtered, rotary evaporated, and subjected to flash silica gel column chromatography (leaching). Lotion: petroleum ether / ethyl acetate=20 / 1) to obtain the intermediate 2-methoxy-4-methyl-N-phenylaniline in a yield of 65%. The above intermediate (106.5 mg, 0.5 mmol) was placed in a reaction tube, palladium acetate (4.5 mg, 0.020 mmol), potassium carbonate (27.6 mg, 0.2 mmol), trimethyl acetic acid (450.0 mg, 4.4 mmol) were added. The reaction mixture was heat...
Embodiment 2
[0023] Example 2: Synthesis of 1,6-dimethoxy-3-methylcarbazole
[0024] According to the method described in Example 1, the difference is that the substrates and reagents used are: 2-methoxy-4-methylphenol (138 mg, 1.0 mmol), potassium carbonate (828 mg, 6.0 mmol), 2- Bromo-N-(4-methoxyphenyl)propionamide (514 mg, 2.0 mmol) and dimethyl sulfoxide (3 ml) were reacted at 80°C for 2 hours, then heated to 170°C for 2 hours. The intermediate 2-methoxy-N-(4-methoxyphenyl)-4-methylaniline was obtained in a yield of 68%. The second step: get the above-mentioned intermediate (121.5 mg, 0.5 mmol), palladium acetate (9.0 mg, 0.04 mmol), potassium carbonate (6.9 mg, 0.05 mmol), trimethyl acetic acid (817.0 mg, 8.0 mmol), 110 ° C , and reacted openly for 24 hours to obtain the product 1,6-dimethoxy-3-methylcarbazole as a white solid with a yield of 79%.
[0025] 1 H NMR (400 MHz, CDCl 3 ) 8.01 (bs, 1H), 7.50 (s, 1H), 7.44 (s, 1H), 7.34 (d, J = 8.8 Hz, 1H), 7.04 (d, J = 7.2 Hz, 1H), 6.7...
Embodiment 3
[0026] Example 3: Synthesis of methyl 1-methoxycarbazole-3-carboxylate
[0027] According to the method described in Example 1, the difference is that the substrates and reagents used are: methyl 3-methoxy-4-hydroxybenzoate (182 mg, 1.0 mmol), sodium hydroxide (160 mg, 4.0 mmol) , 2-bromo-N-phenylpropionamide (681 mg, 3.0 mmol) and N,N-dimethylformamide (3 ml), reacted at 60 °C for 4 hours, then heated to 130 °C and reacted for 9 hours. The intermediate methyl 3-methoxy-4-(anilino)benzoate was obtained in a yield of 60%. The second step: get the above-mentioned intermediate (128.5 mg, 0.5 mmol), palladium acetate (13.5 mg, 0.06 mmol), potassium carbonate (17.9 mg, 0.13 mmol), trimethyl acetic acid (1225.6 mg, 12 mmol), 120 ℃ , and reacted openly for 20 hours to obtain the product, methyl 1-methoxycarbazole-3-carboxylate, as a yellow solid with a yield of 90%.
[0028] 1 H NMR (400 MHz, CDCl 3 ) δ 8.54 (s, 1H), 8.48 (s, 1H), 8.10 (d, J = 7.6 Hz, 1H), 7.59 (s, 1H), 7.50-7.43...
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