A kind of method for preparing dexmedetomidine and its intermediate
A compound and selected technology, applied in the production of bulk chemicals, organic chemistry, etc., can solve the problems of multi-industrial impurities, inconsistent synthesis processes, unfavorable purification process development, etc., to avoid process impurities, ensure quality, and facilitate operation. Effect
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Embodiment 1
[0044] Example 1: Preparation of 1-(2,3-dimethylphenyl)-1-(1H-imidazol-4-yl)ethanol
[0045] Refer to "Laboratory Chemicals Purification Handbook (Original Work Fifth Edition)" to process the solvent tetrahydrofuran used in the reaction, and add an appropriate amount of water, and use the AKF-1 moisture meter to measure its moisture content to be 0.13%.
[0046]
[0047] In a 500ml reaction flask, the temperature was lower than 50°C, magnesium (5.5g, 224mmol) was added to tetrahydrofuran (140ml), and iodine (10mg) was stirred. Cool down to room temperature, add dropwise a solution of 2,3-dimethylbromobenzene (40.2g, 217mmol) in tetrahydrofuran (120ml, the water content is 0.13% as measured by AKF-1 moisture meter), and stir the mixture at 20-25°C for 1.5h . Heat to reflux for an additional hour, then cool to room temperature. A solution of 1-(1H-imidazol-4-yl)ethanone (19.8g, 180mmol) in tetrahydrofuran (50ml) was added dropwise at 20°C, and stirring was continued at room...
Embodiment 2
[0051] Example 2: Preparation of 1-(triphenylmethyl)-1-(1H-imidazol-4-yl)ethanone
[0052]
[0053] In a 2000ml reaction flask, put 41.3g (282mol) of imidazole-4-ethanone hydrochloride (2), 380ml of DMF, 114ml of triethylamine, under the protection of nitrogen, add triphenylchloromethane dropwise at an internal temperature below 15°C 91.2g (327mmol) was dissolved in 570ml of N,N-dimethylformamide (DMF), and the solution was added in about 1 hour, and the reaction was continued for 1 hour. Cool to below 5°C, filter and drain. Take it out, stir evenly in 1140ml of water, filter, and wash the filter cake with water (200ml). After drying, 88.4 g of solids were obtained, with a yield of 89.0%. (TLC detection, developer: chloroform: methanol: ammoniacal liquor=50:5:1), MS (m / z), 353.3 (MH + ).
Embodiment 3
[0054] Example 3: Preparation of 4-[(2,3-dimethylphenyl)-1-hydroxyethyl]-1-(triphenylmethyl)imidazole
[0055] Refer to "Laboratory Chemicals Purification Handbook (Original Work Fifth Edition)" to process the solvent tetrahydrofuran used in the reaction, and add an appropriate amount of water, and use the AKF-1 moisture meter to measure its moisture content to be 0.09%.
[0056]
[0057] In a 2000ml reaction flask, a solution of 2,3-dimethylbromobenzene (46g, 248mmol) in tetrahydrofuran (800ml, its moisture content measured by AKF-1 moisture meter is 0.09%) was added dropwise to magnesium (6g, 0.25 mmol), an appropriate amount of iodine in tetrahydrofuran (200ml) solution, after the addition, heated to reflux for 1 hour, then cooled to room temperature. The above-prepared solution was added dropwise to a solution of 1-(triphenylmethyl)imidazolone 4 (70 g, 199 mmol) in THF (800 ml) at 20°C. After the addition was complete, the mixture was warmed to room temperature and sti...
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