The preparation method of medetomidine
A technology of medetomidine and reaction, applied in the field of preparing medetomidine, can solve the problems of expensive, expensive to use, time-consuming and the like
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Embodiment 1
[0272] Example 1: 2-(2,3-Dimethylphenyl)propan-2-ol, compound of formula (XXIV), prepared via an organomagnesium intermediate
[0273] 1-Bromo-2,3-dimethylbenzene (compound of formula (XXV) wherein Q is Br; 8.43 g, 45.6 mmol) was dissolved in dry THF (15 mL) and placed in a dropping funnel. Separately, Mg filaments (1.10 g, 45.3 mmol) in dry THF (5 mL) were placed in a flask equipped with the above dropping funnel, stirrer and reflux condenser. 1-Bromo-2,3-dimethylbenzene solution (1.0 mL) was added via the dropping funnel, the reaction was started by adding 1,2-dibromoethane (3 drops), followed by the addition of the remaining 1-bromo-2, 3-Dimethylbenzene solution. Add the contents of the dropping funnel at a rate that maintains a small reflux. After the addition was complete, the mixture was refluxed for 1 hour and then cooled to 0°C. A solution of dry acetone (4.2 mL, 58 mmol) in dry THF (15 mL) was added dropwise and the mixture was stirred at 0 to 20 °C for 3 hours. T...
Embodiment 2
[0277] Example 2: 2-(2,3-Dimethylphenyl)propan-2-ol, compound of formula (XXIV), prepared via an organolithium intermediate
[0278] 1-Bromo-2,3-dimethylbenzene (compound of formula (XXV) where Q is Br; 4.25 g, 23.0 mmol) was dissolved in dry THF (15 mL) in a flask equipped with a thermometer and stir bar . The mixture was cooled to -78°C. n-Butyllithium (1.6M in hexane, 17.5 mL, 28.0 mmol) was added dropwise via syringe keeping the temperature below -70 °C. When the addition was complete, the mixture was kept at -78°C and stirred at this temperature for 1 hour. A solution of dry acetone (1.85 mL, 25.2 mmol) in dry THF (5 mL) was then added at -78 °C. The mixture was stirred at -78°C for 30 minutes, the cooling tank was removed and the mixture was allowed to reach room temperature. The mixture was poured into saturated NH 4 Cl aqueous solution (100mL), extracted with hexane (4 times, 50mL each time), passed through Na 2 SO 4 Drying and purification by silica gel column ...
Embodiment 3
[0280] Example 3: 1,2-Dimethyl-3-(2-propenyl)benzene, compound of formula (XXIII)
[0281] 2-(2,3-dimethylphenyl)propan-2-ol (compound of formula (XXIV), 1.10 g, 6.70 mmol) prepared according to Example 1 or Example 2 was dissolved in benzene (20 mL), And p-toluenesulfonic acid monohydrate (35 mg, 0.18 mmol) was added. The mixture was stirred at room temperature for 3 hours. Silica gel (200 mg) was added and stirring was continued for about 16 hours, then the reaction mixture was refluxed for 30 minutes. After cooling to room temperature, the mixture was filtered and washed with K 2 CO 3 Aqueous washing, conventional drying, and concentration under reduced pressure afforded 0.90 g (92%) of the title compound.
[0282] 1 HNMR:2.02(m,3H),2.21(s,3H),2.28(s,3H),4.82(m,1H),5.17(m,1H),6.97(m,1H),7.05(m,2H) .
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