反应详情

温度

-78 °C

3-Bromo-4-methoxybenzoic acid (2.00 g) is dissolved in tetrahydrofuran (50 ml), and the mixture is cooled to −78° C., and thereto is added dropwise a 1.1M methyllithium in diethyl ether (7.7 ml). The mixture is stirred at −78° C. for 5 minutes, and thereto is added dropwise a 1.6M tert-butyllithium in n-pentane (13.2 ml), and the mixture is stirred at −78° C. for 15 minutes, and the mixture is allowed to warm to −45° C., and the mixture is stirred for 45 minutes, and then again cooled to −78° C. Thereto is added dropwise triisopropylborate, and the mixture is stirred at −78° C. for 15 minutes, and the mixture is allowed to warm to room temperature. The mixture is stirred at room temperature for 1.5 hours, and the mixture is concentrated under reduced pressure, and thereto are added water and hexane. The aqueous layer is adjusted to pH 4 by addition of a 6N-hydrochloric acid and a saturated aqueous sodium bicarbonate solution, and the mixture is extracted with ethyl acetate and methanol twice. The organic layer is washed with a saturated brine, dried over magnesium sulfate and concentrated under reduced pressure. To the resulting residue is added diethyl ether, and the resulting solids are collected by filtration to give 2-methoxy-5-carboxyphenylboronic acid (1.37 g) as a crude product.

1. stirringthe mixture is stirred at −78° C. for 15 minutes
2. temperatureto warm to −45° C.
3. stirringthe mixture is stirred for 45 minutes
4. temperatureagain cooled to −78° C
5. stirringthe mixture is stirred at −78° C. for 15 minutes
6. temperatureto warm to room temperature
7. stirringThe mixture is stirred at room temperature for 1.5 hours
8. concentrationthe mixture is concentrated under reduced pressure
9. additionare added water and hexane
10. additionThe aqueous layer is adjusted to pH 4 by addition of a 6N-hydrochloric acid
11. extractiona saturated aqueous sodium bicarbonate solution, and the mixture is extracted with ethyl acetate and methanol twice
12. washThe organic layer is washed with a saturated brine
13. dry with materialdried over magnesium sulfate
14. concentrationconcentrated under reduced pressure
15. additionTo the resulting residue is added diethyl ether
16. filtrationthe resulting solids are collected by filtration