反应详情

Under nitrogen, 10 mL (159 mmol) of a 1.59 mol/L hexane solution of n-butyl lithium and a solution of 23.0 g (71.4 mmol) of 1-iodo-4-isopropoxy-3,5-dimethoxybenzene in anhydrous tetrahydrofuran (100 ml) were added dropwise to anhydrous tetrahydrofuran cooled in a dry ice-methanol bath, and the mixture was stirred for 30 minutes. After addition of 20 mL (87 mmol) of triisopropyl borate, the reaction mixture was stirred for 15 minutes and the dry ice-methanol bath was removed. With stirring, the reaction mixture was allowed to warm to room temperature over about 1.5 hours. After addition of water (4 mL, 200 mmol), the mixture was concentrated under reduced pressure and the residue was dissolved in a 1 mol/L aqueous sodium hydroxide solution (200 mL). After washing with heptane (20 mL) and chloroform (3×15 mL), the resulting solution was stirred in an ice bath, followed by dropwise addition of 35 mL (420 mmol) of concentrated hydrochloric acid. The mixture was stirred with ice cooling for 2.5 hours. The precipitates were collected by filtration, washed with 0.1 mol/L hydrochloric acid and water and air-dried overnight, whereby 16 g of crude crystals were obtained. A solution of crude crystals in tetrahydrofuran (50 mL) was dried over magnesium sulfate and then concentrated under reduced pressure to about 25 mL. The residue heated to about 80° C. was stirred, and heptane (15 mL) was added. After stirring at room temperature and then, in an ice bath, precipitates were collected by filtration and washed with tetrahydrofuran-heptane (1:10:3×7.5 mL), whereby 12.75 g of 4-isopropoxy-3,5-dimethoxyphenylboronic acid was obtained as a colorless crystalline powder (mp: 211.5° C. (decomposed), yield: 71%).

1. temperaturecooled in a dry ice-methanol bath
2. stirringthe reaction mixture was stirred for 15 minutes
3. customthe dry ice-methanol bath was removed
4. stirringWith stirring
5. concentrationthe mixture was concentrated under reduced pressure
6. dissolutionthe residue was dissolved in a 1 mol/L aqueous sodium hydroxide solution (200 mL)
7. washAfter washing with heptane (20 mL) and chloroform (3×15 mL)
8. stirringthe resulting solution was stirred in an ice bath
9. stirringThe mixture was stirred with ice cooling for 2.5 hours
10. filtrationThe precipitates were collected by filtration
11. washwashed with 0.1 mol/L hydrochloric acid and water
12. customair-dried overnight
13. customwhereby 16 g of crude crystals were obtained
14. dry with materialA solution of crude crystals in tetrahydrofuran (50 mL) was dried over magnesium sulfate
15. concentrationconcentrated under reduced pressure to about 25 mL
16. temperatureThe residue heated to about 80° C.
17. stirringwas stirred
18. additionheptane (15 mL) was added
19. stirringAfter stirring at room temperature
20. customin an ice bath, precipitates
21. filtrationwere collected by filtration
22. washwashed with tetrahydrofuran-heptane (1:10:3×7.5 mL)