反应详情

温度

-75 °C

To a solution of n-BuLi (21.2 ml, 0.053 mol) in anhydrous THF (160 mL) at −78° C. under argon was slowly added a solution of 2-(2-bromophenyl)propan-2-ol (XCV) (0.0212 mol, 4.55 g) in anhydrous THF (50 mL) while maintaining the temperature below −65° C. After addition was complete, the reaction mixture was stirred at −75° C. for 30 min. To this mixture was added in portions trimethyl borate (0.032 mol, 3.3 g), and the reaction mixture was stirred at −78° C. for 30 min and then at room temperature overnight. The mixture was cooled to 0° C., carefully quenched with 1M aqueous HCl, and stirred at room temperature for 15 min. The mixture was acidified to pH 3 with 2M HCl and stirring was continued for 1 hour. The two phases were separated and the aqueous layer was extracted with EtOAc. The combined organic phases were dried over MgSO4. The crude product was purified by silica gel chromatography using DCM followed by DCM/MeOH 300/1 to give 3,3-dimethylbenzo[c][1,2]oxaborol-1(3H)-ol (XCVI) as a light yellow oil (1.37 g; 8.5 mmol, 40% yield). 1H NMR (CDCl3) δ ppm 1.54 (s, 6H), 7.25-7.29 (m, 1H), 7.33 (d, J=7 Hz, 1H), 7.45 (td, J=7 Hz, J=1 Hz, 1H), 7.68 (d, J=7 Hz, 1H).

1. temperaturewhile maintaining the temperature below −65° C
2. additionAfter addition
3. stirringthe reaction mixture was stirred at −78° C. for 30 min
4. customat room temperature
5. customovernight
6. temperatureThe mixture was cooled to 0° C.
7. customcarefully quenched with 1M aqueous HCl
8. stirringstirred at room temperature for 15 min
9. stirringstirring
10. waitwas continued for 1 hour
11. customThe two phases were separated
12. extractionthe aqueous layer was extracted with EtOAc
13. dry with materialThe combined organic phases were dried over MgSO4
14. customThe crude product was purified by silica gel chromatography