反应详情

温度

-40 °C

To a solution of 6-bromo-2-methyl-1H-indole (2.0 g, 9.52 mmol) in dry tetrahydrofuran (100 mL) was added sodium hydride (381 mg, 9.53 mmol) with ice-cooling. After stirring for about 30 min, a solution of n-BuLi (15 mL, 2.5 M solution in hexane) was added dropwise with stirring at −78° C. under nitrogen. It was warmed slowly to −40° C. during 45 min and stirred at this temperature for another 30 min. The mixture was cooled again below −78° C. followed by dropwise addition of 4,4,5,5-tetramethyl-2-(propan-2-yloxy)-1,3,2-dioxaborolane (3.54 g, 19.03 mmol). After warming to room temperature, the mixture was quenched with NH4Cl (aq) and extracted with ethyl acetate (3×80 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the residue, which was purified by silica gel column chromatography (2% ethyl acetate in petroleum ether) to afford 2-methyl-6-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indole (1.2 g, 49%).

1. temperaturecooling
2. stirringwith stirring at −78° C. under nitrogen
3. stirringstirred at this temperature for another 30 min
4. temperatureThe mixture was cooled again below −78° C.
5. temperatureAfter warming to room temperature
6. customthe mixture was quenched with NH4Cl (aq)
7. extractionextracted with ethyl acetate (3×80 mL)
8. dry with materialThe combined organic layers were dried over anhydrous sodium sulfate
9. filtrationfiltered
10. concentrationconcentrated under reduced pressure
11. customto give the residue, which
12. customwas purified by silica gel column chromatography (2% ethyl acetate in petroleum ether)