反应详情

A solution of n-butyllithium in hexane (1.6 M, 1.7 mL, 27.2 mmol) was added to 6-bromo-1-methyl indole (5.0 g, 23.8 mmol) in dry THF (100 mL) at −78° C. over 30 min. After 30 min, trimethylborate (2.93 g, 28.2 mmol) in dry THF (25 mL) was added. Stirring was continued at −78° C. for 30 min. Methanol (12.5 mL) and water (12.5 mL) were added, and the mixture was stirred at room temperature for 3 h. It was diluted with ether (100 mL), and washed with sulfuric acid (1 N, 2×100 mL) and water (2×100 mL). The aqueous layer was back extracted with ether (2 ×100 mL). The combined organic extracts were dried (MgSO4), filtered over a pad of silica gel and the pad was washed with ether (100 mL). The filtrate was concentrated and the crude product was chromatographed over silica gel with 10% to 25% ethyl acetate/hexanes to give 1-methyl-1H-indol-6-yl-boronic acid (2.6 g, 62.5%).

1. waitwas continued at −78° C. for 30 min
2. stirringthe mixture was stirred at room temperature for 3 h
3. washwashed with sulfuric acid (1 N, 2×100 mL) and water (2×100 mL)
4. extractionThe aqueous layer was back extracted with ether (2 ×100 mL)
5. dry with materialThe combined organic extracts were dried (MgSO4)
6. filtrationfiltered over a pad of silica gel
7. washthe pad was washed with ether (100 mL)
8. concentrationThe filtrate was concentrated
9. customthe crude product was chromatographed over silica gel with 10% to 25% ethyl acetate/hexanes