反应详情

To a stirred solution of 5-(tert-Butyl-dimethyl-silanyloxymethyl)indole-1-carboxylic acid tert-butyl ester (5-3, 38.6 g, 106.7 mmol) in tetrahydrofuran (400 mL) was slowly added at −78° C. a solution of lithiun diisopropylamide in tetrahydrofuran (2M, 80.1 mL, 160.1 mmol, 1.5 equiv). The reaction mixture was stirred at the same temperature for 1 h, treated with trimethylborate, warmed up to ambient temperature, and partitioned between ethyl acetate and 0.5N-HCl. The organic layer was washed with brine, separated, dried (MgSO4) and concentrated in vacuo to give the crude solid. Trituation of the crude product with hexanes followed by filtration and air-drying afforded the desired boronic acid (5-4) as a white powder; 1H NMR (400 MHz, CDCl3) δ 7.96 (d, 1H, J=6.8 Hz), 7.54 (s, 1H), 7.47 (s, 1H), 7.32 (d, 1H, J=6.8 Hz), 7.10 (s, 1H), 4.82 (s, 2H), 1.74 (s, 9H), 0.95 (s, 9H), 0.11 (s, 6H).

1. custompartitioned between ethyl acetate and 0.5N-HCl
2. washThe organic layer was washed with brine
3. customseparated
4. dry with materialdried (MgSO4)
5. concentrationconcentrated in vacuo
6. customto give the crude solid
7. filtrationTrituation of the crude product with hexanes followed by filtration
8. customair-drying