81% |
With N-Bromosuccinimide; In acetonitrile; at 20℃; |
Commercially available compound II-A (8.41 g, 50 mmol) was dissolved in acetonitrile (150 mL) and stirred at room temperature, to which was added NBS (10.68 g, 60 mmol). The resulting reaction mixture was stirred at room temperature overnight, at which point TLC indicated the completion of the reaction. (0030) The reaction mixture was poured into ice water (500 mL), stirred, and extracted with CH2Cl2 (200 mL x 3). The organic phases were combined, washed successively with saturated Na2CO3 solution (100 mL x 3) and 5% saline solution (200 mL), and dried over anhydrous Na2SO4. The dried organic phase was evaporated on a rotary evaporator to remove the solvent, and the resulting residue was purified by column chromatography to give the product II-1 as a colorless oily substance, yield: 10.01 g, 81%. 1H NMR (DMSO-d6, 400 MHz), delta 8.43-8.47 (m, 1H), 8.13-8.17 (m, 1H), 7.75 (d, 1H, J = 7.6 Hz), 7.66-7.72 (m, 2H), 7.15-7.17 (m, 1H), 2.34-2.41 (m, 1H), 1.03-1.08 (m, 2H), 0.69-0.73 (m, 2H). |