N-bromobutanimide → HCID 69085611, compound

Participants

Reaction Steps

To a solution of 134 (1.5 g, 2.2 mmol), KHCO3 (970 mg, 9.7 mmol), TBAB (70 mg, 0.2 mmol), TEMPO (31 mg, 0.2 mmol) in dichloromethane (50 mL) and H2O (10 mL) was added NBS (423 mg, 2.4 mmol) at 0° C. After stirred for 30 minutes at room temperature, the reaction was diluted with water (50 mL) and the aqueous layer was extracted with dichloromethane (2×30 mL). The combined organic layers was dried over anhydrous sodium sulfate, and concentrated under vacuum to give crude 135, which was dissolved into THF (20 mL). To the solution of 135 in THF was added MeMgBr (3 mL, 6 mmol, 2M in THF) at room temperature. After 1 hr, the reaction mixture was quenched with saturated aqueous NH4Cl solution (10 mL) and extracted with ethyl acetate (4×20 mL). The combined organic layer was washed with brine (2×20 mL), dried over anhydrous sodium sulfate and concentrated under vacuum. The crude residue was purified by a silica gel column, eluted with 10%-20% ethyl acetate in petroleum ether to afford 136 (0.95 g, 63%, two epimers, the ratio was 1:4 determined by 1H NMR) as a light yellow syrup. (ES, m/z) [M+H]+ 709.0; 1H NMR (300 MHz, CDCl3) δ 7.15-7.38 (m, 9H), 6.79-6.92 (m, 4H), 6.11 (m, 1H), 4.50-4.55 (m, 4H), 4.49 (s, 2H), 4.31-4.33 (m, 1H), 4.05-4.06 (m, 1H), 3.83-3.90 (m, 1H), 3.82 (s, 3H), 3.81 (s, 3H), 3.54-3.66 (m, 2H), 3.31-3.52 (m, 3H), 3.11-3.15 (m, 1H) 1.54 (s, 9H), 1.12 (d, J=1.8 Hz, 3H).

Provenance & Evidence