反应详情

A 10-mL single-neck round-bottomed flask equipped with a magnetic stirrer was purged with nitrogen, charged with 31 (2.78 g, 12.7 mmol), acetaldehyde (727 mg, 16.5 mmol) and anhydrous methanol (40 mL). A solution of sodium cyanoborohydride (2.4 g, 38 mmol) and anhydrous zinc chloride (2.6 g, 19.1 mmol) in anhydrous methanol (40 mL) was added, and the reaction was stirred at room temperature for 1 h. After this time, 1N aqueous sodium hydroxide (25 mL) was added, and the methanol was evaporated under reduced pressure. The remaining aqueous solution was extracted with ethyl acetate (3×100 mL). The organic layers were combined, washed with water (100 mL) and brine (100 mL) and dried over magnesium sulfate. The drying agent was removed by filtration and the filtrate concentrated under reduced pressure to afford a 98% yield (3.20 g) of 32 as a yellow oil: 1H NMR (500 MHz, DMSO-d6) δ 8.18 (d, 2H, J=8.5 Hz), 8.02 (d, 1H, J=4.0 Hz), 7.66 (d, 2H, J=8.5 Hz), 4.06 (s, 1H), 3.39 (td, 1H, J=12.0, 4.0 Hz), 3.22 (m, 1H), 3.07 (dt, 1H, J=12.0, 3.0 Hz), 2.50 (m, 1H), 2.37 (m, 1H), 2.21 (m, 1H), 0.91 (t, 3H, J=8.5 Hz); MS (ESI+) m/z 250 (M+H).

1. customA 10-mL single-neck round-bottomed flask equipped with a magnetic stirrer
2. customwas purged with nitrogen
3. customthe methanol was evaporated under reduced pressure
4. extractionThe remaining aqueous solution was extracted with ethyl acetate (3×100 mL)
5. washwashed with water (100 mL) and brine (100 mL)
6. dry with materialdried over magnesium sulfate
7. customThe drying agent was removed by filtration
8. concentrationthe filtrate concentrated under reduced pressure