反应详情

To a stirred solution of ethyl-4-(3,5-dimethylphenyl)-4-oxobutyrate (0.5 g; 2.14 mmol) in THF (5 mL) was added a solution of (−)-chlorodiisopinocampheylborane (1.71 g; 5.34 mmol) in THF (1 mL). The resultant solution stirred at room temperature for 4 days. The reaction was concentrated in vacuo and dried under high vacuo for 1 h. The residue was dissolved in ethyl acetate (10 mL) and diethanolamine (470 mL) was added. A white precipitate formed and the resultant mixture was stirred for 2 h, after which the solid was filtered off and washed with pentane. The filtrate was concentrated in vacuo and purified by flash silica gel chromatography (0-20% EtOAc/hexanes gradient) to afford ethyl (4S)-4-(3,5-dimethylphenyl)-4-hydroxybutanoate as a clear oil. LCMS=219.3 (M+1−18)+. 1H NMR (CDCl3, 500 MHz): δ 6.99 (s, 2H), 6.95 (s, 1H), 4.72-4.69 (m, 1H), 4.16 (q, J=7.1 Hz, 2H), 2.45 (t, J=7.3 Hz, 2H), 2.34 (s, 6H), 2.11-2.06 (m, 2H), 1.29 (t, J=7.2 Hz, 3H).

1. concentrationThe reaction was concentrated in vacuo
2. customdried under high vacuo for 1 h
3. dissolutionThe residue was dissolved in ethyl acetate (10 mL)
4. additiondiethanolamine (470 mL) was added
5. customA white precipitate formed
6. filtrationafter which the solid was filtered off
7. washwashed with pentane
8. concentrationThe filtrate was concentrated in vacuo
9. custompurified by flash silica gel chromatography (0-20% EtOAc/hexanes gradient)