反应详情

Methyl(2S)-2-({3-[(dipropylamino)carbonyl]benzoyl}amino)-4-methylpentanoate (1.65 g, 4.4 mmol) in 20 mL of toluene under nitrogen is cooled to −78° C. To this is added, dropwise over 5 min, 11 mL of a 1 M solution of Dibal in toluene. The mixture is stirred an additional 6 minutes, and is then quenched by addition of 2 mL of methanol. The cold bath is removed and 20 mL of a Rochelle salt solution is added and vigorously stirred while the mixture warms to ambient temperature. The product is extracted into ether and the organic phase is washed successively with Rochelle salt solution, water, and brine. It is dried over Na2SO4, concentrated, and chromatographed over silica gel, eluting with 50% ethyl acetate in heptane, to afford the title compound as a colorless oil (0.79 g, 2.3 mmol, 52%). 1H NMR (CDCl3) δ 9.7 (s, 1H), 7.85 (m, 1H), 7.79 (s, 1H), 7.49 (m, 2H), 6.81 (d, J=7 Hz, 1H), 4.78 (m, 1H), 3.46 (br t, 2H), 3.15 (br t, 2H), 1.82 (m, 2H), 1.70 (m, 2H), 1.62-1.53 (m, 3H), 1.01 (m, 9H), 0.75 (br t, 3H).

1. additionTo this is added, dropwise over 5 min
2. customis then quenched by addition of 2 mL of methanol
3. customThe cold bath is removed
4. addition20 mL of a Rochelle salt solution is added
5. stirringvigorously stirred while the mixture
6. customwarms to ambient temperature
7. extractionThe product is extracted into ether
8. washthe organic phase is washed successively with Rochelle salt solution, water, and brine
9. dry with materialIt is dried over Na2SO4
10. concentrationconcentrated
11. customchromatographed over silica gel
12. washeluting with 50% ethyl acetate in heptane