反应详情

To a pre-cooled (0° C.) solution of N′-((2R,3R)-2-(3-chloro-4-cyanophenylamino)-3-hydroxybutanoyl)-4-cyanobenzohydrazide (1.65 g, 4.15 mmol) in DMF (100 mL) was added imidazole (2.26 g, 33.4 mmol) then TBSCl (2.50 g, 16.60 mmol). The reaction was warmed slowly to room temperature, stirred for 19 h, cooled to 0° C. and quenched with H2O (300 mL). The solution was extracted with EtOAc (250 mL). The organic extract was washed with H2O (2×100 mL) and 5% aq. citric acid (3×80 mL), dried (Na2SO4), filtered and concentrated under reduced pressure to provide a brown oil, which was purified by flash chromatography over silica gel (10-30% EtOAc in hexanes) to provide the title compound as a colourless amorphous solid (2.09 g, 98%): 1H NMR (400 MHz, acetone-d6, δ in ppm) 8.06 (dm, J=8.6 Hz, 2H), 7.92 (dm, J=8.6 Hz, 2H), 7.53 (d, J=8.8 Hz, 1H), 7.04 (d, J=2.2 Hz, 1H), 6.91 (dd, J=2.4, 8.8 Hz, 1H), 6.26 (d, J=7.6 Hz, 1H), 4.42 (pentet, J=5.5 Hz, 1H), 4.31 (dd, J=5.5, 7.8 Hz, 1H), 1.35 (d, J=6.3 Hz, 3H), 0.87 (s, 9H), 0.12 (s, 3H), 0.10 (s, 3H).

1. temperaturecooled to 0° C.
2. customquenched with H2O (300 mL)
3. extractionThe solution was extracted with EtOAc (250 mL)
4. extractionThe organic extract
5. washwas washed with H2O (2×100 mL) and 5% aq. citric acid (3×80 mL)
6. dry with materialdried (Na2SO4)
7. filtrationfiltered
8. concentrationconcentrated under reduced pressure
9. customto provide a brown oil, which
10. customwas purified by flash chromatography over silica gel (10-30% EtOAc in hexanes)