反应详情

To a pre-cooled (0° C.) solution of N′-((2R,3R)-2-(3-chloro-4-cyano-2-methylphenylamino)-3-hydroxybutanoyl)-4-nitrobenzohydrazide (12.0 g, 27.79 mmol) in DMF (650 mL) was added imidazole (15.13 g, 222.31 mmol) then TBSCl (16.75 g, 111.15 mmol). The reaction was warmed slowly to room temperature, stirred for 72 h, cooled to 0° C. and quenched with H2O (600 mL). The solution was extracted with EtOAc (700 mL). The organic extract was washed with H2O (2×300 mL) and 5% aq. citric acid (3×250 mL), dried (Na2SO4), filtered and concentrated under reduced pressure to provide a light yellow oil, which was purified by flash chromatography over silica gel (30-40% EtOAc in hexanes) to provide the title compound as a colourless solid (8.50 g, 56%): 1H NMR (400 MHz, d6-DMSO, δ in ppm) 10.93 (s, 1H), 10.57 (s, 1H), 8.34 (dm, J=8.8 Hz, 2H), 8.07 (dm, J=9.0 Hz, 2H), 7.59 (d, J=8.6 Hz, 1H), 6.84 (d, J=9.0 Hz, 1H), 5.69 (d, J=8.4 Hz, 1H), 5.28 (s, 1H), 4.38 (pentet, J=6.3 Hz, 1H), 4.16 (dd, J=6.5, 8.0 Hz, 1H), 2.26 (s, 3H), 1.27 (d, J=6.3 Hz, 3H), 0.85 (s, 9H), 0.08 (s, 3H), 0.05 (s, 3H).

1. temperaturecooled to 0° C.
2. customquenched with H2O (600 mL)
3. extractionThe solution was extracted with EtOAc (700 mL)
4. extractionThe organic extract
5. washwas washed with H2O (2×300 mL) and 5% aq. citric acid (3×250 mL)
6. dry with materialdried (Na2SO4)
7. filtrationfiltered
8. concentrationconcentrated under reduced pressure
9. customto provide a light yellow oil, which
10. customwas purified by flash chromatography over silica gel (30-40% EtOAc in hexanes)