反应详情

To a pre-cooled (−45° C.) solution of (2R,3S)-2-(3-chloro-4-cyano-2-methylphenylamino)-3-hydroxybutanoic acid (intermediate 1a) (1.97 g, 7.35 mmol) and 4-(trifluoromethyl)benzohydrazide (1.50 g, 7.35 mmol) in anhydrous THF (80 mL) was added 1-Hydroxybenzotriazole monohydrate (1.13 g, 7.35 mmol) and N-(3-Dimethylaminopropyl)-N′-ethylcarbodimide-HCl (2.82 g, 14.7 mmol) at −45° C. followed by triethylamine (2.0 mL, 14.7 mmol). The reaction mixture warmed to room temperature and stirred for 23 h, then quenched with 5% aq. citric acid (300 mL). The solution was extracted with EtOAc (300 mL). The organic extract was washed with 5% aq. citric acid (2×150 mL), sat. aq. NaHCO3 (3×150 mL), H2O (2×150 mL), dried (Na2SO4), filtered and concentrated under reduced pressure to provide the title compound as a off white solid (3.09 g, 92%): 1H NMR (400 MHz, d6-DMSO, δ in ppm) 10.71 (s, 1H), 10.31 (s, 1H), 8.05 (d, J=8.2 Hz, 2H), 7.89 (d, J=8.2 Hz, 2H), 7.61 (d, J=8.6 Hz, 1H), 6.66 (d, J=8.8 Hz, 1H), 5.67 (d, J=7.6 Hz, 1H), 5.31 (d, J=5.7 Hz, 1H), 4.14 (sextet, J=6.1 Hz, 1H), 3.94 (dd, J=5.7, 7.2 Hz, 1H), 2.30 (s, 3H), 1.28 (d, J=6.3 Hz, 3H).

1. customquenched with 5% aq. citric acid (300 mL)
2. extractionThe solution was extracted with EtOAc (300 mL)
3. extractionThe organic extract
4. washwas washed with 5% aq. citric acid (2×150 mL), sat. aq. NaHCO3 (3×150 mL), H2O (2×150 mL)
5. dry with materialdried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated under reduced pressure