反应详情

温度

-10 °C

Under N2 atmosphere, NaH (8.8 g, 0.22 mol, 60% in mineral oil, 1.1 eq.) was added in portions at −10° C. to a 1 L three-neck flask containing (R)-tert-butyl 2-isopropyl-3-oxopiperazine-1-carboxylate (26.7 g, 0.11 mol) in DMF (300 mL). The mixture was stirred at −10° C. for 30 min. The mixture was added dropwise to a 1 L three-neck flask containing methyl 2,4-difluoro-5-nitrobenzoate (26.3 g, 0.121 mol, 1.1 eq.) in DMF (200 mL) at −20° C. over 10 min. After addition, the resulting mixture was stirred between −20° C. and −30° C. for another 10 min. The reaction was quenched with sat. aq. ammonium chloride (200 mL) and then water (800 mL). The aqueous layer was extracted with EtOAc (3×1 L). The combined organic layers were washed with water (3×1 L) and brine, and then dried over anhydrous Na2SO4. After the mixture was filtered and the filter was evaporated under vacuum, the residue was purified by column chromatography on silica gel eluting with PE:EtOAc 8:1˜4:1 to give (R)-tert-butyl 4-(5-fluoro-4-(methoxycarbonyl)-2-nitrophenyl)-2-isopropyl-3-oxopiperazine-1-carboxylate (32 g, 66.3% yield) as a yellow solid. LC-MS MS (ESI) m/z 384.1 [M-56+H]+, 462.1 [M+Na]+. 1H NMR (CDCl3 300 MHz): δ 8.63 (d, J=6.9 Hz, 1H), 7.16 (d, J=10.2 Hz, 1H), 4.61-4.30 (m, 2H), 3.97-3.89 (m, 4H), 3.62-3.48 (m, 2H), 2.40-2.34 (m, 1H), 1.49 (s, 9H), 1.08 (d, J=6.9 Hz, 3H), 1.01 (d, J=6.9 Hz, 3H).

1. additionThe mixture was added dropwise to a 1 L three-neck flask
2. additionAfter addition
3. stirringthe resulting mixture was stirred between −20° C. and −30° C. for another 10 min
4. customThe reaction was quenched with sat. aq. ammonium chloride (200 mL)
5. extractionThe aqueous layer was extracted with EtOAc (3×1 L)
6. washThe combined organic layers were washed with water (3×1 L) and brine
7. dry with materialdried over anhydrous Na2SO4
8. filtrationAfter the mixture was filtered
9. customthe filter was evaporated under vacuum
10. customthe residue was purified by column chromatography on silica gel eluting with PE