反应详情

温度

-45 °C

To a freshly prepared solution of LDA (119 mmol) in anhyd THF (250 mL) at −45° C. was added a solution of commercially available 4-fluoro-2-(trifluoromethyl)benzonitrile (21.5 g, 114 mmol) in THF (30 mL), dropwise at a rate such that the internal temperature remained <−40° C. (became dark brown during addition). The mixture was stirred 30 min at −45° C., cooled to −70° C. and iodine (31.7 g, 125 mmol) was added in one portion (−70° C.→−52° C.). The mixture was stirred for 1 h, removed from the cooling bath and quenched by addition of 10% Na2S2O3 (ca. 250 mL) and 1N HCl (ca. 125 mL). The mixture was extracted with EtOAc (×3). Combined organics were washed (water, brine), dried over Na2SO4 and concentrated in vacuo. The residue was purified by low pressure liquid chromatography (silica gel, EtOAc/hexanes, gradient elution) followed by recrystallization from heptane (30 mL), twice, affording 4-fluoro-3-iodo-2-(trifluoromethyl)benzonitrile (15.79 g, 50.1 mmol, 44.1% yield) as a pale yellow solid: 1H NMR (400 MHz, CDCl3) δ 7.85 (ddd, J=8.6, 5.1, 0.5 Hz, 1H), 7.36 (ddd, J=8.6, 6.6, 0.5 Hz, 1H); MS (GCMS EI) m/z 315 ([M]+, 100%).

1. customremained <−40° C.
2. addition(became dark brown during addition)
3. temperaturecooled to −70° C.
4. stirringThe mixture was stirred for 1 h
5. customremoved from the cooling bath
6. customquenched by addition of 10% Na2S2O3 (ca. 250 mL) and 1N HCl (ca. 125 mL)
7. extractionThe mixture was extracted with EtOAc (×3)
8. washCombined organics were washed (water, brine)
9. dry with materialdried over Na2SO4
10. concentrationconcentrated in vacuo
11. customThe residue was purified by low pressure liquid chromatography (silica gel, EtOAc/hexanes, gradient elution)
12. customfollowed by recrystallization from heptane (30 mL)