2-Ethynyl-4,6-difluoroaniline → 5,7-difluoro-1H-indole

참여 물질

반응 단계

The impure 2-ethynyl-4,6-difluoroaniline (4.2 g, 19 mmol) from the previous example was dissolved in ethanol (75 mL), treated with sodium gold(III) chloride dihydrate (310 mg, 0.77 mmol) and stirred for 3 h under an atmosphere of nitrogen. The mixture was concentrated, taken up in ethyl acetate, washed with water, washed with sat. NaCl, dried over sodium sulfate (Na2SO4) and evaporated. Purification by flash chromatography (SiO2, 100-200 mesh; eluting with 0-15% EtOAc in hexanes containing 2% acetic acid) provided of the title product (2.0 g, ca 85% purity): 1H NMR (400 MHz, CDCl3) δ 8.32 (s, 1H), 7.26 (dd, J=4.8, 2.0 Hz, 1H), 7.09 (dd, J=9.1, 2.2 Hz, 1H), 6.74 (ddd, J=11.2, 9.3, 2.0 Hz, 1H), 6.55 (td, J=3.3, 2.2 Hz, 1H). 19F NMR (376 MHz, CDCl3) δ −122.11, −131.96. EIMS m/z 153.

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