Trimethyl orthoformate → 6-Chloro-5-phenoxy-1H-benzoimidazole

関与物質

反応条件

反応手順

To a solution of 5-chloro-2-nitro-4-phenoxyphenylamine (0.810 g, 3.06 mmol) in DMF (12 mL) was added trimethylorthoformate (12 mL) followed by sodium dithionite (2.66 g, 15.3 mmol), and glacial acetic acid (1.5 mL). The reaction mixture was heated in a sealed tube at 100° C. for 14 h. Additional sodium dithionite (0.5 g) and acetic acid (1 mL) were added and heating was continued at 120° C. for an additional 3 h. The reaction flask was cooled in ice, added cautiously to half-saturated sodium bicarbonate solution (300 mL) and extracted with EtOAc. Combined organic layers were washed with 5% NaHCO3, brine, dried, filtered, and concentrated under reduced pressure. The residue was purified (FCC) (hexanes:EtOAc, 0% to 5% over 20 minutes) to yield the titled compound as a yellow amorphous solid (0.57 g, 76%) as a mixture of tautomers. MS (ESI/CI): mass calcd. for C13H9ClN2O, 244; m/z found, 245 [M+H]+. 1H NMR (500 MHz, CDCl3): 9.55 (s, 1H), 8.06 (s, 1H), 8.0-7.2 (m, 2H), 7.32 (t, J=7.9 Hz, 2H), 7.09 (t, J=7.3 Hz, 1H), 6.96 (d, J=8.3 Hz, 2H).

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