Phosphorus oxychloride → 4-Chloro-2-(2,6-dichloro-4-fluorophenyl)-2H-pyrazolo[4,3-c]pyridine

Participants

Reaction Conditions

Reaction Steps

2-(2,6-Dichloro-4-fluorophenyl)-2H-pyrazolo[4,3-c]pyridine-5-oxide (1.4 g, 4.7 mmol) was slowly added to phosphorous oxychloride (10 mL). Tetrabutylammonium chloride (1.31 g, 4.7 mmol) was then added and the reaction mixture was heated at 85° C. for 45 minutes. The mixture was cooled and concentrated under reduced pressure. The residue was partitioned between ethyl acetate and sodium hydrogen carbonate. The organic layer was washed with sodium hydrogen carbonate (sat. aq.) and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel flash chromatography (10-20% ethyl acetate in cyclohexane) to afford the title compound as a white solid (706 mg, 47% yield). 1H NMR (300 MHz, DMSO-d6): δ 9.28 (s, 1H), 8.11 (d, J=6.3 Hz, 1H), 7.94 (d, J=8.4 Hz, 2H), 7.72 (d, J=6.3 Hz, 1H).

Provenance & Evidence