Sodium Thiosulfate → 2-(2-Chloro-6-fluorophenyl)-2H-pyrazolo[4,3-c]pyridine 5-oxide

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Reaction Steps

mCPBA (2.38 g, 13.88 mmol) was added to a cooled 0° C.) solution of 2-(2-chloro-6-fluorophenyl)-2H-pyrazolo[4,3-c]pyridine (2.27 g, 9.2 mmol) in DCM (55 mL) under nitrogen. The reaction was stirred for 3 hours, warmed to room temperature, and stirred for an additional 2 hours. Sodium thiosulfate (sat. aq.) was added and the layers were partitioned. The organic layer was washed with sodium hydrogen carbonate (sat. aq.) and brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel flash chromatography (5-10% methanol in DCM) to afford the title compound as a beige solid (2.13 g, 88% yield). 1H NMR (400 MHz, DMSO-d6): δ 8.90 (dd, J=1.8, 0.9 Hz, 1H), 8.87 (s, 1H), 7.95 (dd, J=7.5, 1.8 Hz, 1H), 7.83 (dt, J=7.5, 1.0 Hz, 1H), 7.74 (td, J=8.3, 5.8 Hz, 1H), 7.65-7.63 (m, 2H).

Provenance & Evidence