Hydrochloric Acid → 6-Chloro-2-(4-fluoroindolin-2-yl)pyridin-3-ol

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Reaction Steps

A mixture of 6-chloro-2-(4-fluoro-1H-indol-2-yl)pyridin-3-ol (10 g, 38 mmol) and metal Sn (23 g, 190 mmol) in CH3CH2OH/con. HCl (60 mL/40 mL) was stirred under reflux for 3 hours. The mixture was cooled to room temperature and adjusted to pH=7 by saturated NaOH and filtered though a Celit pad. The filtrate was extracted with EtOAc, washed by brine, dried over Na2SO4 and concentrated in vacuo. The resulting residue was purified using silica gel chromatography (petroleum ether:EtOAc=10:1) to get 6-chloro-2-(4-fluoroindolin-2-yl)pyridin-3-ol (8 g, yield: 80%). 1H-NMR (CDCl3, 400 MHz) δ 9.86 (s, 1H), 7.10˜7.20 (m, 3H), 6.33˜6.91 (m, 2H), 5.15˜5.21 (m, 1H), 4.61 (s, 1H), 3.65˜3.71 (m, 1H), 3.04˜3.11 (m, 1H). MS (M+H)+: 265.

Provenance & Evidence