Sodium Hydroxide → 5-Chloro-8-iodo[1,2,4]triazolo[1,5-a]pyridine

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Reaction Steps

(E)-N-(6-chloro-3-iodopyridin-2-yl)-N′-hydroxyformimidamide (6.0 g, 0.02 mol) is treated with polyphosphoric acid (40 g) at 80° C. for 4 h with stirring. The reaction mixture is diluted with cold water (100 mL), and then neutralized with 10 N aq. sodium hydroxide solution to pH 8. The aqueous solution is extracted with dichloromethane (100 mL×3). The combined organic extracts are washed with saturated aq. sodium bicarbonate solution (50 mL), brine (30 mL×3), dried over sodium sulfate, filtered, and filtrate concentrated to afford 5-Chloro-8-iodo-[1,2,4]triazolo[1,5-a]pyridine (5.6 g, 94%) as an off-white solid. LCMS Purity: 95% by UV 254 nm detection; LCMS-ESI (m/z): calcd for C6H3ClIN3, 278.9; [M+H]+ found, 279.9. 1H NMR (300 MHz, DMSO-d6) δ 8.63 (s, 1H), 8.15 (d, J=7.8 Hz, 1H), 7.29 (d, J=7.8 Hz, 1H).

Provenance & Evidence