Dimethylformamide → 8-Chloro-2-(4-fluorophenyl)imidazo[1,2-a]pyridine-3-carboxaldehyde

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Reaction Steps

N,N-Dimethylformamide (10 mL) was cooled to 0° C. and treated with phosphorous oxychloride (1.0 mL, 11 mmol). After the addition was complete, the mixture was warmed to room temperature and stirred for 10 minutes. To this was added 8-chloro-2-(4-fluorophenyl)imidazo[1,2-α]pyridine (1.15 g, 4.7 mmol) and the resulting solution was stirred overnight. Water was added to the reaction. The mixture was neutralized to pH 7 with ammonium hydroxide. The aqueous phase was extracted with dichloromethane (3×50 mL). The combined organics were washed with brine, dried over magnesium sulfate, filtered and concentrated. The residue was recrystallized from acetonitrile to give 8-chloro-2-(4-fluorophenyl)imidazo[1,2-α]pyridine-3-carbaldehyde (1.1 g, 85%) as a white solid. 1H NMR (CDCl3): δ 10.05 (s, 1H), 9.60 (d, 1H), 7.86 (q, 2H), 7.65 (d, 1H), 7.23 (t, 2H), 7.08 (t, 1H); 19F NMR (CDCl3) δ −110.8; MS m/z 275 (M+1).

Provenance & Evidence