1,3-Dichloroacetone → 6-Chloro-2-(chloromethyl)imidazo[1,2-a]pyridine

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Reaction Steps

1,3-Dichloroacetone (7.4 g, 58.3 mmol) was added to a solution of 5-chloropyridin-2-amine (5.0 g, 38.9 mmol) in acetonitrile (100 ml). The mixture was heated at reflux for 14 h (the reaction was monitored by TLC). Upon completion of the reaction as judged by TLC, the mixture was concentrated under reduced pressure. The residue was diluted with water and the pH was adjusted to 7.5 with sodium bicarbonate solution. The mixture was extracted with EtOAc, the combined organics were dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography using 10% ethyl acetate in n-hexane and silica gel (230-400 mesh) to afford 6-chloro-2-(chloromethyl)imidazo[1,2-a]pyridine (1.5 g, 30%,) as a pale yellow solid. 1H NMR: 200 MHz, CDCl3: δ 8.0 (d, 1H), 7.6 (dd, 2H), 6.8 (d, 1H), 4.75 (s, 2H). MS: [M+H]+: m/z=201.9.

Provenance & Evidence