Methyl iodide → 3,5-Dichloro-4-methylpyridine

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Reaction Conditions

Reaction Steps

Diisopropylamine (70 mL, 500 mmol) is dissolved in dry tetrahydrofuran (500 mL), the solution is cooled to −10° C. and buthyl lithium (2.5 N in hexane, 210 mL, 525 mmol) is added dropwise under stirring. After 30 minutes the solution is cooled to −20° C. and 3,5-dichloropyridine (66.6 g, 450 mmol) in tetrahydrofuran (200 mL) is added dropwise. The solution is stirred at −10° C. for 30 minutes, then cooled to −70° C. and iodomethane (50 mL, 1.6 mol) in tetrahydrofuran (100 mL) is added dropwise. The reaction mixture is allowed to warm to room temperature, quenched with water (100 mL) and extracted with diethyl ether (3×100 mL); the combined organic layers are dried over sodium sulphate (5 g) and evaporated to dryness. The crude product is crystallized twice from aqueous ethanol, then from hexane to afford 3,5-dichloro-4-methylpyridine (49.9 g, 306 mmol, 68% yield) as a white solid.

Provenance & Evidence