Hydrochloric Acid → 1-(3,5-Dichloropyridin-2-yl)ethanone

To 20 g of 3,5-dichloropyridine-2-carbonitrile in 150 ml of tetrahydrofuran, 139 ml of a 1M tetrahydrofuran solution of methylmagnesium bromide was added dropwise with stirring under cooling with ice, and the mixture was stirred at the same temperature for 1 hour. After completion of the reaction, the reaction mixture was mixed with 15 ml of concentrated hydrochloric acid and 100 ml of water and extracted with ethyl acetate (100 ml×2), the resulting organic layers were combined, washed with water (100 ml×1) and dried over saturated aqueous solution chloride and then anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was dissolved in 40 ml of ethyl acetate and 10 ml of hexane, 20 g of silica gel was added, the mixture was stirred at room temperature for 1 hour and then subjected to filtration, and the solvent was evaporated under reduced pressure. The precipitated solid was washed with 50 ml of hexane to obtain 17.16 g of the desired product as pale yellow crystals.