120800-05-7

Tetrahedron, 48, p. 9233, 1992 DOI: 10.1016/S0040-4020(01)85613-1

The general procedure for the synthesis of 1-(5,6-dichloropyridin-3-yl)ethanone from 5,6-dichloro-N-methoxy-N-methylpyridine-3-carboxamide and methylmagnesium chloride was as follows: to a stirred tetrahydrofuran solution of 5,6-dichloro-N-methoxy-N-methylpyridine-3-carboxamide (100 mL) at 0 °C and protected by nitrogen was slowly added dropwise to a stirred 3 M methylmagnesium chloride in a tetrahydrofuran solution (18 mL, 54.7 mmol). After the dropwise addition, the reaction mixture was kept stirring at 0°C for 1 hour. Subsequently, the reaction mixture was partitioned with ether and saturated aqueous ammonium chloride solution at 0 °C. The aqueous layer was separated and extracted with ethyl acetate. All organic phases were combined, washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by fast chromatography using a 90:10 to 70:30 gradient elution of hexane:ethyl acetate to give 5.92 g of 1-(5,6-dichloropyridin-3-yl)ethanone as a white solid in an overall two-step yield of 85%.

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