[Mg].Br[C:3]1[CH:4]=[C:5]([Cl:9])[CH:6]=[CH:7][CH:8]=1.[Cl:10][C:11]1[C:16]([C:17]#N)=[CH:15][CH:14]=[C:13]([CH2:19][CH3:20])[N:12]=1.[Cl-].[NH4+].Cl.[O:24]1CCCC1>>[Cl:10][C:11]1[C:16]([C:17](=[O:24])[C:3]2[CH:8]=[CH:7][CH:6]=[C:5]([Cl:9])[CH:4]=2)=[CH:15][CH:14]=[C:13]([CH2:19][CH3:20])[N:12]=1Magnesium (2.72 g, 112 mmol) was added to a tetrahydrofuran (200 ml) solution of 3-bromochlorobenzene (22.1 g, 115 mmol), and the mixture was stirred at room temperature. Since spontaneous exothermic reaction occurred, the stirring was continued until the exothermicity was ceased. The reaction solution was cooled to -20° C., mixed with 2-chloro-3-cyano-6-ethylpyridine (9.33 g, 56 mmol) and then stirred for 16 hours at room temperature. The reaction solution was mixed with saturated ammonium chloride aqueous solution and stirred for 30 minutes at room temperature and then mixed with 1 N hydrochloric acid and extracted with ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate, magnesium-sulfate was removed by filtration and then the filtrate was concentrated under a reduced pressure. Thereafter, the resulting residue was purified by silica gel column chromatography (hexane-ethyl acetate) to give 2-chloro-3-(3-chlorobenzoyl)-6-ethylpyridine (3.48 g, 22%) as a pale yellow oily material.
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