Cl[C:2]1[C:7]([Cl:8])=[CH:6][C:5]([Cl:9])=[CH:4][N:3]=1.[C:10]([O:18][CH2:19][CH3:20])(=[O:17])[CH2:11][C:12]([O:14][CH2:15][CH3:16])=[O:13].C(=O)([O-])[O-].[Cs+].[Cs+]>CS(C)=O>[Cl:8][C:7]1[C:2]([CH:11]([C:12]([O:14][CH2:15][CH3:16])=[O:13])[C:10]([O:18][CH2:19][CH3:20])=[O:17])=[N:3][CH:4]=[C:5]([Cl:9])[CH:6]=1A mixture of 4.56 g 2,3,5-trichloropyridine, 8.80 g of diethyl malonate, 30 ml of dimethyl sulfoxide and 17.9 g of cesium carbonate was stirred for 8 hours at 110° C. under a nitrogen atmosphere. The reaction mixture was allowed to cool to room temperature, then, to this was added ice water, and extracted with ethyl acetate. The organic layer was washed with saturated brine twice, and dried over anhydrous magnesium sulfate, then, concentrated under reduced pressure. 7.45 g of the resultant residue was subjected to silica gel column chromatography, to obtain 7.08 g of diethyl (3,5-dichloro-2-pyridyl)malonate.
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