[C:1]([O:7][CH2:8][CH3:9])(=[O:6])[CH2:2][C:3]([CH3:5])=[O:4].[H-].[Na+].[Cl:12][C:13]1[CH:14]=[C:15]([CH:18]=[CH:19][C:20]=1[Cl:21])[CH2:16]Br.C(OCC)(=O)C>O1CCCC1.O>[C:3]([CH:2]([CH2:16][C:15]1[CH:18]=[CH:19][C:20]([Cl:21])=[C:13]([Cl:12])[CH:14]=1)[C:1]([O:7][CH2:8][CH3:9])=[O:6])(=[O:4])[CH3:5]To a solution of ethyl acetoacetate (1.0 g) in tetrahydrofuran (20 mL) was added sodium hydride (about 60% oil suspension) (0.37 g) in several portions under ice-cooling under a nitrogen atmosphere. After stirring at room temperature for 1 hr, 3,4-dichlorobenzylbromide (1.4 mL) was added to the reaction mixture. After stirring at room temperature for 2 hr, the reaction mixture was poured into a mixture of ethyl acetate and water. The organic phase was washed successively with water and brine, and dried over magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by column chromatography on silica gel by eluting with toluene. An eluted fraction containing the desired product was recovered and evaporated under reduced pressure to give ethyl 2-acetyl-3-(3,4-dichlorophenyl)propanoate (35) (1.6 g).
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