[CH3:1][C:2]([C:4]1[CH:9]=[CH:8][C:7]([Cl:10])=[CH:6][C:5]=1[Cl:11])=[O:3].C([N-]C(C)C)(C)C.[Li+].[C:20]([O:23][CH2:24][C:25](Cl)=[O:26])(=O)[CH3:21].C1C[O:31]CC1>>[Cl:11][C:5]1[CH:6]=[C:7]([Cl:10])[CH:8]=[CH:9][C:4]=1[C:2](=[O:3])[CH2:1][C:25](=[O:26])[C:24]([O:23][CH2:20][CH3:21])=[O:31]A solution of 2,4-dichloroacetophenone (3.78 g) in THF (20 ml) was cooled to −78° C. under a nitrogen atmosphere. To this stirred solution was added lithium diisopropylamide (LDA) (1.0 M, 22 ml) and the resulting solution was stirred at −78° C. for 15 minutes. Acetoxyacetyl chloride (2.3 ml) was injected and the mixture was stirred for 1 hour and then allowed to warm to room temperature. The reaction was quenched with 1N HCl and the product was extracted with diethyl ether (200 ml). The organic layer was dried, concentrated and recrystallized from ether/hexanes, yielding ethyl 4-(2,4-dichlorophenyl)-2,4-diketobutyrate (intermediate 1).
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