[CH2:1]([O:3][CH:4]([O:10][CH2:11][CH3:12])[C:5]([O:7]CC)=O)[CH3:2].[CH2:13]([C:15]1[CH:23]=[CH:22][C:18]([CH2:19][Mg]Cl)=[CH:17][CH:16]=1)[CH3:14].[Cl-].[NH4+]>C1COCC1>[CH2:11]([O:10][CH:4]([O:3][CH2:1][CH3:2])[C:5](=[O:7])[CH2:19][C:18]1[CH:22]=[CH:23][C:15]([CH2:13][CH3:14])=[CH:16][CH:17]=1)[CH3:12]Under an argon atmosphere, to a solution of ethyl diethoxyacetate (1.80 mL, 10.1 mmol) in THF (20 mL) was added slowly a THF solution (42) of (4-ethylbenzyl)magnesium chloride prepared above at −78° C. After stirring at −78° C. for an hour, to this was added 20% aqueous solution of ammonium chloride (10 mL), and the product was extracted with ethyl acetate (×3). The organic layer was sequentially washed with water (×1) and saturated brine (×1), and dried over anhydrous sodium sulfate. After filtration, the mixture was concentrated under reduced pressure and the residue was purified by silica gel flash column chromatography (n-hexane/ethyl acetate=9/1) to give 1,1-diethoxy-3-(4-ethylphenyl)propan-2-one (43) as a colorless oily substance (1.29 g, 5.04 mmol, 50.6%).
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