[CH2:1]([O:3][CH:4]([O:10][CH2:11][CH3:12])[C:5]([O:7]CC)=O)[CH3:2].[CH3:13][C:14]1[CH:15]=[C:16]([CH:20]=[CH:21][CH:22]=1)[CH2:17][Mg]Cl.[Cl-].[NH4+]>C1COCC1>[CH2:11]([O:10][CH:4]([O:3][CH2:1][CH3:2])[C:5](=[O:7])[CH2:13][C:14]1[CH:22]=[CH:21][CH:20]=[C:16]([CH3:17])[CH:15]=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 of (72) 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-(3-methylphenyl)propan-2-one (73) as a colorless oily substance (1.38 g, 5.84 mmol, 58.0%).
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