CC(C)([O-])C.[K+].C(O)(C)(C)C.[CH2:12]([O:14][C:15](=[O:21])[CH2:16][C:17](=[O:20])[CH2:18][CH3:19])[CH3:13].Br[CH2:23][C:24]1[CH:29]=[CH:28][C:27]([Cl:30])=[CH:26][CH:25]=1>O1CCCC1.O>[CH2:12]([O:14][C:15](=[O:21])[CH:16]([CH2:23][C:24]1[CH:29]=[CH:28][C:27]([Cl:30])=[CH:26][CH:25]=1)[C:17](=[O:20])[CH2:18][CH3:19])[CH3:13]A suspension of potassium tert-butoxide (2.8 g) in anhydrous tetrahydrofuran (400 mL) at 0° C. was treated with a mixture of tert-butanol (1.0 mL) and 3-oxopentanoic acid ethyl ester (3.0 g). After stirring at room temperature for 45 minutes a solution of 1-bromomethyl-4-chlorobenzene (4.3 g) in tetrahydrofuran (100 mL) was added and the resulting mixture heated at 70° C. for 24 hours. The mixture was cooled to room temperature, diluted with water and the tetrahydrofuran removed under reduced pressure. The residue was extracted with ethyl acetate and the combined extracts dried over magnesium sulfate and then the solvent removed under reduced pressure. The residue was purified by column chromatography on silica gel, eluting with a mixture of cyclohexane and methyl tert-butyl ether (4:1 by volume) to afford title compound. 4.8 g.
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