[C:1]1([C:7]([CH3:12])([CH3:11])[CH2:8][Mg]Br)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[C:13](OCC)(=[O:19])[C:14]([O:16][CH2:17][CH3:18])=[O:15]>C1COCC1>[CH2:17]([O:16][C:14](=[O:15])[C:13](=[O:19])[CH2:8][C:7]([CH3:12])([C:1]1[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1)[CH3:11])[CH3:18]2-Phenyl-2,2-dimethylethylmagnesium bromide (10 mmol, 20 mL of 0.5 M solution in diethyl ether) was added to solution of diethyl oxalate (1.5 g, 10.5 mmol) in anhydrous THF (20 mL) cooled to −78° C. and maintained under argon. After 1 hour, TLC in hexanes-EtOAc (7:1) indicated most of the diethyl oxalate had been consumed. The reaction mixture was quenched with a saturated solution of ammonium chloride and extracted with three 50 mL portions of EtOAc. The combined extracts were dried over anhydrous sodium sulfate and concentrated in vacuo to give a light brown, thick oil which was purified by flash column chromatography over silica gel eluting with 5% EtOAc in hexanes to yield 4-methyl-2-oxo-4-phenylpentanoic acid ethyl ester as a light yellow oil (1.1 g, 51%).
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