1-(4-Bromophenyl)-2,2-dimethylpropan-1-one (56) was prepared by a method similar to that of Daz-Valenzuela. Tert-butyllithium (1.70 ml, 2.87 mmol, 1.7 M pentane solution) was slowly added to a suspension of copper bromide dimethyl sulfide complex (0.59 g, 2.87 mmol) in tetrahydrofuran (10 ml) at -78 °C and stirred for 30 min to form a sol. Subsequently, a solution of 4-bromobenzoyl chloride (38) (0.7 g, 3.19 mmol) in tetrahydrofuran (3 ml) was added dropwise at -78 °C and stirring was continued at -78 °C for 4 hours. After completion of the reaction, the reaction was quenched with saturated ammonium chloride solution (25 ml), the organic layer was extracted with ethyl acetate (3 x 25 ml), dried over anhydrous magnesium sulfate, filtered and concentrated in vacuum. The product was purified by distillation under reduced pressure (boiling point 140-150 °C/15 torr) to give a colorless oil 56 (0.30 g, 1.24 mmol, 43% yield). Thin layer chromatography (TLC) showed Rf = 0.60 (unfolding agent: hexane/ethyl acetate, 19:1).1H NMR (400 MHz, CDCl3) δ 1.34 (9H, s, C(CH3)3), 7.53-7.58 (2H, m, Ar-H); 13C NMR (100 MHz, CDCl3) δ 27.9 (CH3) 44.1 (C), 125.6 (C), 129.6 (CH), 131.2 (CH), 137.0 (C), 207.7 (C=O).
