A solution of 3-bromo-2-methoxybiphenyl (1.18 g, 4.5 mmol) in anhydrous tetrahydrofuran (20 mL) was stirred under nitrogen at −78° C. and 2.5 M n-butyllithium in hexanes (1.8 mL, 4.5 mmol) was added at such a rate that the temperature did not exceed −70° C. Stirring was continued on the cold bath for 20 min and a solution of 14 (1.55 g, 4.5 mmol) in dry tetrahydrofuran (8 mL) was added at such a rate that the temperature did not exceed −65° C. Stirring was continued on the cold bath for 30 min then the reaction mixture was allowed to reach room temperature and stirred for 2 hr. The reaction mixture was poured on saturated ammonium chloride (150 mL) and extracted with ethyl acetate (180 mL). The organic extract was washed with water (2×80 mL), dried over sodium sulfate and stripped. The crude product was purified by chromatography on silica (85 g) with 0.2% ethyl acetate in heptane (6 L). Pure 15 (1.02 g, 43%) was isolated.
