(4-(tert-Butyldimethylsilyloxy)-3-ethoxyphenyl)methyltriphenylphosphonium bromide (1.15 g, 1.89 mmol, 1.0 equiv.) in THF (8 mL), was cooled to 0° C. After adding n-BuLi (1.6 M in hexanes, 1.2 mL, 1.89 mmol, 1.0 equiv.) at 0° C., the red solution was stirred at 65° C. for 1 h. The mixture was re-cooled to 0° C., 3-(3-isopropylphenyl)butanal (541 mg, 2.84 mmol, 1.5 equiv.) in THF (3 mL) was added, and the mixture was stirred at 65° C. for 18 h. After addition of H2O, the aqueous layer was extracted with cyclohexane (2×), the combined organic phases were washed with brine, dried (MgSO4), filtered and the filtrate was concentrated. The residue was purified by flash chromatography on SiO2 (cyclohexane/EtOAc 98:2) to yield a colorless oil which was dissolved in THF (10 mL). n-Bu4NF (1.0 M in THF, 2.3 mL, 2.27 mmol, 1.2 equiv.) was added, and the mixture was stirred at 25° C. for 1 h. After addition of H2O, the aqueous layer was extracted with EtOAc (2×), the combined organic phases were washed with brine, dried (MgSO4), filtered and the filtrate was concentrated. The residue was purified by flash chromatography on SiO2 (cyclohexane/EtOAc 19:1→9:1) to yield 0.33 g (54% over 2 steps) of the title compound as a yellow oil.
