A solution of (4-(methoxycarbonyl)benzyl)triphenylphosphonium bromide (2.9 g, 6 mmol) in 50 mL of THF was added dropwise via syringe to a solution of LDA (5 mL, 10 mmol) in THF at −78° C. under N2 atmosphere. After 30 min at this temperature 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzaldehyde (1.4 g, 6 mmol) in 50 mL of THF was added dropwise via syringe and then stirred at this temperature for 30 min and then allow warm to room temperature over 4 hours, and stirred overnight. The mixture was poured into H2O (300 mL) and then extracted with ethyl acetate (3×100 mL). The combined organic layer was concentrated and purified by silica gel chromatography (eluting with a mixture of petroleum ether and ethyl acetate=50:1) to give (E)-methyl 4-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)styryl)benzoate (0.9 g, 41%) as a colorless oil. LC-MS: 365 [M+H]+, tR=1.98 min.
