To a suspension of NaH (60%, 18 g, 0.45 mol) in THF (2 L) were added (3,5-bis-methoxymethoxy-benzyloxy)-tert-butyl-dimethyl-silane (220c) (100 g, 0.3 mol) and TMEDA (81.6 g, 0.6 mol) in one portion. The mixture was stirred at 0° C. for 1 hr. n-BuLi (2.5 M in hexane, 180 mL, 0.45 mol) was added drop wise to the mixture at −20° C. and the solution was stirred for 1 hr. CuI (114 g, 0.6 mol) was added in one portion and the reaction was stirred at −20° C. for another 1 hr. Then the mixture was added drop wise cinamy bromide (65 g, 0.3 mol) at −20° C. After stirring for another 30 min, TLC (EtOAc/petroleum ether=1/10) showed that the reaction was complete. The reaction mixture was quenched with H2O (500 mL). The organic layer was separated and the aqueous layer was extracted with EtOAc (2×500 mL). The organic layers were combined, washed with brine (1 L), dried over Na2SO4 and concentrated to give a dark oil. The crude oil was purified by column chromatography (EtOAc/petroleum ether=1/10) to give the title compound (55 g, 34%) as a yellow liquid. 1H NMR (400 MHz, CDCl3): δ 7.16-7.41 (m, 5H), 6.82 (s, 2H), 6.47 (m, 2H), 5.22 (s, 4H), 4.71 (s, 2H), 3.62 (d, 2H), 3.45 (s, 6H), 0.94 (s, 9H), 0.12 (s, 6H).
