Reaction Steps
To a solution of bromine (0.91 mL, 17.8 mmol) in CH2Cl2 (50 mL) at 0° C. was added drop-wise ethyl vinyl ether (2.13 mL, 22.2 mmol). The resulting colorless solution was stirred for 20 min at 0° C. and N,N-diisopropylamine (DIEA) (6.23 mL, 35.6 mmol) added drop-wise, followed by a CH2Cl2 (20 mL) solution of 10 (3.55 g, 8.9 mmol). The resulting solution was stirred for 16 h at 23° C., until all starting material was consumed, as determined by TLC. The mixture was poured onto saturated aqueous NaHCO3 (100 mL), and extracted with CH2Cl2 (3×70 mL). The combined extracts were washed with brine (80 mL), dried (Na2SO4), and concentrated in vacuo to yield orange oil. The crude oil was purified via flash column chromatography (SiO2, 10% EtOAc/hexanes) to give 12 (4.84 g, 99% yield) as a thick orange oil. Rf 0.52 (3:1 hexanes/EtOAc). IR (thin film) 2966, 2944, 2892, 2867, 1684 cm−1. 1H NMR (300 MHz, CDCl3) δ 9.64 (1H, s), 7.85 (1H, d, J=8 Hz), 7.25-7.18 (2H, m), 7.03 (1H, d, J=8 Hz), 6.96 (2H, d, J=8 Hz), 5.06-5.02 (1H, m), 3.98 (3H, s), 3.65-3.55 (1H, m), 3.42-3.34 (1H, m), 3.12-3.01 (2H, m), 1.35-1.20 (3H, m), 1.13 (18H, d, J=7 Hz), 1.05 (3H, t, J=7 Hz). 13C NMR (75 MHz, CDCl3) δ 191.1, 156.9, 156.1, 141.5, 140.5, 132.4, 128.4, 125.1, 119.4, 113.6, 111.0, 103.5, 64.5, 55.9, 31.7, 17.8, 14.9, 12.5. HRMS calcd. for C27H40O5SiBr (MH+) 551.1828. Found 551.1821.
