Reaction Steps
N-Boc-alcohol 2 (1.812 g, 4 mmol) was dissolved in CH2Cl2 (50 ml) and Et3N (1.95 ml, 14 mmol) at 0° C., to which Py.SO3 (2.23 g, 14 mmol) in 10 ml of DMSO was added dropwise. The ice bath was then removed and the mixture was stirred at r.t. until alcohol disappeared by TLC. HCl (1N) was added, and the organic layer was then separated and washed with sat. NaHCO3, brine, and dried over MgSO4. In another flask, Ph3P+CH2OMeCl− (2.74 g, 8 mmol) was added to KOtBu (875 mg, 7.8 mmol) at 0° C. under N2, which was stirred for 0.5 h. The aldehyde in 20 ml of CH2Cl2 was added dropwise, followed by removal of ice bath. The reaction was kept for 2-3 h before sat. NH4Cl was poured into the mixture. CH2Cl2 was used for extraction and the organic layers were washed with sat. NaHCO3 and brine, dried over MgSO4. Chromatography afforded 1.5 g of light yellow solid. Yield: 78% for two steps. mp 150-152° C.; [α]23D=108.1° (c 0.59, CHCl3); 1H NMR (400 MHz, CDCl3, E/Z=2.5:1): δ 7.94-7.91 (m, 2H), 7.88 (d, J=9.2 Hz, 1H), 7.29 (s, 1H), 7.26-7.22 (m, 1H), 6.30 (d, J=12.8 Hz, 0.68H, E isomer), 5.86 (dd, J=6.4 Hz, J=1.6 Hz, 0.28 Hz, Z isomer), 5.72 (m, 0.31H, Z isomer), 5.30-5.25 (d, J=16.8 Hz, 1H+0.67H, E isomer), 4.80 (dd, J=12.8 Hz, J=8.4 Hz, 0.71H, E isomer), 4.59 (d, J=17.2 Hz, 1H), 4.42 (dd, J=8.0 Hz, J=6.4 Hz, 0.29H, Z isomer), 4.12-4.11 (m, 3H), 4.05-4.04 (m, 3H), 4.03-4.02 (m, 3H), 3.62 (s, 0.7111, Z isomer), 3.44-3.32 (m, 1H), 3.36 (s, 211, E isomer), 3.13 (d, J=16.0 Hz, 1H), 1.55 (s, 9H); ESI MS m/z 480.05 (M+H)+.
