Reaction Steps
Potassium carbonate (0.325 g, 2.35 mmol) was added to a solution of 51 (0.128 g, 0.392 mmol) in 1,4-dioxane/H2O 1:1 (5 mL) and followed by tosyl chloride (0.074 g, 0.392 mmol) at room temperature. After stirring for 2 h at room temperature, the resulting mixture was evaporated in vacuo to dryness. Water (10 ml) was added and the resulting white solid was separated by filtration and dried in vacuo. Pure 55 was obtained as an off-white solid (0.122 g, 0.254 mmol, 65%) without further purification, mp 135-137° C. 1H NMR (400 MHz, CD3OD) 1.36 (3H, t, J 7.2 Hz), 2.39 (3H, s), 2.63 (1H, dd, J 8.6, 14.6 Hz), 2.85 (1H, dd, J 6.2, 15.0 Hz), 3.05 (1H, dd, J 7.4, 13.0 Hz), 3.12 (1H, dd, J 6.8, 11.8 Hz), 4.32 (2H, q, J 7.2 Hz), 7.17-7.19 (3H, m), 7.23-7.27 (2H, m), 7.31 (2H, d, J 8.0 Hz), 7.54 (2H, d, J 8.4 Hz), 7.65 (2H, d, J 8.4 Hz), 7.90 (2H, d, J 8.8 Hz). 13C NMR (100 MHz, CDCl3) 14.57, 21.73, 40.65, 42.04, 47.77, 61.07, 119.15, 127.14, 127.75, 127.77, 129.29, 130.07, 130.94, 136.79, 140.74, 142.12, 143.97, 166.36, 170.24. νmax (solid)/(cm−1) 3324, 3191, 1707, 1675, 1597, 1534, 1270, 1157, 1105. MS (API-ES): m/z 481 [M+H]+ (100%), HRMS (API-ES) m/z found 481.1801 [M+H]+.
