Reaction Steps
A solution of 1 N TBAF in THF (19.58 mL, 19.58 mmol) was added to a stirred solution of 172 (7.0 g, 13.05 mmol) in THF (50 mL). The reaction mixture was allowed to stir at room temperature for 2 hours and diluted with DCM (200 mL), washed with water (2×200 mL), brine (2×200 mL) and dried over anhydrous MgSO4. Filtration and removal of excess solvent afforded the crude product, which was purified by flash column chromatography using 50:50 petroleum ether:EtOAc as eluent. Evaporation in vacuo of the pure fractions afforded the product (173) (5.9 g). 1HNMR (270 MHz, CDCl3) δ 7.30 (s, 1H, ArH), 7.24 (s, 1H, ArH), 5.52 (d, 1H, J=9.9 Hz, SEM amino acetal CH2), 4.68-4.64 (m, 2H, SEM amino acetal CH, +2), 4.30 (dd, 1H, J=5.86, 8.24 Hz), 3.91 (s, 3H, OMe), 3.90 (s, 3H, OMe), 3.87-3.51 (m, 4H, SEM 1′ CH2+3), 2.95 (dt, 1H, J=5.31, 13.56 Hz, 1), 2.17-2.08 (m, 1H, 1), 1.02-0.93 (m, 2H, SEM 2′ CH2), 0.03 (s, 9H, 3×SiCH3); 1C NMR (67.8 MHz, CDCl3) δ 169.7, 165.9, 151.9, 147.1, 134.0, 121.1, 111.2, 105.5, 78.2, 69.1, 67.1, 56.5, 56.1, 53.9, 34.9, 18.4, −1.3.
