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). 1H NMR (270 MHz, CDCl3) δ7.30 (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 CH2+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); 13C NMR (67.8 MHz, CDCl3) δ169.7, 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.
