Reaction Steps
To stirring solution of TBDPS ether 7 (119 mg, 0.101 mmol, 1.0 equiv) in DMF, was added a solution containing 1.0 M TBAF in THF (101 μL, 0.101 mmol, 1.0 equiv), and 1.0 M AcOH in DMF (101 μL, 0.101 mmol, 1.0 equiv) in additional DMF (300 μL), via cannula, rinsing once with DMF (300 μL). Stirring continued at rt for 21 h, and the reaction mixture was diluted with 40% EtOAc/hexanes (5 mL) and quenched with water (5 mL). The phases were separated and the aqueous phase was extracted three times with 40% EtOAc/hexanes (5 mL). The combined organic phases were dried over Na2SO4, filtered, and concentrated under reduced pressure. Purification was accomplished using flash column chromatography with a 3×8 cm silica gel column, eluting with 30% EtOAc/hexanes, collecting 13×100 mm test tube fractions. The product containing fractions (6-35) were combined and concentrated under reduced pressure to provide pure alcohol 22 (85.2 mg, 90%) as a clear viscous oil: Rf=0.21 (30% EtOAc/hexanes); [α]D20=+3.1 (c=1.03, CHCl3); 500 MHz 1H NMR (CDCl3) δ 7.38-7.24 (m, 7H), 6.88 (d, J=8.3 Hz, 2H), 6.04 (d, J=16.1 Hz, 1H), 5.46 (dd, J=16.1 6.3, Hz, 1H), 4.80 (d, J=6.8 Hz, 1H), 4.78 (d, J=6.8 Hz, 1H), 4.73 (d, J=1.5 Hz, 2H), 4.67 (s, 1H), 4.63 (s, 2H), 4.59 (s, 1H), 4.50 (d, J=10.7 Hz, 1H), 4.46 (d, J=10.7 Hz, 1H), 4.13-4.09 (m, 1H), 4.07 (ddd, J=9.0, 4.1, 2.4 Hz, 1H), 3.91-3.86 (m, 1H), 3.84-3.70 (m, 4H), 3.80 (s, 3H), 3.56-3.42 (m, 3H), 3.29 (s, 3H), 2.44 (dd, J=8.3, 5.9, Hz, 2H), 2.35 (s, 1H), 2.28-2.17 (m, 4H), 2.04-1.89 (m, 8H), 1.80 (ddd, J=14.3, 8.4, 2.5 Hz, 1H), 1.75-1.56 (m, 4H), 1.52 (ddd, J=11.2, 9.3, 3.4 Hz, 1H), 1.14 (d, J=6.3 Hz, 3H), 1.12 (s, 3H), 1.09 (s, 3H), 0.88 (s, 9H), 0.08 (s, 3H), 0.08 (s, 3H); 125 MHz 13C NMR (CDCl3) δ 207.5, 159.5, 144.6, 144.4, 138.0, 137.3, 130.6, 129.7, 129.2, 128.6, 128.0, 127.9, 114.1, 109.0, 108.9, 104.0, 93.4, 79.4, 75.4 (×2), 75.2, 75.1, 75.0, 72.0, 70.8, 69.8, 69.6, 60.5, 55.5, 52.8, 44.4, 42.9, 41.8, 41.5, 41.2, 41.0 (×2), 40.5, 38.2, 37.7, 36.8, 30.7, 26.1, 23.1, 22.1, 18.3, 14.0, −3.8, −4.4; 125 MHz DEPT 13C NMR (CDCl3) CH3 δ 55.5, 52.8, 26.1, 23.1, 22.1, 14.0, −3.8, −4.4; CH2 δ 109.0, 108.9, 93.4, 72.0, 69.6, 60.5, 42.9, 41.8, 41.5, 41.2, 41.0 (×2), 40.5, 38.2, 37.7, 36.8, 30.6; CH δ 137.3, 129.7, 129.2, 128.6, 128.0, 127.9, 114.1, 79.4, 75.4 (×2), 75.2, 75.1, 75.0, 70.8, 69.8; CH0 δ 207.5, 159.5, 144.6, 144.4, 138.0, 130.6, 104.0, 44.4, 18.3; IR (neat) 3446, 2937, 2857, 2360, 1725, 1652, 1613, 1514, 1463, 1381, 1303, 1250, 1113, 1042, 777 cm−1; HRMS (EI+) calcd for C53H78O10Si (M-MeOH) 902.5370. found 902.5381.
