Reaction Steps
1N aqueous KOH solution (1.2 mL) was added to a stirred solution of the above 97 (0.12 g, 0.12 μmol) in EtOH (12 mL), THF (1 mL) and the mixture was refluxed gently until the ester disappeared (about 5 h) as determined by TLC analysis. The ethanolic solution was concentrated and then diluted with ether (4 mL). After the solution was acidified to pH3 with 1N HCl solution, organic phase was separated and aqueous phase was extracted with Et2O (2×5 mL). The combined organic phases were dried with MgSO4, concentrated and used without further purification: IR (CHCl3) 2957, 2929, 2857, 1692, 1471, 1462, 1254, 1089, 836, 773 cm−1; 1H NMR (300 MHz, CDCl3) δ 7.34 (dd, J=15.1, 11.4 Hz, 1H), 6.64 (ddd, J=16.0, 10.8, 10.5 Hz, 1H), 6.61 (t, J=11.2 Hz, 1H), 6.22 (dd, J=15.4, 6.0 Hz, 1H), 6.09 (t, J=11.0 Hz, 1H), 5.58 (d, J=11.3 Hz, 1H), 5.49-5.39 (m, 2H), 5.34-5.28 (m, 1H), 5.20 (d, J=16.7 Hz, 1H), 5.11 (d, J=10.2 Hz, 1H), 4.55 (m, 1H), 3.95 (m, 1H), 3.76 (m, 1H), 3.50 (m, 1H), 3.27 (m, 1H), 2.81 (m, 1H), 2.58 (m, 2H), 1.71 (m, 1H), 1.57-1.50 (m, 3H), 1.44-1.31 (m, 3H), 1.25 (d, J=7.3 Hz, 3H), 1.21 (d, J=6.1 Hz, 3H), 1.04 (d, J=6.9 Hz, 3H), 0.99 (d, J=7.0 Hz, 3H), 0.96-0.89 (m, 40H), 0.81 (d, J=6.2 Hz, 3H), 0.79 (d, J=5.9 Hz, 3H), 0.11-0.05 (m, 24H); 13C NMR (75 MHz, CDCl3) δ 171.1, 148.1, 147.3, 135.2, 132.8, 132.3, 131.6, 129.9, 126.6, 117.6, 115.0, 81.3, 77.6, 72.7, 66.4, 58.3, 43.0, 42.6, 40.1, 37.9, 36.0, 35.4, 35.2, 33.8, 32.2, 30.6, 26.3, 26.0, 25.9, 25.2, 19.6, 19.0, 18.4, 18.09, 18.05, 17.7, 16.6, 14.5, 7.0, −2.8, −3.45, −3.54, −3.7, −4.1, −4.2, −4.4; LRMS (ESI) 1029.7 [M+Na]+, 915.7, 897.7; HRMS (ESI) calcd for C56H110O7Si4Na 1029.7226 [M+Na]+, found 1029.7257; [α]20D−41.7 (c 1.4, CHCl3).
