[H-].C([Al+]CC(C)C)C(C)C.[C:11]([Si:15]([CH3:36])([CH3:35])[O:16][CH:17]1[CH2:22][CH:21]([O:23][Si:24]([C:27]([CH3:30])([CH3:29])[CH3:28])([CH3:26])[CH3:25])[CH2:20][C:19]([OH:34])([C:31]([O-])=[O:32])[CH2:18]1)([CH3:14])([CH3:13])[CH3:12]>C1(C)C=CC=CC=1>[C:27]([Si:24]([CH3:26])([CH3:25])[O:23][CH:21]1[CH2:22][CH:17]([O:16][Si:15]([C:11]([CH3:12])([CH3:13])[CH3:14])([CH3:35])[CH3:36])[CH2:18][C:19]([OH:34])([CH2:31][OH:32])[CH2:20]1)([CH3:30])([CH3:29])[CH3:28]Diisobutyl aluminum hydride (6 mL, 9 mmol, 1.5M in toluene) was added to a solution of the ester 14 (0.56 g, 1.3 mmol) in anhydrous toluene (20 mL) at -78° C. After 20 min the solution was warmed to 0° C. and stirred for 1 h. The solution was slowly quenched by adding to a stirred 0° C. solution of 2N potassium sodium tartrate. Ethyl acetate was added and the organic layer separated and the water phase extracted with ethyl acetate. The combined organic phase was washed with brine, dried over anhydrous MgSO4, filtered and evaporated. The material was further purified by column chromatography on silica gel with ethyl acetate hexane mixtures to give the diol 15 (0.3 g, 59%) 1H NMR (CDCl3, 500 MHz) δ0.11 (s, 3H), 0.12 (s, 3H), 0.14 (s, 3H), 0.16 (s, 3H), 0.90 (s, 9H), 0.91 (s, 9H), 1.28 (dd, 1H), 1.43 (dd, 1H), 2.00 (ddd 3H), 2.16 (dd, 1H), 3.33 (dd, 1H), 3.40 (dd, 1H), 4.34 (m, 2×1H).
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