Reaction Steps
The mixture of (1R,2R,3R,4S)-3-[(Z)-6-(4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl)hexe-2-nyl]-2-[(phenylsulfonyl)methyl]-4-(triethylsilyloxy)cyclopentanol (ca. 65%) and (1S,2R,3R,4R)-2-[(Z)-6-(4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl)hex-2-enyl]-3-[(phenylsulfonyl)methyl]-4-(triethylsilyloxy)cyclopentanol (ca. 35%) (584 mg of the mixture, yield 15.4%), colorless glaze was obtained; 1H-NMR (CDCl3; 200 MHz) δ 0.57 (6H, 2×q), 0.79 (1.95H, s), 0.80 (1.05H, s), 0.93 (9H, 2×t), 1.34-1.54 (3.5H, m), 1.56-1.78 (3H, m), 1.82-2.20 (6.6H, m), 3.01 (0.65H, dd: 14.4, 11.2 Hz), 3.32 (0.65H, dd: 14.4, 2.6 Hz), 3.56 (0.65H, m), 3.88 (3.9H, s), 3.89 (2.1H, s), 3.90 (0.35H, m), 4.13 (1.30H, m), 5.15-5.38 (2H, m), 7.54-7.74 (3H, m), 7.93-7.99 (2H, m); fractions prepared after washing out with Phase II were combined on the basis of TLC chromatograms, concentrated and dried under vacuum. Glaze was obtained (3.597 g) containing slight amount of triphenylphosphine oxide, which was removed by two-time maceration with Et2O (8 mL, 4 mL). (1R,3S,4R,5R)-4-[(Z)-6-(4-Methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl)hex-2-enyl]-5-[(phenylsulfonyl)methyl]cyclopentane-1,3-diol was prepared (2.0 g, 65.5%); 1H-NMR (CDCl3; 200 MHz) δ 0.80 (3H, s), 1.36-1.52 (3H, m), 1.61 (2H, m), 1.8-2.29 (8H, m), 3.05 (1H, dd: 14.3, 11.2 Hz), 3.33 (1H, dd: 14.3, 2.6 Hz), 3.53 (1H, bs, OH), 3.88 (6H, s), 4.09 (1H, m), 4.31 (1H, m), 5.17-5.39 (2H, m), 7.47-7.74 (3H, m), 7.93-7.99 (2H, m).
