[S:1]([C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)[C@@H:2]1[O:10][C@H:9]([CH2:11][OH:12])[C@H:7]([OH:8])[C@H:5]([OH:6])[C@H:3]1[OH:4].[H-].[Na+].[CH2:21](Br)[C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1.[I-].[K+]>CN(C=O)C.O.CCOCC>[CH2:21]([O:4][C@@H:3]1[C@@H:5]([O:6][CH2:21][C:22]2[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=2)[C@@H:7]([O:8][CH2:21][C:22]2[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=2)[C@@H:9]([CH2:11][O:12][CH2:21][C:22]2[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=2)[O:10][C@H:2]1[S:1][C:13]1[CH:14]=[CH:15][CH:16]=[CH:17][CH:18]=1)[C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1To the crude 9 (72.1 mmol, 1 eq) dissolved in dry DMF (1500 mL) under argon at 0° C. was added sodium hydride (10.7 g, 446.8 mmol, 6.2 eq). After 15 min, were added dropwise benzyl bromide (54 mL, 454 mmol, 6.3 eq) and a catalytic amount of potassium iodide. The mixture was stirred at room temperature for 3 h, diluted with water (500 mL) and Et2O (600 mL). The aqueous phase was extracted with Et2O (3×300 mL). The organic extracts were combined, dried over MgSO4 and concentrated. Purification by flash chromatography on silica gel (petroleum ether/EtOAc 90:10) afforded 10 as viscous syrup (27.5 g, 60% over 2 steps).
Wird geladen…