[CH2:1]([C:5]1[C:9]2[CH:10]=[CH:11][CH:12]=[CH:13][C:8]=2[O:7][N:6]=1)[CH2:2][CH:3]=C.[O:14]1CCOCC1.I([O-])(=O)(=O)=O.[Na+]>[Os](=O)(=O)(=O)=O.O.C(OCC)(=O)C>[O:7]1[C:8]2[CH:13]=[CH:12][CH:11]=[CH:10][C:9]=2[C:5]([CH2:1][CH2:2][CH:3]=[O:14])=[N:6]1Compound 26 (549 mg, 3.2 mmol), water (5 mL), 1,4-dioxane (15 mL) and osmium tetroxide (15 mg, 0.06 mmol) were stirred for 5 min. in a small flask. Sodium metaperiodate (1.56 g, 7.3 mmol) was added over 30 min. and the suspension was then stirred for 1 hour. Ethyl acetate and water were added. The phases were separated and the aqueous phase was extracted with ethyl acetate and dichloromethane. The combined organic phases were dried over magnesium sulphate and evaporated to dryness to produce 784 mg of crude 27, which was used directly without further purification in the synthesis compound 28.
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