[Br:1][C:2]1[C:7]([O:8][CH3:9])=[C:6]([OH:10])[C:5]([Br:11])=[CH:4][C:3]=1[CH2:12][C:13]([CH3:18])([CH3:17])[CH2:14][CH:15]=[O:16].[OH-].[Na+].[CH2:21]([OH:23])[CH3:22]>O.[N+]([O-])([O-])=O.[Ag+]>[Br:1][C:2]1[C:7]([O:8][CH3:9])=[C:6]([OH:10])[C:5]([Br:11])=[CH:4][C:3]=1[CH2:12][C:13]([CH3:18])([CH3:17])[CH2:14][C:15]([O:23][CH2:21][CH3:22])=[O:16]
A solution of Silver Nitrate (0.722 g, 4.25 mmol) in 2.0 ml H2O was added to a solution of the product of STEP 4 (0.775 g, 2.04 mmol) in 20 ml ethanol. A solution of sodium hydroxide (2.71 g, 67.7 mmol) in 3.0 ml H2O was added dropwise at room temperature. After 6 h, the reaction was filtered through a short column of Celite® and washed with H2O. The filtrate was extracted with ether (3×30 ml). The aqueous layer was acidified with concentrated HCl and extracted with chloroform. The organic layer was dried with MgSO4, concentrated and dried in vacuo. The residue (0.75 g) was dissolved in 15 ml ethanol and 15 ml 4N HCl in dioxane. The reaction was stirred at room temperature for 18 h and concentrated. The residue was purified by chromatography (on silica gel, ethyl acetate/hexane=3/7) to afford a pale brown oil in 0.536 g. NMR spectra of the product were consistent for the proposed structure.
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