N[C:2]1[C:7]([C:8]([O:10][CH3:11])=[O:9])=[C:6]([CH3:12])[C:5]([Br:13])=[CH:4][CH:3]=1.N([O-])=[O:15].[Na+].OS(O)(=O)=O>O>[Br:13][C:5]1[C:6]([CH3:12])=[C:7]([C:2]([OH:15])=[CH:3][CH:4]=1)[C:8]([O:10][CH3:11])=[O:9]A 0° C. suspension of Example 106A (1 g, 4.1 mmol) in water (6 mL) was treated dropwise with a solution of NaNO2 (285 mg) in water (1.25 mL), stirred at 0° C. for 15 minutes, then added slowly to a 90° C. solution of concentrated H2SO4 (4 mL) in water (4 mL). The reaction was stirred at 90° C. for 45 minutes, cooled to room temperature, and extracted three times with diethyl ether. The combined extracts were washed with aqueous NaHCO3 and brine, dried (MgSO4), filtered, and concentrated to give 0.87 g of the desired product. MS (ESI(−)) m/e 226 (M−H)−.
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