[Br:1]Br.C([O-])(=O)C.[K+].[C:8]([C:10]1[CH:11]=[C:12]([C:17]2[N:18]=[C:19]([C:22]([O:24][CH2:25][CH3:26])=[O:23])[S:20][CH:21]=2)[CH:13]=[CH:14][C:15]=1[F:16])#[N:9].S([O-])([O-])(=O)=S.[Na+].[Na+]>C(O)(=O)C>[Br:1][C:21]1[S:20][C:19]([C:22]([O:24][CH2:25][CH3:26])=[O:23])=[N:18][C:17]=1[C:12]1[CH:13]=[CH:14][C:15]([F:16])=[C:10]([C:8]#[N:9])[CH:11]=1
At room temperature, 8.10 g (50.6 mmol) of bromine and 4.97 g (50.6 mmol) of potassium acetate are added to 1.40 g (5.07 mmol) of the compound from Example 28A in 80 ml of conc. acetic acid. The mixture is stirred at 100° C. for 48 h, whereby after 24 and 36 h, bromine (in each case 4.05 g, 25.3 mmol) and potassium acetate (in each case 2.49 g, 25.3 mmol) are again added. A 1M aqueous sodium thiosulfate solution is subsequently added, and the reaction solution is extracted with dichloromethane. The combined organic phases are dried over MgSO4, filtered and concentrated under reduced pressure. The crude product is purified by flash chromatography (mobile phase: cyclohexane/ethyl acetate 20:1→10:1). 1.55 g (84% of theory) of the title compound are obtained.
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