[F:1][C:2]1[CH:3]=[C:4]2[C:13](=[CH:14][CH:15]=1)[C:12]1[CH:11]=[CH:10][CH:9]=[CH:8][C:7]=1[N:6]([S:16]([C:19]1[CH:24]=[CH:23][C:22]([O:25]C)=[CH:21][CH:20]=1)(=[O:18])=[O:17])[CH:5]2[CH3:27].B(Br)(Br)[Br:29].ClCCl>C(=O)(O)[O-].[Na+]>[Br:29][C:10]1[CH:9]=[CH:8][C:7]2[N:6]([S:16]([C:19]3[CH:24]=[CH:23][C:22]([OH:25])=[CH:21][CH:20]=3)(=[O:18])=[O:17])[CH:5]([CH3:27])[C:4]3[C:13](=[CH:14][CH:15]=[C:2]([F:1])[CH:3]=3)[C:12]=2[CH:11]=18-Fluoro-5-(4-methoxyphenylsulfonyl)-6-methyl-5,6-dihydrophenanthridine (0.64 g, 1.7 mmol) was treated with 1 M boron tribromide in dichloromethane (6.6 mL, 6.6 mmol) and stirred at room temperature for twelve hours. A solution of saturated, aqueous, sodium bicarbonate (50 mL) was added slowly to the reaction, followed by extraction of the mixture with dichloromethane (6×20 mL). The combined organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo to a crude material. The crude material was filtered through a short column of silica gel, eluted with a mixture of ethyl acetate-hexane (1:4), and the filtrate concentrated in vacuo to a solid. After trituration with dichloromethane and filtration, the title compound was obtained as a homogeneous solid (0.23 g, 37%), m.p. 237-239° C.;
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