O[CH2:2][C:3]1[CH:8]=[CH:7][C:6]([C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[NH:15][C:16]([N:18]([CH3:20])[CH3:19])=[O:17])=[CH:5][CH:4]=1.C[Si]([Br:25])(C)C>C(Cl)Cl>[Br:25][CH2:2][C:3]1[CH:8]=[CH:7][C:6]([C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[NH:15][C:16]([N:18]([CH3:20])[CH3:19])=[O:17])=[CH:5][CH:4]=1A solution of the intermediate obtained in Step B in 4 ml of methylene chloride was treated with 0.16 mL (1.21 mmol) of trimethylsilylbromide. The reaction mixture was stirred at room temperature for 18 hours. T he reaction mixture was diluted with methylene chloride then washed with aqueous saturated sodium chloride (2×). The organic layer was dried over magnesium sulfate, filtered and evaporated under vacuum to yield 133 mg of crude product. 1NMR (400 Hz, CDCl3): δ 2.78 (s, 6H), 4.5 (s, 2H), 6.4 (br s, 1H), 7.08 (t, 1H), 7.16 (dd, 1H), 7.34 (m, 4H), 7.49 (d, 1H), 8.10 (d, 1H).
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