[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[NH:9][C:10]([S:15][C:16]([F:19])([F:18])[F:17])=[CH:11][C:12]=2[C:13]#[N:14])=[CH:4][CH:3]=1.[Br:20]N1C(=O)CCC1=O.C([O-])(=O)C.[Na+].BrBr>O1CCCC1.CCOCC.O.C(O)(=O)C>[Br:20][C:11]1[C:12]([C:13]#[N:14])=[C:8]([C:5]2[CH:6]=[CH:7][C:2]([Cl:1])=[CH:3][CH:4]=2)[NH:9][C:10]=1[S:15][C:16]([F:17])([F:19])[F:18]
Under a nitrogen purge, a solution of 2-(p-chlorophenyl)-5-[(trifluoromethyl)thio]pyrrole-3 -carbonitrile (0.6 g, 0.002 mol) in tetrahydrofuran is treated with N-bromosuccinimide (0.36 g, 0.002 mol), stirred for 16 hours at room temperature and concentrated in vacuo to obtain a residue. The residue is dissolved in ether and diluted with water. The organic phase is separated, washed with water and brine, dried over anhydrous magnesium sulfate and concentrated in vacuo to obtain a solid. High performance liquid chromatography indicates that the solid contains 20% starting material. A solution of the mixture and sodium acetate (0.05 g, 0.006 mol) in acetic acid is treated with bromine (0.03 mL, 0.0006 mol), stirred for 16 hours at 60° C., cooled and concentrated in vacuo to obtain a semi-solid. The semi-solid is partitioned between ethyl acetate and water. The organic phase is separated, washed with water and brine, dried over anhydrous magnesium sulfate and concentrated in vacuo to obtain a solid. The solid is recrystallized from ethylene dichloride to give the title product as an off-white solid (mp 241°-243° C.) which is identified by 1HNMR and 13CNMR spectral analyses.
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