[Br:1]N1C(=O)CCC1=O.[Cl:9][C:10]1[C:15]([CH3:16])=[C:14]([Cl:17])[CH:13]=[CH:12][C:11]=1[S:18]([Cl:21])(=[O:20])=[O:19]>ClC(Cl)C(Cl)Cl.C(OOC(=O)C1C=CC=CC=1)(=O)C1C=CC=CC=1>[Br:1][CH2:16][C:15]1[C:10]([Cl:9])=[C:11]([S:18]([Cl:21])(=[O:20])=[O:19])[CH:12]=[CH:13][C:14]=1[Cl:17]85.44 g (0.48 mol) of N-bromosuccinimide and then 200 mg of benzoyl peroxide are added to a solution, at room temperature, of 41.52 g (0.16 mol) of 2,4-dichloro-3-methylbenzenesulfonyl chloride in 150 ml of 1,1,2,2-tetrachloroethane. The reaction mixture is heated at 120° C. for 2 hours. It is cooled and filtered and the filtrate is washed successively with water, with saturated sodium bicarbonate solution and finally with water until the washings are neutral. The organic phase collected from the filtrate is then dried over magnesium sulfate and concentrated. Recrystallization from hexane gives 25.53 g of the expected product in the form of white crystals (yield =47%).
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