N(OC(C)(C)C)=O.[Br:8][C:9]1[CH:15]=[CH:14][C:12](N)=[C:11]([S:16][CH3:17])[C:10]=1[CH3:18].[CH3:19][S:20]SC>[Cu]>[CH3:18][C:10]1[C:11]([S:16][CH3:17])=[C:12]([S:20][CH3:19])[CH:14]=[CH:15][C:9]=1[Br:8]14.8 g (129 mmol) of tert-butyl nitrite and 20 g of copper powder are initially charged in 50 ml of dimethyl disulfide, and a solution of 20 g (86 mol) of 4-bromo-3-methyl-2-methylthioaniline in 100 ml of dimethyl disulfide is added dropwise at 50-55° C. The mixture is then stirred at 50° C. for 4 hours. For work-up, the solid is filtered off with suction and the solution is diluted with methylene chloride and extracted with dilute hydrochloric acid. The organic phase is washed with saturated aqueous NaHCO3 solution, dried over sodium sulfate, filtered off and concentrated using a rotary evaporator. Excess dimethyl disulfide is removed under oil pump vacuum.
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