Reaction of β-nitrostyrenes with N,N-dichloro-p-toluenesulfonamide (TsNCl2) has been successfully conducted by using either copper(I) chloride or 4-dimethylaminopyridine (DMAP) as the catalyst. The reaction resulted in dichlorohaloamine products with the opposite regiochemistry to that previously observed. In the presence of DMAP, the reaction proceeded smoothly to completion within 24 hours at room temperature and gave good chemical yields (65-88%). The structure of one of the products was confirmed by X-ray crystal structure analysis. This reaction is proposed to occur through a new mechanism involving a chloronium intermediate.