The reaction of the N,N-dichloroamide of 5-chloro-2-thienylsulfonic acid with trichloroethylene as a convenient synthetic route to a series of trichloroethylamides of 5-chloro-2-thienylsulfonic acid

N-(2,2,2-Trichloroethylidene)-5-chlorothien-2-ylsulfonamide, the first representative of the polyhaloalkylidenamides of heterylsulfonic acids, has been synthesized by the reaction of N,N-dichloro- 5-chlorothien-2-ylsulfonamide with trichloroethylene and used as a regioselective C-amidoalkylating agent of aromatic compounds and in reactions with nucleophiles, forming a series of N-(2,2,2-trichloroethyl) amides of 5-chloro-2-thienylsulfonic acid.