SematilideSematilide is an antiarrhythmic agent. It is the same structure as for procainamide, differing only by the placement of a mesyl sulfonamide moiety to the anilino nitrogen.SynthesisSematilide can be synthesized from benzocaine. Reaction with mesyl chloride, followed by saponification and removal of the water from the reaction mixture, gives sodium 4-benzoate. Chlorination with thionyl chloride gives 4-benzoyl chloride. Amide formation with N,''N''-diethylethylenediamine then concludes the synthesis of sematilide.