Sematilide can be synthesized from benzocaine (1).12 Reaction with mesyl chloride, followed by saponification and removal of the water from the reaction mixture, gives sodium 4-[(methylsulfonyl)amino]benzoate (2). Chlorination with thionyl chloride gives 4-[(methylsulfonyl)amino]benzoyl chloride. Amide formation with N,N-diethylethylenediamine (3) then concludes the synthesis of sematilide (4).
Lumma, William C.; Wohl, Ronald A.; Davey, David D.; Argentieri, Thomas M.; Devita, Robert J.; Gomez, Robert P.; Jain, Vijay K.; Marisca, Anthony J.; Morgan, Thomas K.; Reiser, H. J. (1987). "Rational design of 4-[(methylsulfonyl)amino]benzamides as class III antiarrhythmic agents". Journal of Medicinal Chemistry. 30 (5): 755–758. doi:10.1021/jm00388a001. PMID 3572962. /wiki/Doi_(identifier) ↩
David D. Davey, William C. Lumma, Jr., Ronald A. Wohl, U.S. patent 4,544,654 (1985 to Schering A.G.) https://patents.google.com/patent/US4544654 ↩