Modifications on tetrahydropyridin-4-ylidene ammonium salts and their antiprotozoal activities

A new series of tetrahydropyridin-4-ylidene ammonium salts was prepared by a sequence of reactions including Dimroth rearrangements and selective reductions. All new compounds were characterized by UV–Vis spectroscopy, FT-IR spectroscopy, HRMS, and NMR spectroscopy. Their antitrypanosomal and antiplasmodial activities as well as their cytotoxicity were investigated in microplate assays. The results were compared to the activities of formerly investigated compounds and structure–activity relationships are discussed. The modification of the substitution in ring positions 1 and 6 led to a significant increase of both the antiprotozoal properties. Graphical abstract: .