Selenocyanate‐Containing Molecules as <i>Trypanosoma cruzi</i> Inhibitors: Impact of Regioisomerism, Conformational Restriction, and Second‐Ring Substitution

As a continuation of the project aimed at searching for new chemotherapeuticagents against Chagas disease or American trypanosomiasis, new selenocyanate derivatives are designed, synthesized, and biologically evaluated against the clinically more relevant dividing amastigote form of Trypanosoma cruzi, the etiologic agent of this illness. Furthermore, as all the title compounds are fluorine-containing molecules, it seemed to be reasonable to explore the role of fluorine atoms in the aromatic system and to determine the optimal position at the terminal phenoxy group, and therefore, various regioisomers are prepared. The conformationally restricted selenocyates structurally related to WC-9Se exhibited improved antiparasitic activity compared to the lead drugs, Out to be extremely potent inhibitors of T. cruzi growth. In particular, (±)-5-(3-fluorophenoxy)-2-(selenocyanatomethyl)-2,3-dihydrobenzofuran exhibited an EC₅₀ value of 0.032 µM, which resulted in the most potent selenocyanate developed in the laboratory. The presence of the fluorine atom together with the rigidity of the molecules are beneficial for the anti-T. cruzi effect. The resulting antiparasitic activity provides further insight into the role of the selenocyanate group in its effective and putative anti-T. cruzi action.