1,4-Thiazepines derivatives are pharmacologically important heterocycles with different applications in medicinal chemistry. In the present work, we describe the preparation of new bicyclic thiazolidinyl-1,4-thiazepines <b>3</b> by reaction between azadithiane compounds and Michael acceptors. The reaction scope was explored and the yields were optimized. The activity of the new compounds was evaluated against <i>Nippostrongylus brasiliensis</i> and <i>Caenorhabditis elegans</i> as anthelmintic models and <i>Trypanosoma brucei brucei.</i> The most active compound was <b>3l</b>, showing an EC<sub>50</sub> = 2.8 ± 0.7 μM against <i>T. b. brucei</i> and a selectivity index >71.