It is shown that thioacetamide are comfortable synthetic blocks for various heterocycles, including thiazole containing a double exocyclic bonds. This work describes the synthesis of (Z)-2-((Z)-5-arylidene-4-oxo-3-arylthiazolidin-2-ylidene)-N-arylethanethioamide 4 obtained from the Knoevenagel condensation of (Z)-2-(4-oxo-3-arylthiazolidin-2-ylidene)-N-arylylethanethioamide 2. The starting material 2 was synthesized by a Hantzsch reaction of N,N`-diarylmalondithioamides 1 and ethyl 2-chloroacetate. The structures of the obtained products were established by NMR and the structural features are discussed. Several 4-oxothiazolidin-2-ylidenes were studied by UV-visible spectroscopy technique