[2-Carbethoxymethylene-thiazolidones-(4), a novel series of Heterocycles with choleretic properties].

Base-induced condensation of alpha-mercapto-carboxylic esters with activated acetonitriles yields 2-methylene-thiazolidones-(4). The paper presented describes the development of ethyl (Z)-(3-ethyl-4-oxo-5-piperidino-thiazolidin-2-ylidene) acetate (30; piprozoline, Gö 919, Probilin), a novel choleretic with exocrin pancreas stimulating and hepatoprotective properties, by following-up the choleretic parent compound 2, which belongs to the 2-carbethoxymethylene-thiazolidones-(4) series. Synthesis and properties of piprozoline are reported. Structure-activity relationship is discussed in short.