Synthesis of novel thiazolidin-4-ones by reaction of malonthioamide derivatives with dimethyl acetylenedicarboxylate

Novel 2,5-dimethylenethiazolidin-4-one derivatives have been prepared by reaction of malonthioamide derivatives with dimethyl acetylenedicarboxylate. These compounds exist as separate (E,Z)- and (Z,Z)isomers or as a mixture. The (E,Z)-isomer is formed as the initial product which transforms to the (Z,Z)isomer under mild conditions. The structures of the obtained compounds have been confirmed by IR and NMR spectroscopy.