Thioamides as useful synthons in the synthesis of heterocycles

The synthesis of heterocycles was studied by using thioamides as useful synthons. The chemical and physical properties of thioamides were determined by the two active centers: one of them was associated with the nitrogen atom with the unshared pair of electrons and other one was localized on the thiocarbonyl group. It was found that the inductive and conjugation effects on the introduced substituents face in thioamides the mesomeric effect due to delocalization of π electrons and lability of the unshared electron pairs on the nitrogen and sulfur atoms.