Department of Organic Synthesis Technology, Ural State Technical University,
620002 Ekaterinburg, Russia
We have studied the direction of the cyclization of N,N'-disubstituted
malondithioamides 1 into isomeric 5-amino-1,2,3-thiadiazoles 2
and 3. It has been shown that the ratio of isomeric heterocycles
2 and 3 depends on their relative stability. The ratio of
thiadiazoles 2 and 3 in the mixture is also influenced by the
solvent.
In order to prepare new heterocyclic sulfur compounds a systematic study of the
reactions of thioamides 4-6 with acetylenedicarboxylates and propiolates
has been carried out. These reactions were found to take place in three
directions to form thiazine derivatives of types 7 and 9,
thiazoles 8 and allylmercapto imidazoles 10.
We have shown that the direction of these reactions depends on the nature of
thioamide and on the type of acetylene derivative used.
A number of hydrazonoyl thioamides 11 have been prepared to study
their oxidative cyclization. It has been shown that their reaction leads to the
formation of 2-aryl-1,2,3-thiadiazolidene-5-imines 12, 13.
