New quinolin-3-yl-N-hydrazinecarbothioamides in the synthesis of thiazoles and thiazines

Reaction of 2-((4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)methylene)hydrazinecarbothioamides with dimethyl acetylenedicarboxylate afforded, in good yields, the corresponding thiazoles derived from 2-quinolones. However, the reaction of N-ethyl-2-quinonylhydrazinecarbothioamide with 2-(bis(methylthio)methylene)malononitrile or its ester derivative gave the corresponding quinolin-3-yl-methylenehydrazono-1,3-thiazines. The proposed mechanism was discussed. The structure of the obtained products was elucidated via NMR, IR and mass spectra as well as elemental analysis.