An Efficient Catalyst-Free Direct Approach to 5-Polyfluoroalkyl-1,2,4-triazole-3-thiones.

An easy to handle high-efficient approach to 5-polyfluoroalkyl-1,2,4-triazole-3-thiones (11 examples, up to 91% yield) is reported. The tautomerism of thione and thiol forms for the obtained products is discussed. A one step procedure for 6,6-dimethyl-3-(trifluoromethyl)-5,6-dihydro[1,3]thiazolo[2,3- c ][1,2,4]triazole formation from trifluoroacetic acid and 4-methallylthiosemicarbazide has been developed. The structures of the products were unambiguously determined by complex NMR investigation and by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]