Synthesis of 2-polyfluoroalkyl-2,3-dihydro-1,3,4-thiadiazoles via regioselective [3+2] cycloaddition of nitrile imines to polyfluoroalkanethioamides

[3+2] Cycloaddition reactions of polyfluoroalkanethioamides with nitrile imines, generated in situ by dehydrochlorination of the corresponding hydrazonoyl chlorides, in the presence of triethylamine, were studied. A new method was proposed on the basis of these reactions for the synthesis of 2-polyfluoroalkyl-2,3-dihydro-1,3,4-thiadiazoles.