Abstract Thiation of N-(1-tert-butyl-3-methylpyrazol-5-yl) carboxamides 2 with the Lawesson reagent afforded the corresponding thiocarboxamides 3. Heating of 3 in formic acid gave the N-dealkylated thiocarboxamides 4 which were cyclized into 4H-pyrazolo [1, 5-c][1, 3, 5] thiadiazine-4-thiones 5 by treatment with thiophosgene.
