Synthesis of anhydro-3-mercapto-5-pyrazinyl-1,2,4-triazolium hydroxides

The synthesis of some novel anhydro-3-mercapto-5-pyrazinyl-1,2,4-triazolium hydroxides 5 is described. The appropriate 1-methylhydrazides 3 were condensed with isothiocyanates to give the thiosemicarbazides 4 which were cyclized to 5 under mildly basic conditions. A few 1,2,4-triazole-3-thiones 8 were synthesized for comparison, starting with the 2-methylhydrazides 6 and then carrying out analogous synthetic transformations.