Synthesis of new v-triazolopyrimidinium salts

New v-triazolo1,5-α]- and v-triazolo1,5-c]pyrimidinium salts 12a-e, 13a-c have been synthesized via oxidation (i.e. cyclodehydrogenation) of the appropriate pyrimidyl ketone arylhydrazones 3a-e, 6a-c using TBB (2,4,4,6-tetrabromocyclohexa-2,5-dien-1-one) as the reagent. The arylhydrazones were obtained by standard reactions; the Grignard reaction of 2-cyano- and 4-cyanopyrimidine 1a,b, 4a-c gave 2-pyrimidyl- and 4-pyrimidyl ketones 2a-e, 5a-c , which reacted with arylhydrazines to yield the desired ketone arylhydrazones 3a-e, 6a-c.