Ethyl 5-amino-3-trifluoromethyl-1H-pyrazole-4-carboxylate (1) was efficiently synthesized via the condensation of ethyl cyanoacetate and trifluoroacetic anhydride, followed by chloridization and the condensation with aqueous hydrazine. Its unique reactivity was exploited for the synthesis of trifluoromethylated pyrazolo [1, 5-a] pyrimidine (5) and pyrazolo [5, 1-d][1, 2, 3, 5] tetrazine-4 (3H)-ones (8a–j). Among them, 5 was firstly found to be a ...
