Regioselective Synthesis of 5-(Trifluoromethyl)[1,2,4]triazolo[1,5-a]pyrimidines from β-Enamino Diketones

The use of β-enamino diketones as an easy entry to the regioselective synthesis of [1,2,4]triazolo[1,5- a ]pyrimidines is reported. These ketones reacted with 3-amino-1 H -1,2,4-triazoles to furnish exclusively 6-substituted 5-(trifluoromethyl)[1,2,4]triazolo[1,5- a ]pyrimidines in yields of up to 95%. The regioselectivity of the reactions performed was maintained regardless of the substituent in the starting ketone or aminoazole.