Trifluoroacetic acid → 5-Methyl-7-phenyl-2-(trifluoromethyl)-1,2,4-triazolo[1,5-a]pyrimidine

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Reaction Steps

By the procedure reported by V. A. Lopyrev Zh. Obshch. Khim. 53 p. 1684, 1983 (Chemical Abstracts 139865y, 1983) a crude sample of 3-amino-5-trifluoromethyl-1,2,4-triazole was prepared by the cyclocondensation of aminoguanidine bicarbonate with trifluoroacetic acid in refluxing toluene. This material was used effectively without further purification in subsequent ring condensation reactions. To 30 ml. of glacial acetic acid stirring, 3.0 g (19.7 mmol) of 3-amino-5-trifluoromethyl-1,2,4-triazole and 3.5 g (21.6 mmol) of benzoylacetone were added and the mixture heated at reflux for 3 h. A solution soon formed after heating. The solvent was evaporated in vacuo and excess water added to the residue followed by extraction with 200 ml of ethyl acetate. The extract was washed with water, saturated sodium bicarbonate, brine, dried over magnesium sulfate and evaporated in vacuo to give an oily residue. Silica gel column chromatography (methylene chloride) afforded 3.09 g of the title compound which was present as the major component, m.p. 106°-108° C.

Provenance & Evidence