Condensation of 1, 3-dicarbonyl compounds with 5-aminopyrazole (III) and its 3-carboxylic ester (X) was examined and several kinds of 5, 7-disubstituted pyrazolo [1, 5-a]-pyrimidines were obtained. It was observed by the infrared spectrum that the hydroxyl group at 5- and 7-positions of pyrazolo [1, 5-a] pyrimidine ring shows the lactam form in the neutral medium
