A New Synthesis of Pyrazolo[1,5-<i>c</i>]pyrimidines from Acetylenic β-Diketones

Abstract

Abstract 5-Aryl-2-phenylpyrazolo[1,5-c]pyrimidine-7(6H)-thiones have been synthesized by the reaction of 1,5-diaryl-4-pentyne-1,3-diones with thiosemicarbazide and their reactions were studied. The pyrazolopyrimidinethiones give with certain electrophiles the respective 3-substituted 7-thiones. Their oxidation affords the corresponding disulfide. Moreover, they can be converted to the corresponding pyrazolopyrimidinones on reaction with alkaline hydrogen peroxide. The structure of the above compounds was confirmed from their spectral characteristics.