Some Reactions of Pyrazolo (1,5-C) Pyrimidinethiones

Bromination and iodination of the 2,5-diaryl-6H-pyrazolo [1,5-c] pyrimidine-7-thiones gave mono-and/or dihalogenation products, whereas nitration yielded only monosubstitution derivatives. However, with benzenediazonium chloride in the presence of sodium hydroxide afforded the respective monophenylazo disulfides. Acetylation, benzoylation and benzylation of 5-p-chlorophenyl-2-phenyl-6H-pyrazolo [1,5-c] pyrimidine-7-thione furnished the N-substituted derivatives. The pyrazolopyrimidinones were obtained by reaction with alkaline hydrogen peroxide.