Unexpected transformations of 3-bromo-5,7-dimethylpyrazolo[1,5-a]pyrimidine in reactions with BunLi

The possibility of generating a carbanion using the reaction of 3-bromo-5,7-dimethylpyrazolo[1,5- a ]pyrimidine with Bu n Li followed by the electrophilic addition was investigated. The obtained results provide evidence for the presence of several reaction centers in the substrate, resulting in the formation of unexpected reaction products. These results offer new prospects for the functionalization of pyrazolo[1,5- a ]pyrimidines and allow the preparation of new pharmacologically active derivatives of this series. The structures and purity of all the synthesized compounds were confirmed by 1 H and 13 C NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray crystallography.