New glycosylhydrazinyl-pyrazolo[1,5-c]pyrimidines were synthesized by the reaction of respective 5-aryl-7-hydrazino-2-phenylpyrazolo[1,5-c]pyrimidines (1a-d) with glucose, galactose, and xylose in ethanol. Their glycopyranosyl structures were reasoned to be in chair conformations and each have hydrazine moiety in the β-configuration. Also, pyrazolo[1,5-c]triazolo[4,3-a]pyrimidines derivatives were synthesized by the reaction of 1a-d with benzoic acid in the presence of phosphorousoxy chloride or by the reaction with benzaldehyde derivatives followed by cyclization in the presence of bromine. All structures of the compounds were confirmed from their IR, 1 H, 13 C, DPET-135°, 1 H- 1 H COSY, 1 H- 13 C HMQC, 13 C- 1 H HMBC spectra and microanalysis. The synthesized compounds showed inhibition of proliferation of MCF-7 human breast cancer cells with IC 50 values ranging from 0.56 to 8.86 µg/ml. Some of the most active compounds showed acceptable predicted pharmacokinetics and drug-likeness properties. [Figure not available: see fulltext.]. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.