In this work, 5-amino-1H-pyrazole-4-ethyl-carboxylate is synthesized by treating ethyl cyanoacetate and hydrazine hydrate in presence of different nano-metal oxide catalysts under solvent free microwave conditions. The yield quantity of the synthesized compounds varies for specific catalysts. 6-Bromopyrazolo-[1,5-a]-pyrimidine-3-ethyl-carboxylate was synthesized by reaction of 5-amino-1H-pyrazole-4-ethyl-carboxylate with 2-bromo-malonaldehyde using different bases. The rates of reactions were found to be influenced on the strength of bases. The synthesized compounds were confirmed by FT-IR, 1H NMR and LC-MS spectra. The compound 6-bromo-pyrazolo[1,5-a]pyrimidine-3-ethyl-carboxylate was then tested for in vitro biological activity as CDKs inhibitor. It showed better IC50 values for CDK4 and CDK6 than roscovitine. Thus, the synthesized compound is a selective inhibitor or acceptor for abnormal cancer cell line (CDKs).