The researches in the medicinal chemistry are remarkable due to its essential role for human life. Pyrazolo-pyrimidines show a vast contribution towards drug chemistry by acting as an antagonist to several diseases of man. This work reported the synthesis of 6-bromo-pyrazolo-[1,5-a]-pyrimidine-3-ethylcarboxylate (5) by changing bases for succesive trials under microwave conditions from 5-ammino-1H-pyrazole-4carboxylate (3) [1-5]. Reaction time for a strong base like KOH completed at the least time. This inference emerged a new trend for the study of chemical kinetics of organic synthesis. In this article, quantitative synthetic studies of 5-amino-1H-pyrazole-4-carboxylate (3) using different nano metaloxide catalysts is reported [6]. α-Fe 3 O 4 afforded highest yield among four different catalysts used. The compound 5 was screened for the biological activity as CDKs inhibitor with the reference compound roscovitine [7]. It proved as a better potent inhibitor for CDK4 & CDK6 (IC 50) than roscovitine. EXPERIMENTAL All the chemicals including nano-catalysts used were purchased from Sigma-Aldrich (AR) and Merck. Melting points were determined in open capillary tubes in Buchi B-540 melting point apparatus and are uncorrected. The reaction was monitored by thin layer chromatography using silica gel