An efficient and environmental benign regioselectivesynthesis of some new pyrazol-1′-ylpyrazolo[1,5-a]pyrimidines (7b–h) has been accomplished via treatment of 3(5)-amino-5(3)-hydrazinopyrazole dihydrochloride (5) with several unsymmetrical 1,3-diketones (6b–h) using water as a solvent without any catalysts or additives. The structure of 7b–h was established on the basis of rigorous analysis of 1H