A convenient synthesis of a series of thiosemicarbazide, 1,3,4-oxadiazole, 1,3,4-thiadiazole, thiazole, 1,2,4-triazole, pyrazole and dioxoisoindoline derivatives incorporating 1,2,4-triazolo[4,3-a]pyrimidine via the reaction of the readily accessible 1,5-dihydro-5-oxo-1.7-diphenyl-1,2.4-triazolo[4,3-a]pyrimidine-3-carbohydrazide (2) with the appropriate reagents is described. The newly synthesized compounds were found to possess antihypertensive and diuretic activities compared to captopril and furosemide as reference controls, respectively.