Synthesis of certain new 2,4,5(6) trisubstituted-1,2,4-triazolo[1,5-alpha]pyrimidines as potential antihypertensive agents.

: A series of 1,2,4-triazolol[1,5-alpha]pyrimidines bearing at position 2, morpholine, piperidine or piperazine moities has been prepared. In addition, ethyl 4-methyl-2-(4-acylpiperazin-1-yl)-1,2,4-triazolo[1, 5-alpha]pyrimidin-7(4H)-one-6-carboxylates 25,26, which have related structure with prazosin, have been synthesized. Ten representative compounds were tested in vitro and in vivo for their antihypertensive activity where compounds 7, 11 and 25 showed promising activity. The detailed synthesis, spectroscopic and biological data are reported.