Synthesis and evaluation of anti-HIV-1 and anti-HSV-1 activities of 4H-[1,2,4]-triazolo[1,5-a]pyrimidin-5-one derivatives

In a one pot procedure, 18 compounds of 7-(substituted phenyl)-2-substituted-6,7-dihydro-4H-[1,2,4] triazolo [1,5-a] pyrimidin-5-one derivatives (16-33) have been synthesized. 3(5)-Amino-5(3)-substituted-1,2,4-triazole derivatives (7-12) were used as synthones which were cyclocondensed by fusion with substituted methyl cinnamate esters (13-15) to afford the target compounds (16-33). In an effort to develop new non-nucleoside antiviral agents, compounds 16-33 were evaluated for their anti-HIV-1 and anti-HSV-1 activities. Complete inhibition of the proliferation of HIV-1 viruses was achieved by compounds 22, 23 and 24 at concentrations of 25, 25 and 50 μg/ml, respectively. 7-Phenyl-2-(n-pentyl)-6,7-dihydro-4H-[1,2,4]triazolo[1,5-a]pyrimidin-5-one (19) exhibited potential activity against HSV-I with 88% reduction in the viral plaques. The suggested marked specificity of this class of compounds as anti-HIV-1 and HSV-1 agents is discussed.