Potent piperazine hydroxyethylamine HIV protease inhibitors containing novel P3 ligands

The 2-isopropyl thiazolyl group is a highly optimized P₃ ligand for C₂ symmetry-based HIV protease inhibitors, as exemplified in the drug ritonavir. Here we report that incorporation of this P₃ ligand into a piperazine hydroxyethylamine series also yielded novel, highly potent inhibitors. In tissue culture assays, the presence of human serum was less deleterious to the activity of these inhibitors than to that of ritonavir. Furthermore, potent activity against ritonavir resistant HIV was observed.