Synthesis and evaluation of a novel class Hsp90 inhibitors containing 1-phenylpiperazine scaffold

Previously, we identified 1-(2-(4-bromophenoxy)ethoxy)-3-(4-(2-methoxyphenyl)piperazin-1-yl)propan-2-ol (1) as a novel Hsp90 inhibitor with moderate activity through virtual screening. In this study, we report the optimization process of 1. A series of analogues containing the 1-phenylpiperazine core scaffold were synthesized and evaluated. The structure-activity relationships (SAR) for these compounds was also discussed for further molecular design. This effort afforded the most active inhibitor 13f with improved activity in not only target-based level, but also cell-based level compared with the original hit 1.