Efficient synthesis of Hsp90 inhibitor dimers as potential antitumor agents

The PU-H58-dimers 13a-15b were efficiently synthesized and their biological properties were evaluated. The copper-catalyzed alkyne azide coupling was effective in simultaneously linking three components via a triazole formation to afford the target dimers. These synthesized dimers exhibited binding affinity to the N-terminal domain of Hsp90, cytotoxicity, and client degradation activity although these activities were comparative or weak comparable with that of the parent compound.