Small molecule antagonists of protein–protein interactions represent a particular challenge for pharmaceutical discovery. One approach to finding molecules that can disrupt these interactions is to seek mimics of common protein structure motifs. We present an analysis of how molecules based on the 1,4-benzodiazepine-2,5-dione scaffold serve to mimic the side-chains presented by the hydrophobic face of two turns of an α-helix derived from the tumor suppressor protein p53, and thus antagonize the HDM2-p53 protein–protein binding interaction.