Chromatography-Free Entry to Substituted Salicylonitriles: Mitsunobu-Triggered Domino Reactions of Salicylaldoximes

A mild and efficient one-pot procedure is described to transform salicylaldoximes into salicylonitriles using Mitsunobu chemistry. The reactions proceed through the corresponding 1,2-benzisoxazoles that undergo the Kemp elimination in situ to generate the target salicylonitriles in excellent yields. The chemistry exhibits a broad scope, and the salicylonitriles can be readily isolated by a simple acid–base workup. In addition to functioning as useful synthetic precursors, salicylonitriles may serve as more cell penetrable bioisosteres of carboxylic acids

Amphipathic α‑Helix Mimetics Based on a 1,2-Diphenylacetylene Scaffold

In order to mimic amphipathic α-helices, a novel scaffold based on a 1,2-diphenylacetylene was designed. NMR and computational modeling confirmed that an intramolecular hydrogen bond favors conformations of the 1,2-diphenylacetylene that allow for accurate mimicry of the <i>i</i>, <i>i</i> + 7 and <i>i</i> + 2, <i>i</i> + 5 side chains found on opposing faces of an α-helix

Perturbation of the c‑Myc–Max Protein–Protein Interaction via Synthetic α‑Helix Mimetics

The rational design of inhibitors of the bHLH-ZIP oncoprotein c-Myc is hampered by a lack of structure in its monomeric state. We describe herein the design of novel, low-molecular-weight, synthetic α-helix mimetics that recognize helical c-Myc in its transcriptionally active coiled-coil structure in association with its obligate bHLH-ZIP partner Max. These compounds perturb the heterodimer’s binding to its canonical E-box DNA sequence without causing protein–protein dissociation, heralding a new mechanistic class of “direct” c-Myc inhibitors. In addition to electrophoretic mobility shift assays, this model was corroborated by further biophysical methods, including NMR spectroscopy and surface plasmon resonance. Several compounds demonstrated a 2-fold or greater selectivity for c-Myc–Max heterodimers over Max–Max homodimers with IC₅₀ values as low as 5.6 μM. Finally, these compounds inhibited the proliferation of c-Myc-expressing cell lines in a concentration-dependent manner that correlated with the loss of expression of a c-Myc-dependent reporter plasmid despite the fact that c-Myc–Max heterodimers remained intact