Oxadiazolone-Based Aromatic Annulations: A Nitrenoid Precursor for Tricyclic Aminoheterocycles

Nitrogen-containing heterocycles are present in most approved drugs, reflecting the significance of their synthetic strategies. By utilizing oxadiazolone as a nitrenoid (nitrene-like) precursor, we have developed a general strategy for the annulation with nucleophilic heterocycles to access various polycyclic aminoheterocycles. We have discovered that 2-pyrryl-substituted substrates undergo a rearrangement, which indicates a spirocyclization–migration pathway. Given their fluorescence and biological activity as kinase hinge binders, these fragment-like aminoheterocycles represent potential starting points for applications in chemical biology and drug discovery.