“Angular” Spirocyclic Azetidines: Synthesis, Characterization, and Evaluation in Drug Discovery

The previously neglected “angular” spirocyclic azetidines have been synthesized, characterized, and validated in drug discovery. We have shown that these compounds could act as bioisosteres for common saturated six‐membered heterocycles. Their incorporation into the structure of the anticancer drug Sonidegib (instead of morpholine), and Danofloxacine (instead of piperazine) provided novel patent‐free analogs with similar physicochemical properties and high activity.