Cascade Assembly of Bridged N‑Substituted Azaozonides: The Counterintuitive Role of Nitrogen Source Nucleophilicity

Counterintuitively,
the low basicity of the NH2 group
in hydrazides makes them preferred nucleophiles for the synthesis
of the N-substituted azaozonides in acid-catalyzed three-component
condensation with 1,5-diketones and H2O2. In
the case of more basic N sources, e.g., hydrazine and primary amines,
such condensation does not occur under these reaction conditions.
The method can be applied to a wide range of hydrazides and affords
the target bicyclic azaozonides in 27–86% yields.