Transition-Metal-Free Intramolecular Carbene Aromatic Substitution/Büchner Reaction: Synthesis of Fluorenes and [6,5,7]Benzo-fused Rings

Intramolecular aromatic substitution and Büchner reaction have been established as powerful methods for the construction of polycyclic compounds. These reactions are traditionally catalyzed by RhII catalysts with α‐diazocarbonyl compounds as the substrates. Herein a transition‐metal‐free intramolecular aromatic substitution/Büchner reaction is presented. These reactions use readily available N‐tosylhydrazones as the diazo compound precursors and show wide substrate scope. Transition‐metal‐free: The synthesis of fluorenes and [6,5,7]benzo‐fused rings is achieved through a transition‐metal‐free protocol of intramolecular aromatic substitution and Büchner reaction. The new synthetic method uses readily available aromatic N‐tosylhydrazones as the diazo compound precursors and shows wide substrate scope.