Phase‐Transfer‐Catalyzed Interrupted Barton–Zard Reaction Between Electron‐Deficient Indoles and Benzophenone‐Derived Isocyanides

A cascade reaction enabling the construction of pyrrolo3,4‐ b indole core from electron‐deficient and benzophenone‐derived isocyanide precursors under phase‐transfer conditions is described. This transformation proceeds in the presence of a quaternary ammonium catalyst and cesium carbonate, affording functionalized polycyclic cores. The reaction follows the interrupted Barton–Zard reaction pathway and tolerates a broad range of 3‐nitroindole and isocyanide substrates. Performed control experiments provide insight into the generally moderate product yields and clarify why the reaction is not amenable to asymmetric induction.