Indium(III)-Catalyzed\nSynthesis of Pyrroles and Benzo[<i>g</i>]indoles by Intramolecular\nCyclization of Homopropargyl\nAzides

Pyrroles, privileged\nstructural motifs in drug and material science,\nhave been synthesized by indium(III)-catalyzed intramolecular cyclization\nof homopropargyl azides. This methodology exhibits a broad substrate\nscope, providing substituted pyrroles and bispyrroles in good yields.\nFurthermore, an atom-economical sequential method for the synthesis\nof benzo[<i>g</i>]indoles has been discovered from azido-diynes\nusing InCl<sub>3</sub> as catalyst. The method involves two successive\nintramolecular indium-catalyzed 5<i>-endo-dig</i> alkyne\nhydroamination and a hydroarylation reactions with 6<i>-endo-dig</i> regioselectivity.