Indium(III)-Catalyzed Synthesis of Pyrroles and Benzo[]indoles by Intramolecular Cyclization of Homopropargyl Azides.

Pyrroles, privileged structural motifs in drug and material science, have been synthesized by indium(III)-catalyzed intramolecular cyclization of homopropargyl azides. This methodology exhibits a broad substrate scope, providing substituted pyrroles and bispyrroles in good yields. Furthermore, an atom-economical sequential method for the synthesis of benzo[]indoles has been discovered from azido-diynes using InCl as catalyst. The method involves two successive intramolecular indium-catalyzed 5 alkyne hydroamination and a hydroarylation reactions with 6 regioselectivity.