A Synthesis of Multifunctionalized Indoles from [3 + 2] Annulation of 2-Bromocyclopropenes with Anilines.

A new regioselective method for the synthesis of multifunctionalized indoles from [3 + 2] annulation of 2-bromocyclopropenes with anilines has been developed. By employing a nickel complex as a catalyst, 27 examples of indole products were obtained in good yields with excellent regioselectivity. Synthetic utility of the resulting product was demonstrated in a concise synthesis of biologically active compound Paullone.