Aluminum-Catalyzed Cross Selective C3-N1 ' Coupling Reactions of N-Methoxyindoles with Indoles

C3-N1 ' bond formation of bisindoles has been a great challenge due to the intrinsic reactivity of indoles as both C3 and N1-nucleophilic character. Herein, we demonstrate an C3-N1 ' cross-coupling reaction of indoles using N-methoxyindoles as N-electrophilic indole reagents in the presence of Lewis acid. The bisindoles generated in this transformation are latent C3-nucleophile, allowing them to be used as strategic intermediates in sequential C3-N1 '-C3 '-N1 '' triindole formations. The potential synthetic usefulness of this sequential transformation was highlighted upon application to the construction of C3-N1 looped polyindoles.