Octacycles and Nonacycles from 3-Hydroxy-2,2'-bisindole.

3-Hydroxy-2,2'-bisindole undergoes acid- and base-mediated dimerization-skeletal rearrangement processes, generating polyheterocyclic ring systems containing up to nine rings. The mechanistic rationale for these reactions is provided, which infers some overlap with the previously reported reactivity of 3',3″-dihydroxytetraindole under analogous reaction conditions.