Creation of molecular complexities via a new Cu-catalyzed cascade reaction: a direct access to novel 2,2'-spirobiindole derivatives.

A Cu-mediated unprecedented cascade reaction in the presence of air afforded a conceptually new synthesis of 2,2'-spirobiindole derivatives. This reaction proceeds via the rearrangement of several bonds in a cyclopenta[b]indole framework including a facial selective intramolecular ring closure. The potential of this method is highlighted in the straightforward and single step synthesis of a paullone like compound.