Formal [3 + 3] Cycloaddition of Indol-2-yl Carbinol with Azadiene and the Oxidative Ring Expansion Reaction for the Synthesis of Indole Azepinones.

An unprecedented [3 + 3] annulation of indol-2-yl carbinol (I) with azadiene (II) that allows for rapid construction of 6,5,6,6-tetracyclic indoles bearing two quaternary carbon centers is described.