Construction of Polycyclic Indole Derivatives via Multiple Aryne Reactions with Azaheptafulvenes.

An efficient [8 + 2]/aryl-ene tandem reaction between azaheptafulvenes and arynes has been developed, leading to the formation of cyclohepta[b]indoles in a single step with good yield. In addition, employment of excess arynes provides a [8 + 2]/aryl-ene /[6 + 2] tandem reaction to synthesize polycyclic oxacyclohepta[b]indoles. This is the first time that azaheptafulvenes have been employed in tandem reactions with arynes.