Pd-Catalyzed Heteroannulation Route to Polycyclic Indoles

Significance

An intramolecular palladium-catalyzed pathway to polycyclic indoles, starting from easily accessible, alkyne-tethered chloroanilides, is disclosed. A one-pot, two C-C-bond-forming process involving oxidative addition and an unusual (proposed) syn amidopalladation affords the indole derivatives in moderate to good yields. Several structural variations as shown lead to polycyclic indole skeleta with, however, deficiency in indole benzene moiety substituents. As in all sequential transition-metal-catalyzed processes of this nature, the analysis of rate aspects would be interesting and may be rewarding.