Synthesis of Fused Indoles by Sequential Heck Reaction and N-Heteroannulation

A new synthetic route to 3,4-fused indoles by two Pd-catalyzed reactions - intramolecular Heck and reductive N-heteroannulation - is reported. Indoles with various ring sizes (6-8) anchored to the 3- and 4- position of the indole nucleus may be prepared by this method. A number of functional groups (e.g., Me, Ph, Ac, CO2Me) tolerate the conditions of this route. Both hetero­atom (N, O) containing and carbocyclic rings may be anellated to the indole moiety with acceptable yields.