Synthesis of Benzo-fused Heterocycles by Intramolecular α-Arylation of Ketone Enolate Anions

A two-step synthesis of six-, seven-, eight-, and nine-member benzo-fused heterocycles in good to excellent yields is reported. The synthetic strategy involves the generation of a new intramolecular a-aryl ketone bond by the photostimulated S(RN)1 reaction of ketone enolate anions linked to a pendant haloarene as the key step. On the other hand, an intramolecular C-Ar-C-Ar coupling led to the formation of five- and six-member benzo-fused heterocycles (9H-carbazole and phenanthridine) when an aromatic amide anion is competitively formed.