Synthesis of Annulated Arenes and Heteroarenes by Hydriodic Acid and Red Phosphorus Mediated Reductive Cyclization of 2-(Hetero)aroylbenzoic Acids or 3-(Hetero)arylphthalides

Annulated arenes and hetarenes were prepared in good to very good yields by hydriodic acid/red phosphorus mediated reductive cyclization of 3-(hetero)aryl phthalides. The reductive cyclization also proceeded successfully with 2-aroylbenzoic acids and 2-aroylnaphthoic acids.