Benzo-Fused Phosphepines: Synthesis by Gold(I)-Catalyzed Intramolecular Hydroarylation and Ring Inversion.

Gold(I)-catalyzed intramolecular hydroarylation of dialkynyl(biaryl)phosphine oxides provided versatile benzo-fused phosphepine oxides. O-exo adducts were obtained as the major product, and O-endo adducts were the minor product. O-exo and O-endo indicate the position of an oxygen atom with respect to the central phosphepine framework.