Utility of Ligand Effect in Homogenous Gold Catalysis: Enabling Regiodivergent π-Bond-Activated Cyclization

Comprehensive utilization of both electronic and steric properties of ligands in homogeneous gold catalysis is achieved in the regiodivergent intramolecular hydroarylation of alkynes. A flexible electron-deficient phosphite ligand, combined with the readily transformable directing group methoxyl amide, is attached to a cationic Au(I) center in three-coordinate mode, affording sterically hindered ortho-position cyclization. Meanwhile, para-position cyclization is exclusively achieved with the assistance of a rigid electron-abundant phosphine ligand-based Au(I) catalyst, in which ligands manifest the compensating effect for cyclization through steric hindrance and electronic properties. By combining gold with silver catalysts, tetrahydropyrroloquinolinones possessing a congested tricyclic structure are obtained via a proven Au/Ag relay catalytic process.