Tertiary Amino Group in Cationic Gold Catalyst: Tethered Frustrated Lewis Pairs That Enable Ligand-Controlled Regiodivergent and Stereoselective Isomerizations of Propargylic Esters

The development of novel ligands specifically tailored for homogeneous gold catalysis is essential for a new generation of gold catalysis. In this work, we report the development of remotely functionalized biphenyl-2-ylphosphine ligands based on strategic positioning in cationic gold catalysts of frustrated Lewis pairs (FLP), that is, basic tertiary amine moieties and the acidic gold center. By rationally tuning the location and size of the basic group, these Lewis pairs exhibit little or modest quenching and importantly enable regiodivergent and stereoselective isomerizations of propargylic esters into synthetically versatile dienyl esters under exceptionally mild conditions. Notably, the implementation of the concept of FLP in gold catalysis is rare.