Asymmetric Gold-Redox Catalysis in Cyclobutanol Ring Expansion toward the Formation of Quaternary Carbon Chiral Center with Hemilabile P,N-Ligand

Investigations of cyclobutanol ring expansion under gold redox catalysis were conducted as a new approach to the stereoselective synthesis of quaternary carbon centers under mild conditions. The chiral hemilabile P,N-ligand Ad-ChetPhos was identified as the optimal system, affording cyclopentanones in moderate to good yields (up to 90%, >30 cases tested) and enantioselectivities of up to 78% ee. This study not only introduces a new method for the asymmetric synthesis of quaternary carbon centers but also demonstrates the feasibility of asymmetric gold redox catalysis under modified basic conditions, providing valuable mechanistic insights for future developments along this pathway.