Origin of Ligand Effects on Stereoinversion in Pd-Catalyzed Synthesis of Tetrasubstituted Olefins

The mechanism and origin of ligand effects on stereoinversion of Pd-catalyzed synthesis of tetrasubstituted olefins were investigated using DFT calculations and the approach of energy decomposition analysis (EDA). The results reveal that the stereoselectivity-determining steps are different when employing different phosphine ligands. This is mainly due to the steric properties of ligands. With the bulkier Xantphos ligand, the syn/anti-to-Pd 1,2-migrations determine the stereoselectivity. While using the less hindered P(o-tol)(3) ligand, the 1,3-migration is the stereoselectivity-determining step. The EDA results demonstrate that Pauli repulsion and polarization are the dominant factors for controlling the stereochemistry in 1,2- and 1,3-migrations, respectively. The origins of differences of Pauli repulsion and polarization between the two stereoselective transition states are further identified.

Automated summary

DFT calculations and EDA were used to investigate the mechanism and origin of ligand effects on stereoinversion in Pd-catalyzed synthesis of tetrasubstituted olefins. It was found that the steric properties of the ligands lead to different stereoselectivity-determining steps, with Pauli repulsion and polarization playing dominant roles in controlling stereochemistry in 1,2- and 1,3-migrations, respectively. Differences in Pauli repulsion and polarization between the two stereoselective transition states were further identified.